PRP and MSCs on tenocytes artificial wound healing: an in vitro study comparing fresh and frozen PRP

Tendon tissue has poor regenerative capacity due to its low vascularization, cell density and extracellular matrix (ECM) production. Therefore, tendon injuries are an increasing clinical problem because of the formation of scar tissue with traditional therapies. Regenerative medicine aims at triggering a healing response through the use of biological treatments such as mesenchymal stromal cells (MSCs) and growth factors (GFs). MSCs show several advantages in tendon clinical setting, while platelet rich plasma (PRP) has gained popularity because of its high GF concentration, although its applications in the tendon clinical setting are still controversial. The aim of the present study was to evaluate a combined treatment of MSCs and PRP in an in vitro microwound model of tendon injuries. In addition, fresh and frozen PRP were compared. Single human tenocytes cultures or co-cultures with bone marrow derived MSCs (BMSCs) were set up with or without human PRP, fresh or frozen. After 24 hours of culture, it was observed that MSCs alone significantly increased tenocyte migration speed, microwound healing rate, fibronectin, collagen I and aggrecan production. These effects were enhanced by the combination with PRP, fresh being more effective than frozen PRP. In addition, the number of MSCs and tenocytes inside the microwound was significantly increased, especially with fresh PRP. In conclusion, the combination of MSCs and PRP, especially the fresh one, increases tenocytes and MSC migration speed, as well as ECM protein production compared to the use of MSCs alone.