Dot Blots of Solubilized Extracellular Matrix Allow Quantification of Human Antibodies Bound to Epitopes Present in Decellularized Porcine Pulmonary Heart Valves

Background: The present study reports the development of a sensitive dot blot protocol for determining the level of preformed antibodies against porcine heart valve tissue derived from wild-type (WT) and α-Gal-KO (GGTA1-KO) pigs in human sera.

Methods: The assay uses decellularized and solubilized heart valve tissue; antibody binding found in this dot blot assay could be correlated with antibody titers of preformed anti-α-Gal and anti-Neu5Gc antibodies detected by a sensitive ELISA.

Results: The ultimate protocol had an inter-assay variance of 9.5% and an intra-assay variance of 9.2%, showing that the test is reliable and highly reproducible. With the aid of this dot blot assay, we found significant variation with regard to antibody contents among twelve human sera. Binding of preformed antibodies to WT tissue was significantly higher than to GGTA1-KO tissue.

Conclusions: The dot blot assay described herein could be a valuable tool to measure preformed antibody levels in human sera against unknown epitopes on decellularized tissue prior to implantation. Ultimately, this prescreening may allow a matching of the porcine xenograft with the respective human recipients in demand and thus may become an important tool for graft long-term survival similar to current allotransplantation settings.