Abstract 198: The Spleen Is A Pivotal Target Of Functional Recovery After Treatment With Multistem For Acute Ischemic Stroke
Background: There is increasing evidence to suggest that some types of stem cells enhance recovery after stroke by exerting immunomodulatory effects on the peripheral immune system.
Methods: We studied the effects of MultiStem®, an adherent, human pluripotent adult stem cell product, in a model of focal ischemic stroke in rats with and without a spleen. Long Evans male rats were subjected to middle cerebral artery occlusion (MCAo) for 90 minutes. At 24 hrs after stroke, animals were randomly assigned to either receive MultiStem® 12 million cells/kg (N= 9) or saline vehicle (N= 8). A separate group of animals underwent splenectomy two weeks prior to stroke and then were randomized to receive MultiStem® (N=9) or vehicle (N=9). All animals were serially evaluated on a battery of behavioral tests for 28 days. Stroke lesion volume was measured at 28 days after stroke. In another experiment, animals with and without spleens were subjected to MCAo, randomized to cell or saline treatment and then serum cytokines were analyzed at 3 days after treatment (N=5).
Results: MultiStem® improved functional recovery compared with saline treatment at 28 days after stroke in animals with intact spleens; however, in splenectomized rats, there was no difference in neurological deficits between MultiStem® and saline treated groups at 28 days after stroke. MultiStem® treatment reduced lesion size compared with saline-treated controls at 28 days after stroke in both groups with intact spleens or without spleens. Lesion size was reduced in saline-treated animals without spleens compared with animals that had intact spleens. At 4 days after stroke, serum levels of IL-10 were elevated in MultiStem treated animals compared with saline treated animals with intact spleens (p<0.05); however, this elevation in IL-10 was abolished in splenectomized animals treated with MultiStem® compared with vehicle. At 4 days after stroke, the proportion of CD4+ or CD8+ cells significantly decreased and Treg cells significantly increased in the spleens derived from MultiStem® treated animals compared with saline-treated controls. In the same animals at 4 days after stroke, splenocytes were cultured: IL-1β and TNF-α levels in the medium of cultured splenocytes derived from MultiStem® treated animals were significantly reduced (p<0.05) while IL-10 levels were significantly increased (p<0.05) compared with medium of cultured splenocytes derived from saline-treated animals.
Conclusion: MultiStem® improves neurological recovery after stroke through mechanisms involving the spleen. Our data suggest that MultiStem® modulates the immunophenotypes of splenocytes and alters their output of inflammatory cytokines, promoting a protective, anti-inflammatory environment. Regulatory T cells may be one of the pivotal sources of IL-10 and other anti-inflammatory mediators to reduce injury and/or enhance recovery in the brain after stroke.
- © 2012 by American Heart Association, Inc.