Figure 2.

A, Proliferation rate of bone marrow mesenchymal stem cells (BMSCs) stimulated with LIPUS in 10, 30, 50, 70 mW/cm², respectively, was analyzed using the Cell Counting Kit‐8 (CCK‐8). After the incubation with CKK‐8 solution, the absorbance of the collected medium was measured at 450 nm. All the absorbance rates are expressed as percent of the absorbance rate of control group (without LIPUS stimulation), which was set as 100%. Data were obtained from three different cultures and are expressed as mean ± SD BMSCs cell culture obtained the highest level of proliferation rate under 50 mW/cm² LIPUS stimulation for 3 days, 3 minutes per day (P < 0.01 compared with 30 mW/cm² LIPUS stimulation group and 10 mW/cm² LIPUS stimulation group; P < 0.05 compared with 70 mW/cm² LIPUS stimulation group). B, Population doubling time of BMSCs in each group. Doubling time at passage 3 was compared between LIPUS group and control group, values are expressed as means ± SEM; n = 12 per group, P < 0.05. C‐E, TUNEL analysis of BMSCs in control group and LIPUS group. Four sets of pictures in each control group (C) and LIPUS group (D) were analyzed. Every set included three pictures: one for merged picture, green represented the apoptotic cells, while blue stands for all cells. No significant difference was found between control group and experimental group, P > 0.05 (E)