Functional Evaluation Of The Neural Stem Cells Grown On PHA Films Modified By Fusion Proteins PhaP-RGD And PhaP-IKVAV

Neural stem cells (NSCs)-based therapy has shown its potentiality in nerve repair. However, rigorous controls of NSC proliferation and differentiation remain a challenging task that is further complicated by both biochemical and mechanical factors regulating the cellular behaviors. Polyhydroxyalkanoates (PHAs), having demonstrated their remarkable characteristics as tissue engineering biomaterials in the past, can be modified with a variety of growth factors or adhesion proteins to promote cell-cell and cell-matrix interactions. Here, we genetically engineered two recombinant proteins composed of the PHA-based granule binding protein PhaP fused to the extracellular matrix (ECM) proteins-derived peptide RGD or to the laminin-derived peptide IKVAV. Films of poly(3-hydroxybutyrate-co-3-hydroxy- hexanoate) (PHBHHx), poly(3-hydroxybutyrate, 3-hydroxyvalerate and 3-hydroxyhexanoate)(PHBVHHx), and polylactic acid (PLA) were functionalized by the two fusion proteins (PhaP-RGD and PhaP-IKVAV, respectively) as culturing substrates for studying proliferation and differentiation of NSCs. The results indidated that the PHBVHHx film, when coated with PhaP-IKVAV, is a better candidate for NSCs proliferation than the other two materials (PHBHHx and PLA) regardless of their surface mofication by either protein. All materials (including PHBHHx, PHBVHHx, and PLA), when modified by PhaP-IKVAV, facilitated neurite outgrowth of the NSCs derivedβ-tublinⅢ-positive cells.