Blood test could be used to know the effectiveness of transplanted stem cells, according to the researchers from the University of Maryland School of Medicine (UMSOM), the University of Pennsylvania and Emory University.
Stem cell based therapies to foster the heart muscle and treat other diseases are showing promise in various human clinical trials. But, lack of a repeatable time-sensitive and noninvasivetool to assess the effectiveness of the transplanted cells has slowed progress in the stem cell field.
Researchers aimed to achieve their goal by analyzing tiny cellular components called exosomes, secreted from the transplanted stem cells into the recipient blood. They tested their theory in rodent models of heart attack, or myocardial infarction, after transplanting two types of human cardiac stem cells and monitoring their circulating exosomes. The researchers found circulating exosomes delivered cell components to the target heart muscle cells, resulting in cardiac repair. Results are published in the journal Science Translational Medicine.
Through the blood test, which the researchers call a "liquid biopsy," the researchers monitored human cardiosphere-derived cells (CDCs) and cardiac progenitor cells (CPCs) transplanted into rat hearts following myocardial infarction. Blood plasma concentrations of the exosomes were compared seven days after transplant.
After purifying the CDC/CPC-derived exosomes, the researchers found the exosomes contained miRNAs associated with heart muscle recovery. Further, they found CPCs and CDCs produced in culture differed in contents from exosomes produced by transplanted cells in the living organism.
"Our study should be considered the first stepping stone in understanding what stem cells do, but an important point is that the cells we identified as responding changed their gene expression, behavior and secretions," said co-lead author Sudhish Sharma, PhD, UMSOM Assistant Professor of Surgery. "By using these biomarkers, we can understand the mechanism and extent of recovery."