Nanofiber scaffolds for treatment of spinal cord injury.

Spinal cord injury (SCI) is a common neurologic disorder that results in loss of sensory function and mobility. It is well documented that tissue engineering is a potential therapeutic strategy for treatment of SCI. In this connection, various biomaterials have been explored to meet the needs of SCI tissue engineering and these include natural materials, synthetic biodegradable polymers and synthetic non- degradable polymers. Nanofiber scaffolds are newly emerging biomaterials that have been widely utilized in tissue engineering recently. In comparison to the traditional biomaterials, nanofibers have advantages in topography and porosity, thus mimicking the naturally occurring extracellular matrix. Besides, they exhibit excellent biocompatibility with low immunogenicity, and furthermore they are endowed with properties that help to bridge the lesion cavity or gap, and serve as an effective delivery system for graft cells or therapeutic drugs. This review summarizes some of the unique properties of nanofiber scaffolds which are critical to their potential application in treatment of injured spinal cord.

[A two-step protocol for induction of rat adipose tissue-derived stem cells into neuron-like cells].

OBJECTIVE: To investigate the differentiation potential of rat adipose tissue-derived cells (ADSCs) into neuron-like cells in vitro using a two-step induction protocol. METHODS: ADSCs isolated from the epididymal fat pads in male SD rats by means of differential attachment were cultured in vitro and subjected to adipogenic induction. After flow cytometric identification of the cell surface antigens CD106, CD11b, CD45, CD49d, CD90 and CD29, the third-passage ADSCs were induced to transdifferentiate into neural stem cell (NSC)-like cells in DMEM/F12 medium containing 10 ng/ml basic fibroblast growth factor (bFGF), 20 ng/ml epidermal growth factor (EGF) and 2% B27. The resultant NSC-like cells were then induced to differentiate into neuron-like cells in the neurobasal medium containing 10 ng/ml brain-derived neurotrophic factor (BDNF), 10 ng/ml glial cell line-derived neurotrophic factor (GDNF) and 1 µmol/L retinoic acid (RA). Immunocytochemistry was employed to identify the expression of the cell surface markers nestin, MAP2 and NeuN. RESULTS: The isolated ADSCs were positive for CD90 and CD29, and oil red O staining of the induced adipose-like cells yielded positive results. The third-passage ADSCs induced for 7 days aggregated as floating cell spheres positive for NSC surface antigen nestin. Further induction in neurobasal medium for 4 h resulted in adhesion of the cell spheres and the formation of cell processes extending from some peripheral cells, suggesting a morphological resemblance to neurons. Most of the cells showed positivity for MAP2 and NeuN. CONCLUSION: ADSCs can be induced to differentiate into neuron-like cells in vitro under appropriate conditions.

[Induced differentiation of rat adipose-derived stem cells into Schwann-like cells].

OBJECTIVE: To assess the differentiation potential of rat adipose-derived stem cells (ADSCs) into Schwann-like cells in vitro. METHODS: ADSCs isolated from adult SD rats were cultured in vitro and identified with the cell surface antigens CD44, CD49d and CD106 by immunocytochemistry. The ADSCs of the sixth to eighth passages were inoculated in polylysine-coated culture plate and cultured for 12 days in DMEM/F12 culture medium containing 10% fetal bovine serum, 5 ng/ml platelet-derived growth factor, 10 ng/ml basic fibroblast growth factor, 14 micromol/L Forskolin and 200 ng/ml Heregulin to induce their differentiation in vitro. Immunocytochemistry was performed to identify the expression of the cell surface markers nestin, glial fibrillary acidic protein (GFAP), S-100, and P75. RESULTS: The isolated and purified ADSCs were positive for CD44 and CD49d expressions but negative for CD106. After 12 days of culture in the conditional culture medium, most of the cells showed positive expressions of GFAP, S-100, and P75, the specific protein markers of Schwann cells. CONCLUSION: Adult rat ADSCs are confirmed to have potentials of neuroglial differentiation and capable of differentiating into Schwann-like cells in vitro.

Collagen gel coating or cyclosporine A for improving histocompatibility of chicken calamus keratin.

OBJECTIVE: To improve the histocompatibility of chicken calamus keratin (CCK) graft by collagen-gel coating or using of cyclosporine A (CsA). METHODS: Thirty SD rats were equally randomized into 5 groups, and in 4 of them, CCK implantation into the bilateral erector spinae was performed on different treatment protocols. In group A, the rats received daily intraperitoneal injection of CsA (5 mg/kg) for two consecutive weeks after CCK implantation; in group B, CCK was soaked in CsA (2.5 mg/ml) solution at 4 degrees Celsius; for 48 h before grafting; in group C, CCK coated with collagen gel was grafted; and in group D, only CCK was implanted. Rats in the fifth group received only cutaneous incision as well as muscular dissection to serve as the blank control. CCK degradation and its effect on the surrounding tissues were observed at 2, 4 and 8 weeks after grafting. Immunohistochemistry was performed to identify T lymphocyte infiltration in the host tissues. RESULTS: All the rats survived the operation. Numerous macrophages, especially multinucleated giant cells occurred on the peripheral of the CCK grafts, and small degraded CCK pieces were observed in their cytoplasm. Only a few inflammatory cells were seen in the host tissues. At 2, 4 and 8 weeks after CCK implantation, only a few CD3-positive cells were found in all the groups, and in group A and B, the density of T lymphocytes was significantly lower than that in group D, and there was no significant difference between group A and the blank control group. CONCLUSIONS: CsA significantly improves the histocompatibility of CCK material, and short-term systemic CsA administration achieves the best results. Macrophages, especially multinucleated giant cells participate in CCK degradation in vivo.

Co-transplantation of schwann cells promotes the survival and differentiation of neural stem cells transplanted into the injured spinal cord.

The present study investigates whether Schwann cells (SCs) could promote the survival and differentiation of neural stem cells in the injured spinal cord. Neural stem cells were dissociated and cloned from the hippocampal tissue of newborn rats. SCs were also dissociated and purified simultaneously from the sciatic nerves of 4-day-old rats. The results showed that the number of surviving neural stem cells and differentiated neuron-like cells was significantly increased in the co-grafted (SCs and neural stem cells) group compared with the control group (neural stem cells only). Neuron-like cells that developed axon-like processes were observed more commonly in the co-grafted group. These results demonstrate that SCs can promote the survival and differentiation of transplanted neural stem cells in the injured spinal cord.