Mechanical Education In Vitro Enhances Regenerative Capacities Of Human Mesenchymal Stem Cells In Vivo
Marielle Walraven, Akosua Vilaysane, John E. Davies, Boris Hinz.
University of Toronto, Toronto, ON, Canada.
Background: Mesenchymal stem cell (MSC) expansion is crucial to obtain sufficient cell numbers for tissue repair therapies. Traditional culture expansion on stiff surfaces reduces regenerative potential and jeopardizes therapeutic outcomes by inducing scar features in MSCs. In contrast, ‘priming’ on skin-soft culture surfaces preserves regenerative MSCs that improve the healing of rat wounds (Li et al. Nature Materials 2017). We hypothesize that mechanical priming in culture will alter secretory functions and thereby paracrine actions of MSCs in the wound environment. Methods: Human umbilical cord perivascular cells (HUCPVCs) from three donors were soft- or stiff-primed. Mechanical priming was verified using qRT-PCR and Western blotting for markers of stromal cell activation. Conditioned medium from primed HUCPVCs was analyzed using cytokine arrays. Primed HUCPVCs were transplanted to splinted rat full thickness wounds, traced for grafting success, and wound tissue was analyzed for cell and matrix composition. Results: Soft-primed HUCPVCs exhibited faster doubling times (3.0±0.4 vs 4.7±0.4 days) and reduced gene and protein expression of scar markers α-SMA and ED-A fibronectin compared to stiff-primed HUCPVCs. Of 79 cytokines detected in conditioned medium, 48 were down-regulated and 4 were up-regulated in all soft- versus stiff-primed HUCPVCs. Of 10 most differentially expressed cytokines, 7 were related to inflammation and 3 to cell cycle regulation. Soft- and stiff-primed HUCPVCs produced distinct healing outcomes compared to vehicle controls in a rat model of exacerbated wound healing. Conclusions: Soft-priming enhances the regenerative capacity of human MSCs by preserving cell proliferation, suppressing scarring features, and creating distinct paracrine profiles that persist in a wound environment.
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