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Purpose In our previous work,we successfully isolated MSCs from the human degenerated cartilage endplate(CEP)and named them cartilage endplate derived stem cells(CESCs).In vitro study demonstrated CESCs showed superior osteogenic potential compared with bone marrow-derived mesenchymal stem cells(BM-MSCs)harvested from same donors.This study further compared the in vivo bone formation capacity of engineered bones using CESCs and BM-MSCs as seed cells respectively in a rabbit lumbar intertransverse process fusion model. Methods CESCs and BM-MSCs derived from same patients were isolated and expanded,and the cell surface antigen profiles were detected by flow cytometry.After in vitro induction of cells/porous hydroxyapatite(PHA)composites,alkaline phosphatase(ALP)activity and osteogenic specific gene expression were tested.Furthermore,PHA grafts containing no cells and cells/PHA composites using CESCs or BM-MSCs as seed cells were transplanted into rabbit posterolateral lumbar intertransverse processes(L4-L5),respectively.After 8 weeks of implantation,those grafts were checked by manual palpation,spiral computer tomography(CT)scanning,micro-CT and semi-quantitative histological analysis for fusion rate and quality of newly formed bones. Results Cell surface antigen profiles of both types of stem cells fulfilled the criterion described by the International Society for Cellular Therapy(ISCT).CESCs/PHA showed significantly higher ALP activity and expression of some osteogenic specific genes than BMMSCs/PHA(p<0.01).In the rabbit intertransverse process fusion model,CESCs/PHA indicated higher fusion rate than BMMSCs/PHA,but no statistical difference was observed(p>0.05).Finally,the quality of newly formed bone in CESCs group was superior to BM-MSCs group,which was confirmed by micro-CT and semi-quantitative histological analysis. Conclusions Our study indicated that tissue engineered bone formed by CESCs showed superior quality than BM-MSCs,and CESCs might serve as an important alternative for the seed cell source of bone tissue engineering.Those results might pave a foundation for the biological solution of spinal fusion or other bone defect issues.