Influence of growth factors erythropoietin and granulocyte macrophage colony stimulating factor on mechanical strength and healing of colonic anastomoses in rats

Objective: To find out what influence erythropoietin and granulocyte macrophage colony stimulating factor (GM‐CSF) had on the healing of left colonic anastomoses in rats. Design: Experimental study. Setting: University hospital of Ioannina, Greece. Animals: 40 rats. Interventions: An end to end anastomosis was created in the left colon. The rats in the experimental groups were treated with erythropoietin, or GM‐CSF, or the two in combination. Main outcome measures: Tensile breaking strength of the anastomosis, histological characteristics of the anastomosed segment, changes in body weight, and packed cell volume (PCV) during the experiment. Results: The tensile breaking strength of the anastomosis on the seventh postoperative day was significantly greater in the erythropoietin group (mean 2.18N, 95% confidence interval (CI) 0.12N, p 0.0004) than in the control group (mean 1.60N, 95% CI 0.12N). It did not differ from the GM‐CSF groups (mean 1.67N, 95% CI 0.21N, p 0.68) or erythropoietin GM‐CSF (mean 1.67N, 95% CI 0.11N, p 0.44). The PCV was significantly higher in the two groups given erythropoietin (p < 0.001) but not in the GM‐CSF group (p 0.8) while that in the control group was significantly lower (p < 0.001). The body weight followed the same pattern, being significantly more in the two groups given erythropoietin (p = 0.03 and 0.003) but not in controls (p = 0.09) or the GM‐CSF group (p = 0.2). Conclusions: Erythropoietin enhances the healing of anastomosis in rat colon by increasing the number of fibroblasts and accelerating the maturation of new vessels. Copyright © 1999 Taylor and Francis Ltd.