[Dynamic change of epidermal stem cells in the wound healing course of diabetic rats]

To observe the epidermal width, the amount variation and distribution character of epidermal stem cells(ESCs) and the wound healing rate at different periods of diabetes mellitus(DM) rats after trauma, then to study the correlation of them.

Forty-eight Wistar rats were divided into DM group and normal control group randomly (n=24). The DM rats were induced by streptozocin (STZ) and then made chronic healing wound by special perforex. At the 3rd, 4th, 7th, 14th and 21st days after trauma, the healing rate was calculated, the wound edge and granulation tissue were obtained for haematoxylin-eosin (HE) staining and immunohistochemical staining of keratin 19 (K19) and beta1 integrin. Then the epidermal width, the area and the gradation value of positive unit (PU) were measured.

At the 3rd, 7th, 14th and 21st days after trauma, the wound healing rates of normal rats were 24. 48% +/- 3.37%, 50.46% +/- 1.26%, 92.82% +/- 2.12% and 99.41% +/- 0.66% respectively, while those of DM rats were 2.43% +/- 1.02%, 40.59% +/- 1.65%, 80.77% +/- 3.57% and 85.40% +/- 0.94% respectively, showing significant differences (P < 0.01). Before trauma, there was no significant difference in the epidermal width between normal rats and DM rats (P > 0.05). However, at the 3rd, 7th, 14th and 21st days after trauma, the epidermal widths of normal rats were 26.43 +/- 3.21, 33.29 +/- 3.52, 31.53 +/- 3.35 and 26.01 +/- 3.19 microm respectively, while those of DM rats were 23.58 +/- 2.33, 31.02 +/- 3.38, 33.72 +/- 5.49 and 21.80 +/- 4.02 microm respectively, the epidermal widths in DM rats were significantly lower than those in normal rats (P < 0.01). The average PU value of K19 in normal rats were 91.68%, 93.14%, 72.27% and 70.31% respectively, while those in DM rats were 40.29%, 40.79%, 29.94% and 10.37% respectively. The average PU value of beta1 integrin in normal rats were 49.6%, 91.16, 77.13% and 57.17% respectively, while those in DM rats were 38.94%, 24.16%, 61.36% and 38.83%. The results indicated that the average PU values of K19 and beta1 integrin in DM rats were significantly lower than those in normal rats (P < 0.05).

The amount and activity decrease of ESCs may be one of the important mechanisms of difficult recovering wounds of DM rats.