On Monday April 24th, 2023 Dan Su successfully defended her PhD thesis with the title "Identification and Functional Analyses of Stem Cell Niches During Oral Tissue Development and Regeneration"

Oral health is the state of the mouth, teeth and orofacial structures which allows individuals to perform oral functions such as breathing, chewing and speaking. Oral diseases comprise a series of diseases and conditions that can be congenital or acquired over the life course. Nowadays, a tool for oral tissue engineering and regenerative therapy has drawn both clinical and scientific attention, which highly involves stem/progenitor cells in the oral cavity. Thus, identification and functional analyses of stem cell niches during oral tissue development and regeneration are imperative.

In our study, we have found Wolf-Hirschhorn Syndrome Candidate 1 (WHSC1), a causative gene  for a craniofacial syndrome, is expressed from early stage of mouse incisor development. In the dental epithelial stem cell niche, WHSC1 functions to mediate the considered earliest tooth gene Paired Like Homeodomain 2 (PITX2) in regulating tooth development. In addition, tooth- related microRNAs miR-23-a/b and miR-24-1/2 negatively regulate WHSC1 in the differentiated dental epithelial cell types to restrict its expression. Thus, we define a role of WHSC1 as a stem cell marker that regulates tooth development.

Gingiva recession is an irreversible process of losing gingiva tissue, which will largely affect oral function. Gingiva regeneration depends on the stem cells that resides in the gingiva. However, the genetic and molecular mechanism is still largely unknown. We report that Iroquois Homeobox 1 (IRX1) is expressed in the stem cell niches in human and mouse epithelium and mesenchyme under homeostasis and confirm that IRX1 haploinsufficiency impairs re-epithelialization during gingival wound healing.

Congratulations Dan!

Dr. Dan Su and Mentor Dr. Brad Amendt