Abstract: Abstract:Objective To isolate mesenchymal stem cells (MSCs) from the amniotic membrane of human term placenta or  the femur and tibia of Wistar rats and to study the methods of isolation and cultivation,biological characteristics,surface markers and multidirectional differentiation potential of human placenta-derived  MSCs(HPMSCs) and rat bone marrow mesenchymal stem cells(BMSCs). Methods The  HPMSCs were isolated from human term placenta tissue by digestion of collagenase Ⅱ.The BMSCs from the femur and tibia of Wistar rats aged 4  weeks were isolated,cultured and purified by the whole bone marrow adherence method. The proliferation ability was detected by living cell number counting method. The positive expression rates of the surface markers of two kinds of  cells were detected by flow cytometry. The cells were induced into osteoblasts with dexamethasone,vintamin C, and β sodium glycerophosphate; and they were also induced into adipocytes with insulin,dexamethasone,IBMX, and indometacin. After induction,the cells were observed by alizarin red staining and oil red O  staining. Results HPMSCs  were spindle-shaped adherent cells  with  strong proliferation ability.The positive expression rates of CD44 and CD34 were 94.45% and 1.67%，respectively.The MSCs isolated from the femur and tibia of rats were rounded,spindle-shaped and polygonal adherent cells with strong proliferation ability.The positive expression rates of CD44 and CD34 were 93.10% and 2.68%,respectively. After induction,the results of  alizarin red staining and oil red O staining  were both positive.Conclusion HPMSCs have similar biological characteristics to rat BMSCs. They also have multidirectional differentiation potential,but HPMSCs have stronger proliferation ability.

Key words: human placenta-derived mesenchymal stem cells, bone marrow mesenchymal , stem cells, surface markers, multi-directional differentiation capacity