The effects of platelet-rich plasma on bone marrow stromal cell transplants for tendon healing in vitro

Purpose In this study, we investigated the effect of platelet-rich plasma (PRP) and bone marrowderived stromal cell (BMSC)seeded interposition in an in vitro canine tendon repair model. Methods Bone marrow, peripheral blood, and tendons were harvested from mixed-breed dogs. Bone marrowderived stromal cells were cultured and passaged from adherent cells of bone marrow suspension. Platelet-rich plasma was purified from peripheral blood using a commercial kit. A total of 192 flexor digitorum profundus tendons were used for the study. Tendons repaired with a simple suture were used as a control group. In treatment groups, a collagen gel patch was interposed at the tendon repair site before suture. There were 3 treatment groups, according to the type of collagen patch: a patch with PRP, a patch with BMSC, and a patch with PRP and BMSC. The repaired tendons were evaluated by biomechanical testing and by histological survey after 2 and 4 weeks in tissue culture. To evaluate viability, cells were labeled with PKH26 red fluorescent cell linker (Sigma, St. Louis, MO) and surveyed under confocal microscopy after culture. Results The maximum breaking strength and stiffness of the healing tendons with the BMSC-seeded PRP patch were significantly higher than those of the healing tendons without a patch or with a cell-seeded patch (p < .02). Viable BMSCs were present at both 2 and 4 weeks. Conclusions Platelet-rich plasma enhanced the effect of BMSC-seeded collagen gel interposition in this in vitro model. Based on these results, we now plan to investigate this effect in vivo.