This paper describes a modification of a balloon-compression technique to produce spinal cord injury in adult rats. A 2-French Fogarty catheter is inserted into the dorsal epidural space through a small hole made in T10 vertebral arch, advanced cranially to T8-9 spinal level, and inflated for 5 min. Spinal cord damage is graded by increasing the volume of saline used to inflate the balloon. Quantitative neurological and histopathological outcomes are presented with three different volumes (10, 15, and 20 μl of saline) to characterize the gradation of injury. Volume of 15 μ l produced complete paraplegia followed by gradual recovery, finally reaching approximately the middle of the scale used to quantitate the locomotor performance. With these animals, after 4 weeks, the center of the lesion shows complete loss of grey matter and partial sparing of the white matter. We conclude that 15 μl volume produced submaximal injury that will be useful for studying the pathophysiology and effects of protective therapies with this compression-injury model.

Transplantation of bone marrow mesenchymal stromal cells (MSCs) has been shown to improve the functional recovery in various models of spinal cord injury (SCI). However, the issues of the optimal dose, timing, and route of MSC application are crucial factors in achieving beneficial therapeutic outcomes. The objective of this study was to standardize the intrathecal (IT) catheter delivery of rat MSCs after SCI in adult rats. MSCs labeled with PKH-67 were administered by IT delivery to rats at 3 or 7 days after SCI as one of the following treatment regimens: (1) a single injection (5×10⁵ MSCs/rat), or (2) as three daily injections (5×10⁵ MSCs/rat/d for a total of 1.5×10⁶ MSCs/rat over 3 days, injected on days 3, 4, and 5, or days 7, 8, and 9 following SCI. The animals were behaviorally tested for 4 weeks using the Basso, Beattie, and Bresnahan (BBB) locomotor rating scale, and histologically assessed for MSC survival, distribution, and engraftment properties after 28 days. Rats treated with a single injection of MSCs at 3 or 7 days post-injury showed a modest, non-significant improvement in function and low survival of grafted MSCs, which were found attached to the pia mater or accumulated around the anterior spinal artery. In contrast, rats treated with three daily injections of MSCs at days 7, 8, and 9, but not on days 3, 4, and 5, showed significantly higher motor function recovery (BBB score 16.8±1.7) at 14–28 days post-injury. Transplanted PKH-67 MSCs were able to migrate and incorporate into the central lesion. However, only a limited number of surviving MSCs, ranging from 24,128±1170 to 116,258±8568 cells per graft, were observed within the damaged white matter. These results suggest that repetitive IT transplantation, which imposes a minimal burden on the animals, may improve behavioral function when the dose, timing, and targeted IT delivery of MSCs towards the lesion cavity are optimized.