Effect of poly(D,L-lactic acid), hydroxyapatite, and ozonated saline on the modulation of tissue repair in experimental chronic wounds: an integrated morphological, biochemical, and metabolomic approach

Abstract

Chronic wounds are characterized by persistent inflammation, oxidative stress, and impaired tissue repair. This study evaluated poly(D,L-lactic acid) (PDLLA)- and hydroxyapatite (HA)-containing formulations, ozonized saline solution, and their combinations in Wistar rats with experimentally induced impaired wound healing. Two experimental protocols with different induction and treatment durations were investigated. Treatment responses were assessed through macroscopic wound closure, histological and collagen analyses, redox biomarkers, and untargeted metabolomics of plasma and skin tissue. The PDLLA-containing formulation showed the most consistent macroscopic response, with greater wound closure than the Control group. Semi-quantitative histological analysis revealed no statistically detectable differences among groups at the endpoint, whereas ozone-containing treatments were associated with changes in collagen deposition. Redox analyses showed treatment-specific alterations without a uniform response across treatments. Metabolomics revealed distinct treatment-associated profiles, particularly in plasma samples from ozone-containing groups, involving metabolites related to antioxidant, lipid, sphingolipid, amino acid, purine, and energy metabolism. No statistically significant difference between the experimental protocols was detected for the cumulative macroscopic wound-closure response. Overall, the findings suggest that the evaluated treatments produced distinct and outcome-dependent responses, with the PDLLA-containing formulation showing the most consistent association with wound closure and ozone-containing treatments being associated with specific collagen, redox, and metabolic alterations.