Researchers at the University of California-Irvine’s Sue & Bill Gross Stem Cell Research Center report that stem cells taken from bone marrow may help patients recover from a stroke. Steven Cramer, M.D., a neurologist, and Weian Zhao, Ph.D., a biomedical engineer, identified 46 studies that examined the use of mesenchymal stromal cells (MSCs), a type of multipotent adult stem cells mostly processed from bone marrow, in animal models of stroke. They found MSCs to be significantly better than control therapy in 44 of the studies.
“In preclinical studies, MSCs have consistently improved multiple outcome measures, with very large effect sizes,” wrote the investigators. “Results were robust across species studied, administration route, species of MSC origin, timing, degree of immunogenicity, and dose, and in the presence of comorbidities. In contrast to meta-analyses of preclinical data for other stroke therapies, higher-quality MSC preclinical studies were associated with larger behavioral gains. These findings support the utility of further studies to translate MSCs in the treatment of ischemic stroke in humans.”
“Stroke remains a major cause of disability, and we are encouraged that the preclinical evidence shows [MSCs'] efficacy with ischemic stroke,” said Dr. Cramer, whose team published its study (“Meta-analysis of preclinical studies of mesenchymal stromal cells for ischemic stroke”) in Neurology. “MSCs are of particular interest because they come from bone marrow, which is readily available, and are relatively easy to culture. In addition, they already have demonstrated value when used to treat other human diseases.”
He explained that MSCs do not differentiate into neural cells. Normally, they transform into a variety of cell types, such as bone, cartilage, and fat cells. “But they do their magic as an inducible pharmacy on wheels and as good immune system modulators, not as cells that directly replace lost brain parts,” he said.
In an earlier report focused on MSC mechanisms of action, Drs. Cramer and Zhao reviewed the means by which MSCs promote brain repair after stroke. The cells are attracted to injury sites and, in response to signals released by these damaged areas, begin releasing a wide range of molecules. In this way, MSCs orchestrate numerous activities: blood vessel creation to enhance circulation, protection of cells starting to die, growth of brain cells, etc.
At the same time, when MSCs are able to reach the bloodstream, they settle in parts of the body that control the immune system and foster an environment more conducive to brain repair.