Search

The murine lower incisor ectodermal organ contains a single epithelial stem cell (SC) niche that provides epithelial progenitor cells to the continuously growing rodent incisor. The dental stem cell niche gives rise to several cell types and we demonstrate that the miR‐200family regulates these cell fates. The miR‐200family is highly enriched in the differentiated dental epithelium and absent in the stem cell niche. In this study, we inhibited the miR‐200family in developing murine embryos using new technology, resulting in an expanded epithelial stem cell niche and lack of cell differentiation. Inhibition of individual miRs within the miR‐200cluster resulted in differential developmental and cell morphology defects. miR‐200inhibition increased the expression of dental epithelial stem cell markers, expanded the stem cell niche and decreased progenitor cell differentiation. RNA‐seq. identified miR‐200regulatory pathways involved in cell differentiation and compartmentalization of the stem cell niche. The miR‐200family regulates signaling pathways required for cell differentiation and cell cycle progression. The inhibition of miR‐200decreased the size of the lower incisor due to increased autophagy and cell death. New miR‐200targets demonstrate gene networks and pathways controlling cell differentiation and maintenance of the stem cell niche. This is the first report demonstrating how the miR‐200family is required for in vivo progenitor cell proliferation and differentiation. The LaCL stem cell niche does not express miR‐200, which regulates Sox2 expression. Progenitor cells exiting the stem cell niche start expressing miR‐200 to promote differentiation and the specification of cell fates for mature tooth development. miR‐200 therefore acts to compartmentalize the stem cell niche

Advanced fabrication methods for bone grafts designed to match defect sites that combine biodegradable, osteoconductive materials with potent, osteoinductive biologics would significantly impact the clinical treatment of large bone defects. In this study, we engineered synthetic bone grafts using a hybrid approach that combined three-dimensional (3D-)printed biodegradable, osteoconductive β-tricalcium phosphate (β-TCP) with osteoinductive microRNA(miR)-200c. 3D-printed β-TCP scaffolds were fabricated utilizing a suspension-enclosing projection-stereolithography (SEPS) process to produce constructs with reproducible microarchitectures that enhanced the osteoconductive properties of β-TCP. Collagen coating on 3D-printed β-TCP scaffolds slowed the release of plasmid DNA encoding miR-200ccompared to noncoated constructs. 3D-printed β-TCP scaffolds coated with miR-200c-incorporated collagen increased the transfection efficiency of miR-200cof both rat and human BMSCs and additionally increased osteogenic differentiation of hBMSCs in vitro. Furthermore, miR-200c-incorporated scaffolds significantly enhanced bone regeneration in critical-sized rat calvarial defects. These results strongly indicate that bone grafts combining SEPS 3D-printed osteoconductive biomaterial-based scaffolds with osteoinductive miR-200c can be used as superior bone substitutes for the clinical treatment of large bone defects.