Granulocyte-colony stimulating factor improves the survival of ischaemic skin flaps by the induction of angiogenesis

In this study the effects of granulocyte-colony stimulating factor (G-CSF) on angiogenesis and the survival of ischaemic skin flaps are evaluated. Thirty adult Wistar rats were equally randomised into three groups. Caudal-based, ischaemic skin flaps of 10 x 3 cm were designed on the back and injected with saline in group I and with 100 mu g/kg G-CSF in groups 2 and 3. The injections were performed just prior to flap elevation in groups 1 and 2 and 2 days earlier in group 3. Peripheral leukocyte counts, tissue myeloperoxidase enzyme assays, necrotic to total flap area ratio (NA/TA) calculations, flap tissue inflammation gradings, immunohistochemical vessel counts, and electron microscopic evaluation of endothelial cells were performed on the 8th day. No significant difference was encountered between the groups in terms of the leukocyte counts, myeloperoxidase enzyme assays and inflammation gradings (P > 0.05), demonstrating the absence of an increased inflammatory response within the flap tissue. The surviving flap portions were observed to be increased with the application of G-CSF. The mean NA/TA results (when measured in situ) were 0.44 +/- 0.13 for group 1, 0.30 +/- 0.17 for group 2, and 0.22 +/- 0.16 for group 3. The difference between groups 1 and 3 was statistically significant (P = 0.009). The mean vessel count was 3.53 +/- 1.20 in group 1, 7.36 +/- 1.41 in group 2 and 7.43 +/- 0.92 in group 3. The differences between groups 1 and 2 and groups 1 and 3 were statistically significant (P <= 0.001). Early apoptotic changes were encountered in the endothelial cells of group 1, while activated and proliferating endothelial cells were seen in groups 2 and 3 with electron microscopy. G-CSF promotes angiogenesis by increasing the number of activated and proliferating endothelial cells within the ischaemic flaps by the resettlement of G-CSF-stimulated endothelial progenitor cells into the ischaemic tissue. The overall result is an improved survival of ischaemic skin flaps. These effects are more pronounced when G-CSF is introduced 2 days prior to flap elevation. (C) 2008 Published by Elsevier Ltd on behalf of British Association of Plastic, Reconstructive and Aesthetic Surgeons.