Effects of GHK peptide and its structural analogues on dynamics of healing and bacterial contamination of infected wound

INTRODUCTION: Currently, a promising trend to accelerate wound process seems to be the use of NH₂-Gly-L-His-L-Lys-COOH (GHK) tripeptide, which acts on the tissue regeneration, possesses antioxidant, immunotropic and anti-inflammatory effects. At the same time, the disadvantage of all peptides is their rapid degradation by proteolytic enzymes. One method to increase the stability of peptide molecules is the incorporation of D-isomers of amino acids in their structure. It was previously found by us that GHK-D-Ala produces a more marked effect on regenerative processes in the wound and facilitates increase in the number of fibroblast cells and macrophages in the wound with the underlying decrease in the number of granulocytes and lymphocytes; a significant effect of D-Ala-GHK and GHK-D-Ala on the parameters of the inborn immunity and lipid peroxidation was shown.

AIM: To evaluate the healing dynamics and bacterial contamination of an infected wound when using Glycyl-Histidyl-Lysine (GHK) peptide and its structural modifications with D-alanine (D-Ala).

MATERIALS AND METHODS: The experiments were conducted on Wistar rats. In the work, GHK peptide and its structural analogues D-Ala-GHK and GHK-D-Ala were used; they were administered intracutaneously around the wound at doses of 0.5 µg/kg and 1.5 µg/kg every 24 hours for 3^rd, 7^th and 10^th days. The wound area with calculation of the relative wound healing coefficient (RWHC), the healing rate, the time of perifocal edema disappearance, wound cleansing, appearance of granulation and onset of marginal epithelialization were assessed. Bacterial contamination was determined by counting colonies on the nutrient media after inoculation of wound biopsy material on them.

RESULTS: On day 3^rd, RWHC increased 3.2–5.3 times (p < 0.05–0.01) after the use of D-Ala-GHK and GHK-D-Ala peptides at both doses with no effect after the injection of GHK. On day 7^th, the reduction of the wound area reached statistically significant differences in all experimental groups. By day 10^th, the use of peptides resulted in decrease in the wound area most evident after the injection of GHK-D-Ala peptide (by 93%, p < 0.001) in all groups. On days 7^th–10^th, GHK-D-Ala increased the healing rate 4.7–5.3 times (p < 0.05-0.01) with no significant changes after the injection of GHK and D-Ala-GHK. Also, GHK-D-Ala at both doses resulted in the earliest disappearance of perifocal edema, wound cleansing, emergence of granulation and the onset of marginal epithelialization in all experimental groups. Significant reduction in bacterial contamination was observed after administration of all peptides on days 7^th and 10^th, being most pronounced after the use of GHK-D-Ala.

CONCLUSION: The application of GHK peptide and its structural analogues D-Ala-GHK and GHK-D-Ala in infected skin wounds accelerated wound healing against the background reduction of bacterial contamination. The most pronounced changes of these parameters were observed after administration of GHK-D-Ala peptide, which indicates the importance of protecting GHK molecule against the impact of carboxypeptidases. A promising continuation of the research in this direction can be the development of local means with antibacterial effect for stimulation of the regeneration processes in the wound.