| Mesenchymal stem cells (MSC) are widely used in biomedical field. It is becoming more and more important to modulate the differentiation behavior of MSC through changing the properties of materials. On one hand, the differentiation behavior of MSC on the surface of two dimensional matrix with controlled physiochemical properties was studied. On the other hand, the influence of nanoparticles internalization on MSC differentiation was investigated.Polyelectrolyte films (PEMs) were chosen, which is widely used for modification of biomaterial interface. Graphene oxide hybrid poly(L-lysine) (PLL)/hyaluronan (HA) PEMs were prepared through layer-by-layer assembly. The property was modulated by simply changing the position of graphene oxide. It was found that when the graphene oxide layer was closer to the surface, the neurogenesis of MSC on the PEMs was significantly enhanced in terms of expressions of nestin and β3-tubulin.In order to study the combinational effect of alendronate sodium (Aln) and modulus on osteogenesis of MSC, gelatin-based hydrogels with defined stiffness (4 and 40kPa) and Aln density (0,0.2 and 4 μM) were successfully prepared by radical polymerization. The differentiation behavior of MSC was studied on these hydrogels in terms of expressions of alkaline phosphatase (ALP), collagen type I (COL) and osteocalcin (OCN), and calcium deposition. It was found that enhancing the stiffness and Aln density could improve osteogenesis of mesenchymal stem cells synergistically, and the osteo-inductive effect of Aln and higher modulus of the substrate was comparable to some extent.The interaction between extracellular environment and cells is focusing on the interaction between MSC and matrix, meanwhile cellular uptake of nanoparticles facilitates the direct interaction between materials and intracellular components. Therefore, the differentiation behavior of MSC was studied after internalization of bovine serum albumin coated poly(lactide-co-glycolide) (PLGA-BSA) particles. The results showed that after internalization of PLGA-BSA particles, ALP activity was significantly increased, and expressions of COL and OCN at mRNA and protein levels were promoted. Meanwhile, the adipogenic differentiation was impaired as evidenced by the down-regulated expression of lipoprotein lipase (LPL) at mRNA and protein levels. Therefore, internalization of PLGA-BSA particles promotes osteogenesis but impairs adipogenesis.In order to study the influence of in situ magnetic response on MSC differentiation after cellular uptake, hybrid BSA particles with different saturation magnetization were prepared by coprecipitation. After co-incubation with these particles for 24 h, the magnetic field was applied to study the MSC behavior. It was found that employing the magnetic field could suppress the proliferation behavior of MSC after internalization of magnetic particles (FB3.4 and FB13.6). Furthermore, applying the magnetic field could promote osteogenesis of MSC in terms of ALP activity, expressions of COL and OCN, and calcium deposition. Therefore, osteogenesis of MSC can be improved after internalization of magnetic particles by applying static magnetic field. |
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