P21Cip/WAF1 and P27Kip1 are two important negative regulatory factors of cell cycle. Proliferating cell nuclear antigen (PCNA) is an index reflecting stem cell proliferation.OBJECTIVE:
To study the expression of P21Cip/WAF1, P27Kip1and PCNA gene during differentiation of human bone marrow mensenchymal stem cells (BMSCs) into hepatocytes in vitro.DESIGN, TIME AND SETTING:
The cytology, gene level, observation experiment was conducted at the Laboratory of Linbaixin Medical Institute Center, Second Affiliated Hospital, Sun Yat-sen University from December 2006 to June 2007.MATERIALS:
Bone marrow was collected from healthy donors undergoing bone marrow aspiration at the Second Affiliated Hospital, Sun Yat-sen University.METHODS:
Human BMSCs were isolated by the whole bone marrow adherence method in vitro. At passage 5, BMSCs were incubated in opti-MEM I low-serum medium containing 20 μ g/L hepatocyte growth factor, 10 μ g/L fibroblast growth factor-4 to induce the differentiation into hepatocytes.MAIN OUTCOME MEASURES:
After induction, the expression of P21Cip/WAF1, P27Kip1and PCNA mRNA in BMSCs was detected by RT-PCR.RESULTS:
After BMSCs were induced for 0 day, 1 day, 3 days, 5 days, 7 days, the relative P21Cip/WAF1 mRNA value gradually increased (P < 0.01), but no significant differences in relative P27Kip1 mRNA value (P > 0.05). The relative PCNA mRNA value gradually decreased (P < 0.01), except no significant differences were detected at 0 and 1 day (P > 0.05).CONCLUSION:
Overexpression of P21Cip/WAF1 inhibits BMSC proliferation, and has a regulatory effect during the differentiation of BMSCs into hepatocytes. P27Kip1 may has no effects. PCNA expression has an opposite effect compared to P21Cip/WAF1, resulting in a gradually decreased tendency.