Objective: Tendon injuries are major cause of orthopaedic injuries in athletic horses. Tissue engineering (TE) provides an alternative method for managing these disorders. One of the major challenges in TE is the fabrication of a suitable scaffold that can provide proper niche for cells (such as mesenchymal stem cells) and three- dimensional structure. Among biological scaffolds, the use of decellularized tendons represent a good approach to regenerative medicine. Thus, this study aimed to decellulrize equine superficial digita flexor tendon (SDFT) for obtaining an efficient scaffold. Materials and Method: Equine SDFT was aseptically harvested from the forelimb of a 1.5 aged horse which euthanized for conditions unrelated to musculoskeletal disease. 10 cm pieces in length of tendon were divided into 2 groups as control and treatment. Samples was decellularized using 4 freeze-thaw cycles followed by 48h incubation in 1 M Tris–HCl (pH 7.8) combined with 1% sodium dodecyl sulfate (SDS), 10 mg/ml DNase-I under continuous agitation at 4˚C. Samples were embedded in paraffin, longitudinally sectioned into 5 μm slices, and stained with H&E and Masson’s trichrome to assess cells and morphological extracellular matrix. Results: The histological results demonstrated very few visible nuclei in treatment group compared with control along with a small increase inporosity and maintenance of collagen content following decellularization. This condition provides a physical environment similar to native tendon with minimal residual cellular debris which can be used as a therapeutic graft material. Conclusions: The results showed that the modified freeze-thaw method could provide a decellularized SDF tendon which can be used as a suitable scaffold in equine tenogenic differentiation studies and for treatment of tendon disorders.

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