ABSTRACT
The qualities of an ideal agent for tracking stem cells in biological tissue have been outlined by Frangioni and Hajjar (2004) and include the criteria that the agent (a) be biocompatible, safe, and nontoxic; (b) not require any genetic modi‹cation or perturbation to the stem cell; (c) permit single-cell detection at any anatomic location; (d) allow quanti‹cation of cell number; (e) have minimal or no dilution with cell division; (f) have minimal or no transfer to non-stem cells; (g) permit noninvasive imaging in the living subject over months to years; and (h) require no injectable contrast agent for visualization. This chapter provides a brief overview of traditional and newer cell-labeling agents, highlighting some of their pitfalls and the way in which quantum dot (QD) nanoparticles may represent a unique solution to the challenge of stem cell tracking by satisfying many of the criteria proposed.
