Gui-Bo Liu, Yong-Xia Cheng, Yu-Kuan Feng, Chao-Jian Pang, Qi Li, Ying Wang, Hua Jia, Xiao-Jie Tong A B C Figure 1. Rat ADSCs exhibit properties of stem cells. Rat ADSCs were passaged 3-5 times after initial plating of the primary culture. A – under phase contrast microscope, cultured ADSCs appeared as spindle-shaped. Rat ADSCs could undergo multi- lineage differentiation, including osteogenesis (B) and adipogenesis (C), as visualized by staining with Alizarin Red S or Oil-Red O, respectively (light microscope, ×200) Histological examination The segments of the nerves were immersed in 2.5% Na-cacodylate-buffered glutaraldehyde solution for 2 h, and fixed for 2 h in 2% Na-caco- dylate-buffered osmium tetroxide, then serially dehydrated in increasing concentrations of ethanol, infiltrated and embedded in Epon 812 (Ted Pella, CA, USA). A 1-μm-thick cross-section was obtained and then stained with toluidine blue to evaluate the efficacy of nerve regeneration. Statistical analysis The data were expressed as mean ± SD and analysed by SPSS 13.0 software. Analysis of variance was used for significant difference test. Student’s t-test was used for inter-group comparison. Value of p < 0.05 was considered statistically significant. Results Characterization of cultured adipose-derived stem cells Rat ADSCs within 3-5 passages appeared as a monolayer of large and flat cells (Figure 1 A). When induced with appropriate lineage-specific induction medium, ADSCs underwent adipogenesis (Figure 1 B) and osteogenesis (Figure 1 C), demons- trating that we successfully isolated ADSCs with stem cell characteristics. Adipose-derived stem cells implantation promotes nerve regeneration None of the 20 rats developed any serious post- surgical complications. Wounded tissues healed spontaneously, and there were no trophic ulce- rations on the operated legs. About 3 or 4 weeks later, muscular atrophy of operated legs of control groups was obvious. The adherence was very slight between the grafts and around tissues with no formation of neuroma. To evaluate the efficacy of ADSCs in functional improvement in peripheral nerve injured rats, we first compared the SFI between the ADSC-treated group and the control group. Typical walking tracts obtained from the rats 12 weeks after surgery are shown in Figure 2. The SFI analysis showed that functional recovery of the ADSC-treated group was significant better than that of the control group (p < 0.05) (Table I). In addition, electrophysiological analysis revealed higher nerve conduction velocities and peak amplitudes, and shorter incubation period in the ADSC-treated group compared to the control group and the differences were statistically significant (p < 0.05) (Table II). After 12 weeks of nerve injury, the right gastrocnemius and soleus muscles degenerated and lost weight. The muscle-mass conservation ratio showed that ADSC trans- plantation could reduce sciatic nerve injury-induced weight loss (Table II). To evaluate the regeneration efficacy of myelinated nerves after grafting with nerve grafts, 594 Arch Med Sci 4, August / 2011