1Department of Orthopaedics, the Second Hospital of Lanzhou University, Lanzhou   730030, Gansu Province, China

2Institute of Orthopaedics, the Second Hospital of Lanzhou University, Lanzhou   730030, Gansu Province, China

Bin Zhao☆, Studying for doctorate, Attending physician, Department of Orthopaedics, the Second Hospital of Lanzhou University, Lanzhou  730030, Gansu Province, China Zhao B, Han H, Wang SK, Gao BR, Sun ZY. Differentiation of endogenous neural precursors following spinal cord injury in adult rats. Neural Regen Res 2008;3(7):705-9

Abstract

BACKGROUND: Studies have shown that cell death can activate proliferation of endogenous neural stem cells and promote newly generated cells to migrate to a lesion site.

OBJECTIVE: To observe regeneration and differentiation of neural cells following spinal cord injury in adult rats and to quantitatively analyze the newly differentiated cells.

DESIGN, TIME AND SETTING: A cell biology experiment was performed at the Institute of Orthopedics and Medical Experimental Center, Lanzhou University, between August 2005 and October 2007.

MATERIALS: Fifty adult, Wistar rats of both sexes; 5-bromodeoxyuridine (BrdU, Sigma, USA); antibodies against neuron-specific enolase, glial fibrillary acidic protein, and myelin basic protein (Chemicon, USA).

METHODS: Twenty-five rats were assigned to the spinal cord injury group and received a spinal cord contusion injury. Materials were obtained at day 1, 3, 7, 15, and 29 after injury, with 5 rats for each time point. Twenty-five rats were sham-treated by removing the lamina of the vertebral arch without performing a contusion.

MAIN OUTCOME MEASURES: The phenotype of BrdU-labeled cells, i.e., expression and distribution of surface markers for neurons (neuron-specific enolase), astrocytes (glial fibrillary acidic protein), and oligodendrocytes (myelin basic protein), were identified with immunofluorescence double-labeling. Confocal microscopy was used to detect double-labeled cells by immunofluorescence. Quantitative analysis of newly generated cells was performed with stereological counting methods.

RESULTS: There was significant cell production and differentiation after adult rat spinal cord injury. The quantity of newly-generated BrdU-labeled cells in the spinal cord lesion was 75-fold greater than in the corresponding area of control animals. Endogenous neural precursor cells differentiated into astrocytes and oligodendrocytes, however spontaneous neuronal differentiation was not detected. Between 7 and 29 d after spinal cord injury, newly generated cells expressed increasingly more mature oligodendrocyte and astrocyte markers.

CONCLUSION: Spinal cord injury is a direct inducer of regeneration and differentiation of neural cells. Endogenous neural precursor cells can differentiate into astrocytes and oligodendrocytes following adult rat spinal cord injury.

Key Words: spinal cord injury; nerve regeneration; neural stem cells; adult; quantitative analysis

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