RESUMO
OBJECTIVES: This study aims to compare the histological healing process and gene expression profile in tendon after the administration of human recombinant epidermal growth factor (hrEGF) and platelet-rich plasma (PRP). MATERIALS AND METHODS: A total of 24 mature New Zealand white rabbits (6-month-old; weight 2.5-3.0 kg) were used in the study. Patellar tendons of rabbits were tenotomized and then repaired. Rabbits were separated into three groups and repair areas were injected with 1 mL hrEGF in group 1 (n=9) and 1 mL PRP in group 2 (n=9). No injection was performed in group 3 (controls, n=6). Tissue samples were obtained from the repaired patellar tendons of three rabbits each from groups 1 and 2 and of two rabbits from group 3 at the end of the first, second, and fourth weeks, and these tissues were histologically and genetically assessed. Expression levels of tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, IL-8, and chemokine receptors (CXCR1, CXCR2) were examined. RESULTS: The frequency of neovascularization was detected to be higher in group 1 compared to group 3 at the end of the second and fourth weeks (p=0.018 and p=0.009, respectively). Group 1 was detected to show more increase in terms of the prevalence of tenocytes (p=0.014 and p=0.009, respectively) at the end of the second week, and in terms of collagen intensity at the end of the fourth week (p=0.0018 and p=0.034, respectively) compared to groups 2 and 3. Highest levels of TNF-α, IL-6, and IL-8 were detected in group 1, followed by groups 2 and 3 at all time points. Highest CXCR2 gene expression was detected in group 1. CONCLUSION: Compared to PRP, hrEGF caused more increase in healing tissue at neovascularization, tenocyte, fibroblast, collagen, and tissue macrophage levels; and higher levels of TNF-α, IL-6, IL8, and CXCR2. Intralesional hrEGF administration can effectively accelerate tendon healing.