Degree

Doctor of Philosophy (PhD)

Department

Veterinary Clinical Science

Document Type

Dissertation

Abstract

For the potential benefit of progenitor cells to be realized in cell-based clinical therapies, it is vital to investigate the mechanism between progenitor cells and abnormal tissue formation. Laminitis is a fatal condition that is often presented by equine hoof inflammation and hoof tissue disarrangement. The persistence of abnormal tissue formation after the resolution of equine laminitis suggests there is progenitor cell compromise. So far, there is limited information about equine hoof progenitor cells and the effects of inflammation on hoof progenitor cells. To pursue a better understanding of both hoof progenitor cell and hoof growth as well as find potential progenitor cell-based treatments for hoof injuries, we choose hoof progenitor cells to create an in vitro model to study hoof cell characteristics. Primary progenitor cells were isolated from fresh equine laminae as well as cryopreserved laminar tissue and characterized in vitro. Results indicate hoof progenitor cells from fresh tissue have multilineage differentiation capacity and show similar cell doublings, CFU frequencies, surface antigen, and gene expressions when compared to other reported stem cells. The majority of hoof progenitor cell isolates are K14+CD105+ population that may result from the specific dermal-epidermal hoof structure. K14+CD105+ progenitor cells, progenitor cells from unaffected, laminitic and cryopreserved laminar tissue show different cell behaviors on decellularized laminar scaffolds and distinct ultrastructural morphology. This indicating hoof progenitor cells have variable metabolic and synthetic capabilities determined by different preharvest tissue conditions and postharvest conditions. K14+CD105+ progenitor cells have a stronger proliferation rate and higher epithelial to mesenchymal transition (EMT) marker expression compared to heterogeneous cell isolates. This suggests that cell plasticity required to maintain both the interface and two tissue types may be enhanced by EMT capabilities. Cells loss epithelial characteristics by culturing with inflammatory cytokines while normal matrix may promote epidermal gene expression. EMT protein expression was increased by culturing with medium containing inflammatory cytokines, which indicating inflammatory cytokines may support a propensity for EMT. Overall, outcomes in this dissertation provide invaluable information for a better understanding of hoof cell composition and hoof disease prevention. Likewise, the work informs future progenitor cell-based dermal-epidermal tissue engineering.

Date

10-25-2019

Committee Chair

Lopez, Mandi

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