Research of arginylglycylaspartic to promote osteogenesis of bone marrow mesenchymal cells on chitosan/hydroxyapatite scaffolds.

A high degree of cell adhesion to a scaffold at the initial stage of cell inoculation is essential to bone tissue engineering. In realising high cell adhesion rate on a scaffold within a few hours, a chitosan/hydroxyapatite (CS/HA) scaffold with a channel/sphere pore was prepared via in situ hybridisation in combination with lyophilisation, in which the HA nanoparticles were dispersed in the CS uniformly. The size of the channel pore and the sphere pore of the CS/HA scaffold was 150 µm to 650 µm and 3 µm to 15 µm, respectively. The compression strength and porosity of the CS/HA scaffold were 3.54 ± 0.32 MPa and 88.4%, respectively. The nitrogen content increased by 7.5% compared with the CS/HA scaffold without Arg-Gly-Asp (RGD) modification. More than 67% of the RGD in the PBS solution diffused into the CS/HA scaffold spontaneously. The effect of the RGD peptide on bone marrow mesenchymal stem cells (MSCs) on the CS/HA scaffold was investigated through cell adhesion rate, alkaline phosphatase (ALP) activity, and mineralised calcium nodules. The cell adhesion rates of the CS/HA scaffold with different RGD concentrations (50, 100 mg/L) were 71.6% and 80.7%, respectively, after 4 hours of culture; the rates were 30.9% and 47.5% higher than that of the CS/HA group (54.7%), respectively. The expressed ALP content of the CS/HA scaffold with RGD (191 ± 6 U/g protein) was 107.7% higher than that (92 ± 9U/g protein) of CS/HA (p<0.01). Furthermore, a higher amount of mineralised calcium nodules with red brown appeared in the CS/HA scaffold with RGD as opposed to that in the CS/HA group. The RGD peptide in the CS/HA scaffold not only achieved high cell adhesion in a short period of time, but also enhanced cell adhesion ability and promoted the MSCs to differentiate from osteoblasts.