Histopathological study of granulation tissue of chronic wounds modulated by intermittent negative pressure therapy under limited access dressing

Aim: Negative pressure wound therapy (NPWT) has achieved widespread success in the treatment of chronic wounds. However, its effects have been only partially explored, and investigations have generally concentrated on the wound‑dressing interface; a detailed histopathological description of the evolution of wounds under NPWT is still lacking. The present study was performed to investigate the effect of a limited access dressing (LAD) which exerts intermittent NPWT in a moist environment on chronic wounds. Methods: A total of 140 patients were randomized into 2 groups: LAD group (n = 64)and conventional dressing group (n = 76). By histopathological analysis of the granulation tissue, the amount of inflammatory infiltrate, necrotic tissue, angiogenesis, and extracellular matrix (ECM) deposition was studied and compared to determine healing between the 2 groups. Results: After 10 days of treatment, histopathological analysis showed a significant decrease in necrotic tissue with LAD compared to the conventional dressing group (mean ± standard error, 11.5 ± 0.48 vs. 10.1 ± 0.30; P = 0.007), the number of inflammatory cells (12.6 ± 0.60 vs. 8.63 ± 0.35; P = 0.018), a significant increase in new blood vessels (12.8 ± 0.58 vs. 9.3 ± 0.29; P = 0.005) and ECM deposit (13.3 ± 0.50 vs. 9.6 ± 0.24; P = 0.001). Conclusion: LAD exerts its beneficial effects on chronic wound healing by decreasing the amount of necrotic tissue and inflammatory cells while increasing the amount of ECM deposition and angiogenesis.