Wound healing of experimental equine skin wounds and concurrent microbiota in wound dressings following topical propylene glycol gel treatment.

The research explores the effects of a propylene glycol (PG) gel, a common component in topical wound treatments, on healing rates and microbiota changes in experimental horses. It was discovered that applying this gel resulted in slightly slower wound healing rates, altered immune cell presence, and significantly influenced the microbiota diversity in the wound dressings.

Research Context

• Topical wound treatments often utilize carrier formulations with minimal biological impact. One such common carrier is a propylene glycol (PG) gel.
• This research sought to understand how PG gel affects measures of wound healing, particularly microbial populations inside the wound dressings utilized on horse wounds.
• Wound microbiome is typically analyzed using next-generation sequencing methods on tissue or wound fluid samples. Here, the researchers evaluated the potential of primary wound dressings to characterize equine wound microbiota in the context of topical treatments.

Research Methodology

• Experiments were conducted on six mature horses using a surgically-created, distal limb wound model. The evaluation relied on histology of sequential wound biopsies, photographic wound measurements, and microbiota profiling based on 16s rRNA sequencing of wound dressing samples.
• The researchers surveyed the experimental wounds for 42 days, either treating them with PG gel or leaving them unexposed. They analyzed wound surface area, relative and absolute microbial abundances, diversity indices, and histologic parameters within the treatment and control groups.

Research Findings

• The study revealed that compared to untreated wounds, PG gel treatment slowed the wound healing rate and delayed the reduction of polymorphonucleated cells in wound beds. The cell type is indicative of an immune response, suggesting that PG gel might prolong the inflammation stage of wound healing.
• Also, PG gel treatment lowered alpha-diversity indices for microbiota in primary wound dressing, implying lesser bacterial diversity compared to untreated wounds. Recognizing this impact is crucial as it may affect the wound healing process and the risk of infection.
• Despite these differences, clinical outcomes 42 days post-wounding seemed similar irrespective of PG gel exposure. This suggests that PG gel’s impact on wound healing and microbiome might be significant during the healing process but might not affect the final outcome.

Research Implications and Future Directions

• The study’s findings emphasize that exposure to seemingly innocuous vehicles like PG gel could alter relevant wound outcome measures. Therefore, robust experimental controls are crucial to accurately evaluate the effect of topical treatments.
• The study’s findings suggest that primary wound dressings could be an alternate sample source for characterizing the wound microbiome, potentially reducing the need for additional interventions.
• Future studies should contrast the microbiome in wound dressings against that on wound surfaces to validate the feasibility and accuracy of this approach.