Fracture Healing Effects of Locally-Administered Adipose Tissue-Derived Cells

PURPOSE: Although the applications of adipose tissue-derived cells (ADCs) in regenerative medicine have been investigated, the role of ADCs in fracture healing remains unclear. In this study, we examined the fracture-healing effects and survival of transplanted ADCs using micro-computed tomography (CT) and bioluminescence imaging (BLI). MATERIALS AND METHODS: Luciferase-expressing ADCs were suspended in solubilized basement membrane preparation (SBMP) and xenografted on defects in the right femur of nude mice (n=5). SBMP alone was grafted on a defect in the contralateral femur. Serial in vivo micro-CT and BLI were performed for 20 days. Ex vivo BLI images of both femurs were obtained. Differences in the Hounsfield unit (HU), HU(ratio), and luciferase activities were compared using Wilcoxon signed-rank tests and non-parametric longitudinal analyses (p<0.05). RESULTS: In vivo BLI revealed a signal drop on day 2, reconstitution on day 5, and continuous decrement thereafter. Ex vivo BLI revealed residual activity in the ADC-implanted and adjacent areas. No activity was detected in the contralateral femur. The overall increment rate of normalized HUs was higher for ADC-treated femurs than for SBMP-treated femurs. Cell migration to distant injury sites was not detected. CONCLUSION: Enhanced bone density in the implant area suggests that ADCs have fracture-healing effects.