IADR Abstract Archives
Harnessing the Mechanism of JAGGED1- Mediated Craniofacial Bone Regeneration
Objectives: Craniofacial (CF) bone loss is a clinical problem with limited regenerative solutions, including bone grafts or “off-label” administration of bone morphogenetic protein 2, which can be time-consuming, expensive or accompanied by life-threatening side effects, creating a need for novel bone regenerative therapies. A promising candidate is the osteogenic factor JAGGED1, shown to be essential for mouse cranial neural crest (CNC) cell-osteoblast commitment, via a non-canonical NOTCH pathway involving JAK2-STAT5. Here, we investigate mechanisms of JAGGED1-mediated osteogenesis in pediatric human bone-derived osteoblast-like cells (HBOs) as a translational tool with therapeutic potential.
Methods: Eight HBOs treated with JAGGED1 (5.7μM) were probed for ALP activity and mineralization. We delivered JAGGED1 (20μM) ± DAPT (15μM), a NOTCH canonical pathway inhibitor, with HBOs in PEG-MAL hydrogels into critically-sized (4mm) cranial defects in NOD-SCID mice (n=15) as 2 separate doses (Initial dose, Week 4). After 8 weeks, we harvested skulls and quantified bone deposition by MicroCT analysis. Further, lysates, of five HBOs that were treated with JAGGED1 (5.7μM) ± DAPT (15μM), were subjected to luminex-based signaling assays. Data was subjected to ANOVA and presented as mean ± SD with p-values reported.
Results: We demonstrate that JAGGED1 induces ALP production and mineralization in all eight HBOs in vitro and co-delivery of JAGGED1 with HBOs into critically-sized cranial defects significantly stimulates bone regeneration in NOD-SCID mice. In addition, JAGGED1 significantly increased phosphorylation of multiple signaling molecules, including STAT5, P38 and p70-S6K in HBOs.
Conclusions: These data suggest that JAGGED1 induces HBO cell-osteoblast commitment and differentiation in vitro, and bone regeneration in vivo via a non-canonical NOTCH pathway involving p70-S6K, the signaling target where all the signaling pathways that were identified, in this study, downstream of JAGGED1, converge. These compelling data suggest that JAGGED1 and/or its downstream targets can be harnessed as powerful bone regenerative therapies for pediatric CF bone loss.
Methods: Eight HBOs treated with JAGGED1 (5.7μM) were probed for ALP activity and mineralization. We delivered JAGGED1 (20μM) ± DAPT (15μM), a NOTCH canonical pathway inhibitor, with HBOs in PEG-MAL hydrogels into critically-sized (4mm) cranial defects in NOD-SCID mice (n=15) as 2 separate doses (Initial dose, Week 4). After 8 weeks, we harvested skulls and quantified bone deposition by MicroCT analysis. Further, lysates, of five HBOs that were treated with JAGGED1 (5.7μM) ± DAPT (15μM), were subjected to luminex-based signaling assays. Data was subjected to ANOVA and presented as mean ± SD with p-values reported.
Results: We demonstrate that JAGGED1 induces ALP production and mineralization in all eight HBOs in vitro and co-delivery of JAGGED1 with HBOs into critically-sized cranial defects significantly stimulates bone regeneration in NOD-SCID mice. In addition, JAGGED1 significantly increased phosphorylation of multiple signaling molecules, including STAT5, P38 and p70-S6K in HBOs.
Conclusions: These data suggest that JAGGED1 induces HBO cell-osteoblast commitment and differentiation in vitro, and bone regeneration in vivo via a non-canonical NOTCH pathway involving p70-S6K, the signaling target where all the signaling pathways that were identified, in this study, downstream of JAGGED1, converge. These compelling data suggest that JAGGED1 and/or its downstream targets can be harnessed as powerful bone regenerative therapies for pediatric CF bone loss.
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