The effects of bone marrow stromal cell transplants on tendon healing in vitro.

The purpose of this study was to investigate the effect of bone marrow stromal cells (BMSCs) on tendon healing in a canine ex vivo model. Bone marrow was harvested and BMSCs were isolated and cultured according to established protocols. Cells were seeded into 0.5mg/ml collagen gels and cultured for 24h to allow gel contraction, and then implanted between the lacerated ends of repaired flexor digitorum profundus tendons. Tendons repaired with a gel patch alone and without a gel patch served as control groups. After 2 and 4 weeks in culture, the repaired tendons were evaluated for breaking strength and stiffness. Cell viability was assessed by labeling the cells with PKH26 red fluorescent cell linker. The maximal strength and stiffness of repaired tendons with the BMSC-seeded patch were significantly higher than the repaired tendons without a patch or with a patch without cells, at both 2 and 4 weeks (p<0.05). Viable BMSC were present between the cut tendon ends at both 2 and 4 weeks. We conclude that BMSC-seeded gel patch transplantation has the potential to enhance flexor tendon healing, and we plan to investigate this effect in vivo.