Journal of Stem Cell Research & Therapy

Abstract

Biocompatibility Evaluation Criteria for Novel Xenograft Materials: Distribution and Quantification of Remnant Nucleic Acid and Alpha-Gal Epitope

Naso Filippo, Aguiari Paola, Iop Laura, Spina Michele and Gerosa Gino

Objective: Commercially decellularized xenogeneic scaffolds are currently employed as for the healing of diseased tissues. Strangely enough their use is permitted even in absence of any assessment of the elimination of xenogeneic cell material, as the alpha-Gal epitopes. In addition, the decellularization procedures are not monitored to prove the elimination of the calcific potential associated to the nucleic acids remnants. The currently treatment with glutaraldehyde is unable to grant a complete immuno-tolerance of implanted xenogeneic tissues, reducing but not eliminating the immunogenicity particularly for the alpha-Gal epitope (the major hindrance for the success of xenotransplantation). Recently, our group has extensively reported studies focused on the evaluation of biocompatibility properties of xenogeneic tissues. In this report we are performing this investigation and nucleic acid detection to novel xenogeneic tissues that have shown very promising preclinical/clinical results in different areas of application. Methods: The alpha-Gal quantification was conducted by an ELISA test previously developed and patented by our research team which involves the use of the monoclonal anti apha-Gal antibody M86. Immunofluorescence analysis was performed for the visual distribution of both xenogeneic epitopes and nucleic acids residues. Finally for the total DNA quantification a commercially available kit was adopted. Results: While the amount and distribution of the alpha-Gal epitopes was found different between the investigated biomaterials, the presence of nucleic acid remnants has been revealed as common feature, even in those tissues delivered as acellular by the manufacturer. Conclusion: Insufficient quantitative evaluations performed at preclinical level about the residual content of xenogeneic epitopes, detergents and nucleic acid materials in scaffolds have led to disappointing and disastrous results. The risk of these dramatic accidents reoccurring remains very high unless safety parameters, among which the complete removal of major xenogeneic determinants (alpha-Gal) and calcification-prone nucleic acid residues, are identified and introduced in manufacturing practices.