Objective       To investigate the promotion of type Ⅱ collagen (collagen Ⅱ) on differentiation of rat bone marrow mesenchymal stem cells (BMSCs) into chondrocytes.       Methods       BMSCs

seeded with different concentrations of type Ⅱ collagen (25

50

100 and 200 μg/mL) and control group

were assessed by CCK-8 assay on days 7

14 and 21. qPCR and immunofluorescence assay were used to detect the mRNA and protein expression of collagen Ⅱ

SOX9 and aggrecan in different intervention groups.       Results       CCK-8 assay showed that the cell viability had no significance on days 7

14 and 21 in different intervention groups (P0.05). The mRNA expression of collagen Ⅱ

SOX9 and aggrecan was up-regulated on day 21 (P0.05)

especially those in the 100 μg/mL intervention group most significant (P0.01)

while the mRNA expression in group of 100 μg/mL was highly up-regulated on day 14 (P0.05)

but there was no significance on day 7

compared with control group (P0.05). Immunofluorescence assay results showed that the protein levels of collagen Ⅱ

SOX9 and aggrecan were obviously enhanced in the 100 μg/mL intervention group than the other groups (P0.05).       Conclusion      Collagen Ⅱ promotes rat BMSCs differentiation into chondrocytes in vitro

with the dose of 100 μg/mL having the best efficiency.