Development of a rat model of spinal cord injury and cellular transplantation

Intravenously or intraspinally delivered human umbilical cord blood (UCB) cells and mesenchymal stem cells have been previously shown to improve the functional recovery of spinal cord-injured rats. Obtaining an animal model in the laboratory setting is critical for the development of experimental therapies. We have established a rat model of spinal cord injury (SCI) with basic histological and functional evaluations, ready to use for cell transplantation experiments.

In the first phase 10 Sprague-Dawley (SD) rats were used to standardize the laminectomy at D9-D10 without secondary lesions. In a second phase, 28 SD rats were laminectomized and injured at D9 by spinal cord compression for 3 to 5 seconds with an aneurysmal clip. Open-field behavior was assessed at days 2 and 7 postoperatively, and weekly until their sacrifice, using the Basso, Beattie, and Bresnahan locomotor rating scale. Two weeks postinjury, 14 immunosuppressed rats received a double intraspinal cell transplant of previously frozen UCB mononuclear cells (MNCs). Using a Hamilton syringe, 2.5 x 10(5) unlabelled MNCs in 10 microL medium were transplanted, rostrally and caudally to the lesion site. Rats were sacrificed at 4 weeks posttransplant by transcardial perfusion with 4% paraformaldehyde, and spinal cords were dissected and further fixated for histological analysis.

No wound infections were observed. Thirteen rats developed urinary tract infections and two animals showed autophagia grade 3. We observed a common spontaneous mobility improvement until a certain limit, depending on the degree of lesion and intrinsic characteristics of the animal.

An animal model of SCI has been established. Critical parameters in the survival and correct functional analysis are continuous animal care postinjury, urinary tract infections, autophagia, and weight loss. In addition, electrophysiological measures might be necessary to properly assess functional modifications.