Changes of the donor nerve in end-to-side neurorrhaphies with epineurial window and partial neurectomy: a long-term evaluation in the rat model.

End-to-side (ETS) neurorrhaphy has been applied in the repair of peripheral nerve injuries and in babysitter procedures. However, the long-term changes of donor nerve and muscle after ETS remain unknown. This study was designed to investigate long-term changes in donor nerve and muscle in a rat model. Sixty Lewis rats were equally allocated into three groups of 20 rats. The peroneal nerve was divided. In Group A, end-to-end (ETE) neurorrhaphy was performed. In Group B, ETS was performed to an epineurial window on the tibial nerve. In Group C, ETS was performed to the tibial nerve with 40% partial neurectomy. The following data were obtained at 6, 12, 18, and 24 weeks postoperatively: latency delaying rate (LDR), amplitude recovery rate (ARR), myelinated fiber counts, muscle force and weight, and cross-sectional area of gastrocnemius muscle fibers. The results showed no significant changes of the donor nerve and muscle in Group B. Nerve regeneration was found in the peroneal nerve, and myelinated fiber number was significantly decreased when compared to the nerve with ETE. In Group C, the myelinated axon number in the peroneal nerve was equivalent to the level in ETE repair. However, function and structure of the donor nerve and muscle were significantly impaired in the early postoperative period. Nonetheless, full recovery was observed 24 weeks after surgery. Both ETS with epineurial window and 40% donor nerve neurectomy showed reinnervation of the recipient nerve without structural and functional changes of the donor system in a long-term follow-up. Partial neurectomy may promote recipient nerve regeneration, but at the cost of donor neuromuscular compromises in the early postoperative period. This study provides long-term evidence for further investigation of ETS in peripheral nerve repair and in babysitter procedures.

Vancomycin-loaded nano-hydroxyapatite pellets to treat MRSA-induced chronic osteomyelitis with bone defect in rabbits.

OBJECTIVE: To investigate nano-hydroxyapatite (nHA) pellets as carriers for vancomycin in the treatment of chronic osteomyelitis and bone defects due to methicillin-resistant Staphylococcus aureus (MRSA) strains. METHODS: Chronic osteomyelitis was induced in 45 New Zealand white rabbits. After 3 weeks (chronic infection), all animals were treated with debridement. The rabbits were divided into an experimental group (the bone was filled with vancomycin-loaded nHA pellets), a control group (the bone was filled with nHA pellets alone), and a blank group. The drug release profiles were determined in vitro and in vivo. X-rays, bone specimens, and microorganism cultures were used to evaluate the efficacy of the treatments. RESULTS: Following a rapid initial release into the circulation, the drug concentration remained effective in the osseous and soft tissues for 12 weeks after debridement. Within 3 months, all rabbits in the experimental group recovered from osteomyelitis without a recurrence of the infection and the bone defects were partially repaired, whereas the infection and bone defects persisted in the control and blank groups. CONCLUSIONS: The results demonstrate that vancomycin-loaded nHA pellets successfully repair bone defects and control infection in MRSA-induced chronic osteomyelitis. In addition, nHA is an effective and safe controlled-release vancomycin carrier for chronic osteomyelitis with bone defects that is induced by MRSA.

[The treatment of monosegmental fixation and short-segment fixation on thoracolumbar burst fracture a retrospective controlled study].

OBJECTIVE: To investigate the safety and therapeutic effects of monosegment pedicle instrumentation in treating incomplete thoracolumbar burst fracture. METHODS: A retrospective analysis was conducted on 56 inpatients with incomplete thoracolumbar burst fracture (AO classification: A3.1 and A3.2) from April 2005 to January 2010. There were 28 cases were fixed with monosegment pedicle instrumentation (MSPI), 28 cases were fixed with short segment pedicle instrumentation (SSPI). The operative time, blood loss, visual analogue scale (VAS) and vertebral kyphotic angle (VK) before and after surgery were evaluated. RESULTS: In the group of MSPI, the mean operative time was (93 ± 20) min; the intraoperative blood loss was (184 ± 64) ml; the VK angle was 17° ± 10° before operation, 7° ± 7° at one week after operation, and 10° ± 7° at latest follow-up; VAS score was 7.6 ± 1.5 before operation, 2.4 ± 0.8 at one week after operation, and 1.5 ± 0.9 at latest follow-up; no adjacent segment degeneration was found. In the group of SSPI, the operative time was (102 ± 30) min; the intraoperative blood loss was (203 ± 88) ml; the VK angle was 17° ± 9° before operation, 7° ± 7° at one week after operation, and 8° ± 5° at latest follow-up; VAS score was 6.8 ± 1.3 before operation, 3.1 ± 0.5 at one week after operation, and 1.2 ± 0.7 at latest follow-up. One case of adjacent segment degeneration was found in 36 months after operation. There were no significantly statistical differences between two groups in operative time, blood loss, VAS score and VK angle before and after surgery (P > 0.05). The VAS score and VK angle at one week after surgery and latest follow-up all decreased obviously than preoperative ones in both groups (P < 0.05). CONCLUSIONS: MSPI for incomplete thoracolumbar burst fracture is effective and safe. The operative blood loss, the mean operative time, the improvement of VAS score and the VK angle in group MSPI are equal to those in group SSPI.

Granulocyte-macrophage colony-stimulating factor and interleukin 4 induce the malignant transformation of the bone marrow-derived human adult mesenchymal stem cells.

BACKGROUND: The purpose of the study was to examine the effects of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin 4 (IL-4) on the bone-marrow-derived human adult mesenchymal stem cells (hMSCs). METHODS: The hMSCs were isolated and cultured with GM-CSF and IL-4 for a period of one month. A single colony of transformed cells was then isolated and their phenotype was characterized by morphology, surface marker expression, and in vivo tumorigenesis. RESULTS: After one month culture, the transformed mesenchymal cells exhibited the morphology and phenotype similar to those of tumor cells, and also caused multiple fast growing lung deposits when it was injected into immunodeficient mice. CONCLUSION: Cytokines-driven malignant transformation of hMSCs may be a useful model for studying signaling pathways initiating malignant transformation of hMSC.

[Osteoblastic differentiation and in vivo osteogenic activity of marrow-derived mesenchymal stem cells stimulated by Tacrolimus: experiment with rats].

OBJECTIVE: To investigate the effect of the immunosuppressant Tacrolimus (FK506) on the osteoblastic differentiation and in vivo osteogenic inducement of bone marrow-derived mesenchymal stem cells (MSCs). METHODS: MSCs were derived from Fischer 344 rats. Some MSCs were cultured with L-ascorbic acid-2-phosphate (AsAP) and beta-glycerophosphate (beta-GP) or FK506 plus AsAP and beta-GP. The alkaline phosphatase (APase) activity and calcium deposition were detected 4, 8, 12, and 16 days after the culture. Scanning electron microscopy was used to examine the calcified nodules. Northern blotting was used to detect the mRNA expression of osteocalcium. Multiparous beta-tricalcium phosphate (beta-TCP) ceramic cubes were dipped into 2 kinds of suspension of MSCs, treated by FK506 + AsAP + beta-GP or AsAP + beta-GP, so as to produce 48 pieces of MSCs/beta-TCP complex that were randomly divided into 2 equal groups to be cultured with AsAP + beta-GP or AsAP + beta-GP + FK506 for 4 weeks. The these pieces were transplanted into the subcutaneous sites of the rats' backs and were taken out 4 and 8 weeks later respectively for histological examination. RESULTS: In vitro assays showed that the APase activity, calcium deposition, expression of osteocalcin mRNA of the FK506 + AsAP + beta-GP group at any time points were all significantly higher than those of the AsAP + beta-GP group (all P < 0.05). SEM showed that since the 16th day after culture calcified nodules began to be seen in the FK506 + AsAP + beta-GP group. Since the 4th weeks after transplantation remarkable new bone formation could be seen in the FK506 treated MSCs/beta-TCP complexes in comparison with those MSCs/beta-TCP complexes without treatment with FK506. CONCLUSION: Greatly enhancing the in vitro osteoblastic differentiation and in vivo osteogenesis of MSCs, FK506 has a potential value as a bone growth factor and may improve the clinical result of bone transplantation used to treat large bone defect. The results of this experiment also contributes to a better understanding on the mechanism of immunosuppressants.