Permissive environment in postnatal wounds induced by adenoviral-mediated overexpression of the anti-inflammatory cytokine interleukin-10 prevents scar formation.

Wound healing in the mid-gestation fetus is scarless with minimal inflammation and a unique extracellular matrix. We have previously documented the relative lack of inflammatory cytokines in this environment. We demonstrate that interleukin (IL)-10 is highly expressed in mid-gestation human fetal skin but is absent in postnatal human skin. We hypothesize that overexpression of IL-10 in postnatal skin may replicate a permissive environment for scarless healing. To study the mechanism underlying this process we performed immunohistochemistry for IL-10 in human mid-gestation fetal and postnatal skin. We also determined if adenoviral-mediated overexpression of IL-10 could allow for scarless wound healing in a murine incisional wound model. Wounds were analyzed at 1-90 days postwounding for effects on scar formation, inflammatory response, and biomechanical properties. Ad-IL-10 reconstitutes a permissive environment for scarless healing as shown by reconstitution of a normal dermal reticular collagen pattern and distribution of dermal elements. Compared with controls, Ad-IL-10 treated wounds showed reduced inflammatory response and no difference in biomechanical parameters. Therefore, overexpression of IL-10 in postnatal wounds results in a permissive environment for scarless wound repair, possibly by replicating a fetal wound environment.

Enhanced epithelial gap closure and increased angiogenesis in wounds of diabetic mice treated with adult murine bone marrow stromal progenitor cells.

The direct application of bone marrow (BM) can accelerate the healing of chronic wounds. We hypothesized that this effect is due to the presence of stromal progenitor cells (SPCs) found within whole BM preparations. To test this hypothesis, we isolated adult murine SPCs from whole BM and examined their ability to enhance impaired wound healing compared with ficoll separated BM cells in the diabetic (db/db) mouse model. SPCs significantly enhanced reepithelialization, granulation tissue formation, and neovascularization compared with control wounds treated with BM or PBS alone. Higher frequencies of donor SPC cells compared with donor BM cells were observed in treated wounds at 7 days. Transdifferentiation into GFP-positive mature endothelial cells was not observed. These observations suggest that SPCs improve wound healing through indirect mechanisms which lead to enhanced vascularization rather than through direct participation and incorporation into tissue. We conclude that topical application of BM-derived SPCs may represent an effective strategy for the treatment of chronic diabetic wounds.

Long-term transgene expression in cardiac and skeletal muscle following fetal administration of adenoviral or adeno-associated viral vectors in mice.

BACKGROUND: In utero gene transfer may provide advantages for the correction of congenital genetic disorders. In the present study we compare the ability of adenovirus (AdCMVLacZ), and two serotypes of adeno-associated virus (AAVCMVLacZ serotypes 2 and 2/5), to target cardiac and skeletal muscle after prenatal systemic or intramuscular injection in mice and assess the immune response to the vectors. METHODS: Day 14 gestation fetal mice underwent direct intraperitoneal or intramuscular injection of AdCMVLacZ, and AAVCMVLacZ serotypes 2 and 2/5 vectors. Tissues were processed for beta-galactosidase expression in frozen or high-resolution thin plastic sections at early and late time points. Neutralizing antibodies to Ad and AAV were analyzed in separate fetal experimental and neonatal or adult control groups after administration and re-administration of the vectors. RESULTS: A single injection of each vector in utero resulted in sustained expression of beta-galactosidase transgene in skeletal and cardiac muscle. Transgene expression was detected for the length of the study, i.e. 86, 58, and 31 weeks after birth for AdCMVLacZ, and AAVCMVLacZ serotypes 2 and 2/5, respectively. High-level expression in the myocardium was observed independent of the vector or route of administration. Neutralizing antibody responses to AAV and Ad antigens were reduced and long-term expression in muscle was not ablated on postnatal re-administration of vector. CONCLUSIONS: Sustained, high-level cardiac and skeletal muscle transgene expression can be obtained after prenatal gene transfer with each of these vectors. The potential for immune response to viral antigens is altered, but not entirely ablated after in utero exposure.