Fabrication of Silk-Hyaluronan Composite as a Potential Scaffold for Tissue Repair.

Interest is rapidly growing in the design and preparation of bioactive scaffolds, mimicking the biochemical composition and physical microstructure for tissue repair. In this study, a biomimetic biomaterial with nanofibrous architecture composed of silk fibroin and hyaluronic acid (HA) was prepared. Silk fibroin nanofiber was firstly assembled in water and then used as the nanostructural cue; after blending with hyaluronan (silk:HA = 10:1) and the process of freeze-drying, the resulting composite scaffolds exhibited a desirable 3D porous structure and specific nanofiber features. These scaffolds were very porous with the porosity up to 99%. The mean compressive modulus of silk-HA scaffolds with HA MW of 0.6, 1.6, and 2.6 × 106 Da was about 28.3, 30.2, and 29.8 kPa, respectively, all these values were much higher than that of pure silk scaffold (27.5 kPa). This scaffold showed good biocompatibility with bone marrow mesenchymal stem cells, and it enhanced the cellular proliferation significantly when compared with the plain silk fibroin. Collectively, the silk-hyaluronan composite scaffold with a nanofibrous structure and good biocompatibility was successfully prepared, which deserved further exploration as a biomimetic platform for mesenchymal stem cell-based therapy for tissue repair.

X-ray therapy promotes structural regeneration after spinal cord injury in a rat model.

OBJECTIVE: This study aims to investigate the therapeutic effects and mechanisms of x-ray treatment on rats following spinal cord injury (SCI). METHODS: Forty-six female Sprague-Dawley rats were subjected to spinal cord injury using the modified Allen weight-drop method. The animals were randomly divided into six groups. Two of the animal groups were irradiated with 10 Gy at the lesion site; another two groups were irradiated with 20 Gy; and the last two groups without irradiation were regarded as the sham group. One of the each of two animal groups was euthanized at different time points at 4 and 12 weeks, respectively, after irradiation. Spinal cord calluses were assessed using kinology and electrophysiology and histology methods. RESULTS: In all of the groups, the neurofilament (NF) counts at 14 weeks were found to be higher than that at 6 weeks after SCI. Both 10-Gy irradiated and 20-Gy irradiated groups were higher than those of the sham group at each time point (P < 0.05). The myelin basic protein (MBP) count decreased at 14 weeks after SCI in the irradiated groups (P < 0.05) but increased at 14 weeks in the sham group (P < 0.05). Furthermore, the MBP count of the irradiated groups was lower than that of the sham group at 14 weeks (P < 0.05). The glial fibrillary acidic protein (GFAP) and Nogo-A counts at 14 weeks were higher than those at 6 weeks in all the groups (P < 0.05), and there was no statistical significance with kinology and electrophysiology tests in all groups. CONCLUSIONS: A self-repair mechanism exists after spinal cord injury, which lasts at least 14 weeks. X-ray therapy promotes the regeneration of the spinal cord system after injury.

Pedicle screw instrumentation plus augmentation vertebroplasty using calcium sulfate for thoracolumbar burst fractures without neurologic deficits.

OBJECTIVE: To evaluate the efficacy of posterior instrumentation plus vertebroplasty and posterolateral fusion using calcium sulfate for thoracolumbar burst fractures without neurologic deficits. METHODS: Between July 2005 and January 2008, a total of 45 patients who had been diagnosed as having thoracolumbar burst fractures without neurologic deficits were treated with pedicle screw instrumentation plus vertebroplasty using calcium sulfate in our unit. The Cobb angles and loss rates of anterior-middle columns height at different time intervals were measured on lateral radiographs, and the preoperative and postoperative functional outcomes were evaluated using the Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI). RESULTS: The Cobb angles and loss rates of anterior-middle columns height postoperatively period were restored significantly compared with those noted preoperatively. The angles and heights were well maintained for at least two years using this technique. The mean postoperative VAS (back pain) score was 2.1 ± 0.8, which was significantly better (P < 0.001) than the mean preoperative VAS score 7.9 ± 1.1. The average preoperative ODI was 66.6 ± 8.1% and this had improved significantly to 15.5 ± 4.5% by the latest follow-up (P < 0.001). No instrumentation failure was detected in this study. The calcium sulfate had been absorbed completely by 3-6 months postoperatively. CONCLUSION: Pedicle screw instrumentation plus augmentation vertebroplasty with calcium sulfate is an economic, efficient and reliable technique for treating unstable thoracolumbar fractures without neurologic deficits.

Ginsenoside Rg1 promotes proliferation and neurotrophin expression of olfactory ensheathing cells.

Transplantation of olfactory ensheathing cells (OECs) is currently considered to be one of the most promising repair strategies for human spinal cord injury. However, the factors that regulate OECs are still poorly understood. Ginsenoside Rg1 (Rg1), the phytosterol from Panax ginseng, is a potent neuroprotective agent that promotes axonal regeneration. The aim of this study is to determine whether Rg1 would influence the biological activity of OECs. Primary cultured OECs from the olfactory bulb of neonatal rats were treated with Rg1 of various concentrations and durations. Using MTT and bromodeoxyuridine assays, we found that Rg1 significantly promoted cell proliferation, with an optimal concentration of 40 mug/ml of Rg1 at 72 h. In addition, RT-PCR and ELISA assays showed that Rg1 could upregulate the mRNA expression and secretion of glial cell-derived neurotrophic factor, brain-derived neurotrophic factor, and nerve growth factor. These results suggest that Rg1 may have a great potential in OEC therapy.

The application of platelet-rich plasma may be a novel treatment for central nervous system diseases.

As a potential biological product, platelet-rich plasma (PRP) has been widely utilized in the areas of oral and maxillofacial reconstruction, bone and soft tissue restoration and wound healing. A recent study reported that the application of PRP on interrupted sciatic nerve could promote remyelinization of peripheral nerve. This renovated a notion that the application of PRP might extend to the nervous system. Most central nervous system (CNS) diseases have a series of common pathological changes in the later period of diseases which induce neurons and glia apoptosis and aggravate neurological dysfunction. It has been demonstrated that the potent restorative function of PRP is mainly based on neurotrophic capacity of preparation rich in growth factors (PRGFs) and scaffolding effect of platelet-rich gel (PRG), all of which could be certified to ameliorate the pathological process of CNS diseases. In view of this, we propose a hypothesis that the application of PRP and its derivatives might provide a novel therapeutic approach for CNS diseases, especially for traumatic brain or spinal cord injury, autoimmune diseases and neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis.

[Local X-irradiation promotes regeneration of spinal cord central nervous system in a rat model].

OBJECTIVE: To evaluate the effect of local X-irradiation on spinal cord injury by using physiology, kinology, electrophysiology and histology method. METHODS: 46 female Sprague-Dawley rats were subjected to spinal cord injury by weight dropping on T(11-12). All animals were divided into 3 groups randomly. One of the animal groups was irradiated with 10 Gy at the lesion site; another was irradiated with 20 Gy, the other without irradiation is regarded as sham-group. The animals were euthanized at different time points at 4 and 12 weeks after irradiation. Spinal cord callus was assessed by using physiology, kinology, and electrophysiology and histology method. RESULTS: In all the groups, the NF at 14 weeks were found higher than that of 6 weeks. Both 10 Gy irradiated and 20 Gy irradiated groups were higher than those of group at each time point (P < 0.05). The MBP decreased at 14 weeks in irradiated groups (P < 0.05), but increased at 14 weeks in sham-group (P < 0.05), the MBP of irradiated groups was lower than that sham-group at 14 weeks (P < 0.05). The GFAP and Nogo-A at 14 weeks were higher than that in 6 weeks in all the groups (P < 0.05), and there was no statistical significance with physiology, kinology, electrophysiology test in all groups. CONCLUSION: A self-repair mechanism exists after SCI, which will last at least 14 weeks. Local irradiation promotes the regeneration of spinal cord system after injury to some extent.

[Surgical management of traumatic injury of upper cervical spine].

OBJECTIVE: To analyze retrospectively the clinical outcome of surgical management for upper cervical spine injury caused by trauma. METHODS: From January 2005 to March 2007, 16 patients with injury of upper cervical spine were treated by different management. There were 11 males and 5 females with an average age of 44 years ranging from 24 to 75. Of all, 5 cases were the odontoid fracture, 3 were atlas fracture, 5 were Hangman's fracture, 3 were atlanto-axial dislocation. MR imaging of cervical spine showed cervical cord compression and changes of T2 high signal in 5 cases. According to the injury mechanism, the imageological appearance, fracture classification, the methods of treatment were selected. RESULTS: Seven patients received non-operative treatment and nine patients underwent operation. Sixteen patients were followed up for 7 to 34 months (means 10.5 months). All fractures were healing or bone graft fusion and no internal fixation was lossing. There were no injuries of vertebral artery, nerve root or spinal cord. CONCLUSION: CT and MRI are required in the course of diagnosis for the traumatic injury of upper cervical spine. The optimal modus operandi should be choose to retain upper cervical spine, meanwhile, can reserve the cervical movement.