The journey of decellularized vessel: from laboratory to operating room

Over the past few decades, there has been a remarkable advancement in the field of transplantation. But the shortage of donors is still an urgent problem that requires immediate attention. As with xenotransplantation, bioengineered organs are promising solutions to the current shortage situation. And decellularization is a unique technology in organ-bioengineering. However, at present, there is no unified decellularization method for different tissues, and there is no gold-standard for evaluating decellularization efficiency. Meanwhile, recellularization, re-endothelialization and modification are needed to form transplantable organs. With this mind, we can start with decellularization and re-endothelialization or modification of small blood vessels, which would serve to address the shortage of small-diameter vessels while simultaneously gathering the requisite data and inspiration for further recellularization of the whole organ-scale vascular network. In this review, we collect the related experiments of decellularization and post-decellularization approaches of small vessels in recent years. Subsequently, we summarize the experience in relation to the decellularization and post-decellularization combinations, and put forward obstacle we face and possible solutions.

Hydrogel-polyurethane fiber composites with enhanced microarchitectural control for heart valve replacement

Polymeric heart valves offer the potential to overcome the limited durability of tissue based bioprosthetic valves and the need for anticoagulant therapy of mechanical valve replacement options. However, developing a single-phase material with requisite biological properties and target mechanical properties remains a challenge. In this study, a composite heart valve material was developed where an electrospun mesh provides tunable mechanical properties and a hydrogel coating confers an antifouling surface for thromboresistance. Key biological responses were evaluated in comparison to glutaraldehyde-fixed pericardium. Platelet and bacterial attachment were reduced by 38% and 98%, respectively, as compared to pericardium that demonstrated the antifouling nature of the hydrogel coating. There was also a notable reduction (59%) in the calcification of the composite material as compared to pericardium. A custom 3D-printed hydrogel coating setup was developed to make valve composites for device-level hemodynamic testing. Regurgitation fraction (9.6 ± 1.8%) and effective orifice area (1.52 ± 0.34 cm2 ) met ISO 5840-2:2021 requirements. Additionally, the mean pressure gradient was comparable to current clinical bioprosthetic heart valves demonstrating preliminary efficacy. Although the hemodynamic properties are promising, it is anticipated that the random microarchitecture will result in suboptimal strain fields and peak stresses that may accelerate leaflet fatigue and degeneration. Previous computational work has demonstrated that bioinspired fiber microarchitectures can improve strain homogeneity of valve materials toward improving durability. To this end, we developed advanced electrospinning methodologies to achieve polyurethane fiber microarchitectures that mimic or exceed the physiological ranges of alignment, tortuosity, and curvilinearity present in the native valve. Control of fiber alignment from a random fiber orientation at a normalized orientation index (NOI) 14.2 ± 6.9% to highly aligned fibers at a NOI of 85.1 ± 1.4%. was achieved through increasing mandrel rotational velocity. Fiber tortuosity and curvilinearity in the range of native valve features were introduced through a post-spinning annealing process and fiber collection on a conical mandrel geometry, respectively. Overall, these studies demonstrate the potential of hydrogel-polyurethane fiber composite as a heart valve material. Future studies will utilize the developed advanced electrospinning methodologies in combination with model-directed fabrication toward optimizing durability as a function of fiber microarchitecture.

Recent progress in functional modification and crosslinking of bioprosthetic heart valves

Valvular heart disease (VHD), clinically manifested as stenosis and regurgitation of native heart valve, is one of the most prevalent cardiovascular diseases with high mortality. Heart valve replacement surgery has been recognized as golden standard for the treatment of VHD. Owing to the clinical application of transcatheter heart valve replacement technic and the excellent hemodynamic performance of bioprosthetic heart valves (BHVs), implantation of BHVs has been increasing over recent years and gradually became the preferred choice for the treatment of VHD. However, BHVs might fail within 10-15 years due to structural valvular degeneration (SVD), which was greatly associated with drawbacks of glutaraldehyde crosslinked BHVs, including cytotoxicity, calcification, component degradation, mechanical failure, thrombosis and immune response. To prolong the service life of BHVs, much effort has been devoted to overcoming the drawbacks of BHVs and reducing the risk of SVD. In this review, we summarized and analyzed the research and progress on: (i) modification strategies based on glutaraldehyde crosslinked BHVs and (ii) nonglutaraldehyde crosslinking strategies for BHVs.

Hemocompatibility tuning of an innovative glutaraldehyde-free preparation strategy using riboflavin/UV crosslinking and electron irradiation of bovine pericardium for cardiac substitutes

Hemocompatibility tuning was adopted to explore and refine an innovative, GA-free preparation strategy combining decellularization, riboflavin/UV crosslinking, and low-energy electron irradiation (SULEEI) procedure. A SULEEI-protocol was established to avoid GA-dependent deterioration that results in insufficient long-term aortic valve bioprosthesis durability. Final SULEEI-pericardium, intermediate steps and GA-fixed reference pericardium were exposed in vitro to fresh human whole blood to elucidate effects of preparation parameters on coagulation and inflammation activation and tissue histology. The riboflavin/UV crosslinking step showed to be less efficient in inactivating extracellular matrix (ECM) protein activity than the GA fixation, leading to tissue-factor mediated blood clotting. Intensifying the riboflavin/UV crosslinking with elevated riboflavin concentration and dextran caused an enhanced activation of the complement system. Yet activation processes induced by the previous protocol steps were quenched with the final electron beam treatment step. An optimized SULEEI protocol was developed using an intense and extended, trypsin-containing decellularization step to inactivate tissue factor and a dextran-free, low riboflavin, high UV crosslinking step. The innovative and improved GA-free SULEEI-preparation protocol results in low coagulant and low inflammatory bovine pericardium for surgical application.

A versatile modification strategy for functional non-glutaraldehyde cross-linked bioprosthetic heart valves with enhanced anticoagulant, anticalcification and endothelialization properties

Valvular heart disease is a major threat to human health and transcatheter heart valve replacement (THVR) has emerged as the primary treatment option for severe heart valve disease. Bioprosthetic heart valves (BHVs) with superior hemodynamic performance and compressibility have become the first choice for THVR, and more BHVs have been requested for clinical use in recent years. However, several drawbacks remain for the commercial BHVs cross-linked by glutaraldehyde, including calcification, thrombin, poor biocompatibility and difficulty in endothelialization, which would further reduce the BHVs' lifetime. This study developed a dual-functional non-glutaraldehyde crosslinking reagent OX-VI, which can provide BHV materials with reactive double bonds (CC) for further bio-function modification in addition to the crosslinking function. BHV material PBAF@OX-PP was developed from OX-VI treated porcine pericardium (PP) after the polymerization with 4-vinylbenzene boronic acid and the subsequent modification of poly (vinyl alcohol) and fucoidan. Based on the functional anti-coagulation and endothelialization strategy and dual-functional crosslinking reagent, PBAF@OX-PP has better anti-coagulation and anti-calcification properties, higher biocompatibility, and improved endothelial cells proliferation when compared to Glut-treated PP, as well as the satisfactory mechanical properties and enhanced resistance effect to enzymatic degradation, making it a promising candidate in the clinical application of BHVs. STATEMENT OF SIGNIFICANCE: Transcatheter heart valve replacement (THVR) has become the main solution for severe valvular heart disease. However, bioprosthetic heart valves (BHVs) used in THVR exhibit fatal drawbacks such as calcification, thrombin and difficulty for endothelialization, which are due to the glutaraldehyde crosslinking, resulting in a limited lifetime to 10-15 years. A new non-glutaraldehyde cross-linker OX-VI has been designed, which can not only show great crosslinking ability but also offer the BHVs with reactive double bonds (CC) for further bio-function modification. Based on the dual-functional crosslinking reagent OX-VI, a versatile modification strategy was developed and the BHV material (PBAF@OX-PP) has been developed and shows significantly enhanced anticoagulant, anti-calcification and endothelialization properties, making it a promising candidate in the clinical application of BHVs.

Infrared Spectroscopic Verification of a α-Helical Collagen Structure in Glutaraldehyde-Free Crosslinked Bovine Pericardium for Cardiac Implants

The degeneration of heart valve bioprostheses due to calcification processes is caused by the intercalation of calciumhydroxyapatite in pericardium collagen bundles. Variations of the protein secondary structure of biomaterials according to preparation are relevant for this mineralization process and thus the structural characterization of innovative bioprostheses materials is of great importance. The gold standard for prostheses preparation is glutaraldehyde (GA)-fixation of bovine pericardium that adversely promotes calcification. The novel GA-free SULEEI-treatment of bovine pericardium includes decellularization, UV-crosslinking, and electron beam sterilization. The aim of this study is the structural characterization of SULEEI-treated and GA-fixed bovine pericardium. IR spectroscopic imaging combined with multivariate data and curve fit analysis was applied to investigate the amide I and amide II regions of SULEEI-treated and GA-fixed samples. The spectroscopic images of GA-fixed pericardial tissue exhibited a generally high content of amine groups and side chains providing nucleation points for calcification processes. In contrast, in SULEEI-treated tissue, the typical α-helical structure was retained and was supposed to be less prone to deterioration.

Improved Cytocompatibility and Reduced Calcification of Glutaraldehyde-Crosslinked Bovine Pericardium by Modification With Glutathione

Bioprosthetic heart valves (BHVs) used in clinics are fabricated via glutaraldehyde (GLUT) crosslinking, which results in cytotoxicity and causes eventual valve calcification after implantation into the human body; therefore, the average lifetime and application of BHVs are limited. To address these issues, the most commonly used method is modification with amino acids, such as glycine (GLY), which is proven to effectively reduce toxicity and calcification. In this study, we used the l-glutathione (GSH) in a new modification treatment based on GLUT-crosslinked bovine pericardium (BP) as the GLUT + GSH group, BPs crosslinked with GLUT as GLUT-BP (control group), and GLY modification based on GLUT-BP as the GLUT + GLY group. We evaluated the characteristics of BPs in different treatment groups in terms of biomechanical properties, cell compatibility, aldehyde group content detection, and the calcification content. Aldehyde group detection tests showed that the GSH can completely neutralize the residual aldehyde group of GLUT-BP. Compared with that of GLUT-BP, the endothelial cell proliferation rate of the GLUT + GSH group increased, while its hemolysis rate and the inflammatory response after implantation into the SD rat were reduced. The results show that GSH can effectively improve the cytocompatibility of the GLUT-BP tissue. In addition, the results of the uniaxial tensile test, thermal shrinkage temperature, histological and SEM evaluation, and enzyme digestion experiments proved that GSH did not affect the ECM stability and biomechanics of the GLUT-BP. The calcification level of GLUT-BP modified using GSH technology decreased by 80%, indicating that GSH can improve the anti-calcification performance of GLUT-BP. Compared with GLUT-GLY, GLUT + GSH yielded a higher cell proliferation rate and lower inflammatory response and calcification level. GSH can be used as a new type of anti-calcification agent in GLUT crosslinking biomaterials and is expected to expand the application domain for BHVs in the future.

In vivo evaluation of Vivere bovine pericardium valvular bioprosthesis with a new anti-calcifying treatment

The objective of this study was to evaluate the effect of chemical treatment with glutamic acid to avoid calcification of biological cardiac valves. The bovine pericardium (BP) tissues were fixed with 0.5% glutaraldehyde (BP/GA), followed by treatment with glutamic acid (BP/GA + Glu) for neutralization of the free aldehyde groups. Microscopic analysis showed that the wavy structure of collagen fibrils was preserved, but changes in elastin's integrity occurred. However, the treatment did not promote undesirable changes in the thermal and mechanical properties of the modified BPs. These samples were systematically studied in rat subcutaneous tissue: control (BP/GA) and anticalcificant (BP/GA + Glu). After 60 days, both groups induced similar inflammatory reactions. In terms of calcification, BP/GA + Glu remained more stable with a lower index (3.1 ± 0.2 μg Ca²⁺ /mg dry tissue), whereas for BP/GA it was 5.7 ± 1.3 μg Ca²⁺ /mg dry tissue. Bioprostheses made from BP/GA + Glu were implanted in the pulmonary position in sheep, and in vivo echocardiographic analyses revealed maintenance of valvar function after 180 days, with low gradients and minimal valve insufficiency. The explanted tissues of the BP/GA + Glu group had a lower average calcium content 3.8 ± 3.0 μg Ca²⁺ /mg dry tissue. The results indicated high anticalcification efficiency of BP/GA + Glu in both subcutaneous implant in rats and in the experimental sheep model, which is an advantage that should encourage the industrial application of these materials for the manufacture of bioprostheses.

Epoxy Chitosan-Crosslinked Acellular Bovine Pericardium with Improved Anti-calcification and Biological Properties

Glutaraldehyde (GA) was conventionally used to crosslink bovine pericardium to prepare bioprosthetic heart valves (BHVs), which usually fail within 10 years because of valve deterioration and calcification. To overcome the high cytotoxicity and severe calcification of GA-crosslinked BHVs, a quaternary ammonium salt of epoxy chitosan (epoxy group-modified 3-chlorine-2-hydroxypropyl trimethyl chitosan, abbreviated as "eHTCC") was developed to modify the acellular bovine pericardium to substitute GA and improve its anti-calcification and biocompatible properties. Mechanical test, enzymatic stability test, blood compatibility assay, and cytocompatibility assay were used to investigate its mechanical property and biocompatibility. The anti-calcification effect of the eHTCC-modified bovine pericardium (eHTCC-BP) was assessed by in vitro assay and rat subcutaneous implantation assay. The results showed that eHTCC-BP could improve the mechanical properties and anti-enzymolysis ability of BP, as well as retain the original three-dimensional structure, compared with the uncrosslinked-BP group. Moreover, the in vivo calcification level of the eHTCC-BP group was much lower than that of the GA-BP group, which was 5.1% (2 weeks), 2.3% (4 weeks), and 0.8% (8 weeks) of the GA-BP group. In summary, this study demonstrated that eHTCC could be a potential crosslinking agent for the extracellular matrix for its favorable crosslinking effects, anti-enzymolysis, anti-calcification, and biocompatibility.

Mammalian Pericardium-Based Bioprosthetic Materials in Xenotransplantation and Tissue Engineering

Bioprosthetic materials based on mammalian pericardium tissue are the gold standard in reconstructive surgery. Their application range covers repair of rectovaginal septum defects, abdominoplastics, urethroplasty, duraplastics, maxillofacial, ophthalmic, thoracic and cardiovascular reconstruction, etc. However, a number of factors contribute to the success of their integration into the host tissue including structural organization, mechanical strength, biocompatibility, immunogenicity, surface chemistry, and biodegradability. In order to improve the material's properties, various strategies are developed, such as decellularization, crosslinking, and detoxification. In this review, the existing issues and long-term achievements in the development of bioprosthetic materials based on the mammalian pericardium tissue, aimed at a wide-spectrum application in reconstructive surgery are analyzed. The basic technical approaches to preparation of biocompatible forms providing continuous functioning, optimization of biomechanical and functional properties, and clinical applicability are described.

Guided tissue regeneration in heart valve replacement: from preclinical research to first-in-human trials

Heart valve tissue-guided regeneration aims to offer a functional and viable alternative to current prosthetic replacements. Not requiring previous cell seeding and conditioning in bioreactors, such exceptional tissue engineering approach is a very fascinating translational regenerative strategy. After in vivo implantation, decellularized heart valve scaffolds drive their same repopulation by recipient's cells for a prospective autologous-like tissue reconstruction, remodeling, and adaptation to the somatic growth of the patient. With such a viability, tissue-guided regenerated conduits can be delivered as off-the-shelf biodevices and possess all the potentialities for a long-lasting resolution of the dramatic inconvenience of heart valve diseases, both in children and in the elderly. A review on preclinical and clinical investigations of this therapeutic concept is provided with evaluation of the issues still to be well deliberated for an effective and safe in-human application.

Crosslinking effect of dialdehyde starch (DAS) on decellularized porcine aortas for tissue engineering

Biological tissue-derived biomaterials must be chemically modified to avoid immediate degradation and immune response before being implanted in human body to replace malfunctioning organs. DAS with active aldehyde groups was employed to replace glutaraldehyde (GA), a most common synthetic crosslinking reagent in clinical practice, to fix bioprostheses for lower cytotoxicity. The aim of this research was to evaluate fixation effect of DAS. The tensile strength, crosslinking stability, cytotoxicity especially the anti-calcification capability of DAS-fixed tissues were investigated. The tensile strength and resistance to enzymatic degradation of samples were increased after DAS fixation, the values maintained stably in D-Hanks solution for several days. Meanwhile, ultrastructure of samples preserved well and the anti-calcification capability of samples were improved, the amount of positive staining points in the whole visual field of 15% DAS-fixed samples was only 0.576 times to GA-fixed ones. Moreover, both unreacted DAS and its hydrolytic products were nontoxic in cytotoxicity study. The results demonstrated DAS might be an effective crosslinking reagent to fix biological tissue-derived biomaterials in tissue engineering.

Development of a next-generation tissue valve using a glutaraldehyde-fixed porcine aortic valve treated with decellularization, α-galactosidase, space filler, organic solvent and detoxification

OBJECTIVES

Conventional crosslinking with glutaraldehyde (GA) renders cardiac xenografts inert, non-biodegradable and non-antigenic, but is a main cause for dystrophic calcification due to phospholipids, free aldehyde groups and residual antigenicity. A significant immune reaction to the galactose-α-1,3 galactose β-1,4-N-acetylglucosamine (α-Gal) of a GA-fixed cardiac xenograft occurs, leading to calcification. We developed a next-generation α-Gal-free tissue valve with GA-fixed cardiac xenografts, treated using a novel combined anticalcification protocol including immunological modification, which was demonstrated effective in a small animal study.

METHODS

Porcine aortic valves were decellularized with 1% sodium dodecyl sulphate, 1% Triton X-100 and 1% sodium lauroyl sarcosinate and immunologically modified with α-galactosidase. The valves were treated by a polyethylene glycol space filler, fixed with GA in 75% ethanol + 5% octanol and detoxified with glycine. We manufactured the tissue valve with the porcine aortic valve mounted on a Nitinol (nickel-titanium memory alloy) plate. The tissue valve was placed under in vitro mock circulation, and durability from mechanical stress was evaluated for 100 days. Ten sheep underwent mitral valve replacement with the tissue valve, and haemodynamic, radiological, immunohistopathological and biochemical results were obtained for 18 months after implantation.

RESULTS

The in vitro circulation experiment demonstrated that the valve functioned well with good morphology. Eight sheep survived for 1, 2, 5, 10, 14, 53, 546 and 552 days after mitral valve replacement, but two sheep did not survive. An evaluation by echocardiography and cardiac catheterization demonstrated good haemodynamic status and function of the mitral valve at 18 months after implantation. The xenografts were well preserved without a α-Gal immune reaction or calcification based on the immunological, radiographic, microscopic and biochemical examinations.

CONCLUSIONS

We developed a next-generation α-Gal-free tissue valve with simultaneous use of multiple anticalcification therapies and novel tissue treatments such as decellularization, immunological modification with α-galactosidase, space filler, an organic solvent and detoxification. Future investigations should evaluate α-Gal-free substitutes such as our tissue valve, and a future clinical study is warranted based on these promising preclinical results.

Development of novel combined anticalcification protocols including immunologic modification for prolonged durability of cardiac xenograft: preclinical study using large-animal long-term circulatory models

Cardiac xenografts are conventionally cross-linked with glutaraldehyde (GA) to impart tissue stability, reduce antigenicity, and maintain tissue sterility. However, GA-fixed xenografts are prone to calcification after long-term implantation in humans, because of phospholipids, free aldehyde groups, and residual antigenicity. We evaluated preclinical safety and efficacy using large-animal long-term circulatory models for our novel combined anticalcification protocol including immunological modification, which had been proven effective in small animal experiments. Bovine/porcine xenografts were treated with decellularization, immunological modification with α-galactosidase, GA fixation with organic solvent, and detoxification with glycine. Valve conduits made of these xenografts were transplanted into the pulmonary root of goats, and hemodynamic, radiological, immunohistopathological, and biochemical results were obtained for 12 months after implantation. Evaluation of echocardiography and cardiac catheterization demonstrated good hemodynamic status and function of the pulmonary xenograft valves. Durability of the xenografts was well preserved without calcification by specimen radiography and immunohistopathological examination. The calcium concentrations of the explanted xenografts were lower than the control xenografts. This preclinical study using large-animal long-term circulatory models demonstrated that our synergistic and simultaneous employment of multiple anticalcification therapies and novel tissue treatments, including immunological modifications, have promising safety and efficacy and should be examined further in future clinical studies.

In vivo efficacy for novel combined anticalcification treatment of glutaraldehyde-fixed cardiac xenograft using humanized mice

The animal immune response against Galα1,3-Galβ1-4GlcNAc-R(α-Gal) epitopes gives an important cause for the failure of glutaraldehyde(GA)-fixed cardiac xenografts. This study aimed to assess the in vivo effect of our novel combined anticalcification treatment, which includes immunologic modification, using α1,3-galactosyltransferase knock-out mice to mimic human immunologic environment. Bovine pericardia were cross-linked with GA and treated with decellularization, immunologic modification with α-galactosidase, space-filler with polyethylene glycol, organic solvent, and detoxification. The bovine pericardia were subcutaneously implanted into humanized and wild type mice, and titers of anti α-Gal IgM and IgG were evaluated at various time intervals. In vivo calcification and immunohistochemistry staining was assessed for the explanted xenografts several months after implantation. In humanized mice, titers for anti α-Gal IgM and IgG increased as the period of implantation increased, and reduced with our anticalcification treatments. The humanized mice had more in vivo calcification in GA-fixed xenografts treated with our anticalcification protocol compared with wild type mice. In humanized mice, in vivo calcification reduced with our combined anticalcification treatment, and the immunohistochemistry of the harvested xenografts proved the compatible findings with the results of in vivo immunogenicity and calcification. Humanized mice are effective model for the assessment of in vivo calcification, and our combined anticalcification treatments reduced in vivo calcification as well as in vivo immunogenicity in humanized mice group, suggesting that the animal immune reaction is the cause for calcification. Our novel combined anticalcification strategies of decellularization, immunologic modification, space-filler, organic solvent, and detoxification have possible promise to prolong the lifespan of cardiac xenograft.

Valved conduit with glutaraldehyde-fixed bovine pericardium treated by anticalcification protocol

BACKGROUND

A preclinical study was conducted for evaluating a valved conduit manufactured with a glutaraldehyde (GA)-fixed bovine pericardium treated using an anticalcification protocol.

METHODS

Bovine pericardia were decellularized, fixed with GA in an organic solvent, and detoxified. We prepared a valved conduit using these bovine pericardia and a specially designed mold. The valved conduit was placed under in vitro circulation by using a mock circulation model, and the durability under mechanical stress was evaluated for 2 months. The valved conduit was implanted into the right ventricular outflow tract of a goat, and the hemodynamic, radiologic, histopathologic, and biochemical results were obtained for 6 months after the implantation.

RESULTS

The in vitro mock circulation demonstrated that valve motion was good and that the valved conduit had good gross and microscopic findings. The evaluation of echocardiography and cardiac catheterization demonstrated the good hemodynamic status and function of the pulmonary xenograft valve 6 months after the implantation. According to specimen radiography and a histopathologic examination, the durability of the xenografts was well preserved without calcification at 6 months after the implantation. The calcium and inorganic phosphorus concentrations of the explanted xenografts were low at 6 months after the implantation.

CONCLUSION

This study demonstrated that our synergistic employment of multiple anticalcification therapies has promising safety and efficacy in the future clinical study.

The Anti-calcification Effect of Dithiobispropionimidate, Carbodiimide and Ultraviolet Irradiation Cross-linking Compared to Glutaraldehyde in Rabbit Implantation Models

Background

Glutaraldehyde (GA) is a widely used cross-linking agent for improving mechanical properties and resistance to enzymatic degradation of collagenous tissue, but it has several drawbacks such as calcification and cytotoxicity. The aim of this study was to find the alternative effective cross-linking methods to GA.

Materials and Methods

Bovine pericardium was processed with GA with ethanol+octanol and glycine detoxification, and polyethylene glycol (PG) space filler, dimethyl 3,3'-dithiobispropionimidate (DTBP), 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) treatment, and the physical fixation of ultraviolet irradiation were done. The biologic material properties of variously treated pericardial tissues were assessed by biochemical, mechanical and histological tests. Treated pericardial tissues were also implanted subcutaneously or intramuscularly into the rabbit for 10 weeks to assess the xenoreactive antibody response of immunoglobulin G and M, their anti-calcification effect.

Results

The biochemical and mechanical properties of EDC fixed pericardial tissues were comparable to the GA fixed tissue. The cytotoxicity was lowest in space filler treated GA fixed group. In rabbit subcutaneous or intramuscular implantation models, decellularization, space filler, EDC treatment group showed significantly lower calcium content than GA only and DTBP treatment group (p<0.05, analysis of variance). The titer of anti Galα1-3Galβ1-4GlcNAc-R antibodies did not change in the postimplantation serial enzyme-linked immunosorbent assay. Hematoxylin and eosin and von Kossa staining showed that decellularization, space filler, EDC, and ultraviolet treatment had less inflammatory cell infiltration and calcium deposits.

Conclusion

The decellularization process, PG filler, and EDC treatments are good alternative cross-linking methods compared to GA only fixation and primary amine of DTBP treatment for cardiovascular xenograft preservation in terms of the collagen cross-linking stability and in vivo anti-calcification effects.