Letter by Taguchi et al Regarding Article, “Granulocyte Colony-Stimulating Factor in Patients With Acute Ischemic Stroke: Results of the AX200 for Ischemic Stroke Trial”

Transplantation of hematopoietic stem cells: intra-arterial versus intravenous administration impacts stroke outcomes in a murine model

Based on results of hematopoietic stem cell transplantation in animal models of stroke, clinical trials with hematopoietic stem cells administered intra-arterially or intravenously have been initiated in patients. Although intra-arterial injection is expected to deliver transplanted cells more directly to the ischemic tissue, the optimal route for enhancing clinical outcomes has not been identified in the setting of stroke. In this study, we compared the therapeutic potential of intra-arterial versus intravenous injection of bone marrow derived-mononuclear cells (BM-MNCs) and CD133-positive (CD133(+)) cells in a murine stroke model. We have found that intra-arterial injection of BM-MNCs exaggerates inflammation with accompanying loss of microvascular structures in poststroke brain and no improvement in cortical function. In contrast, intravenous injection of BM-MNCs did not similarly enhance inflammation and improved cortical function. Our results indicate that the optimal route of cell transplantation can vary with different cell populations and highlight possible issues that might arise with intra-arterial cell administration for acute ischemic cerebrovascular disease.

Intravenous Autologous Bone Marrow Mononuclear Cell Transplantation for Stroke: Phase1/2a Clinical Trial in a Homogeneous Group of Stroke Patients

The goal of this clinical trial was to assess the feasibility and safety of transplanting autologous bone marrow mononuclear cells into patients suffering severe embolic stroke. Major inclusion criteria included patients with cerebral embolism, age 20–75 years, National Institute of Health Stroke Scale (NIHSS) score displaying improvement of ≤5 points during the first 7 days after stroke, and NIHSS score of ≥10 on day 7 after stroke. Bone marrow aspiration (25 or 50 mL; N = 6 patients in each case) was performed 7–10 days poststroke, and bone marrow mononuclear cells were administrated intravenously. Mean total transplanted cell numbers were 2.5 × 10⁸ and 3.4 × 10⁸ cells in the lower and higher dose groups, respectively. No apparent adverse effects of administering bone marrow cells were observed. Compared with the lower dose, patients receiving the higher dose of bone marrow cells displayed a trend toward improved neurologic outcomes. Compared with 1 month after treatment, patients receiving cell therapy displayed a trend toward improved cerebral blood flow and metabolic rate of oxygen consumption 6 months after treatment. In comparison with historical controls, patients receiving cell therapy had significantly better neurologic outcomes. Our results indicated that intravenous transplantation of autologous bone marrow mononuclear cells is safe and feasible. Positive results and trends favoring neurologic recovery and improvement in cerebral blood flow and metabolism by cell therapy underscore the relevance of larger scale randomized controlled trials using this approach.