The increased intragraft mRNA expression of porcine MIP-1α, IL-8, HMGB1 and HSP90 seen at days 7 and 14 post-transplantation suggest that small xenoantigens such as these could diffuse through the microcapsule pores and initiate an immune response which correlates with the appearance of PFO seen at day 7. Here, HMGB1 is linked to Patent foramen ovale.