Effect of type I collagen on the adhesion, proliferation, and osteoblastic gene expression of bone marrow-derived mesenchymal stem cells

Objective: To investigate the effects of porous poly lactide-co-glycolide （PLGA） modified by type I collagen on the adhesion, proliferation, and differentiation of rabbit marrow-derived mesenchymal stem cells （MSCs）. Methods: The third generation MSCs isolated from mature rabbits by density gradient centrifugation were cultured at different initial concentrations on （0.3 cm）×（1.2 cm）×（2.0 cm） 3-D porous PLGA coated by type I collagen in RPMI 1640 containing 10% fetal calf serum, while cultured on PLGA without type I collagen as control. The cells adhesive and proliferative behavior at 7, 14, and 21 days after inoculation was assessed by determining the incorporation rate of [3H]-TdR. In order to examine MSCs differentiation, the expression of osteoblasts marker genes, osteocalcin （OCN）, alkaline phosphatase （ALP）, osteopontin （OPN） mRNA, were evaluated by reverse transcription-polymerase chain reaction （RT-PCR）, and further more, the cell morphology at 21 days was also observed by scanning electron microscope （SEM）. Results: Type I collagen promoted cell adhesion on PLGA. The valve was significantly higher than controls (6 h, 2144 cpm±141cpm vs. 1797 cpm±118 cpm, P=（0.017）; 8 h, 2311 cpm±（113 cpm） vs. 1891 cpm±103 cpm, P=（0.01）). The cells which cultured on PLGA coated with type I collagen showed significantly higher cell proliferation than controls on the 7th day (（1021 cpm）±159 cpm vs. 451 cpm±67 cpm, P=（0.002）), the 14th day (1472 cpm±（82 cpm） vs. 583 cpm±67 cpm, P<（0.001）) and 21th day (1728 cpm±78 cpm vs. 632 cpm±55 cpm, P<（0.001）). Osteoblasts markers, OCN, ALP, OPN mRNA, were all detected on PLGA coated by type I collagen on the 21th day, but OCN, OPN mRNA could not be found in controls. Spindle and polygonal cells well distributed on the polymer coated by type I collagen while cylindric or round cells in controls. Conclusions: Type I collagen is effective in promoting the adhesion, proliferation and differentiation of MSCs on PLGA.