Undifferentiated Human Adipose Tissue-Derived Stromal Cells Induce Mandibular Bone Healing in Rats

Objective: To test the osteo-regenerative potential of adipose tissue derived stromal cells (ATSCs), an attractive human source for tissue engineering, in a rat modelof mandibular defect. Human dermal fibroblasts (HDFs)were used as a differentiated cellular control in the study. Design: The ATSCs and HDFs were isolated from human lipoaspirate and skin biopsy specimens, respectively. Cells were characterized in vitro and then adsorbed on an osteo-conductive scaffold to be transplanted in a mandibular defect of immunosuppressed rats. Naked unseeded scaffold was used as a negative control. Main Outcome Measures: Bone healing was studied by computerized tomography and histologic analysis after 4, 8, and 12 weeks. Results: Computed tomography showed that undifferentiated ATSCs induced successful bone healing of the mandible defect when transplanted in animals, compared with HDFs and negative controls. Histologic analysis demonstrated that the newly formed tissue in the surgical defect retained the features of compact bone. Conclusion: Undifferentiated human ATSCs are suitable for cell-based treatment of mandibular defects, even in the absence of previous osteogenic induction in vitro.