OBJECTIVETo evaluate the potential effects of uncultured adipose-derived stromal vascular fraction on tendon healing.

METHODSTwenty 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. The injury model was completed by unilateral 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 treatment and control groups, respectively. Immobilization with cast was continued for two weeks after surgery. Animals were sacrificed at eight weeks after surgery and tendons underwent histological, immunohistochemical, and mechanical evaluations. Statistical analyses of quantitative and qualitative data were assessed using one-way analysis of variance and Mann-Whitney U-test, respectively.

RESULTSHistological evaluations demonstrated superior fibrillar linearity and continuity, and decreased vascularity in treatment group indicated improved organization and remodeling of neotendons. Immunohistochemistry de- monstrated a significant increase in collagen I expression in treatment group. Ultimate load and energy absorption capacity were both significantly increased in cell-treated repairs compared with controls.

CONCLUSIONThe present study shows that intratendinous injection of uncultured adipose-derived stromal vascular fraction results in improved structural and mechanical properties of tendon repairs and it could be an effective modality for treating tendon injury.