Abstract:

BACKGROUND: Osteogenic induction has been regarded as an indispensable step for adipose-derived stromal cells (ADSCs) to transform into osteoblasts, thus to secret bone matrix to repair bone defects. However, this conclusion has not been confirmed.
OBJECTIVE: Tissue-engineered constructs were prepared from osteogenically induced ADSCs and scaffolds. The constructs were implanted into bone defects and non-bone areas. Whether osteogenically induced ADSCs were transformed into osteoblasts was determined according to bone formation.
METHODS: ADSCs were prepared by collagenase Ⅰ digestion of subcutaneous fat from the back of dogs aged 12 months. Passage 3 ADSCs were harvested and seeded on the biphasic calcium phosphate ceramics to form a cell-scaffold construct. Box-like bone defects, 20 mm in length and 10 mm in height, were created in the mandibular bilaterally in each dog along the alveolar bone where teeth had been extracted. Then the cell-scaffold constructs were implanted in dog mandibular bone defects. An empty defect group was used as control. The tissue-engineered constructs and osteoinductive calcium phosphate ceramics were implanted in muscle. After implantation for 6 and 12 weeks, bone formation was analyzed using histomorphometry.
RESULTS AND CONCLUSION: ADSCs-scaffold construct promoted bone formation in bone defect area, but not in muscle area, however, osteoinductive calcium phosphate ceramics promoted bone formation in muscle area. ADSCs were not transformed into osteoblasts after osteogenic induction. The precise mechanism needs further investigation.