15.Radiation survival and colony size of human epidermal keratinocytes in the presence of keratinocyte growth factor (rhKGF)

Abstract

The capacity of recombinant human keratinocyte growth factor (rhKGF) to ameliorate the radiation response of mouse oral mucosa and other epithelial tissues was recently reported. However, the exact mechanisms of action of KGF remain unclear. The aim of the present study was to investigate the effect of rhKGF on survival and colony size of normal human epidermal keratinocytes in vitro. Primary human neonatal keratinocytes (HEKn) were irradiated with doses of 0 Gy and 2 Gy (200 kV X-rays) and incubated in the presence or absence of 100ng/ml rhKGF. Plating efficiency (PE) and surviving fraction (SF2) were determined in a clonogenic assay. In cell cultures without rhKGF the mean PE was 4.6%. Irradiation with 2 Gy resulted in a SF2 of 51%. In cell cultures with rhKGF, the mean PE was identical (4.6%). After irradiation with 2 Gy, a similar SF2 of 54% was observed, indicating that KGF did not change the survival characteristics of HEKn keratinocytes. Individual colony size, however, in all cultures incubated with rhKGF was significantly increased compared to incubation without rhKGF. The number of extremely large colonies (□2 mm) was clearly higher (p=0.0000) with rhKGF-containing culture medium. In conclusion, rhKGF does not affect keratinocyte survival after irradiation, but stimulates proliferation of surviving cells.