Low-level laser and chitosan nanoparticles therapy speeds up the process of skin wound healing in mice: histological, hematological, and proinflammatory cytokines assessment

Abstract Background The combination of low level laser therapy (LLLT) and nano-sized particles (NPs) of chitosan (Chit) is hypothesized to be more effective in skin wound healing. A total of 63 CD1 mice were divided into the normal group and injured mice groups that were subjected to a 21-day therapy course of laser exposure (650 ± 5 nm, power density 180 mw/cm 2 ), topically applied 2% Chit NPs and a combination of both. Results On day 21, the wound healing rate reached 100% in mice treated by laser plus Chit NPs while other single treatments did not reach this record. After 48 h, therapy with laser plus Chit NPs significantly enhanced re-epithelization, granulation, inflammation, and angiogenesis scores compared to the non-treated wound group. After 21 days, the other single treatments showed improvements to some histological parameters, but the combined treatment exhibited complete epidermal remodeling with a decrease in inflammatory exudate. During the late phase, the count of RBCs and hemoglobin% was significantly increased in the treated group of laser plus Chit NPs. In contrast, the differential count of neutrophils, lymphocytes, and monocytes was markedly lower than in the untreated wound group. Within 48 h, the group that received laser plus Chit NPs treatment showed a significant ( P < 0.001) decrease in the elevated serum levels of TNF-α and IL-1β compared to the non-treated wound group. Conclusions Therapy by laser or Chit NPs alone showed beneficial effects, but a combination of both accelerated the wound healing rate and displayed the highest improved lesion score.