OBJECTIVE The effect of platelet-derived wound healing factor (PDWHF) on wound healing in diabetic rats was studied. METHODS Forty-four male SD rats were randomly divided into 2 groups. Thirty-two rats of experimental group accepted intraperitoneal injection of alloxan (1.5 mg/10 g body weight). Within one or two days after injection, while the blood sugar of the rats was higher than 180 mg/dl, the animal model of diabetic rat should have been established. Then a dorsal incision was given to every rat. After the addition of PDWHF (the experimental group) or bovine albumin (the control group), the incision was sutured up. Seven, ten and fourteen days after operation, the breaking strength of the wound was measured. On another hand, specimen from the wound was taken for the culture of fibroblasts. When the cultured fibroblasts have been incubated with 10% PDWHF for 4, 8 and 12 hours, the procollagen I (alpha 1) mRNA levels were examined respectively, and compared with those of control. RESULTS Significant difference in wound breaking strength had been observed between PDWHF-treated incisions and the control on 7, 10 and 14 days after wounding (P lt; 0.01). Experiment in vitro demonstrated that the procollagen I (alpha 1) mRNA levels in wound fibroblasts incubated with 10% PDWHF for 4, 8 and 12 hours were 0.9, 3.7 and 2.2 folds higher than those in fibroblasts in control. CONCLUSION It was suggested that direct stimulation of procollagen I (alpha 1) gene expression was one of the ways that PDWHF played its role in accelerating wound healing.
It was reported in this article that a preparation of acid/heat-stable peptides (AHSP) from pig serum with a molecular-weight less than 18 ku a without antigenity and toxicity could exert enhancement effect on wound healing. Two pieces of polyvinyl alcohol (PVA) sponge implanted in rat dorsal subcutaneous pouchs of 20 mice were selected as the wound model. The subcutaneous pouch having one piece of sponge was taken as the experimental group and the other as the control. Injection of 50 microliters of such peptide preparation into the test sponge was performed once a day from the time of injury on for 5 consecutive times, while 50 microliters of BSA (5 mg/ml) into the control sponge in the same way. The levels of total DNA, protein and hydroproline in AHSP-treated sponge were observed significantly higher than those in the control sponge on the 7th and 10th days after wounding (P lt; 0.05). No significant difference was seen on the 14th postinjury day (P gt; 0.05). The effect of AHSP on proliferation of wound fibroblast cultured in vitro was also detected. In conclusion, such peptides derived from pig serum had the activity to accelerate wound healing without resultant excessive healing and its direct stimulation of the proliferation of wound fibroblast was probably one of the way which AHSP exerted its action.
Abstract To study the regulation of growth and proliferation of tissue-repair cell from wound microenvironment, the effects of wound fluid (WF) on the growth and proliferation of wound fibroblast were studied in vitro. Thirty rats were divided into 6 groups. On the back of every rat, an incision of 0.5～1.0cm was performed a subcutaneous sac was made by blunt dissection. A piece of sponge was put in, and the wound was sutured. After 1,3,7,9,11,15 days, one group of the rats were sacrificed respectively, and WF was collected from the sponge. Two kinds of medium were made with each WF: 1640+1%FCS+10%WF and1640+10%FCS+10%WF. After 48 hours incubation with newly prepared wound fibroblasts, the growth of the cells was observed. It was shown that (1) Under 1%FCS, WFfrom1,3,7 days stimulated cell proliferation, and WF from 9,11,15 days caused cell death. (2) Under 10%FCS, WF from 9,11,15 days inhibited cell growth. It was suggested that the wound microenvironment stimulated the fibroblasts to proliferate for one week after injury, and beyond that further growth seemed to be arrested, and that there might be some growth inhibitory factors present in the microenvironmentduring the late stage of wound healing.