Application of tissue-engineered bone grafts for alveolar cleft osteoplasty in a rodent model

The clinical standard for alveolar cleft osteoplasty is augmentation with autologous bone being available in limited amounts and might be associated with donor site morbidity. The aim of the present study was the creation of tissue-engineered bone grafts and their in vivo evaluation regarding their potential to promote osteogenesis in an alveolar cleft model. Artificial bone defects with a diameter of 3.3 mm were created surgically in the palate of 84 adult Lewis rats. Four experimental groups (n = 21) were examined: bovine hydroxyl apatite/collagen (bHA) without cells, bHA with undifferentiated mesenchymal stromal cells (MSC), bHA with osteogenically differentiated MSC. In a control group, the defect remained empty. After 6, 9 and 12 weeks, the remaining defect volume was assessed by cone beam computed tomography. Histologically, the remaining defect width and percentage of bone formation was quantified. After 12 weeks, the remaining defect width was 60.1% for bHA, 74.7% for bHA with undifferentiated MSC and 81.8% for bHA with osteogenically differentiated MSC. For the control group, the remaining defect width measured 46.2% which was a statistically significant difference (p < 0.001). The study design was suitable to evaluate tissue-engineered bone grafts prior to a clinical application. In this experimental set-up with the described maxillary defect, no promoting influence on bone formation of bone grafts containing bHA could be confirmed. The creation of a sufficient tissue-engineered bone graft for alveolar cleft osteoplasty could preserve patients from donor site morbidity.