Identifier

etd-04232012-151737

Degree

Master of Science (MS)

Department

Biomedical and Veterinary Medical Sciences - Veterinary Clinical Sciences

Document Type

Thesis

Abstract

Laminitis is an often fatal condition in horses with few available and only moderately effective treatment options. Separation of laminar dermis and epidermis lead to rotation or ventral deviation of the third phalanx inside the hoof capsule. Despite being a modified skin, equine laminar tissue does not completely return to normal after laminitis. The hypothesis tested was that adult progenitor cells in the equine laminar tissue are irreversibly damaged by laminitis. A method to harvest and culture cells in vitro from the equine lamina was established; and progenitor cells from unaffected and laminitic hooves were characterized and compared. Laminar tissue was harvested from horses with and without evidence of laminitis. Cells were isolated from each tissue type, unaffected (UC) and laminitic (LC). Cell doublings (CD) and doubling times (DT) were quantified for passage (P) 0-5 cells. For P0, 2, and 5, fibroblastic colony forming units (CFU-F), progenitor (OCT4, SOX-2, CD29, CD44, and CD105) and keratin (K14, K15, and K19) target gene mRNA levels (qRT-PCR) and protein expression (flow cytometry) as well as multipotentiality were assessed. Keratins were localized with immunohistochemistry. Overall LC CD was significantly higher than UC. Progenitor gene mRNA levels were significantly higher in P0 LC versus UC. K14 and K15 mRNA levels in P0 were lower in LC when compared to UC. Keratins were localized to secondary epidermal lamina. Osteogenic, adipogenic and chondrogenic differentiation was confirmed in both cell types Increases in progenitor mRNA in UC over passages is consistent with selection of progenitor cells by plastic affinity and confirms maintenance of progenitor cell characteristics through multiple passages. Results of this study highlight specific progenitor cell changes in laminitic hooves that result in a constant state of hyperproliferation without cell maturation. These changes may explain the abnormal tissue organization and function that result from laminitic episodes. The procedures developed in this study provide a unique and consistent model to study the intricacies of equine laminitis in the horse. Future studies using the model designed here will be used for in vitro investigations aimed at identifying specific mechanisms to reverse or prevent the cellular changes from laminitis.

Date

2012

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Lopez, Mandi

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