Plastic Surgery Research Council
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Presenter: Ginger C Slack, BS
Co-Authors: Yuan J; Bueno B; Bradley JP

Background: Although cleft lip and palate deformities are the most common facial birth defect (1 in 600 births) only a few genes, IRF6 (associated with Van der Wounde) and transforming growth factor-beta 3 (TGF≤B3), have been implicated in the disease. Dental pulp stem cells (DPSC) have similar developmental process with neural crest migration into core mesoderm and ectoderm and may be used to gain insight into the cell matrix interaction of epithelial-mesenchymal transition (EMT) during palatogenesis. Previous microarray comparative analysis of cleft dental pulp stem cells identified candidate genes (MMP3, ACAN, COL4A1, COL4A2, and COL15A1) known to be involved in cell matrix interaction of the EMT during palatogenesis.

Methods: Normal and Cleft Palate (TGF≤-beta 3KO; IRF-6) murine organ cultures explanted at 14.5 days gestation were placed with the medial edge epithelia in close proximity. Gene expression (rt-PCR) and localization (In situ hybridization) of above listed candidate genes was performed. Then, to induce clefting in normal palates, lentivirus vectors were used to over-express our candidate genes. Then, rescue of cleft palate fusion was attempted with siRNA to our clefting organ culture explants.

Results: Differential expression of candidate genes was seen in cleft explants with an up-regulation of ACAN, COL4A1, COL4A2 in TFG-beta 3 KOs and an up-regulation of ACAN, COL4A1 in IRF-6 compared to wild-type palatogenesis. Over expression of these three genes in the wild-type murine explants caused persistence of the medial epithelium or clefting in 37% of normal explants. Normal palatogenesis was still seen in approximately 58% and abnormal bony bridging was seen in 5%. When suppression of gene expression was directed at ACAN, COL4A1, COL4A2 in TGF≤-beta 3 KO explants there was 33% less clefting. This was not found with IRF-6 explants.

Conclusions: Expression of dental pulp stem cell candidate cleft genes differed within the EMT of normal palatogenesis compared to known cleft models. Palatogenesis may be influenced by the change in DPSC cleft genes.

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