Cell therapy using bone marrow stromal cells in chronic paraplegic rats: Systemic or local administration?

Recent studies showed the therapeutic effect of bone marrow stromal cells (BMSC) after spinal cord injury (SCI). In the present study, we compared the effect of systemic and local administration of BMSC in adult Wistar rats suffering chronic paraplegia as consequence of severe SCI. Adult Wistar rats were subjected to a weight-drop impact causing complete paraplegia, and 3 months later, all the animals remained without signs of functional recovery. At this moment, 3 × 106 BMSC were injected intravenously (n: 20) or into traumatic spinal cord cavity (n: 20). Outcome was evaluated until sacrifice of the animals, 6 months later, using the Basso–Beattie–Bresnehan (BBB) score, the cold spray test, and measuring the thigh perimeter. After sacrifice, samples of spinal cord tissue were studied histologically. The results showed that intravenous administration of BMSC achieves some degree of functional recovery when compared to controls. Nevertheless, administration of BMSC into postraumatic spinal cord cavity promotes a clear and progressive functional recovery, significantly superior to the recovery obtained by means of the intravenous administration. This effect is associated to long-term presence of BMSC in the injured spinal cord tissue, with images suggesting neuronal differentiation and spinal cord reconstruction.