Stem Cell-Associated Marker Expression in Canine Hair Follicles

Abstract

SummaryFunctional hair follicle (HF) stem cells (SCs) are crucial to maintain the constant recurring growth of hair. In mice and humans, SC subpopulations with different biomarker expression profiles have been identified in discrete anatomic compartments of the HF. The rare studies investigating canine HF SCs have shown similarities in biomarker expression profiles to that of mouse and human SCs. The aim of our study was to broaden the current repertoire of SC-associated markers and their expression patterns in the dog. We combined analyses on the expression levels of CD34, K15, Sox9, CD200, Nestin, LGR5 and LGR6 in canine skin using RT-qPCR, the corresponding proteins in dog skin lysates, and their expression patterns in canine HFs using immunohistochemistry. Using validated antibodies, we were able to define the location of CD34, Sox9, Keratin15, LGR5 and Nestin in canine HFs and confirm that all tested biomarkers are expressed in canine skin. Our results show similarities between the expression profile of canine, human and mouse HF SC markers. This repertoire of biomarkers will allow us to conduct functional studies and investigate alterations in the canine SC compartment of different diseases, like alopecia or skin cancer with the possibility to extend relevant findings to human patients. (J Histochem Cytochem 64:190-204, 2016)

Progenitor cells expressing nestin, a neural crest stem cell marker, differentiate into outer root sheath keratinocytes

“…Several studies have described that immunolabelling for nestin was diffusely recognized in the ORS at the isthmic region of anagen hair follicles in humans and dogs . Other studies have described that nestin immunoreactivity was recognized only in dermal sheath and dermal papilla, but not in hair follicle epithelial cells, in anagen hair follicles of human scalp and canine truncal skin . The exact reason for this discrepancy is unknown.…”

Establishment and characterization of a canine keratinocyte organoid culture system

“…In both organoid types, immunostaining of early (passages 1–2) and later passages (Passage 6) revealed immunoreactivity for KRT5 in the outer/basal cell layer of organoids, the early differentiation marker KRT6 (more pronounced in the centre of the organoids) as well as the proliferation marker KI67 (Figure b). No immunoreactivity against KRT15, a marker enriched in the canine bulge, was found in the organoids at either time point (Figure ).…”

“…KRT6 is expressed in the inner root sheath of hair shafts; however, expression of KRT6 can also be seen in the process of wound healing and is recognized as a hyperproliferation marker . For the characterization of HF‐derived organoids we chose stem cells markers that are known to be present in the canine HF …”

“…The establishment of an in vitro system to investigate canine epidermal and follicular stem cells is therefore critical to understanding the pathogenesis of alopecic disorders. Of note, the expression pattern of follicular stem cells varies between mice and humans, whereas expression is similar in human and canine HFs …”

Horse hair follicles: A novel dermal stem cell source for equine regenerative medicine

“…This is consistent with the report by Joannides et al who were also not able to detect nestin in native human skin and used fetal human cortex precursors as positive control. In dog skin, Gerhards et al did detect nestin in the hair follicle dermal compartments. Here, it should be emphasized that besides some scattered positive DS cells, the higher magnification image of the DP showed nestin‐expression adjacent to the capillary loop which is in accordance with the detection of nestin in newly formed blood vessels .…”