Skin Electroporation of a Plasmid Encoding hCAP-18/LL-37 Host Defense Peptide Promotes Wound Healing

Abstract

Host defense peptides, in particular LL-37, are emerging as potential therapeutics for promoting wound healing and inhibiting bacterial growth. However, effective delivery of the LL-37 peptide remains limiting. We hypothesized that skin-targeted electroporation of a plasmid encoding hCAP-18/LL-37 would promote the healing of wounds. The plasmid was efficiently delivered to full-thickness skin wounds by electroporation and it induced expression of LL-37 in the epithelium. It significantly accelerated reepithelialization of nondiabetic and diabetic wounds and caused a significant VEGFa and interleukin (IL)-6 induction. IL-6 was involved in LL-37-mediated keratinocyte migration in vitro and IL-6 neutralizing antibodies delivered to mice were able to suppress the wound healing activity of the hCAP-18/LL-37 plasmid. In a hindlimb ischemia model, electroporation of the hCAP-18/LL-37 plasmid increased blood perfusion, reduced muscular atrophy, and upregulated the angiogenic chemokines VEGFa and SDF-1a, and their receptors VEGF-R and CXCR-4. These findings demonstrate that a localized gene therapy with LL-37 is a promising approach for the treatment of wounds.

Local Sustained Delivery of 25-Hydroxyvitamin D3 for Production of Antimicrobial Peptides

“…LL-37 is derived from an inactive proform (hCAP-18) produced in humans by various types of cells (e.g., keratinocytes, monocytes, neutrophils, macrophages, and epithelial cells) following exposure to active vitamin D (1,25-dihydroxyvitamin D 3 ) with local production critically dependent on the storage form of vitamin D (25-hydroxyvitamin D 3 ) (11-14). Direct peptide application and over expression following gene therapy approaches have been used to alter local concentrations of LL-37, but significant issues have developed precluding this direct approach: toxicity to eukaryotic cells, formation of toroidal pore, and risk of unintended and undesired tissue destruction and inflammation in the area of surgical incision (15-19). …”

The site of administration influences both the type and the magnitude of the immune response induced by DNA vaccine electroporation

“…Electroporation is a non-viral delivery method based on membrane destabilization and DNA electrophoresis, mediated by electric pulses. Efficient delivery of plasmid into muscle, skin, tumor and other tissues using in vivo electroporation has thus been demonstrated [4][5][6][7][8][9][10].…”

Non-Invasive Intravital Imaging of siRNA-Mediated Mutant Keratin Gene Repression in Skin

“…Several siRNAs have entered clinical trials [1][2][3], including a mutant-specific siRNA (K6a.513.12) designed for local administration to skin for the treatment of PC [4]. Although a multitude of skin nucleic acid delivery technologies have been reported with varying effectiveness [4,22,[27][28][29][30][31], the realization of siRNA skin therapeutics as a new drug class will require development of more efficient and patient-friendly delivery technologies. Since trials with human volunteers are limited by ethical and practical considerations (e.g., the limited number of PC patients), suitable pre-clinical animal models are required for testing and optimizing of therapeutic approaches.…”