Pressure effects on angiogenesis and tissue proliferation in NPWT-treated wounds

Background Negative - pressure wound therapy (NPWT) has shown efficacy in promoting wound healing in clinical settings. The therapeutic effect of NPWT varies with the value of negative pressure. We hypothesized that this might be a result of the regulation of wound healing and associated cytokines to varying extents induced by different negative pressures. Methods The full-thickness skin defect rat model was constructed, and then treated with NPWT at -75, -125, and − 300 mmHg for 4, 7, 10, and 14 days. Wound closure area, bacterial content (cfu/g), and blood perfusion were measured. After 7 days of treatment, wound rim tissues were analyzed by immunohistochemistry for VEGF, bFGF, Ang 1/2, CD34, α-SMA, Bcl-2, Bax, and caspase 3 expression. Results NPWT contributed to an increase in wound closure area, a decrease in bacterial content in the wound, and an increase in wound blood perfusion at the late stage (7–14 days) of wound healing. In particular, NPWT at -125 mmHg exhibited the strongest effect, followed by -300 mmHg. Furthermore, NPWT at -125 mmHg remarkably upregulated the expression of vascular endothelial growth factor, basic fibroblast growth factor, angiotensin 2, and Bcl-2 while downregulating that of Bax and caspase 3. NPWT at -300 mmHg showed slightly weaker effects than at -125 mmHg. Conclusions These findings verified our hypothesis that the therapeutic effects of NPWT at different negative pressures are associated with the varying - extent modulation of angiogenesis and apoptosis - related cytokines.