Investigation into the effect of systemic single high-dose erythropoietin on the healing of Achilles tendons in rats

Objective: This study aimed to examine systemic erythropoietin's effect on the Achilles tendon's healing in a rat model. Methods: Twenty-five adult Wistar rats were randomly assigned to one of two groups. The Achilles tendon of each rat was transected 5 mm proximal to its insertion to the calcaneus. All Achilles tendons were then repaired using modified Kessler methods. A single dose (5000 U/kg) of intraperitoneal erythropoietin (EPO) was administered to group I. Group II was a control group and did not receive an EPO injection. Four rats from each group were sacrificed at 1, 3 and 6 weeks after injection. Histopathological assessments were performed by observers blinded to the treatment. Results: Groups I and II showed a similar increase in fibroblast cytoplasmic content and fibrillar collagen in the extracellular matrix. Collagen deposition, cellular proliferation, number of lipid vacuoles and capillary increases were similar between the groups. Conclusion: Evidence from this study has shown no direct effect of a single systemic high dose of EPO on the histological properties of the Achilles tendon in rats.