In vivo regenerative strategies: use of adult stem cells and platlet-rich plasma in lesioned flexor tendons.

Injection of mesenchymal stem cells (MSC) and/or platelet rich plasma (PRP) into the core of a damaged tendon aims to take maximal advantage of reparative mechanisms that occur naturally in the animal body. In this study we examined the effects of autologous MSC derived from peripheral blood (PB-MSC), PRP and a combination of both for improving the regeneration of experimentally lesioned digital flexor tendons of sheep. Success of applications was evaluated at 30 and 120 days post treatments comparing clinical, histo- and immunohistochemical features. Concerning tendon morphology and extracellular matrix composition significant differences were found between all treated groups and their corresponding controls (placebo). However, our results indicate that the combined use of PRP and MSC did not produce a synergistic regenerative response whereas stressed the predominant positive effect of MSC on healing of tendons.