Comparison of the effects of systemic and subcutaneous injection of recombinant human erythropoietin on the tissue-healing process in BALB/c Mice

Erythropoietin (EPO) is a glycoprotein hormone that is secreted for biological responses and is regulated by the interaction between EPO and specific cytokine receptors. The EPO is a mediator of angiogenesis and erythropoiesis and can increase several growth factors. The current research aimed to compare the effects of systemic and subcutaneous injection of recombinant human EPO on the tissue-healing process.

For the purposes of the study, 30 male BALB/c mice were selected and divided into three groups. The first one received EPO treatment with systemic injection (n=10) while the second one received EPO treatment with subcutaneous injection (n=10). The third group was the control or placebo group without any treatment (n=10). The biopsies were studied on days 4, 7, 10, and 14 through staining by hematoxylin-eosin and Mallory's trichrome. In each group, 3 mice were sacrificed due to exposure to high doses of anesthetic on days 4 and 7. Moreover, 2 other mice were sacrificed after 10 and 14 days. The collected data and images were analyzed in SPSS (version 18.0) and ImageJ software, respectively. Furthermore, they were analyzed using Wilcoxon signed-rank and analysis of variance tests in. During all the analytical processes, a p-value of <0.05 was considered statistically significant

According to the results, the density of inflammatory cells significantly decreased in EPO-treated groups, compared to the control group. Moreover, the EPO-treated groups underwent an increase regarding the number of fibroblast cells, new capillary formation, and epithelial thickness in the margins of the wound, unlike the control group.

Findings of the present study indicated that the systemic injection of EPO resulted in a better physiological response regarding the acceleration of tissue-healing in comparison with the subcutaneous injection. Furthermore, the systemic injection of EPO improved the parameters related to skin wound repair.