A comparative study on the effects of pristine and functionalized single-walled carbon nanotubes on osteoblasts: ultrastructural and biochemical properties.

A comparative study was performed to investigate the ultrastructural and biomolecular properties of osteoblasts induced by three types of single-walled carbon nanotubes (SWNTs). The results on cellular uptake and ultrastructural alteration indicate that SWNTs enter osteoblasts by endocytosis. SWNTs-COOH and SWNTs-OH particles were freely dispersed in the cytoplasm, while pristine SWNTs were localized to the periphery of the cell. Both SWNTs-OH and SWNTs-COOH promoted cell changes in cell activity regarding mRNA expression at doses of 50 and 100 µg/mL in the first 24 h. When treated with 50 µg/mL SWNTs-COOH for 48 h, the expression of type I collagen increased by 6.3-fold (for MG63) or 9.1-fold (for primary osteoblasts) compared with the control group. The present study observed for the first time that SWNTs-COOH initiated the prompt and the maximum upregulation of type I collagen gene expression, and simultaneously induced the expansion of the endoplasmic reticulum for increased protein synthesis, which in turn accelerated the mineralization process. However, impaired cell properties and mitochondrial injury were detected following treatment with SWNTs at 100 µg/mL after 48 h. In conclusion, we believe that SWNTs-COOH is a good candidate for the fabrication of biomedical scaffolds for bone regeneration.

Evaluation of PRGD/FK506/NGF conduits for peripheral nerve regeneration in rats.

CONTEXT: Both tacrolimus (FK506) and nerve growth factor (NGF) enhance peripheral nerve regeneration, and in vitro experimental results demonstrate that the combination of FK506 and NGF increased neurite outgrowth compared with either treatment alone. AIM: To determine if the combination of FK506 and NGF benefits peripheral nerve regeneration compared with either treatment alone in vivo. SETTINGS AND DESIGN: Rat sciatic nerves were cut off to form a 10 mm defect and repaired with the nerve conduits. All of the 32 Wistar rats were randomly divided into 4 groups: Group A: RGD peptide modification of poly{(lactic acid)-co-[(glycolic acid)-alt-(L-lysine)]} (PRGD)/FK506/NGF; Group B: PRGD/FK506; Group C: PRGD/NGF; and Group D: autologous nerves. MATERIALS AND METHODS: At 3 months after surgery, the regenerated rat sciatic nerve was evaluated by electrophysiology, calf triceps wet weight recovery rate, and histologic assessment. STATISTICAL ANALYSIS USED: The SPSS 10.0 software (Bizinsight, Beijing China) was used for statistical analysis. RESULTS: The compound muscle action potentials (CMAPs) of groups A and D were significantly stronger than those of groups B and C. The calf triceps wet weight recovery rate of groups A and D were higher than those of groups B and C. The regenerated nerves of groups A and D were more mature than those of groups B and C. There was no significant difference between groups A and D. CONCLUSIONS: PRGD/FK506/NGF sustained-release nerve conduits are more effective in regenerating nerves than both PRGD/FK506 sustained-release nerve conduits and PRGD/NGF sustained-release nerve conduits. The effect is as good as that of an autograft.