Heparin mimics and fibroblast growth factor-2 fabricated nanogold composite in promoting neural differentiation of mouse embryonic stem cells.

The replacement therapy or transplantation using neural cells, which differentiated from stem cells, has emerged as a promising strategy for repairing damaged neural tissues and helping functional recovery in the treatment of neural system diseases. The challenge, however, is how to control embryonic stem cell fate so that neural differentiation can be efficiently directed to enrich a neuron cell population, and meanwhile to maintain their bioactivities. This is a key question and has a very significant impact in regenerative medicine. Here we proposed a new neural-differentiation inductive nanocomposite, containing gold nanoparticles (AuNPs), poly(2-methacrylamido glucopyranose-co-3-sulfopropyl acrylate) (PMS), and basic fibroblast growth factor (FGF2), for the high efficient directional neural-specific differentiation of mouse embryonic stem cells (mESCs). In this AuNP-PMS/FGF2 composite, PMS, playing as the high-active mimic of heparin/heparan sulfate (HS), is covalently anchored to AuNPs and bound with FGF2 on the surface of nanoparticles, forming a HS/FGF2 complex nanomimics to facilitate its binding to FGF receptor (FGFR) and promote high neural-inductive activity of mESCs. The stability, bioactivity and biocompatibility of the composite are investigated in this study. The results showed that the AuNP-PMS/FGF2 composite could maintain a long-term stability at room temperature for at least 8 days, and greatly promote the neural differentiation of mESCs. Compared with the other materials, the AuNP-PMS/FGF2 composite could significantly stimulate the expression of the specific neural differentiation markers (nestin and β3-tubulin), while obviously down-regulate the mRNA production of pluripotency marker Oct-4 in mESCs. Moreover, the promotion effect of the composite on neuronal maturation marker β3-tubulin expression achieved maximally at the low concentration of FGF2 (4 ng/mL), which suggested the high efficiency of AuNP-PMS/FGF2 composite in neural differentiation of mESCs. Meanwhile, both mESCs and L929 cells showed desirable growth during the incubation with AuNP-PMS/FGF2 composite. The AuNP-PMS/FGF2 system presents a new way to achieve HS/FGF2 complex nanomimics efficiently for the neural differentiation of mESCs.