A comparison of electrospun polymers reveals poly(3-hydroxybutyrate) fiber as a superior scaffold for cardiac repair.

The development of biomaterials for myocardial tissue engineering requires a careful assessment of their performance with regards to functionality and biocompatibility, including the immune response. Poly(3-hydroxybutyrate) (PHB), poly(e-caprolactone) (PCL), silk, poly-lactic acid (PLA), and polyamide (PA) scaffolds were generated by electrospinning, and cell compatibility in vitro, and immune response and cardiac function in vitro and in vivo were compared with a noncrosslinked collagen membrane (Col) control material. Results showed that cell adhesion and growth of mesenchymal stem cells, cardiomyocytes, and cardiac fibroblasts in vitro was dependent on the polymer substrate, with PHB and PCL polymers permitting the greatest adhesion/growth of cells. Additionally, polymer substrates triggered unique expression profiles of anti- and pro-inflammatory cytokines in human peripheral blood mononuclear cells. Implantation of PCL, silk, PLA, and PA patches on the epicardial surface of healthy rats induced a classical foreign body reaction pattern, with encapsulation of polymer fibers and induction of the nonspecific immune response, whereas Col and PHB patches were progressively degraded. When implanted on infarcted rat heart, Col, PCL, and PHB reduced negative remodeling, but only PHB induced significant angiogenesis. Importantly, Col and PHB modified the inflammatory response to an M2 macrophage phenotype in cardiac tissue, indicating a more beneficial reparative process and remodeling. Collectively, these results identify PHB as a superior substrate for cardiac repair.