EFFECTS OF BONE MARROW-DERIVED MESENCHYMAL STEM CELLS (BMSCS) ON EARLY STAGES OF DDF TENDON INJURIES REPAIR IN RABBITS: A BIOMECHANICAL AND IMMUNOHISTOCHEMICAL STUDY

Injuries to tendons are among the most common injuries to body. A repaired tendon needs to be immobilized for weeks until it has accrued enough strength to handle physiological loads. Tissue-engineered cell therapies offer many new treatment options for repair of diseased and damaged tissues. The present study aimed to investigate the effect of intratendinous injection of bMSCs on the rate and extent of early stages of tendon healing after primary repair in a rabbit model. Twenty seven skeletally mature New Zealand white rabbits weighing 1.8- 2.5 kg were used. Twenty rabbits were used as the experimental animals, and seven others were used as a source of allogenic bMSCs. Under general anesthesia an experimental tenotomy was made through the midsubstance of the DDF tendon. The transected tendon was immediately repaired with use of a locking-loop suture. No treatment was given to the control group. In the treatment group, bMSCs injected intartendinously at the repair site as well as externally around the repair site. The operated limbs were immobilized for two weeks post operatively. Samples from operated tendons were harvested at weeks of three of operation for biomechanical (tensile strength, yield point and stiffness) and immunohistochemical (type and extent of produced collagens) evaluations. Biomechanical findings revealed that there were significant improvements in biomechanical properties such as tensile strength and yield point (P<0.05). Immunohistochemical findings showed that three weeks after surgery production of collagen type Ι around the repair site in the bMSCs treated group was significantly denser and more regular than in the control group. Intratendinous application of bone marrow-derived mesenchymal stem cells following primary tendon repair can significantly improve the biomechanical and immunohistochemical parameters in the early stage of tendon healing. Early time period during tendon healing is crucial in the treatment of tendon injuries.