OBJECTIVEThis study was to investigate the growth and proliferation characteristics of rat bone mesenchymal stem cells (BMSCs) isolated by the method of whole bone marrow culture and to explore the effect of cell inoculation density and incubation period on cell proliferation, with an aim to provide multipotential seed cells for preventing from degenerative disease.

METHODSBone mesenchymal stem cells were isolated by the method of whole bone marrow culture and then cultured in vitro. The cell morphologic features were observed by inverted microscope. The cell surface antigens were identified by flow cytometry. The effect of cell inoculation density and culture period on cell growth and proliferation was explored by analyzing the characteristics of a ten-day cell growth curve in 96-well plates.

RESULTSFlow cytometry results showed the detection rates for CD29, CD34 and CD45 were 97.68% (7607/7788), 7.93% (661/8340) and 2.76% (215/7788) respectively, which was consistent with the expression characteristics of BMSCs surface antigens. BMSCs became uniform after three cell passages, existing in a typical shape of whirlpool or radial colony. The senescent cells started to appear at 7(th) passage, and more senescent cells were found at 10(th) passage. The growth curve for moderate inoculation density was typically S-shaped. Lag phase was found during the first two days, and logarithm growth phase was in the following three days. Plateau phase started from the 6(th) day and cell numbers decreased slightly from the 8(th) day.

CONCLUSIONThe whole bone marrow culture is an effective way to obtain BMSCs. A moderate inoculation density was more advantageous to cell proliferation, by which more seed cells could be obtained.