Project description:Environmental factors that enhance regeneration are largely unknown. We hypothesized that skin bacteria modulate regeneration. Here, we assessed low, medium, and high levels of bacterial burden in Wound Induced Hair follicle Neogenesis (WIHN), a rare adult organogenesis model. WIHN levels and stem cell markers indeed correlated with bacterial counts, being lowest in germ free (GF), intermediate in conventional specific pathogen free (SPF), and highest even in mice infected with pathogenic Staphylococcus aureus. We identified IL-1β and keratinocyte-dependent IL-1R-MyD88 signaling as necessary and sufficient for bacteria to promote regeneration. Finally, in a small clinical trial, we found that a topical broad-spectrum antibiotic slowed skin wound healing. These results counter conventional notions that infection inhibits regeneration and the need for full sterility of small wounds.
Project description:Mesenchymal cells were isolated from day 5 dorsal skin wound beds of 7-weeks old and >24-months old using FACS. This experiment describes multiple unique subsets of wound bed myofibrolbasts capable of contributing to tissue repair.
Project description:Tissue regeneration is a process that recapitulates the molecular and mechanical aspects of development and evolution. We use the wound-induced hair neogenesis (WIHN) model to investigate the mechanical and molecular responses of the laboratory (Mus) and African spiny (Acomys) mice. Laboratory and spiny mice showed an opposite trend of spatiotemporal morphogenetic field for WIHN during wound healing, and wound stiffness gradient across the whole wound bed predicated pattern of hair formation. Using bulk and single-cell RNA-seq analysis and K14-Cre-Twist1 transgenic mice, we identified the central role of the Twist1 pathway as the mediator of epidermal-dermal interaction and the emergence of periodic hair primordia. Lastly, we generated a Turing model with an underlying measure of stiffness to support a two-scale tissue mechanic model to explain the setup of a morphogenetic field from a wound bed (mm scale) or periodically arranged hair primordia from a morphogenetic field (μm scale). Delineating the common and distinct chemo-mechanical events during regenerative wound healing between laboratory and African spiny mice reveal its evo-devo advantages, which provide new perspectives for regenerative medicine.
Project description:Small extracellular vesicles (EVs) are released by cells and deliver biologically active payloads important in the intercellular signaling that coordinates the response of multiple cell types in cutaneous wound healing. Here we focus on the use of EV reporters to address cell type specificity and central questions regarding EV source cells, target cells, heterogeneity, payload, and activity using a combination of molecular approaches to address some of the barriers to translation in the use of engineered EVs. We identify a role for EVs released by resident macrophages present in adipose tissue and dermis to stimulate proliferation of overlying basal layer of keratinocytes. For these studies we use an allograft model, where donor EVs are harvested from subcutaneous implants, then purified for transplantation into the wound bed of recipient mice with a defined impaired wound healing phenotype. We demonstrate that EVs isolated from diabetic obese mice decreased keratinocyte proliferation and delayed wound closure, and that EVs loaded with specific miRNAs like miR-425-5p increased proliferation and accelerated wound closure. Utilizing a CD9-GFP reporter system, we show that fibroblasts uptake macrophage-derived EVs. In this work, we show that cell type-specific approaches can be used to unravel the biochemical activity of EVs in the complex microenvironment of the wound bed and form the basis for developing targeted pro-reparative EV payloads.
Project description:Tissue regeneration is a process that recapitulates the molecular and mechanical aspects of development and evolution. We use the wound-induced hair neogenesis (WIHN) model to investigate the mechanical and molecular responses of the laboratory (Mus) and African spiny (Acomys) mice. Laboratory and spiny mice showed an opposite trend of spatiotemporal morphogenetic field for WIHN during wound healing, and wound stiffness gradient across the whole wound bed predicated pattern of hair formation. Using bulk and single-cell RNA-seq analysis and K14-Cre-Twist1 transgenic mice, we identified the central role of the Twist1 pathway as the mediator of epidermal-dermal interaction and the emergence of periodic hair primordia. Lastly, we generated a Turing model with an underlying measure of stiffness to support a two-scale tissue mechanic model to explain the setup of a morphogenetic field from a wound bed (mm scale) or periodically arranged hair primordia from a morphogenetic field (μm scale). Delineating the common and distinct chemo-mechanical events during regenerative wound healing between laboratory and African spiny mice reveal its evo-devo advantages, which provide new perspectives for regenerative medicine.