Hyaluronic Acid and Re-epithelialization
Hyaluronic acid (hyaluronan, HA) is a large glycosaminoglycan and an essential extracellular component of skin It is active throughout the entire process of wound healing being involved in proliferation, migration, and tissue remodelling.
Wound healing is a complex biological process defined as barrier restoration, involving cross-talk between keratinocytes, fibroblasts, and immune cells.
Erika Nyman published 2019 this interesting study in which he investigated the influence of exogenous HA on re-epithelialization, erythema, and protein expression in a minimally invasive in vivo human deep dermal incisional wound model. The experimental hypothesis was that HA accelerates complete reepithelialisation, which is the primary endpoint.
All 10 subjects completed the investigation, and no unexpected skin reactions or adverse events were reported.
A total of 8 standardized deep dermal incisional wounds (depth 1.6mm, width 1.8mm) per subject were induced in 10 healthy volunteers. Two of the wound sites per subject were pre-treated with injections of HA and 2 with saline solution. At 2 time points (24 hours and 14 days), 2 biopsies for each treatment group (one for histology and one for proteomics) were taken. Skin erythema was measured at 24-hour intervals for 14 days as a surrogate measurement of inflammation. The wounds and biopsy specimens were intended to be as small as possible to minimize scarring.
The biopsies showed that wounds treated with HA showed a complete re-epithelialization at 24 hours in 8 of 9 wounds. No re-epithelialization could be seen in the group with wounds that were injected with saline solution. At 24 hours, most of the cells seen in the wound histologically were assessed to be red blood cells and inflammatory cells. After 14 days, a clearly visible dermal scar with few remaining inflammatory cells was noted and all wounds in both groups were re-epithelialized.
The study demonstrated that the wounds treated with exogenous HA had an accelerated reepithelialisation and an altered protein expression compared with wounds treated with saline solution. The histological results showed that injection of HA had a positive effect on re-epithelialization that was not seen after saline solution injections. These results supported the hypothesis that HA stimulated migration and proliferation of keratinocytes
Nyman and Coll concluded that exogenous intradermal HA accelerates re-epithelialization and alters protein expression in human in vivo deep dermal skin wounds.
Further studies will focus on addressing the dermal component of wound healing after treatment with HA and analysing protein concentrations from individual samples and interpreting of altered proteins.