Summary Kind I collagen has at all times aroused nice curiosity within the area of life-science and bioengineering, because of its favorable structural properties and bioactivity. Because of this, within the final 5 many years it has been broadly studied and employed as biomaterial for the manufacture of implantable medical gadgets. Generally used sources of collagen are represented by bovine and swine however their functions are restricted due to the zoonosis transmission dangers, the immune response and the spiritual constrains. Thus, type-I collagen remoted from horse tendon has not too long ago gained rising curiosity as a sexy various, in order that, though bovine and porcine derived collagens nonetheless stay the most typical ones, increasingly corporations began to convey to market a numerous vary of equine collagen-based merchandise. On this context, this work goals to overview the properties of equine collagen making it significantly interesting in medication, cosmetics and prescribed drugs, in addition to its foremost biomedical functions and the at the moment accredited equine collagen-based medical gadgets, specializing in experimental research and medical trials of the final 15 years. To the perfect of our information, that is the primary assessment specializing in the usage of equine collagen, in addition to on equine collagen-based marketed merchandise for healthcare. Key phrases: sort I collagen, equine, biomaterials, medical gadgets
1. Introduction Collagen is the physique’s cement that retains every thing in place [1]. With its 28-members household it’s an important protein of vertebrates’ connective tissues that accounts for the 30% of the entire physique protein content material [2]. Amongst collagens, fibril-forming sort I subspecies is probably the most plentiful because it accounts for the 70% of the entire household [3,4,5]. The construction of sort I collagen, distributed on the degree of all tissues within the organism, is thought from 1938 [6,7,8]. It consists in three right-handed polyproline-II helices of about 1000 amino acids (referred to as α strand) that by imply of interchain hydrogen bonds are held collectively in a left-handed triple helix [9]. As it’s already recognized, every α strand is characterised by the repetition of the Gly-X-Y triplet, the place the “X” and “Y” positions are normally occupied by proline and hydroxyproline [10]. On this neat sequence, glycine performs a key function within the three α strand packing [11], whereas proline and hydroxyproline cowl a elementary function in stabilizing the triple helical construction by stopping helices free rotation, because of the presence of pyrrolidine rings which scale back the diploma of freedom of the polypeptide chain [12,13]. Furthermore, the post-translational hydroxylation of the 11%–14% of proline residues by the enzyme proxyl-4-hydroxylase (PH4) (EC 1.14.11.2) is a course of that offers to collagen a singular attribute attributable solely to sort I collagen, essential each for its recognition and quantification [14]. Collagen covers a vital structural function for the upkeep of tissues’ structure and form and it dictates specialised regulatory features, particularly throughout growth and restore [15,16,17]. Thus, collagen shouldn’t be solely accountable of tensile power and elasticity [16] but additionally of the integrity preservation of pores and skin, connective tissues, tendons and bones by mediating a elementary inter- and intracellular signaling. The repetition of the Gly-X-Y sequence is certainly elementary for collagen to correctly carry out its operate and, to this, it stays virtually unchanged throughout the course of evolution of the animal kingdom [18]. To this, mutations within the collagen COL1A1 gene, have been related to greater than 400 human illness [19]. Due to the essential function in cell signaling, the collagen triple helical molecule is characterised by the presence of a excessive variety of integrin binding websites (i.e., the “GxOGER” sequence, the place “G” is glycine, “O” is hydroxyproline, “E” is glutamate, “R” is arginine and “x” is a hydrophobic amino acid) elementary for cells adhesion and interplay [20,21]. Due to this fact, non-structural features of collagen are of nice relevance for cell communication, proliferation, differentiation in addition to for therapeutic processes [4,22,23]. The prevalence of collagen in human tissues and the essential roles lined within the extracellular matrix (ECM), make it a pure alternative for its employment as uncooked materials [10]. Being the primary part of the ECM, collagen is intrinsically biodegradable, biocompatible and bioactive [15,24,25,26,27]. Its abundance and ubiquity make it not perceived as exogenous constituent of the physique [10]. As befits the first structural protein within the physique, collagen is of course proof against proteolysis however prone to assault of matrix metalloproteinase (MMPs) (i.e., MMP-1, MMP-2, MMP- 8, MMP-13 and MMP-14) [25,28,29]. The collagen fragments ensuing from the motion of collagenases, are additional degraded by gelatinases and non-specific proteases. The presence of an correct and sophisticated degradation system for the endogenous collagen makes the exogenous collagen extremely biodegradable [25]. Furthermore, collagen and its degradation merchandise may additionally promote the tissue’ construction and performance restoration [30]. Lastly, collagen may be simply processed to manufacture a number of sorts of substrates like sponges, hydrogels, tubes, powders and movies in keeping with the ultimate software [31]. All these engaging and advantageous options of sort I collagen make it some of the broadly used biomaterial in health-related sectors, together with medical care, pharmaceutics and cosmetics [32,33,34,35,36,37]. Extra particularly recognized is its employment as biomaterial for the manufacture of Tissue Engineering Medical Merchandise (TEMPs) for tissues therapeutic and regeneration. Moved by the nice benefits in its use, numerous vertebrates have been extensively employed to isolate sort I collagen. Despite a number of makes an attempt of extraction from completely different animal species, the perfect collagen sources are represented by mammals, akin to bovine and swine, for the excessive sequence homology with human collagen [19]. Nevertheless, the incidence of immune responses, the chance of zoonosis transmission and a few spiritual considerations restricted their use and favored horses use as a safer collagen supply. Thus, the equine tissues seem as a sexy various, since they’re virtually free from zoonosis [38] and there are not any documented immune reactions [39]. This assessment will particularly take care of scientific analysis carried on equine tendon collagen. Herein, the benefits and downsides in horse tendon use as extraction supply are mentioned together with its favorable organic properties and associated functions. Accordingly, the final 15 years experimental research and medical trials on equine tendon collagen-based and accredited gadgets for medical use are argued. To the perfect of our information, that is the primary assessment that take care of solely on horse tendon collagen-based merchandise.
2. Why Equine Collagen Kind I collagen’s use as biomaterial for the manufacture of merchandise associated to the healthcare sector, the meals industries and cosmetics could be very excessive. The commercial manufacturing of collagen relies on its purification from animal tissues relatively than from recombinant manufacturing methods [40]. The lack to breed the full-length collagen molecule with the native post-translational modifications (i.e., hydroxylation) decreased the curiosity in the usage of each prokaryotic and eukaryotic hosts (i.e., yeast, micro organism, mammalian cells, bugs or vegetation) for its synthesis [41]. As regards collagen extraction from animal tissues, a number of sources have been investigated [36], together with mammals (bovine [42], porcine [43], ovine [44], equine [45,46], rat [47]), avian (hen [48]) and fish (jellyfish, fish, sponges) [49], with the intention of discovering the optimum one when it comes to biocompatibility, security and availability. The extremely out there marine collagen, that has a decrease menace of transmissible ailments and no spiritual considerations, is proscribed in its use within the healthcare sector due to its low denaturation temperature and enzymatic resistance [49]. On the opposite aspect, though the evolutionary closeness to vertebrates, poultry collagen molecule has an amino acid composition completely different from different mammals [50]. Furthermore, the avian influenza transmission danger shouldn’t be a negligible facet [51]. Undoubtedly, mammals signify the perfect supply for the excessive sequence homology with human collagen ( ) [19,52,53,54]. Furthermore, the abundancy of waste supplies (e.g., pores and skin, tendons, bones, fatty tissues) from meat processing favored the exploitation of low-cost by-products for the purification a biomaterial with a excessive added worth. The usage of waste merchandise for the extraction of a extremely required product, akin to collagen, not solely makes discards precious useful resource but additionally reduces their disposal prices and environmental influence. Nevertheless, solely within the final 50 years the usage of heterologous collagen as medical product unfold with the event of each correct extraction processes that allowed eradicating allergenics and efficient sterilization procedures [55]. Open in a separate window Kind I collagen might be remoted from a number of physique districts. Amongst these, mammal pores and skin and tendons are most well-liked because of the excessive protein yield [24,56]. As regards tendons, roughly 60%–85% of the dry weight is collagen [24,56] and sort I collagen constitutes 90%–95% of the entire collagen content material [48,57,58]. To this, the bottom quantity of protein contaminants is current on this district [59]. In any other case, collagen content material in mammalian dermal tissue is about 60%–70% and contains many different parts akin to blood vessels, lymph vessels, hair follicles and sweat glands [25,43], for which an correct purification step is required. The extraction supply not solely influences the yield and purity of the ultimate product but additionally its physical-chemical properties because the collagen construction and traits are deeply affected by the operate it has within the belonging tissue [60]. The construction of tendon is such that the collagen fibers are aligned in the primary load bearing course and fiber diameter is bigger than in pores and skin [61,62]. The diameter and the orientation of fibers play an essential function in tissue stability: a larger orientation of the fibers displays the next molecules compaction, leading to a larger chemical-physical stability. Herein, collagen molecules have been sometimes aligned and full of a conserved stagger of 67 nm to kind fibers with a medium diameter of 400 nm [46,59,63]. In pores and skin as an alternative, even when collagen is anisotropically distributed (alongside Langer’s traces) it’s organized in a unfastened community [60,64]. Apart from, the collagen extracted from a tissue with a strict hierarchical group, akin to tendon, nonetheless retains a partial lateral packing association regardless of the disruptive remedies of the extraction course of [60,63,65]. The partial retention of the lateral association of collagen molecules may be ascribed to the well-known greater share of lysine and hydroxylysine within the α-helices of tendon collagen than in different tissues. These amino acids, elementary for the intra- and intermolecular crosslinks, make tendon an extraction supply of a sort I collagen with superior properties over collagens derived from different tissues [56]. Thus, the very best sort I collagen content material and the bottom quantity of protein contaminants on this physique district [59], in addition to the interesting physical-chemical properties, make mammalian tendon as a sexy supply for medical grade collagen. Furthermore, mammalian tendons might be simply harvested from slaughterhouses with out interfering with the meat harvesting course of [56], whereas mammalian skins must be appropriately separated from meat and hair. Amongst mammals, bovine and swine are the most typical extraction sources. The explanation lies in the truth that these two species are the very best consumed mammalian meats per capita in the USA [31,66]. Nevertheless, though bovine and porcine collagens cowl many of the market measurement and tendon recuperate is simple, their use is proscribed due to immune response, zoonosis issues and spiritual constraints. Regardless of collagen is especially poor immunogen [67] and the triple helical domains of bovine and porcine collagens are extremely homologous to human collagen, immunologically related variations lay within the telopeptide areas [68]. Bovine collagen triggers immune reactions in in regards to the 2%–4% of the World inhabitants [69]. Nevertheless, this sensitivity has been thought of usually acceptable for tissue engineered implants for human use [70]. Moreover, the truth that as much as 3% of the inhabitants manifests an inherent immunity [67,71], is sufficient to routinely carry out allergy testing previous to materials implantation [70]. To this, two consecutive unfavorable pores and skin checks at 6 and a couple of weeks are required earlier than any remedy [72]. Amongst points, the zoonosis transferring danger (e.g., the foot and mouth illness (FMD) and the group of the bovine spongiform encephalopathies (BSE), amongst which probably the most harmful for people is the transmissible spongiform encephalopathy (TSE)) is probably the most severe. Porcine collagen causes much less allergic response [36] however, identical to the bovine supply, the setback of zoonosis restricted its use [73]. As well as, there are cultural or spiritual considerations related to the usage of porcine (Jewish, Islamic religion) and bovine (Sikh, Buddhism) collagen, which additional prohibit their applicative potential [34]. The ovine, a mammal of curiosity as dietary supply of milk and meat, has no spiritual constrains however has the disadvantage of being prone to a particular sort of transmissible spongiform encephalopathy, specifically scrapie. Nevertheless, such a prion is thought to not trigger any ailments because the human-like variant Creutzfeldt–Jakob illness (vCJD), which is attributable to BSE publicity to people [74]. The one exploitable ovine supply is the Australian one that’s the sole illness and prion free on this planet [75]. Holista Colltech, with a patent manufacturing course of for ovine collagen, has the exclusivity to supply a zoonosis-free ovine collagen and doesn’t have the sufficient means (when it comes to uncooked supplies disposability) to maintain the World’s excessive demand of collagen-based merchandise [75]. Rat tail tendon is likely one of the mostly used supply of sort I collagen amongst researchers (in distinction to the commercial use), given the intensive quantity of literature regarding isolation and characterization [40]. Nevertheless, it’s not used for the manufacture of medical merchandise due to the unavailability of medical-grade sort I collagen. Conversely, horse-derived collagen is mostly acknowledged as virtually free from zoonosis transmission dangers [38], with no reported immune reactions [39,57,76,77]. Nevertheless, equine meat and thus equine collagen-based merchandise are religiously not accepted by Jews and Muslims. Though it’s not well-known, equids are additionally uncovered to alphaviral equine encephalomyelitis (AEE), a mosquito-borne zoonotic an infection that features: (i) Jap equine encephalomyelitis (EEE), (ii) Western equine encephalomyelitis (WEE) and (iii) Venezuelan equine encephalomyelitis (VEE) [78]. The AEE endemic life cycle entails completely different mosquito species (i.e., Psorophora, Ochlerotatus, Coquillettidia, Ochlerotatus, Aedes and Culex) and mammalian hosts (i.e., birds, rodents) to be unfold to horses and different animals that are dead-end hosts [79]. Often AEE can spill over to contain people as dead-end hosts. Particularly VEE typically causes huge epizootics in horses and epidemics in human, whereas for EEE and WEE particular person instances or restricted outbreaks in each horses and people have been registered [78]. Some AEE instances have been reported prior to now however lately, solely few instances yearly occurred and no epidemics have by no means been reported. Nevertheless, needs to be famous that many instances might go unreported and undiagnosed since AEE infections normally are asymptomatic and encephalitis happens in lower than 4% of symptomatic instances [79]. Furthermore, mortality charges of symptomatic instances are fairly low (1%–7% for VEE and WEE, 50%–70% for EEE) [78,79]. Though the zoonosis transmission danger shouldn’t be negligible, the incidence of few encephalitis instances and the very low AEE-due mortality fee result in the consideration of equine by-products as zoonosis-free extraction sources for medical-grade collagen. However, in comparison with collagen from different mammals, equine collagen is characterised by the very best homology sequence with human collagen, after bovine (Supplementary Determine S1). The excessive share of sequence alignment is because of the taxonomical closeness of equines and bovines to people ( ). The low evolutionary hole and the excessive conservation of sort I collagen amino acid composition amongst vertebrates make that homology as much as 95%. Thus, equine collagen, that in comparison with bovine is equally much like human collagen from a compositional viewpoint, appears to be a legitimate various to bovine collagen. Furthermore, as earlier than talked about, collagen extracted from a tissue with a strict hierarchical group, akin to tendon, is characterised by the next share of lysine and hydroxylysine than different tissues. Curiously, collagen from equine tendon revealed to have the very best lysine and hydroxylysine degree in comparison with these extracted from different mammal tendons ( ). The peculiar amino acid composition of equine tendon collagen and the associated stronger fibers packing is the rationale why gadgets manufactured with native horse tendon collagen are intrinsically extra proof against degradation and mechanical stress [63]. As reported by Angele et al., equine tendon collagen in comparison with bovine tendon collagen was discovered to have the next thermal stability and an inclination to rupture below greater mechanical resistance [45]. Desk 1 Amino Acids Equine [45] Bovine [45] Ovine [74] Rat [80] Human [52] Alanine 120 124 113 105 114 Arginine 56 61 63 55 53 Aspartate 50 53 48 35 45 Cysteine 0 0 0 1 0 Glycine 219 222 317 332 334 Glutamate 97 97 76 68 78 Histidine 11 7 0 5 6 Hydroxy lysine 13 10 0 12 9 Hydroxy proline 104 103 94 91 86 Isoleucine 13 15 11 12 10 Leucine 32 30 28 27 25 Lysine 26 21 30 27 24 Methionine 4 2 10 7 6 Phenylalanine 19 18 14 11 14 Proline 142 147 117 121 120 Serine 39 35 35 39 34 Threonine 22 20 18 21 17 Tryptophan 0 0 0 0 0 Tyrosine 5 2 4 3 4 Valine 28 27 23 26 26 Imino acid 246 250 211 212 205 TOT. 1000 1000 1000 1000 1000 Open in a separate window The partial preservation of fibers packing [63,81], is a key facet as a result of it influences not solely bioengineering parameters but additionally the cell-biomaterial interplay because the nanometric fibril group is acknowledged by cells as information for cell progress and migration throughout the transforming section of the therapeutic course of [26,27,60,82]. By the way in which, it needs to be famous how regardless of collagen extraction protocols are arrange so as to protect its native construction as potential, the applying of mechanical, chemical and enzymatical remedies brings to a partial de-structuration of the strict hierarchical group of collagen fibrils. Particularly, the enzymatic remedy cuts collagen molecules on the N− and C− termini, modifying their native state and making them extra prone to enzymatic digestion and thermal denaturation. Thus, whereas sort I collagen fibrils are frequently packed in tendon, the remoted ones are characterised by smaller diameter and size and thus by decrease mechanical properties. Furthermore, it shouldn’t be uncared for that collagen extraction sources are animal tissues and numerous elements, akin to animals age, intercourse and inter-species variability, make collagen chemical and bodily properties not punctual however inside a variety of values. Thus, the structural group of the native tissue shouldn’t be fully preserved within the extracted product. About this subject, some makes an attempt have been made so as to in vitro reorganize collagen fibrils (i.e., fibrillogenesis) in fibers that might resemble the pure tendon ones. Though a partial alignment might be obtained, to this point it’s not potential to fully reassemble the extracted tendon collagen fibrils in vitro, within the ordered hierarchical group naturally current in tendon. However, the strict hierarchical group of equine tendon, in comparison with different horse tissues and tissues kind different mammals, permits to raised retain collagen native construction after the extraction course of and the next processing [60]. Nevertheless, needs to be famous how, to the perfect of our information, few information have been reported in regards to the comparability of equine tendon collagen properties with collagen from tendon of different animals with the identical extraction technique and substrate synthesis protocol utilized. Furthermore, the patent-due confidentiality of the collagen isolation protocols hinders such comparability since processing variations strongly affect the ultimate merchandise properties. Though the dearth of exhaustive, quite a few and public supporting information, the benefits supplied by way of equine collagen as biomaterial are seen from its employment by a number of well-known Corporations (as argued in Part 4). Undoubtedly, the horse tendon with its structural fascinating options and the liberty from the afore-mentioned source-related points can be thought of as a legitimate and various extraction web site of medical grade sort I collagen.
3. Equine By-Merchandise Accessibility As beforehand argued, collagen is normally extracted from meat processing waste by-product. By comparability to different meat producing species akin to porcine, poultry, bovines or ovine, horse meat manufacturing represents solely 0.25% of the entire worldwide meat manufacturing [83,84]. The low consumption of horse meat is because of cultural, financial and social causes that strongly influence on consuming habits. Historically, horses have been employed over time as farm staff, companions for recreations or sporting causes. This historic affiliation and the associated constructive feelings generated, akin to affection, closeness or tenderness, led to the adoption of horses as a pet in lots of cultures and thus to the rejection of equines as a supply of meat for human consumption [83,84]. Further constraints are imposed by the Islamic and Jewish faith for which horse meat is forbidden (haram). On the similar time, equids meat can also be the middle of the controversial problems with the economically-motivated improper adulteration of meals. The horsemeat scandal in 2013 negatively affected the picture of equine meat and led to a boycott of horsemeat-based merchandise by some customers, leading to a discount in gross sales of processed meat [84,85]. Other than cultural, social and spiritual limitations, horse meat varieties a big a part of the culinary traditions of many international locations, significantly in Europe, South America and Asia for which giant quantities of horse meat, akin to a mean of 750,000 tons of meat for 12 months, are consumed. The latest reconsideration of equines as an industrial meat supply is correlated with the BSE unfold. Thus, though meat manufacturing from horse continues to be decrease than that registered for different species, FAO information reported a crescent horse slaughtering (about 5,045,488 of slaughtered horses in 2018) with a proportional improve in horse meat consumption that reached a price of about 800,000 tons in 2018 ( ). Open in a separate window Horse meat consumption shouldn’t be solely affected by cultural, social and spiritual elements but additionally by robust laws. Horse meat and its by-products may be thought of as reputable meals components or merchandise for human consumption provided that acceptable actions are taken akin to veterinary inspections and slaughter in accredited and licensed slaughterhouses [84]. Ought to be famous that not all equines might be slaughtered for the manufacturing of meat for human consumption. Horses that aren’t bred for meals (i.e., equids for sport competitors) which can be frequently administered with medication or different chemical substances are forbidden. Furthermore, horses which were euthanized by imply of deadly intravenous injections of medication (i.e., sodium pentobarbital) couldn’t be used for meat manufacturing. The potential hazard of consuming meat contaminated with such chemical substances continues to be fully unknown. To this, the EU, the FDA and the USDA prohibit the presence of many on a regular basis equine medication akin to antibiotics, anesthetics, anti-inflammatories, de-wormers in meat for human consumption. In addition to horse meat, additionally by-products comply with the identical regulation and restrictions. Horses tendons chosen for the extraction of fibrillar sort I collagen meant for use as uncooked materials for the event of biomedical merchandise or meals dietary supplements for human use, don’t derive from animals which were euthanized by imply of a deadly injection or sport horses to whom medication or different substances have been administered. Every by-product batch is due to this fact subjected to strict inspections and it’s equipped with official conformity certificates. The presence of solely licensed drug-free meat and by-products for human consumption enable to have a enough availability of waste materials eligible for collagen extraction. Furthermore, the latest increment in horse meat consumption straight will increase the supply of by-products. Though horse meat traditionally got here from previous animals used for farm-working, these days it’s usually equipped by younger animals bred for this function [83]. The request of a sure the diploma of tenderness is certainly a big age-related facet of meat high quality. This pattern is in accordance with the needing of younger horses for the extraction of collagen from tendon. Particularly, equids of 18–48 month have been most well-liked. The maturation of equine tendon collagen fibrils throughout the progress strongly impacts on collagen options akin to solubility and reactivity and thus considerably influences the ultimate product properties. The rise of intramolecular and intermolecular cross bonds with age make collagen fibrils much more insoluble [86] and consequently much less reactive because of the discount of accessible reactive teams. The robust fiber packing makes collagen fibrils much less prone to the enzymatic proteolytic assault and to acid or alkaline remedies, elementary extraction course of steps. Thus, the age-related maturation of collagen makes extraction from tendons of previous equids harder and with a decrease yield than that one achievable from younger people. To this, tendons of younger animals are most well-liked and normally chosen for this function.
4. At the moment Authorised Equine Collagen-Primarily based Gadgets The usage of xenogeneic collagen as a contemporary biomaterial started in 1881 when Joseph Lister and his former scholar William Macewen independently reported on the British Medical Journal some great benefits of a biodegradable suture termed “catgut” derived from the small gut of a sheep [87]. From that second on, the thought of exploiting xenogeneic materials for human surgical practices unfold to the scientific neighborhood. The excessive conserved compositional similarity amongst mammals is a robust level that might be exploited to succeed in a greater natural-like tissue therapeutic [53]. Citations relationship to the Nineteen Forties and Fifties pertains to experimental makes an attempt of purified collagen implantation in animals [88]. Solely 30 years later, the primary medical use of collagen in people was reported by Knapp with an injectable collagen gel formulation for tender tissues augmentation [89]. In 1980, one of many first mammal collagen formulations (i.e., Zyderm® by McGhan Medical Company, Fremont, CA, USA) began to be commercialized [90]. Over the following years, numerous collagen-based formulations have been manufactured with the intention to revive or restore tender and exhausting tissues physiological operate [91,92]. The historical past of implantable collagen-based merchandise tell us in regards to the excessive curiosity that turns round it. Due to this fact, it has at all times been a goal not solely to isolate collagen from animal tissues but additionally to acquire a secure xenogeneic product, which meets regulatory necessities and which may be implanted with out triggering undesirable reactions. For example, medical gadgets to be commercialized ought to meet the important necessities outlined within the Annex I of the Council Directive 93/42/EEC (which goes to get replaced by the Medical Gadget Regulation (MDR) 2017/745 in Could 2020) [93]. The manufacturing technique of a tool, together with all features going from the uncooked supplies to the supply of the ultimate product, needs to be absolutely validated to make sure reproducibility and security for human use. Among the many numerous features, the accredited for human use merchandise should above all be free from allergens or poisonous compounds that might set off immune response. Even when collagen is usually low immunogenic, different ECM proteins (i.e., DNA, RNA, cells remnants, α-gal epitope and MHC-1) are capable of evoke immune response, adversarial reactions and rejections [70,94]. Since immunogenicity is the first explanation for immunotoxicity, the immunogenicity analysis is a important however important facet for collagen merchandise. A not-negligible facet is the fabric contamination by bacterial endotoxins (i.e., lipopolysaccharides), which can be parts of the exterior cell membrane of Gram-negative micro organism capable of stimulate the inflammatory response at very low doses (0.5 EU/mL) [95,96]. One more reason why collagen merchandise may evoke adversarial results is the crosslinking, particularly chemical crosslinking. Bodily crosslinking because the dehydrothermal remedy (DHT) as an alternative is safer and biocompatible [97,98]. Throughout resorption, chemical crosslinking seemingly impacts MMPs bioactivity towards native collagen, producing an imbalance in ECM turnover [70]. The delayed resorption and the substrate inertness to degradation prolongs implant presence within the tissue, exacerbating host responses to the implant. Moreover, not-natural collagen degradation fragments, bearing remnants of added artificial chemical crosslinkers, are acknowledged as antigens and amplify the overseas physique response [99,100]. That’s the reason virtually all business merchandise are usually not chemically crosslinked. Gadgets sterilization is the final key course of to precisely set previous to the merchandise packaging. Collagen is a temperature delicate biomaterial that might not be autoclaved. For this, various sterilization processes have been investigated however till immediately the perfect method has not been recognized. Any recognized sterilization method induces molecular alteration to collagen triple helical construction with a consequent lower of properties such because the mechanical and the enzymatical resistance [101]. Nevertheless, some strategies are extra permissive than others. Ethylene oxide sterilization and β-ray irradiation induce much less harm than γ-ray however their applicability will depend on the kind of collagen-based machine to be produced [91,101]. The preservation of the native collagen construction as a lot as potential among the many complete manufacturing course of is most well-liked because it accelerates the regeneration stage, shorts the wound therapeutic time, reduces the extent of bacterial contamination, alleviates the ache syndrome and reduces the recurrence fee [102]. So far, quite a few preparations based mostly on equine tendon collagen acquired the approval of the US Meals and Drug Administration (FDA) for human use and are commercially and clinically out there. From 1990 onwards, the date at which the primary machine was registered based mostly on horse tendon collagen for wound therapeutic (Condress® now referred to as Biopad® by Euroresearch), corporations like Baxter, Bioteck, Euroresearch, Finceramica, Fidia Farmaceutici, Innocoll Prescription drugs, MLM Biologics, Nycomed, Opocrin, Resorba, Savecoll, Takeda, Vebas manufactured and commercialized gadgets based mostly on equine tendon collagen with a number of patented methods ( ). Desk 2 Firm Product Components Type Software Ref. B. & B. Dental
(Bologna, Italy) T-Barrier – Sheet Hemostasis, Arduous tissue [103] Baxter
(Rome, Italy) Gentafleece Gentamicin sulphate Sponge Hemostasis, Wound therapeutic [104,105,106] TissuFoil E – Sheet Wound therapeutic [107,108] TissuDura – Sheet Wound therapeutic [109,110,111,112,113,114] TissueFleece – Sponge Hemostasis [115,116,117] Zimmer Biomet
(Warsaw, USA) Septocoll Gentamicin sulphate Sponge Hemostasis [118] Bioteck
(Vicenza, Italy) Biocollagen – Membrane Arduous tissues [119,120,121] Bio-gen Spongy bone Powder Arduous tissues [122] MeRG Glycosaminoglycans Membrane Mushy tissues [123,124] Xenomatrix – Sheet Mushy tissues [125,126] Euroresearch
(Milano, Italy) Biopad – Sponge Wound therapeutic, Arduous tissues [26,127,128] Bioart – Powder Arduous tissues – Nithya – Gel Mushy tissues, Anti-aging [39] Revamil Honey Sponge Wound therapeutic – Versuspray Silver Powder Wound therapeutic – EUSA Pharma
(Langhorne, USA) Collatamp Gentamicin sulphate Sponge Wound therapeutic [129,130] Finceramica
(Faenza, Italy) MaioRegen Hydroxyapatite Membrane Mushy tissue [131,132,133,134] Fidia Farmaceutici
(Bologna, Italy) Bionect pad Hyaluronic acid Sponge Wound therapeutic [135] Innocoll
(Athlone, Eire) Collexa Bovine collagen Sponge Wound therapeutic [136] MLM Biologics
(Gainesville, USA) Bio-conneKt – Membrane Wound therapeutic [136] Nycomed
(Munich, Germany) TachoTop – Sponge Hemostasis, Wound therapeutic [137,138] TachoComb Human fibrinogen and bovine thrombin Sponge Hemostasis, Wound therapeutic [139,140,141,142,143] TachoSil Human fibrinogen and human thrombin Sponge Hemostasis, Wound therapeutic [143,144,145,146,147,148,149,150,151,152] Opocrin
(Modena, Italy) Antema – Sheet Hemostasis, Wound therapeutic [57,153] Resorba Medical GmbH (Nürnberg, Germany) Genta-coll Gentamicin sulphate Sponge Hemostasis, Arduous tissues [154,155,156] Kollagen – Sponge Hemostasis, Arduous tissues [82,157,158,159,160,161,162,163,164,165,166] Parasorb – Membrane Hemostasis, Arduous tissues [77,167,168] Salvecoll
(Como, Italy) Salvecoll-E – Gel Wound therapeutic [100] Takeda
(Tokyo, Japan) CollGARA – Sponge Hemostasis, Wound therapeutic [169] GABA Vebas
(Roma, Italy) Paroguide Chondroitin sulphate Membrane Wound therapeutic [170] Open in a separate window Because of its intrinsic biocompatibility [26,27] and regenerative properties, equine tendon collagen-based gadgets have been manufactured and utilized in relation to a wide range of medical functions ( ) akin to in reconstructive surgical procedure to hurry up wounds closure, to regenerate burned pores and skin and tender tissues in addition to to information bone and cartilage restore. Between the listed ones, the use as hemostat is likely one of the most essential software. Open in a separate window 4.1. Hemostatic System Efficient hemostatic methods for traumatic or surgical lesions of sentimental tissues akin to viscera, liver [143,146,147,171], coronary heart [106,145,151,155], lymphatic system [150], kidney [144,148], post-cesarean uterus [149], blood vessels [139,142], have at all times been of nice significance. Throughout surgical interventions on parenchymatous organs, hemorrhages are exhausting to regulate. Other than completely different surgical measures to cease such bleedings (compression, ligation, suturing, clipping argon beam coagulation, electrocautery), a quite common technique consists in the usage of topical brokers with excessive hemostasis energy (collagen-based sealants, cellulose fleece, cotton gauze, artificial glues, fibrin sealants) [145]. Amongst these, promising outcomes got by collagen-based pads that demonstrated to have the ability to promote coagulation inside couple of minutes after the applying (3–5 min) [143,171] by naturally favoring platelets recall by chemotaxis in addition to their adhesion and aggregation. The contact of platelets with collagen begin a response cascade which ends up in platelets aggregation to kind a clot that successfully reduces bleeding [82]. It’s value noting that the cascade of occasions may be induced by native collagen relatively than its denatured kind [82,171], explanation why all hemostatic business merchandise (TissueFleece®, Biocollagen®, Tachotop®, Antema®, CollGARA®, Kollagen®, Parasorb®) take care in sustaining the nativeness and thus the pure binding websites of collagen throughout the manufacturing course of. The intrinsic adhesiveness of collagen demonstrates its efficacy within the remedy of wounds not solely by selling good hemostasis but additionally by favoring repairing processes [171]. This “secondary” property of collagen is essential to lower the likelihood to have surgical web site infections. Publish-operative problems typically require further surgical procedure in addition to a considerably longer hospitalization, rising medical care prices and sufferers’ morbidity and mortality charges [155]. On this surroundings, an equine tendon collagen sponge enriched with the antibiotic gentamicin (i.e., Genta-coll®, Gentafleece®, Septocoll®, Collatamp®) considerably reduces post-surgical infections and associated morbidities whereas performing its foremost hemostatic operate [106,118,129,130,155]. The efficacy of some horse tendon collagen-based merchandise for hemostasis was upgraded by the addition of coagulation elements akin to thrombin and fibrinogen (TachoSil®, TachoComb®) so as to be superior to the usual hemostatic suturing, argon beamer coagulation and standard hemostatic supplies [139,140,142,144,145,146,147,150,151]. Upon the contact with physique fluid the clotting elements of fibrinogen and thrombin dissolve and kind a fibrin community, which glues the equine tendon collagen sponge to the wound floor [142,150]. The applying of an equine tendon collagen sponge enriched with fibrin/thrombin decreases each post-operative problems, blood transfusion and, consequently, hospital keep and addressed medical prices [146]. Other than hemostasis, equine tendon collagen-based substrates (TissuFoil®, CollGARA®) have been efficiently evaluated additionally as protecting barrier between the polypropylene mesh implant and stomach organs with the intention to separate the adjoining tissues and organs within the areas of the stomach cavity [107,169]. 4.2. Therapeutic of Wounds Initially developed to behave as a barrier towards a dangerous exterior setting [127], equine tendon collagen formulations (e.g., sponge, foil, membrane) revealed to be appropriate as tissues non permanent substitutes. Collagen, with its potential to soak up and retain a considerable amount of fluids, offers for a moist setting that promotes wound therapeutic [77,172]. Numerous biochemical, histological and immuno-histochemical investigations revealed how a number of pro-regenerative actions are mediated by collagen (proteases inhibition, vascularization promotion, fibroblast progress) [173,174]. Native collagen interplay with platelets ends in the formation of a clot that gives a matrix for the inflow of inflammatory cells and within the secretion of progress elements just like the platelet-derived progress issue (PDGF), the reworking progress factor-beta (TGF-β) and the endothelial progress issue (EGF) [40]. Whereas the PDGF along with proinflammatory cytokines contributes to draw neutrophils for bacterial elimination, the TGF-β contributes to transform monocytes into macrophages, which provoke the event of granulation tissue and launch numerous proinflammatory cytokines (e.g., interleukins 1 and 6 (IL-1, IL-6)) [40]. TGF-β and PDGF play a key function within the conversion of fibroblasts into myofibroblasts, which generate contraction forces that facilitate the wound closure [40]. The formation of the granulation tissue is of elementary significance for the synthesis, deposition and group of a brand new collagen-rich ECM. An in vivo research on epithelial cells derived from dermal microvessels demonstrated how sort I collagen prompts angiogenesis, a elementary course of to succeed in an excellent degree of tissue regeneration [102]. The absence of blood vessels is certainly the primary explanation for regeneration processes failure since no cytokines, progress issue, cells and vitamins may attain the injured web site. One other essential function of native collagen, particularly when coping with power wounds, is its potential to inhibit proteases and cytokines (neutrophil elastase, MMP-2, IL-6, IL-8, IL-1, superoxide-anion, peroxynitrate) by imply of its excessive binding capability for them [102,175]. Persistent wounds comprise elevated ranges of pro-inflammatory cytokines like IL-1β and TNF-α, elevated launch of reactive oxygen species (ROS) by neutrophils and elevated expression of proteases that result in extreme tissue harm and impairs wound-healing [175]. Therefore, the discount of the extent of MMP and IL in wounds mattress is prime to keep away from the breakdown of progress elements and different brokers that stimulate native fibroblasts to supply the granulation tissue, a key step in wound therapeutic [136,172]. Normally, collagen dressings are manufactured primarily from the tendon of horses (Biopad®, Bionect®, Collexa®, Revamil®, Bio-ConneKt®) and bovine, in addition to from the pores and skin of bovine and pigs [174]. Nevertheless, the selection of the collagen origin influences the wound dressing efficiency. Collagen of assorted origin displays a unique binding capability for IL-1β and TNF-α and elastase. As regards TNF-α, bovine collagen exhibited the perfect binding capability in vitro, adopted by equine and porcine collagen that confirmed a comparable capability [172]. Within the case of IL-1β, the binding affinity of bovine collagen is adopted by the considered one of equine and lastly of porcine collagen [172]. Elastase ranges as an alternative are likewise lowered by bovine and equine collagen [175]. Though bovine collagen appears to have the perfect in vitro response, equine collagen-based wound dressing formulations exhibit the perfect structural compromise when in comparison with analogues gadgets manufactured from bovine or porcine collagen. A comparative research of Karr et al., demonstrated equine tendon collagen pad to be the one product that retains the identical total construction throughout publicity to collagenases and on the similar time to permit the collagen interlaced matrix to be clearly frayed off [127]. The upkeep of the structural integrity for an extended interval could also be a key situation for a greater therapeutic course of by imply of an extended native collagen-wound interplay. Within the comparability between business merchandise, the truth that collagen-based merchandise are usually not all the identical couldn’t be neglected. Recognized is how variations in composition and diploma of preservation of the pure collagen matrix strongly affect the ultimate product medical effectiveness [102]. Extra not too long ago, an equine tendon collagen injectable gel (Salvecoll®) was proposed for the post-surgical remedy of fistulas with the intention to eradicate sepsis, mechanically fill the defect and promote therapeutic by offering a transition matrix [100]. The invasion of the collagen gel by fibroblasts from the encompassing tissues stimulates the immune system and thus the discharge of progress elements elementary for tissue therapeutic [100]. Regardless of the variations in attenuating the power inflammatory response and in favoring therapeutic, all mammal-derived collagens personal such intrinsic properties that aren’t achievable by some other materials [174]. Conventional dressings (paraffine gauze, cotton pad, rayon/cellulose sandwich) have very excessive absorption capability however they trigger speedy dehydration. Their each day elimination from the wound floor may cause bleeding and harm of the newly fashioned epithelium [90,174]. As well as, some of the vital downside encountered in conventional dressing is the overseas physique response within the wound attributable to cotton fibers [90]. Collagen-based dressings as an alternative don’t must be eliminated and may be left on the wound for as much as seven days [174]. Distinctive is the therapeutic time within the case of diabetic foot and heel ulcers that with an equine tendon collagen sponge happens in roughly 31 days [176]. Even when collagen wound dressings are rather more costly than conventional gauze and pad, a quicker therapeutic course of is obtained in addition to much less frequent dressing change [174]. The preliminary greater expenditure is due to this fact mitigated by the quicker and higher sufferers’ restoration. Superior and nonetheless experimental approaches for the remedy of wounds have been supplied by tissue engineering overture. A number of analysis teams reported research on equine tendon collagen merchandise meant for use as service for cells [109,117,161], medication [162] or genes [138], with the intention to bettering injured tissues’ regeneration and physiological features restoration. Few cell populations akin to adipose stem cells [117], adipose tissue stromal cells [161] and fetal pores and skin cells [109], have been investigated. As regards burns, the mixed use of a organic bandage and autologous cells helps within the total pores and skin restore and tender tissue reconstruction. For this, adipose stem cells remoted from affected person’s tissues have been built-in inside an equine tendon collagen scaffold to supply a greater cell supply system to the burned web site. Research of Krahenbuhl et al. demonstrated how adipose stem cells already combine into the matrix at 24 h and, after 48 h, strongly adhere and migrate throughout the scaffold [117]. An identical method was adopted by Hohlfeld et al., that handled pediatric burns with equine tendon collagen sheets seeded with fetal pores and skin cells [109]. The highly effective proliferation and migration potential of fetal pores and skin cells led to a high-quality pores and skin restoration simply after two-week remedy with out the addition of fixative (i.e., glue, staples, stitches, silicones) and anesthesia [109]. A greater wound closure was obtained in comparison with the standard autograft technique that not solely wants extra therapeutic time (three weeks) however typically entails the formation of an hypertrophic granulation tissue [109]. With the intention to enhance equine tendon collagen-based scaffolding properties in wound therapeutic by avoiding extreme scar formation, an try was finished by embedding medication. Garrier et al. pre-clinically evaluated the influence of a photodynamic liposomal formulation (Foslip® by biolitec analysis GmbH, Jena, Germany)) embedded in an equine tendon collagen scaffold on therapeutic processes with promising outcomes [162]. 4.3. Mushy Tissues Regeneration Much less and nonetheless experimental are therapeutic makes an attempt of human tender tissues akin to tendon [58,177,178,179], peripheral nerve [105,115] and adipose tissue [161]. However, clinically accredited are equine tendon collagen gadgets for dura mater [111,112,113,114] and cartilage [123,124,131,132,133,134,141,180,181,182,183,184] restore. Tendon problems are answerable for marked incapacity that strongly impacts on affected person high quality of life. Regardless of a excessive variety of makes an attempt, the regeneration of this tissue by imply of a temporal substitute continues to be one of many largest challenges in tissue engineering. Collagen is the primary load-bearing part within the pure ECM by conferring mechanical power required for load-bearing [58]. The lack of mechanical operate in repaired tendon is because of formation of a distorted ECM with misaligned collagen fibers [123]. The usage of equine tendon collagen scaffold by which collagen maintains an aligned construction may supply an opportunity. After assessed scaffolds suitability for human tendon regeneration [153], electrostatically oriented multilamellar equine tendon collagen membranes in vitro confirmed how fiber orientation offers an instructive sample for cell progress and drives cell alignment mimicking that seen in regular tendon [177,178]. Nevertheless, main in direction of a partial tendon therapeutic, this sort of substrate was prompt for human tendon augmentation relatively than a tendon temporal substitute [177]. One of many issues encountered in creating an equine tendon collagen-based machine for tendon regeneration is the low mechanical power in comparison with that of the native. An try to extend the low order magnitude of collagen when it comes to mechanical properties was finished in a pilot in vivo research carried out with a core-shell scaffold manufactured from equine collagen, 1,4-butanediol diglycidyl ether (BDDGE) and elastin [179], with promising outcomes. The restoration of peripheral nerves operate after traumatic accidents is one other problem for tissue engineering. Equine tendon collagen sponge revealed to have the ability to in vivo enhance motor operate and proprioceptive restoration [115]. Nevertheless, regenerating axons didn’t penetrate the scaffolds of their full size and thus didn’t contribute to the numerous enchancment of purposeful restoration. An try to enhance nerve regeneration after end-to-end reconstruction was in vivo carried out by enwrapping an equine tendon collagen scaffold seeded with N1E-115 neural cells across the lesion web site, with out profitable outcomes [105]. Furthermore, equine tendon collagen scaffold may function service of adipose tissue. Though adipose tissue is a much less frequent goal, it’s extremely required in plastic and reconstructive surgical procedure, particularly facial [161]. Apart from its important metabolic features, adipose tissue offers the form and quantity of the outer physique contour and preserves the mobility of tissue layers [161]. The implantation of equine tendon collagen microcarriers charged with adipose tissue stromal cells might be a resolutive technique within the case of adipose tissue lack in congenital problems, in aesthetic surgical procedure and after tumor ablation [161]. Nevertheless, with the intention of biorestructuring the dermis for aesthetic functions, a not too long ago out there cell-free injectable equine tendon collagen formulation (Nithya®) confirmed medical efficacy [39]. The dura mater is a thick membrane that surrounds the mind and spinal wire whose operate is to mechanically shield tissues current under. After cranial, spinal and trans sphenoidal neurosurgical procedures, the proper reconstruction of the dura mater is required. The applying of an equine tendon collagen foil (TissuDura®) with out suturing revealed to be the only option for dura mater reconstruction since no native toxicity or problems (i.e., cerebrospinal fluid leaks, adherences or irritation) have been noticed [113,114]. Furthermore, the complete degradation of the equine tendon collagen matrix and its substitute with native collagen neodura with neoangiogenesis formation was noticed after 12 months [112,114]. In comparison with different dural substitutes, one of many foremost good thing about equine tendon collagen foils is the transparency that permits to examine the operative cavity after implantation and to simply allow an eventual second surgical procedure [113]. Furthermore, equine tendon collagen foils resulted to be simply adaptable, impermeable to exterior brokers and hemostatic [111,112], best options for implantable gadgets. Cartilage is usually uncovered to traumatic, inflammatory or degenerative accidents who led to incapacity and ache. Present methods for the regeneration of cartilage normally contain the usage of hyaluronic acid-based formulations for its viscosupplementation properties and collagen (MeRG®, MaioRegen®) for its pro-regenerative properties [182,185]. The needing of a regenerative assist is because of the truth that the intrinsic therapeutic potential of the broken cartilage is proscribed due to the absence of blood vessels and innervation [180]. The lacking of vascularization stimulation properties is the rationale why many of the merchandise available on the market fail to supply long-term outcomes [183]. However, equine tendon collagen scaffolds in vitro revealed their potential in cartilage regeneration by selling and supporting chondrocytes progress and proliferation [141,180,181,183,184]. Numerous cell populations seeded and cultured on pure sort I collagen, multiplicate and specific chondrocyte cells phenotype (i.e., expression of vimentin, Sox9, Matrilin-1, S100, CD99, aggrecan, collagen sort II), accompanied by the manufacturing of ECM (i.e., immunohistochemical evaluation on collagen sort I, sort II and proteoglycans) [180,181,183]. Greater than chondral, the osteochondral lesions are much more problematic since they contain two completely different tissues. To this, a novel multilayer scaffold manufactured from equine tendon collagen and hydroxyapatite (MaioRegen®) efficiently induced the therapeutic of the chondral and the deep osteochondral defects in animal fashions, in all probability by inducing the selective differentiation of resident progenitor cells [131,132]. Promising ends in vivo have been clinically confirmed by equine tendon collagen-based scaffold implanted in knee defects [123,124,133,134,182], even when many doubts nonetheless exist concerning the power to assist each hyaline cartilage formation and subchondral bone ingrowth [134]. 4.4. Arduous Tissues Regeneration The ECM of mineralized tissues akin to bones and enamel consists of natural (35%) and inorganic (65%) phases, the place the predominant natural protein, sort I collagen, drives the heterogeneous nucleation of hydroxyapatite nanocrystals onto its fibrils, by activation of particular management mechanisms [186]. Arduous tissues’ therapeutic course of is a fancy biochemical process that entails the migration of osteoblasts, the formation of latest blood vessels, the synthesis of collagen and new ECM and the cooperation of a wide range of cytokines. On this surroundings, blood vessels present a conduit for the recruitment of cells concerned bone deposition and are due to this fact a vital situation for tissues regeneration [160]. Osteogenesis and angiogenesis are clearly linked in a robust codependent relation. As regards dental care, equine tendon collagen merchandise successfully scale back bone resorption after enamel elimination and induce bone regeneration with a bone construction much like pure [167]. To this, a excessive variety of equine tendon collagen merchandise (t-Barrier®, Biocollagen®, Xenomatrix®, Bio-gen®, Bioart®, Kollagen®, Parasorb®) are literally clinically used for the remedy of periodontitis [121,126], alveolar ridge preservation after tooth extraction [77,168], edentulism [125], maxillary sinus raise [119], intraoral donor websites regeneration [164], root perforation [163] and radicular cyst [120]. In periodontitis, collagen sheets are efficiently utilized on the bone root to extend the quantity of periodontal connective tissue attachment, with new cementum and new bone formation, so as to lower the pocket depth and restore the gingival recession [121,126]. After tooth extraction, bone resorption is averted by bettering alveolar bone regeneration by imply of an equine tendon collagen sponge that, by the formation on a steady blood clot, offers a pure assist for osteoid differentiation and the next calcification [119,168], in addition to guides epithelial and connective cells essential for the post-extraction soft-tissues therapeutic [125]. The enhancement of the bone power in sockets or bone gaps by collagen could also be as a result of its intrinsic angioconductivity and osteoconductivity [77,119]. The constructive impact on alveolar bone therapeutic derived from the applying of an equine tendon collagen gadgets suggests its routinely use within the socket after enamel extraction [77]. Current research investigated the opportunity of enhancing bone regeneration properties of equine tendon collagen with the addition osteoinductive molecules (akin to progress elements or genes) [160,165] or by mixing with different osteoconductive biomaterials [128]. The mix of an osteoconductive scaffold with osteoinductive protein such because the vascular endothelial develop issue (VEGF) higher stimulates and helps bone therapeutic and regenerating processes [158,160]. Some makes an attempt have been made by combining the bioactive properties of collagen with the osteoconductive properties of the poli-(L-lactic) acid [128] and of the hydroxyapatite [128,186,187], with promising outcomes. Not negligible is the tissue engineering-based method for which adipose tissue-derived stromal cells have been seeded on equine tendon collagen scaffold so as to induce osteogenic differentiation [159]. Even when the replication of the pure mineralized tissues continues to be a problem, these reported research demonstrated the feasibility in creating mechanically steady scaffold with the power to imitate the physical-chemical options of the pure bone.
5. Equine Collagen-Primarily based Gadget Market Within the final 15 years, with the event of regenerative medication and tissue engineering, collagen has been outlined probably the greatest scaffolding supplies, being biocompatible, biodegradable, bioactive in addition to simply manufactured. The outstanding benefits supplied by this extraordinary and archaic pure protein signifies that the demand for collagen and collagen-based merchandise by no means fades, relatively it tends to extend with the rising want of latest efficient and superior therapies [188]. The native collagen market measurement was globally esteemed to be round USD 160.5 Million in 2018 [189]. Among the many a number of software sectors by which collagen market is split, the healthcare is the biggest software space, adopted by meals and beauty. Healthcare dominates the collagen market with about 50% share of the complete market quantity in 2025 [189,190]. Herein, in 2014 it has been esteemed a world addressable market of c. $16 bn on the end-market worth, by counting c. $14 bn for bone graft and superior wound therapeutic, c. $1.2 for regenerative medication scaffold and c. $0.2 bn for in vitro diagnostic [190]. The esteemed market ought to improve over years because the request of collagen for medical gadgets and drug supply methods is increasing along with the pattern in direction of minimally invasive applied sciences and its effectiveness in wound therapeutic. Certainly, as regards tissue engineering merchandise, the esteemed international market of $1.5 bn in 2014 [190], almost doubled to c. $2.4 bn in 2017 with an anticipated compound annual progress fee (CAGR) from 2017 to 2025 of 10.4% [191,192]. To the perfect of our information, even when no particular info on equine tendon collagen market can be found, the curiosity in horse tendon collagen and derivates is clearly seen not solely from the variety of scientific researches but additionally from the variety of patented manufacturing processes on equine tendon collagen and equine tendon collagen-based gadgets for biomedical and beauty software [193]. The long-time seek for higher methods, the superior manufacturing methods used, the in-depth investigations on the properties of the merchandise, the performance checks (in vitro and preclinical testing), the protection assurance and the administration prices gave to the healthcare merchandise a excessive closing price. Basically, no medical grade collagen-based merchandise have been discovered value lower than $10,000 USD/kg [75]. Nevertheless, even when the excessive closing price of all collagen-based merchandise might be limiting, the ratio between prices and advantages needs to be thought of. As afore talked about, tendon collagen-based gadgets are capable of promote pure therapeutic processes quicker and higher than different biomaterials available on the market [174]. Sooner therapeutic is related to a decrease danger of creating post-treatment or post-surgical problems, for which additional remedies or second surgical procedures are wanted. The lower of therapeutic time and problems fee reduces the needing of further remedies, drug therapies and surgical procedures and consequently positively impacts on the affected person’s psycho-physical state. Furthermore, not negligible is the profit in relation to different price drivers akin to hospital inpatient stays and personnel prices.
6. Concluding Remarks Collagen has at all times been employed for a number of causes. In historic instances, its use is recorded as the primary ingredient of glues fashioned from the boiling of animals’ pores and skin, tendons and ligaments. Solely within the nineteenth century the world “collagen,” from the Greek κόλλα (kólla, “glue”) and -γενής (-genés, “-forming”), was coined to designate that constituent of the connective tissues that yields gelatin after boiling [194]. The usage of collagen as a contemporary biomaterial started in 1881 [87] and pre-clinical trials with collagen-based merchandise began across the Nineteen Forties [88]. Nevertheless, research on purified collagen use started within the late Fifties, after the event of collagen dissolution (i.e., solubilization) strategies [92]. From 1959, when Pappas and Hyatt used movie of reconstructed solubilized collagen for wounds therapeutic in mice for the primary time [195], preclinical and medical research on collagen-based gadgets for healthcare by no means stopped and proceed these days. The usage of heterologous collagen as medical product actually unfold within the final 50 years because of the event of each correct extraction processes and efficient sterilization procedures [55]. Advances in purification processes allowed to understand collagen preparations with minimal immunogenicity each with excessive purity ranges. Dilute acetic acid, pepsin digestion, filtration to take away impurities/insoluble matter, salt precipitation and dialysis are essential steps within the manufacturing of excessive purity and low immunogenicity collagen [10]. Accordingly, primarily due to the BSE transmission danger from bovine collagen, the necessity of a xenogeneic product as secure as potential pushed in direction of the identification amongst mammals of horses as the perfect issue-free extraction supply. The absence of immune response is one other not negligible benefit of equine collagen. Apart from, concerning the extraction web site, tendon represents the physique district with the very best content material of sort I collagen and the bottom quantity of contaminants [24,48,57,58,59]. The selection of equine tendon as collagen extraction supply has outstanding benefits not solely when it comes to security but additionally when it comes to chemical-physical and organic properties of the purified uncooked materials. Regardless of the disruptive remedies of the extraction course of, horse tendon collagen retains a partial lateral packing [46,59,60,63,65], because of the upper content material of lysine and hydroxylysine in comparison with different mammal tendon collagens. This characteristic makes collagen and collagen-based gadgets from horse tendon intrinsically extra proof against degradation and mechanical stress [45,63]. Furthermore, the preservation of the native construction and packing influences not solely bioengineering parameters but additionally the fabric bioactivity because the integrity of native cell-binding websites is prime of cell recognition [26,27,60,82]. Certainly, variations within the efficacy of native collagen-based gadgets not solely rely from manufacturing processes but additionally from the proportion of preserved protein construction [62]. Equine tendon collagen gadgets have anti-inflammatory, analgesic and hemostatic results, in addition to the power to hinder the entry of outer microorganisms, to guard the wound, to limit edema and fluid loss, to stimulate angiogenesis, osteogenesis and the migration of fibroblasts. All these options belonging to no different materials make collagen probably the greatest biomaterials for the manufacturing gadgets for biomedical functions. Because of this, many native horse tendon collagen-based gadgets are at the moment efficiently utilized in reconstructive surgical procedure for the remedy of burns, trauma, infectious and surgical wounds. The looks available on the market of equine tendon collagen and equine tendon collagen gadgets suggests how this biomaterial is much more gaining the eye of the scientific neighborhood in all healthcare-related purviews akin to medical, pharmaceutical and beauty sectors.
Supplementary Supplies The next can be found on-line at https://www.mdpi.com/2079-4983/11/4/79/s1, Determine S1: Amino acid sequences alignment of α1 and α2 chains of equine, bovine, suine, ovine, rodent and poultry collagen as compared with human collagen, carried out by imply of Clustal Omega (EMBL-EBI) sequence alignment bioinformatic instrument. Click on right here for extra information file.(210K, pdf)
Writer Contributions Conceptualization, L.S.; methodology, N.G.; software program, N.G.; validation, L.S. and M.L.N.; formal evaluation, M.L.N.; investigation, N.G.; assets, A.S.; information curation, N.G.; writing—Unique draft preparation, N.G. and M.L.N.; writing—Evaluate and enhancing, N.G. and L.S.; visualization, N.G.; supervision, L.S. and A.S.; mission administration, L.S. and A.S.; funding acquisition, L.S. and A.S. All authors have learn and agreed to the printed model of the manuscript.
Funding This analysis acquired no exterior funding.
Conflicts of Curiosity The authors declare no battle of curiosity.