Functional integration of quantum dot labeled mesenchymal stem cells in a cardiac microenvironment.

Bone marrow derived multipotent mesenchymal stem cells (MSCs) have the potential to differentiate into bone, cartilage, fat, and muscle cells and are being investigated for their utility in cell-based therapies. Stem cell transplantation therapy represents a novel and innovative approach with the promise to restore function to diseased or damaged heart muscle. Transplanted MSCs are expected to engraft, differentiate, and remodel in response to the surrounding cardiac microenvironment significantly changing the therapeutic approach for heart disease. Quantum Dots (QDs) offer an alternative to organic dyes and fluorescent proteins to label and track cells in vitro and in vivo. Here, we describe in vitro QD labeling of MSCs, MSC integration in a cardiomyocyte co-culture microenvironment, and a fluorescent recovery after photobleaching (FRAP) technique to assess functional cell-cell communication. FRAP techniques establish an optical record of dynamic cellular interactions with high spatial and temporal resolution and can be used to successfully evaluate dynamic changes in cellular coupling in multicellular preparations.