Application of the Chemokine CXCL12 Expression Plasmid Restores Wound Healing to Near Normal in a Diabetic Mouse Model

Background: CXCL12 is a chemokine involved in postinjury leukocyte chemotaxis, migration, and homing of stem cells. We hypothesized that by increasing the level of the chemokine CXCL12 in wounds of diabetic mice, we would increase stem cell recruitment to the wound and, thus, accelerate time to wound closure. Methods: Eighteen Lepr db-/db- (B6.Cg-m +/+ Leprdb/J; Jackson Labs, Bar Harbor, ME) and their nondiabetic littermates were wounded and treated either with an empty plasmid or a plasmid containing the CXCL12 gene. Wounds were measured approximately every 5 days until they closed completely and were analyzed using planimetry. Wounds were harvested, and relative expression of CXCL12 mRNA was measured using an ABI Prism SDS 7000. To study stem cells affected by this, the plasmid's affect on stem cell recruitment, we used flow cytometry. Results: The diabetic wounds contain a significantly decreased level of CXCL12 mRNA at day 7 postwounding, and these wounds take 55 days to heal. Application of a CXCL12 plasmid to diabetic wounds significantly increases CXCL12 mRNA at day 7, and these wounds heal in 23 days. Conclusions: Lack of CXCL12 in diabetic wounds contributes to delayed wound healing and can be reversed via single application of a CXCL12-containing plasmid.