Biological characteristics and multi-directional differentiation results of human adipose-derived stem cells  After primary cultured for 6 hours, a small amount of fibroblast-like cells began to scatter and adherent and most of the un-adherent cells were spherical or circular blood cells. After cultured for 24 hours, most of the adherent cells were presented as large and flat fibroblast-like cells, and a small amount of triangular and polygonal cells were observed. Additionally, the cells in the colony were spindle shaped. After cultured for 6-8 days, the cells could form 80%-90% confluent dense layer, and after cultured for 9-10 days, the cells could form 100% confluent dense monolayer. After passage, the morphology of the cells was spindle, a small amount of cells were triangular or polygonal, (Figure 1A). The growth speed of the cells after passage was faster than that before passage; the average doubling time was about 40 hours, and there was no significant change in the morphology of the cells in each generation, while the CD29 and CD44 immunofluorescence staining of passage three adipose-derived stem cells was positive (Figures 1B, C). After adipogenic induction for 14 days, translucent lipid droplets could be observed in the passage three adipose-derived stem cells, and the lipid droplets were red with oil red O staining (Figure 2); after chondrogenic induction for 14 days, highly aggregated cell mass were observed with patchy or nodular shape, and the surrounding cells were in radial-type; the nodules were large and visible; alcian blue staining showed the nodules and the surrounding gathered cells were blue (Figure 3)."

Effect of ginsenoside Rb1 on the proliferation of human adipose-derived stem cells The ginsenoside Rb1 could decrease the proliferative capacity of human adipose-derived stem cells and showed a time- and dose-dependent manner. Ginsenoside Rb1 (0.5 μmol/L) had significant promotion effect on the proliferation of human adipose-derived stem cells, and after cultured for 7 days, the cell growth reached plateau phase. With the increasing of the concentration of ginsenoside Rb1, the mitogenic activity was decreased gradually; 6.0 μmol/L ginsenoside Rb1 had significant inhibition effect on the proliferation. 2,3-bis-(2-methoxy-4-nitro-5-sulphenyl)- (2H)-tetrazolium-5-carboxanilide detection showed after cultured for 5, 7 and 9 days, the absorbance value in the 0.5 μmol/L and 1.0 μmol/L groups was significantly higher than that in the control group (P < 0.05), while the absorbance value in the 4.0 μmol/L and 6.0 μmol/L groups was significantly lower than that in the control group (P < 0.05; Figure 4)."

Effect of ginsenoside Rb1 on the alkaline phosphatase activity of human adipose-derived stem cells  Compared with the control group, after cultured for 3 days, 6.0, 4.0 and 2.0 μmol/L ginsenoside Rb1 could increase the alkaline phosphatase activity of human adipose-derived stem cells (P < 0.05); after cultured for 7 days, 6.0, 4.0 and 2.0 μmol/L ginsenoside Rb1 could increase the alkaline phosphatase activity in human adipose-derived stem cells (P < 0.05), it indicated that the effect of ginsenoside Rb1 on the alkaline phosphatase activity of human adipose-derived stem cells was related with the culture time and dose (Figure 5). As alkaline phosphatase was the indicator to evaluate the osteogenic differentiation of mesenchymal stem cells, the results showed that ginsenoside Rb1 had the osteogenic activity that can early promote the oeteogenic differentiation of human adipose-derived stem cells."

Effect of ginsenoside Rb1 on the expression of osteocalcin in human adipose-derived stem cells Osteocalcin is the sign to evaluate the differentiation of mesenchymal stem cells into mature osteoblasts[6]. Compared with the control group, 6.0, 4.0, 2.0, 1.0 and 0.5 μmol/L ginsenoside Rb1 could significantly increase the osteocalcin expression in human adipose-derived stem cells in the middle and advanced stage of osteogenic differentiation (14 and 21 days) (P < 0.05), and the increase degree of 6.0 and 4.0 μmol/L ginsenoside Rb1 was better than that of 2.0, 1.0 and 0.5 μmol/L ginsenoside Rb1 (Figure 6)."

Effect of ginsenoside Rb1 on the formation of calcified nodules in human adipose-derived stem cells Alizarin red staining results showed that after cultured with ginsenoside Rb1 for 28 days, 0.5, 1.0 and  2.0 μmol/L ginsenoside Rb1 could induce cell aggregation-like growth, and promote deposition of extracellular calcium, and the punctate and positive stained calcified nodules could be observed in the center of aggregation growth; 4.0 and 6.0 μmol/L ginsenoside Rb1 had more stronger promotion effect on the formation of calcified nodules, and the formed calcified nodules was larger in number, and the area (clumps shape) of the calcified nodules was larger than former; no calcified nodules formation was observed in the control group, and the cells were not in aggregation growth (Figure 7)."