Effects of Uncultured Adipose Derived Stromal Vascular Fraction on Tendon Healing in Rabbits: A Histological and Immunohistochemical Study

Objective- To evaluate the potential effects of uncultured adipose derived stromal vascular fraction on tendon healing. Design- Prospective descriptive study. Animals- Twenty five adult male New Zealand white rabbits, weighing 2.5-3.0 kg were used. Five rabbits were used as donors of adipose tissue and the rest were divided into control and treatment groups. Procedures- The injury model was unilateral complete tenotomy through the middle one third of deep digital flexor tendon. Immediately after suture repair, either fresh stromal vascular fraction from enzymatic digestion of adipose tissue or placebo was intratendinously injected at tendon stumps in treatments and controls, respectively. Immobilization with cast was continued for two weeks after surgery. Animals were sacrificed at three and eight weeks after surgery and tendons underwent histological and immunohistochemical evaluations. Results- By histology, superior fibrillar organization and remodeling of neotendon were observed in response to the treatment at both time points. As the main finding of immunohistochemistry, treatment at the later time point resulted in significant increase in collagen I and decrease in collagen III expression compared to controls. Conclusions and clinical Relevance- The present study showed that intratendinous injection of uncultured adipose derived stromal vascular fraction resulted in improved structural properties of tendon repairs and it could be an effective modality for treating tendon injury.