[Role of biological protective dressing in microskin grafting in rabbit]

To study the effect of biological protective dressing made from porcine peritoneum in covering wounds with microskin grafts.

Twenty New Zealand rabbits were divided into ten couples according to the random number table. Rabbits in each couple underwent surgery at the same time. A piece of full-thickness skin of 5 cm in diameter was removed symmetrically from the left and right sides of the back of each rabbit, thus forming two wounds with full-thickness skin defect. One fifth of one piece of skin of one rabbit was cut into tiny pieces of 0.2-0.5 mm in size (microskin). Then the microskin pieces were spread on the two wounds of the donor rabbit with the microskin/wound area ratio 1:10. The two wounds of each rabbit covered with microskin were divided into two groups according to the random number table. One wound was covered with biological protective dressing prepared with porcine peritoneum as experiment group, and the other was covered with the rest allograft in full size obtained from the other rabbit of each couple as control group. The general condition of wound was observed at post operation week (POW) 1-4. Wound healing rate was calculated at POW 3 and 4. Wound healing time was recorded. Specimens were harvested from wounds for histological observation at POW 1-4. Data were processed with paired t test.

(1) At POW 1, the biological protective dressings were found to attach firmly to the wounds in experiment group without obvious inflammatory response; the allografts survived well on the wounds in control group. At POW 2, the coverings attached well to the wounds of both groups, but became drier and darker as compared with those at POW 1. At POW 3, some wounds of the two groups healed when the coverings desiccated and separated. At POW 4, all the wounds of both groups healed without obvious difference in appearance. (2) The wound healing rates of the experiment and control groups were respectively (92.8 ± 6.2)% and (91.3 ± 7.3)% (t = 0.54, P > 0.05) at POW 3 and (98.1 ± 2.3)% and (97.0 ± 4.6)% (t = 0.38, P > 0.05) at POW 4. (3) The wound healing time was (25.0 ± 3.9) d in experiment group and (24.8 ± 2.3) d in control group. The difference between them was not statistically significant (t = 0.82, P > 0.05). (4) Histological observation showed that wounds of the two groups were all infiltrated by inflammatory cells, and new blood vessels were observed at POW 1 and 2. The survived microskin proliferated under the coverings. At POW 3 and 4, the coverings on the wounds of two groups were gradually degenerated and became necrotic and separated from the wound beds, while the wounds underneath were re-epithelialized.

The effect of biological protective dressing in covering wounds grafted with microskin is as good as that of the allograft, as they both help the auto-microskin proliferate and repair the wound. It could be considered to be new biological material for clinical application.