Grafting of human bone marrow stromal cells into spinal cord injury: a comparison of delivery methods

Abstract

Study design: Three groups of 6 rats received subtotal cervical spinal cord hemisections followed with marrow stromal cell (MSC) transplants by lumbar puncture (LP), intravenous delivery (IV), or direct injection into the injury (control). Animals survived for 4 or 21 days.

Objective: Cell therapy is a promising strategy for the treatment of spinal cord injury (SCI). The mode of cell delivery is crucial for the translation to the clinic. Injections directly into the parenchyma may further damage already compromised tissue; therefore, less invasive methods like LP or IV delivery are preferable.

Summary of background data: Human MSC are multipotent mesenchymal adult stem cells that have a potential for autologous transplantation, obviating the need for immune suppression. Although previous studies have established that MSC can be delivered to the injured spinal cord by both LP and IV, the efficacy of cell delivery has not been directly compared with respect to efficacy of delivery and effects on the host.

Methods: Purified MSC from a human donor were transplanted into the CSF at the lumbar region (LP), into the femoral vein (IV), or directly into the injury (control). After sacrifice, spinal cord sections were analyzed for MSC graft size, tissue sparing, host immune response, and glial scar formation, using specific antibodies and Nissl-myelin staining.

Results: LP delivery of MSC to the injured spinal cord is superior to IV delivery. Cell engraftment and tissue sparing were significantly better after LP delivery, and host immune response after LP delivery was reduced compared with IV delivery.

Conclusion: LP is an ideal minimally invasive technique to deliver cellular transplants to the injured spinal cord. It is superior to IV delivery and, together with the potential for autologous transplantation, lends itself for clinical application.

Figure 1

(A) LP delivery increased graft volume compared to IV at 4 and 21 days; * p < 0.005; ** p < 0.05. (B and C) Representative micrographs of tissue sections with MSC transplants delivered via IV (B) or LP (C) at 4 days. Dashed outline indicates injury border.

Figure 2

(A) LP delivery increases tissue sparing compared to IV delivery at 4 days. No difference in tissue sparing was seen at 21 days; * p < 0.05; ** p < 0.01. (B) Glial scar was more prominent after IV delivery compared to LP delivery at 4 days; no significant difference was seen at 21 days; * p < 0.05; ** p < 0.01. (C and D) Representative Nissl-myelin stained sections after IV (C) and LP (D) delivery at 4 days. Injury borders are outlined with dashed line.

Figure 3

(A and B) Macrophage/microglia response appeared decreased at 4 days after LP delivery compared to IV; p < 0.06. A significantly decreased T-cell response was observed at 4 days after LP delivery compared to IV delivery; * p < 0.01. At 21 days, no significant differences in the host immune response were observed. (C and D) Representative sections for IV (C) and LP (D) animals stained with ED-1 are shown. Dashed line indicates injury border.