LAUSR

BACKGROUND The standard graft material for alveolar cleft repair (ACR) is autogenous iliac crest. However, a promising alternative potential graft adjunct - newborn human umbilical cord mesenchymal stem cells (h-UCMSC) - has yet to be explored in vivo. Their capacity for self-renewal, multipotent differentiation, and proliferation allows h-UCMSC to be harnessed for regenerative medicine. Our study seeks to evaluate the efficacy of using tissue-derived h-UCMSC and their osteogenic capabilities in a murine model to improve ACR. METHODS Foxn1 mice were separated into three groups with the following calvarial defects: (1) no-treatment (empty defect; n=6), (2) poly (D,L-lactide-co-glycolide) (PLGA) scaffold (n=6), and (3) h-UCMSC with PLGA (n=4). Bilateral 2-mm diameter parietal bone critical-sized defects were created using a dental drill. Micro-CT imaging occurred at 1, 2, 3, and 4 weeks postoperatively. The mice were euthanized 4 weeks postoperatively for RNAscope analysis, immunohistochemistry, and histology. RESULTS No mice experienced complications during the follow-up period. Micro-CT and histology demonstrated that the no-treatment (1) and PLGA-only (2) defects remained patent without significant defect size differences across groups. In contrast, the h-UCMSC with PLGA group (3) had significantly greater bone fill on micro-CT and histology. CONCLUSIONS We demonstrate a successful calvarial defect model for the investigation of h-UCMSC-mediated osteogenesis and bone repair. Furthermore, evidence reveals that PLGA alone has neither short-term effects on bone formation nor any unwanted side effects, making it an attractive scaffold. Further investigation using h-UCMSC with PLGA in larger animals is warranted to advance future translation to patients requiring ACR. CLINICAL RELEVANCE STATEMENT Our results demonstrate a successful murine calvarial defect model for the investigation of h-UCMSC-mediated osteogenesis and bone repair and provide preliminary evidence for the safe and efficacious use of this graft adjunct in alveolar cleft repair.