Biocompatible nanoparticle labeling of stem cells and their distribution in brain

Nanolabeling is an invaluable novel technique in biology to detect and characterize different parts of biological systems including microscopic entities, viz., cells inside the living systems. Stem cells (SCs) are multipotent cells with the potential to differentiate into bone, cartilage, fat, muscle cells, and neurons and are being investigated for their utility in cell-based transplantation therapy. Yet, adequate methods to track transplanted SCs in vivo are limited, precluding functional studies. Nanoparticles (quantum dots) offer an alternative to organic dyes and fluorescent proteins to label and track cells in vitro and in vivo. These nanoparticles are resistant to chemical and metabolic degradation, demonstrating long-term photo stability. Here, we describe the technology of labeling the stem cells with silver nitrate nanoparticles in an in vitro coculture model. This is followed by defining the procedure of administering these cells in vivo and studying the distribution pattern and resultant regenerative effects of the "tagged" stem cells.