SDF1-A Facilitates Lin−/Sca1+ Cell Homing following Murine Experimental Cerebral Ischemia

Background Hematopoietic stem cells mobilize to the peripheral circulation in response to stroke. However, the mechanism by which the brain initiates this mobilization is uncharacterized. Methods Animals underwent a murine intraluminal filament model of focal cerebral ischemia and the SDF1-A pathway was evaluated in a blinded manner via serum and brain SDF1-A level assessment, Lin−/Sca1+ cell mobilization quantification, and exogenous cell migration confirmation; all with or without SDF1-A blockade. Results Bone marrow demonstrated a significant increase in Lin−/Sca1+ cell counts at 24 hrs (272±60%; P<0.05 vs sham). Mobilization of Lin−/Sca1+ cells to blood was significantly elevated at 24 hrs (607±159%; P<0.05). Serum SDF1-A levels were significant at 24 hrs (Sham (103±14), 4 hrs (94±20%, p = NS) and 24 hrs (130±17; p<0.05)). Brain SDF1-A levels were significantly elevated at both 4 hrs and 24 hrs (113±7 pg/ml and 112±10 pg/ml, respectively; p<0.05 versus sham 76±11 pg/ml). Following administration of an SDF1-A antibody, Lin−/Sca1+ cells failed to mobilize to peripheral blood following stroke, despite continued up regulation in bone marrow (stroke bone marrow cell count: 536±65, blood cell count: 127±24; p<0.05 versus placebo). Exogenously administered Lin−/Sca1+ cells resulted in a significant reduction in infarct volume: 42±5% (stroke alone), versus 21±15% (Stroke+Lin−/Sca1+ cells), and administration of an SDF1-A antibody concomitant to exogenous administration of the Lin−/Sca1+ cells prevented this reduction. Following stroke, exogenously administered Lin−/Sca1+ FISH positive cells were significantly reduced when administered concomitant to an SDF1-A antibody as compared to without SDF1-A antibody (10±4 vs 0.7±1, p<0.05). Conclusions SDF1-A appears to play a critical role in modulating Lin−/Sca1+ cell migration to ischemic brain

Manual versus Automated Rodent Behavioral Assessment: Comparing Efficacy and Ease of Bederson and Garcia Neurological Deficit Scores to an Open Field Video-Tracking System

Animal models of stroke have been crucial in advancing our understanding of the pathophysiology of cerebral ischemia. Currently, the standards for determining neurological deficit in rodents are the Bederson and Garcia scales, manual assessments scoring animals based on parameters ranked on a narrow scale of severity. Automated open field analysis of a live-video tracking system that analyzes animal behavior may provide a more sensitive test. Results obtained from the manual Bederson and Garcia scales did not show significant differences between pre- and post-stroke animals in a small cohort. When using the same cohort, however, post-stroke data obtained from automated open field analysis showed significant differences in several parameters. Furthermore, large cohort analysis also demonstrated increased sensitivity with automated open field analysis versus the Bederson and Garcia scales. These early data indicate use of automated open field analysis software may provide a more sensitive assessment when compared to traditional Bederson and Garcia scales

Enumeration of bone marrow and blood Lin−/Sca1+ cell numbers following stroke and SDF1-A Antibody.

<p>(A) Twenty-four hour post stroke+SDF1-A antibody mice show a marked increase in the number of Lin−/Sca1+ cells present in the bone marrow compared to controls. (B) Twenty-four hour post stroke mice showed a marked decrease in the mobilization of these cells to the blood. * P<0.05.</p

SDF1-A levels in serum and brain.

<p>(A) Serum SDF1-A levels reached significance at 24 hours post surgery. (B) Brain tissue levels of SDF1-A demonstrated significant elevations at both 4 and 24 hours post stroke compared to sham animals. *P<0.05.</p

Enumeration of bone marrow and blood Lin−/Sca1+ cell numbers following stroke.

<p>(A) Twenty-four hour post stroke mice show a marked increase in the number of Lin−/Sca1+ cells present in the bone marrow compared to controls. (B) Twenty-four hour post stroke mice also showed a marked increase in the mobilization of these cells to the blood. * P<0.05.</p

Y chromosome Positive cells in brain.

<p>Male Lin−/Sca1+ cells injected IV post stroke were counted in female ischemic hemisphere at 24 hours post stroke; Animals which received SDF1-A antibody in addition to the IV Lin−/Sca1+ cells, had a significantly lower number of cells detected in the brain by FISH (*P<0.05). Green = Y chromosome.</p