In vitro evaluations of innate and acquired immune responses to electrospun polydioxanone–elastin blends

Immune response testing of biomaterials is an essential component of biocompatibility assessment, particularly when the materials of interest are used to design bioresorbable scaffolds with the potential to promote in situ regeneration. Current trends in immune response testing of biomaterials typically examine few elements of the immune system, and they often undertake a mechanistic approach without first determining if material exposure results in physiologically relevant modulation of both innate and acquired immunity. Here, we present a comprehensive in vitro evaluation of biomaterial-induced modulation of acquired (i.e. cell-mediated and humoral) and innate immune responses following exposure to electrospun blends of polydioxanone (PDO) and elastin (ELAS). Results indicated that in vitro exposure of murine spleen cells to PDO–ELAS blends produced statistically significant immunosuppression in multiple cell-mediated and humoral endpoints. Results suggested that ELAS is the primary cause of cell-mediated immunosuppression. In contrast, PDO and ELAS were equally suppressive of humoral immune responses, while blends of the two were more immunosuppressive than either pure polymer alone. Evaluations of innate immune responses demonstrated few significant effects, with statistically significant immunosuppression observed in natural killer cell activity but not in macrophage functional assays. This work presents an approach for assessing potential modulation of immune responses resulting from exposure to biomaterials, and such evaluations are essential to obtaining comprehensive assessments of biocompatibility.