Immunohistochemical Insights into Enhanced Burn Wound Healing by Poly(vinyl alcohol)/Gentamicin and Poly(vinyl alcohol)/Chitosan/Gentamicin Hydrogels

Novel poly (vinyl alcohol) (PVA)/gentamicin (Gent) and PVA/chitosan (CHI)/Gent hydrogels have previously demonstrated improved burn wound healing in a rat model, based on clinical assessment and histological analysis. This study aims to provide immunohistochemical insight into the effects of PVA/Gent and PVA/CHI/Gent on burn wound healing by analyzing markers of macrophage presence (CD68), angiogenesis (VEGF and ESM1), proliferation (Ki-67), and apoptosis (TUNEL) on post-burn days 3, 7, 14 and 21. Both hydrogels increased macrophage presence, with PVA/CHI/Gent producing earlier effects. Angiogenesis was more pronounced in the PVA/CHI/Gent-treated group, in terms of both the number of VEGF+ cells and the relative density of blood vessels (ESM1), while PVA/Gent generally exceeded the control values without significant differences. On day 21, macrophage presence and angiogenesis were reduced in the treated groups, with significantly higher values in the control group. Proliferation was greater in the treated groups during the early healing phase (on days 3 and 7), whereas it was predominant in the control group during the later stages (on days 14 and 21). Conversely, apoptosis was predominant in the control group at the first three time points; however, by day 21, it was more pronounced in the treated groups, particularly in the PVA/CHI/Gent-treated group. Overall, both hydrogels showed similar temporal cellular and tissue responses, but PVA/CHI/Gent induced earlier and more sustained effects and demonstrated superior pro-angiogenic activity.