Depending on the protocol, decellularization may have an impact on the structural and mechanical properties of the treated tissue. According to decellularization protocols differ significantly in terms of alteration of ECM histoarchitecture. For instance, decellularization protocols have a strong impact on the amount of GAGs remaining in a tissue. Removing GAGs from a tissue leads to adverse effects on pericardial viscoelastic properties. This can be easily understood since water retention is an important function of GAGs in tissues. Moreover, GAG content plays a key biological role in cellular signaling and communication. Thus, decreasing GAG content leads to an impaired tissue response and repair. Therefore, the decellularization protocol has to be carefully chosen depending on the tissue type as well as the targeted application. Ideally, the process should remove all cellular antigens without compromising the structure and mechanical properties of the tissue.

Liao et al. investigated the effect of three decellularization protocols on the mechanical and structural properties on porcine aortic valve leaflets. These protocols were based on the use of SDS, Trypsin and Triton X-100. They showed that decellularization resulted in collagen network disruption, and that the ECM pore size varied as a function of the protocol used. For example, leaflets treated with SDS displayed a dense ECM network and small pore sizes, characteristics that may have an impact on the decolonization of interstitial cells. It has been demonstrated that decellularization of bovine pericardium with SDS causes irreversible denaturation, swelling and a decrease in tensile strength compared to native tissue. Because of these deleterious effects on pericardial tissue, non-ionic detergents are preferred for decellularization processes Nevertheless; some issues may be encountered with the use of non-ionic detergents. Indeed, toxic effects and estrogenic effects have been reported after the use of non-ionic detergents such as alkyl phenol ethylates.

Decellularization mediates alterations of the structural and mechanical properties of the tissue, but this impact varies depending on the protocol used. For instance, Mirsadraee et al. did not observe any significant changes using an SDS-based decellularization protocol in the ultimate tensile strength compared to native tissue on human pericardial tissue. They also observed an increased extensibility of the tissue when cut parallel to collagen bundles. Tissue decellularization reduces the cellular and humeral immune response targeted against the bio prosthesis. However, removing cells does not ensure adequate removal of xenoantigens, or mitigation of the immune response. For this reason, decellularization protocols have turned to antigen removal protocols. The presence of cell membrane antigens, such as oligosaccharide beta-Gal has been reported to lead to an immune response that can be prevented by effective decellularization. Interestingly, Griffiths et al. used an immunoproteomic approach to study the ability of bovine pericardium to generate a humeral immune response.

They identified thirty one putative protein antigens. Some of them, such as albumin, hemoglobin chain A and beta hemoglobin have been identified as xenoantigens. Recently, Ariganello et al. provided evidence that decellularized bovine pericardium induced less differentiation of the monocytes to macrophages compared to polydimethylsiloxane or polystyrene surfaces. Nevertheless, the effects of the host immune response to acellular pericardium remain to be fully characterized. Understanding this phenomenon is necessary to develop new pericardium preparations and thus improve biological scaffold integration and clinical safety.

Thanks & Regards,
Nicola B
Editorial Team
Journal of Biochemistry & Biotechnology