[Strain-induced tenogenic differentiation of bone marrow mesenchymal stem cells]

To study the possibility of bone marrow mesenchymal stem cells (BMSCs) differentiation into tenocytes (TCs) under strain stimulation by co-culture of BMSCs-small intestinal submucosa (SIS) composites in vitro.

BMSCs were isolated by adherent culture from the bone marrow of 1-week-old SD rats. Inducing method of multiple differentiation and flow cytometry were applied to identify the cells. The stress-strain curve of SIS was measured with Instron machine. Purified BMSCs (2nd passage, 2.5 x 10(5) cells/cm2) were seeded on SIS (3 cm x 1 cm at size) and cultured for 2 days and then continued for another 5 days under strain stimulation (stretching frequency was 0.02 Hz, action time was 15 minutes/hour and 12 hours/day, strain amplitude was 5%) as experimental group, while the BMSCs-SIS composites were sustained static culture as control group. TCs were isolated from tail of 1-week-old SD rats. TCs-SIS composites were cultured under non-strained as positive control group. Scanning electron microscope (SEM) was used to examine the morphological changes of BMSCs after strain stimulation. The contents of Scleraxis and Tenomodulin in supernatant were tested by ELISA kit. Results The BMSCs could be induced to differentiate into osteoblasts and lipocytes, and showed the results of CD34-, CD45-, and CD90+, which were accorded with the biological characteristics of BMSCs. The failure test of SIS showed that the average elastic strain was 39.5%. SEM observation showed that the strain-stimulated BMSCs had the TCs-like morphological characteristics. The contents of Scleraxis and Tenomodulin in supernatant of experimental group, control group, and positive control group were (3.56 +/- 0.91) micromol/L and (4.27 +/- 1.10) micromol/L, (0.23 +/- 0.14) micromol/L and (0.16 +/- 0.10) micromol/L, and (14.73 +/- 2.30) micromol/L and (10.65 +/- 1.51) micromol/L, respectively. There were significant differences among 3 groups (P < 0.05).

Appropriate strain stimulation could induce BMSCs differentiate into TCs, and the best conditions of strain stimulation need more experiments.