Effect of epidermal growth factor (EGF) on blood flow and albumin extravasation in experimental granulation tissue

This work was prompted by an earlier observation according to which daily local administration of epidermal growth factor (EGF) enhances granulation tissue formation. Effects of EGF on blood flow and albumin extravasation in developing granulation tissue and various skin regions were studied in the rat. Cylindrical hollow cellulose sponge implants were used as an inductive matrix for the growth of granulation tissue. In the test group the implants were injected daily with a solution containing 5 micrograms of EGF in 0.1% albumin while the implants of the control group were treated correspondingly with the carrier solution only. Analyses of local blood flow and albumin extravasation were made 7 days after implantation. In EGF-treated rats granulation tissue blood flow was significantly higher than that in control rats. In both groups blood flow values of the incision scar region were significantly higher than those of the lumbar skin, but no inter-group differences were detected. In implants injected with EGF the albumin extravasation clearly exceeded that of control implants. Albumin extravasation in the incision scar region was higher than that in the lumbar skin in both groups. Elevated local blood flow and increased albumin extravasation as a possible sign of enhanced neovascularization and augmented inflammatory response may partly explain the accelerated repair observed in EGF-treated wounds.