Reconstruction of epidural fat with engineered adipose tissue from adipose derived stem cells and PLGA in the rabbit dorsal laminectomy model.

Epidural fibrosis resulted from epidural fat destruction following laminectomy operation is regarded as a main cause of failed back surgery syndrome, which represents one of the most common complications in spine surgery. Up to now, the effectiveness of currently available treatments to prevent such a syndrome is quite limited. In the present study, we aimed to restore epidural fat using adipose tissue engineered from adipose derived stem cells (ASCs) in a rabbit dorsal laminectomy model. ASCs isolated from subcutaneous fat were first expanded to passage 3, seeded on porous poly(lactic-co-glycolic acid, PLGA) scaffold and then adipogenically induced for 7 days in vitro to form cell-scaffold complex. Laminectomy sites were created at T13-L1 level in each animal. The laminectomy defect was implanted either with cell-scaffold complex or PLGA scaffold alone. Non-treated defect was also included as a control. The animals were subjected to MRI evaluation at 1, 12 and 24 weeks post-surgery, and sacrificed at 24 weeks for gross and histological observation. It was demonstrated by MRI evaluation that scar tissue of coarse and high density was formed within laminectomy site in PLGA alone and non-treated groups as early as 12 weeks. However, the defect implanted with engineered adipose had formed a continuous linear adipose tissue regenerated along the spinal cord at 24 weeks. Histologically, a distinct area of adipose tissue just overlaying the dura mater could be identified in cell-scaffold complex treated group at 24 weeks post-operation. Regeneration of epidural fat was further confirmed by positive Oil Red O staining. As to the defect treated with PLGA alone or left untreated, either fine or dense scar tissue adhering to the dura mater was observed. Moreover, we could track the implanted ASCs labeled by magnetic nanoparticles within epidural area for as long as four weeks by MRI detection. Thus, adipose tissue engineered from ASCs exhibited great potential in restoration of epidural fat to prevent formation of epidural fibrosis.

Distraction osteogenesis in the dog mandible under 60-Gy irradiation.

OBJECTIVE: The objective of this study was to explore the probability of distraction osteogenesis (DO) in the irradiated dog mandible after 60-Gy irradiation. STUDY DESIGN: Fourteen Chinese dogs were randomly divided into 2 groups. Twelve dogs received a preoperative unilateral irradiation from (60)Co (group R) in the mandible with a total dose of 24.8 Gy in four 6.2-Gy fractions (biologically equivalent to 60 Gy/25 fractions). The other 2 dogs without irradiation served as the control (group C). Bilateral corticotomies were made 6 months after completion of irradiation. Bone distraction was activated at a rate of 0.5 mm twice daily for 10 days after a 1-week latency period, followed by a consolidation phase of 8 weeks. The inferior alveolar nerve (IAN) underwent electrophysiologic analysis. Dog mandibles were subsequently subjected to histologic and radiographic analysis. RESULTS: All the animals had successful distractions. After 8 weeks of consolidation, no difference was found between the percentage area of new bone in both groups. New bone was more mature and organized in group C than in group R. The action potential of IAN showed corresponding alternation during the irradiation and distraction process. CONCLUSIONS: Based on this study it seems that DO may be feasible in dog mandible under 60-Gy irradiation. Further research is indicated.