Medium chain length polyhydroxyalkanoates as potential matrix materials for peripheral nerve regeneration

Polyhydroxyalkanoates are natural,biodegradable,thermoplastic and sustainable polymers with a huge potential in fabrication of bioresorbable implantable devices for tissue engineering.We describe a comparative evaluation of three medium chain length polyhydroxyalkanoates(mcl-PHAs),namely poly(3-hydroxyoctanoate),poly(3-hydroxyoctanoate-co-3-hydoxydecanoate)and poly(3-hydroxyoctanoate-co-3-hydroxydecanoate-co-3-hydroxydodecanoate),one short chain length polyhydroxyalkanoate,poly(3-hydroxybutyrate),P(3HB)and synthetic aliphatic polyesters(polycaprolactone and polylactide)with a specific focus on nerve regeneration,due to mechanical properties of mcl-PHAs closely matching nerve tissues.In vitro biological studies with NG108-15 neuronal cell and primary Schwann cells did not show a cytotoxic effect of the materials on both cell types.All mcl-PHAs supported cell adhesion and viability.Among the three mcl-PHAs,P(3HO-co-3HD)exhibited superior properties with regards to numbers of cells adhered and viable cells for both cell types,number of neurite extensions from NG108-15 cells,average length of neurite extensions and Schwann cells.Although,similar characteristics were observed for flat P(3HB)surfaces,high rigidity of this biomaterial,and FDA-approved polymers such as PLLA,limits their applications in peripheral nerve regeneration.Therefore,we have designed,synthesized and evaluated these materials for nerve tissue engineering and regenerative medicine,the interaction of mcl-PHAs with neuronal and Schwann cells,identifying mcl-PHAs as excellent materials to enhance nerve regeneration and potentially their clinical application in peripheral nerve repair.