Enhanced proliferation and differentiation of neural stem cells grown on PHA films coated with recombinant fusion proteins

Polyhydroxyalkanoates (PHAs) belong to a family of copolyesters with demonstrated biocompatibility. We hypothesize that genetically fusing evolutionarily preserved cell binding motifs, such as RGD or IKVAV, to the PHA-binding protein phasin (PhaP) for surface functionalization of PHA materials could better support the growth and differentiation of neural stem cells (NSCs). This hypothesis is tested on three polyester materials of the same aliphatic family: poly(L-lactic acid) (PLA) and two PHB copolymers, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (PHBVHHx). Experimental results indicate that surface coating of the two fusion proteins, PhaP-RGD and PhaP-IKVAV, provides short-term advantages in promoting the adhesion, proliferation and neural differentiation of rat NSCs compared to the PhaP-coated or uncoated material. Among the tested samples, the combination of coating PhaP-IKVAV on an PHBVHHx surface yields the highest levels in cell adhesion and proliferation, while the PLA film coated with PhaP-IKVAV promotes better neural differentiation and neurite outgrowth in the early stage. Because both PhaP-RGD and PhaP-IKVAV could be produced in an inexpensive manner, our data suggest that PhaP-IKVAV is an ideal nonspecific coating agent to functionalize hydrophobic biomaterials in the application of neural tissue engineering.