Objective To investigate tissue engineered spinal cord which was constructed of bone marrow mesenchymal stem cells (BMSCs) seeded on the chitosan-alginate scaffolds bridging the both stumps of hemi-transection spinal cord injury (SCI) in rats to repair the acute SCI. Methods BMSCs were separated and cultured from adult male SD rat. Chitosan-alginate scaffold was produced via freeze drying, of which the structure was observed by scanning electron microscope (SEM) and the toxicity was determined through leaching l iquor test. Tissue engineered spinal cord was constructed by seeding second passage BMSCs on the chitosan-alginate scaffolds (1 × 106/mL) in vitro and its biocompatibil ity was observed under SEM at 1, 3, and 5 days. Moreover, 40 adult female SD rats were made SCI models by hemi-transecting at T9 level, and were randomly divided into 4 groups (each group, n=10). Tissue engineered spinal cord or chitosan-alginate scaffolds or BMSCs were implanted in groups A, B, and C, respectively. Group D was blank control whose spinal dura mater was sutured directly. After 1, 2, 4, and 6 weeks of surgery, the functional recovery of the hindl imbs was evaluated by the Basso-Beattie-Bresnahan (BBB) locomotor rating score. Other indexes were tested by wheat germ agglutinin-horseradish peroxidase (WGA-HRP) retrograde tracing, HE staining and immunofluorescence staining after 6 weeks of surgery. Results Chitosan-alginate scaffold showed three-dimensional porous sponge structure under SEM. The cells adhered to and grew on the surface of scaffold, arranging in a directional manner after 3 days of co-culture. The cytotoxicity of chitosan-alginate scaffold was in grade 0-1. At 2, 4, and 6 weeks after operation, the BBB score was higher in group A than in other groups and was lower in group D than in other groups; showing significant differences (P lt; 0.05). At 4 and 6 weeks, the BBB score was higher in group B than in group C (P lt; 0.05). After 6 weeks of operation, WGA-HRP retrograde tracing indicated that there was no regenerated nerve fiber through the both stumps of SCI in each group. HE and immunofluorescence staining revealed that host spinal cord and tissue engineering spinal cord l inked much compactly, no scar tissue grew, and a large number of neurofilament 200 (NF-200) positive fibers and neuron specitic enolase (NSE) positive cells were detected in the lesioned area in group A. In group B, a small quantity of scar tissue intruded into non-degradative chitosan-alginate scaffold at the lesion area edge, and a few of NSE flourescence or NF-200 flourescence was observed at the junctional zone. The both stumps of SCI in group C or group D were filled with a large number of scar tissue, and NSE positive cells or NF-200 positive cells were not detected. Otherwise, there were obviously porosis at the SCI of group D. Conclusion The tissue engineered spinal cord constructed by multi-channel chitosan-alginate bioscaffolds and BMSCs would repair the acute SCI of rat. It would be widely appl ied as the matrix material in the future.
Objective To investigate the influence of different transplantating times on the survival and immigration of the bone marrow mesenchymal stem cells (BMSCs) in injured spinal cord by subarachnoid administration, and to evaluate the most optimal subarachnoid administration times for BMSCs. Methods Eight adult male rats (weighing 120 g) were used to isolate BMSCs that were cultured, purified and labeled with Hoechst 33342 in vitro. Another 75 adult Wistar rats (weighing 220 g) were made the spinal cord injury (SCI) models at T9,10 level according to the improved Allen’s method and were randomly divided into 5 groups (groups A, B, C, D, and E, n=15). The labeled BMSCs at 1 × 107/mL 0.1 mL were injected into subarachnoid space of the rats via a catheters under the subarachnoid space in groups A (one time at 1 week), B ( two times at 1 and 3 weeks), C (3 times at 1, 3, and 5 weeks) and D (5 times at 1, 3, 5, 7, and 9 weeks) and 0.2 mL phosphate-buffered sal ine (PBS) was injected in group E (5 times at 1, 3, 5, 7, and 9 weeks) as blank control. The neurological functions were evaluated using the Basso-Beattie-Bresnahan (BBB) scale 1, 3, 5, 7, 9, and 12 weeks after transplantation. The migration, survival, differentiation, and histomorphological changes of BMSCs were observed by HE, immunohistochemistry, and fluorescence microscopy. Results At 3 weeks after injury, there were significant differences in the BBB scores between group E and groups A, B, C, D (P lt; 0.01), and between groups A, B and groups C, D (P lt; 0.01). At 7, 9, and 12 weeks, the BBB scores were significantly higher in groups C and D than in groups A and B (P lt; 0.01), and in group B than in group A (P lt; 0.01). There were no significant differences in the BBB scores between groups C and D (P gt; 0.05). The fluorescence microscopy showed that the transplanted BMSCs survived and grew in the injured region at 3 weeks after injury and as time went on, the transplanted cells gradually decreased in group A; in groups B, C, and D, BMSCs count reached the peak values at 5 and 7 weeks and then gradually decreased. At 12 weeks, the survival BMSCs were significantly more in groups C and D than in groups A and B (P lt; 0.01). HE staining showed that the formation of cavity was observed in each group at 3 weeks after injury and the area of cavity gradually decreased in groups A, B, C, and D. At 12 weeks, the area of cavity was the miximal in groups C and D, moderate in groups A and B, and the maximal in group E. The immunohistochemistry staining indicated that the expression of NF-200 was more intense in groups C and D than in groups A and B. The expression of NF-200-positive fibers was more intense in group C. Conclusion Multiple administration of BMSCs promotes the restoration of injured spinal cord and improves neurological functions, and three times for BMSCs transplantation is best