Modification of decellularized vascular xenografts with 8-arm polyethylene glycol suppresses macrophage infiltration but maintains graft degradability

Investigation of anti-adhesion ability of 8-arm PEGNHS-modified porcine pericardium

In post-adhesion surgery, there is a clinical need for anti-adhesion membranes specifically designed for the liver, given the limited efficacy of current commercial products. To address this demand, we present a membrane suitable for liver surgery applications, fabricated through the modification of decellularized porcine pericardium with 20 KDa hexaglycerol octa (succinimidyloxyglutaryl) polyoxyethylene (8-arm PEGNHS). We also developed an optimized modification procedure to produce a high-performance anti-adhesion barrier. The modified membrane significantly inhibited fibroblast cell adherence while maintaining minimal levels of inflammation. By optimizing the modification ratio, we successfully controlled post-adhesion formation. Notably, the 8-arm PEG-modified pericardium with a molar ratio of 5 exhibited the ability to effectively prevent post-adhesion formation on the liver compared to both the control and Seprafilm®, with a low adhesion score of 0.5 out of 3.0. Histological analysis further confirmed its potential for easy separation. Furthermore, the membrane demonstrated regenerative capabilities, as evidenced by the proliferation of mesothelial cells on its surface, endowing anti-adhesion properties between the abdominal wall and liver. These findings highlight the membrane's potential as a reliable barrier for repeated liver resection procedures that require the removal of the membrane multiple times.

Effect of multi arm-PEG-NHS (polyethylene glycol n-hydroxysuccinimide) branching on cell adhesion to modified decellularized bovine and porcine pericardium

Implanting physical barrier materials to separate wounds from their surroundings is a promising strategy for preventing postoperative adhesions. Herein, we develop a material that switches from an anti-adhesive surface to an adhesive surface, preventing adhesion in the early stage of transplantation and then promoting recellularization. In this study, 2-arm, 4-arm, and 8-arm poly(ethylene glycol) succinimidyl glutarate (2-, 4-, 8-arm PEG-NHS) were used to modify the surface of decellularized porcine and bovine pericardium. The number of free amines on the surface of each material significantly decreased following modification regardless of the reaction molar ratio of NH2 and NHS, the number of PEG molecule branches, and the animal species of the decellularized tissue. The structure and mechanical properties of the pericardium were maintained after modification with PEG molecules. The time taken for the PEG molecules to detach through hydrolysis of the ester bonds differed between the samples, which resulted in different cell repulsion periods. By adjusting the reaction molar ratio, the number of PEG molecule branches, and the animal species of the decellularized pericardium, the duration of cell repulsion can be controlled and is expected to provide an anti-adhesion material for a variety of surgical procedures.

Surfactant-Free Decellularization of Porcine Auricular Cartilage Using Liquefied Dimethyl Ether and DNase

The most common decellularization method involves lipid removal using surfactant sodium dodecyl sulfate (SDS) and DNA fragmentation using DNase, and is associated with residual SDS. We previously proposed a decellularization method for the porcine aorta and ostrich carotid artery using liquefied dimethyl ether (DME), which is free from the concerns associated with SDS residues, instead of SDS. In this study, the DME + DNase method was tested on crushed porcine auricular cartilage tissues. Unlike with the porcine aorta and the ostrich carotid artery, it is important to degas the porcine auricular cartilage using an aspirator before DNA fragmentation. Although approximately 90% of the lipids were removed using this method, approximately 2/3 of the water was removed, resulting in a temporary Schiff base reaction. The amount of residual DNA in the tissue was approximately 27 ng/mg dry weight, which is lower than the regulatory value of 50 ng/mg dry weight. Hematoxylin and eosin staining confirmed that cell nuclei were removed from the tissue. Residual DNA fragment length assessment by electrophoresis confirmed that the residual DNA was fragmented to less than 100 bp, which was lower than the regulatory limit of 200 bp. By contrast, in the uncrushed sample, only the surface was decellularized. Thus, although limited to a sample size of approximately 1 mm, liquefied DME can be used to decellularize porcine auricular cartilage. Thus, liquefied DME, with its low persistence and high lipid removal capacity, is an effective alternative to SDS.

Immunogenicity of decellularized extracellular matrix scaffolds: a bottleneck in tissue engineering and regenerative medicine

Tissue-engineered decellularized extracellular matrix (ECM) scaffolds hold great potential to address the donor shortage as well as immunologic rejection attributed to cells in conventional tissue/organ transplantation. Decellularization, as the key process in manufacturing ECM scaffolds, removes immunogen cell materials and significantly alleviates the immunogenicity and biocompatibility of derived scaffolds. However, the application of these bioscaffolds still confronts major immunologic challenges. This review discusses the interplay between damage-associated molecular patterns (DAMPs) and antigens as the main inducers of innate and adaptive immunity to aid in manufacturing biocompatible grafts with desirable immunogenicity. It also appraises the impact of various decellularization methodologies (i.e., apoptosis-assisted techniques) on provoking immune responses that participate in rejecting allogenic and xenogeneic decellularized scaffolds. In addition, the key research findings regarding the contribution of ECM alterations, cytotoxicity issues, graft sourcing, and implantation site to the immunogenicity of decellularized tissues/organs are comprehensively considered. Finally, it discusses practical solutions to overcome immunogenicity, including antigen masking by crosslinking, sterilization optimization, and antigen removal techniques such as selective antigen removal and sequential antigen solubilization.

A PEGylation method of fabricating bioprosthetic heart valves based on glutaraldehyde and 2-amino-4-pentenoic acid co-crosslinking with improved antithrombogenicity and cytocompatibility

With the development of diagnostic techniques, the incidence of bioprosthetic heart valve thrombosis (BHVT) is found to be seriously underestimated. Developing bioprosthetic heart valves (BHVs) that have good hemocompatibility without sacrificing other properties such as hydrodynamics and durability will be an effective strategy to alleviate BHVT. In this study, we developed a PEGylation method by co-crosslinking and subsequent radical polymerization. 2-amino-4-pentenoic acid was used to introduce carbon-carbon double bonds for glutaraldehyde crosslinked pericardia. Then poly (ethylene glycol) diacrylate (PEGDA) was immobilized on pericardia by radical polymerization. A comprehensive evaluation of the modified pericardia was performed including structural characterization, hemocompatibility, cytocompatibility, mechanical properties, component stability, hydrodynamic performance and durability of the BHVs. The modified pericardia significantly reduced platelet adhesion by more than 75% compared with traditional glutaraldehyde crosslinked pericardia. Cell viability in the modified pericardia group was nearly 5-fold higher than that in glutaraldehyde crosslinked pericardia. The hydrodynamic performance met the requirements of ISO 5840-3 under physiological aortic valve conditions and its durability was proved after 200 million cycles of accelerated fatigue test. In conclusion, PEGDA modified pericardia exhibited improved antithrombogenicity and cytocompatibility properties compared with glutaraldehyde crosslinked pericardia. STATEMENT OF SIGNIFICANCE: Bioprosthetic valve (BHV) implantation requires BHV to be structurally stable as well as biocompatible in vivo. Traditional glutaraldehyde crosslinking method prepared BHV suffers from severe cytotoxicity, thrombosis, and calcification. BHV modification methods that have simultaneously improved structural stability and biocompatibility were rarely reported. Here, we proposed a PEGylation method for BHV based on co-crosslinking strategy that could improve its structural stability as well as hemocompatibility. We take the advantage of high efficiency of glutaraldehyde crosslinking and demonstrate the feasibility and superiority of the PEGylated strategy, offering a promising option in glutaraldehyde-based BHV fabrication in the future.

4-Arm PEG-Functionalized Decellularized Pericardium for Effective Prevention of Postoperative Adhesion in Cardiac Surgery

Postoperative adhesions are a very common and serious complication in cardiac surgery, and the development of an effective anti-adhesion membrane showing resistance to the physical stimulus generated by the pulsation of the heart is desirable. In this study, an anti-adhesion material was developed through amine coupling between decellularized bovine pericardia (dBPCs) and 4-arm poly(ethylene glycol) succinimidyl glutarate (4-arm PEG-NHS) for the postoperative care of cardiac surgical patients. The efficacy of the 4-arm PEG-functionalized dBPCs in the prevention of adhesions after cardiac surgery was investigated in a rabbit heart adhesion model. The dBPCs meet the requirements for biocompatibility, flexibility, and sufficient suturable strength, and the 4-arm PEG moieties provide an anti-adhesion effect by the high excluded volume interactions of the PEG chains with proteins. The 4-arm PEG-functionalized dBPCs had a significantly greater anti-adhesion effect than the other materials tested and showed re-establishment of the mesothelial monolayer. These results suggested that the 4-arm PEG-functionalized dBPCs are a favorable material for an anti-adhesion membrane.

Decellularized scaffold and its elicited immune response towards the host: the underlying mechanism and means of immunomodulatory modification

The immune response of the host towards a decellularized scaffold is complex. Not only can a number of immune cells influence this process, but also the characteristics, preparation and modification of the decellularized scaffold can significantly impact this reaction. Such factors can, together or alone, trigger immune cells to polarize towards either a pro-healing or pro-inflammatory direction. In this article, we have comprehensively reviewed factors which may influence the immune response of the host towards a decellularized scaffold, including the source of the biomaterial, biophysical properties or modifications of the scaffolds with bioactive peptides, drugs and cytokines. Furthermore, the underlying mechanism has also been recapitulated.

Extracorporeal high-pressure therapy (EHPT) for malignant melanoma consisting of simultaneous tumor eradication and autologous dermal substitute preparation

Surgical resection of skin tumors leads to large defects in surrounding normal tissues, which should be reconstructed thereafter using the patient's own tissues taken from the other site. Our challenge is to solve this problem in dermal malignant melanoma (MM) by a novel process, named extracorporeal high pressure therapy (EHPT), in which the tissue containing tumor is resected and pressurized, and the treated tissue is re-transplant back to the same position as a tumor-free autologous dermal substitute. The key points are complete tumor death and preservation of native extra cellular matrix (ECM) by the hydrostatic pressure. We found that high hydrostatic pressure at 200 MPa for 10 min at room temperature is completely cytocidal against MM cells in suspension form, in monolayer form, and even in the solid tumor form. MM tumor-bearing nude mice were established by injected human MM cells intradermally and treated by EHTP. The denaturation of the dermal extra cellular matrices was so mild that the pressurized skin was well engrafted as tumor free autologous dermal tissues, resulting in the complete eradication of the MM without any unnecessary skin reconstruction surgery. This very simple and short pressing treatment was proved to make the tumor tissue to the transplantable and tumor-free autologous dermal substitute, which can be applicable to the other temporally resectable tissues.