Microencapsulated equine mesenchymal stromal cells promote cutaneous wound healing in vitro

Leen Bussche, Rebecca M Harman, Bethany A Syracuse, Eric L Plante, Yen-Chun Lu, Theresa M Curtis, Minglin Ma, Gerlinde R Van de Walle

The prevalence of impaired cutaneous wound healing is high and treatment is difficult and often ineffective, leading to negative social and economic impacts for our society. Innovative treatments to improve cutaneous wound healing by promoting complete tissue regeneration are therefore urgently needed. Mesenchymal stromal cells (MSC) have been reported to provide paracrine signals that promote wound healing, but (i) how they exert their effects on target cells is unclear and (ii) a suitable delivery system to supply these MSC-derived secreted factors in a controlled and safe way is unavailable. The present study was designed to provide answers to these questions using the horse as a translational model. Specifically, we aimed to (i) evaluate the in vitro effects of equine MSC-derived conditioned medium (CM), containing all factors secreted by MSC, on equine dermal fibroblasts, a cell type critical for successful wound healing, and (ii) explore the potential of microencapsulated equine MSC to deliver CM to wounded cells in vitro. Mesenchymal stem cells (MSC) were isolated from the peripheral blood of healthy horses. Equine dermal fibroblasts from the NBL-6 line were wounded in vitro, and cell migration and expression levels of genes involved in wound healing were evaluated after treatment with MSC-CM or NBL6-CM. These assays were then repeated using the CM collected from MSC encapsulated in core-shell hydrogel microcapsules. Our salient findings were that equine MSC-derived CM stimulated the migration of equine dermal fibroblasts and increased their expression level of genes that positively contribute to wound healing. In addition, we found that equine MSC packaged in core-shell hydrogel microcapsules had similar effects on equine dermal fibroblast migration and gene expression, indicating that microencapsulation of MSC does not interfere with the release of bioactive factors. Our results demonstrates that the use of CM from MSC might be a promising new therapy for impaired cutaneous wounds and that encapsulation may be a suitable way to effectively deliver CM to wounded cells in vivo.