Chapter 2 Searching for In Vivo Traces of Mesenchymal Stem Cells and Their Ancestors

摘要

Mesenchymal stem cells (MSCs) have been well identified in cultures obtained from various human tissues. However, they give no clue as to their native identity, frequency, or anatomical location. Based on in vivo and in vitro experimental studies, the most promising candidate for the MSC niche is the vicinity of blood vessels. Capillaries to large-caliber arteries and veins house multipotent progenitor cells that share many morphological, phenotypical, and developmental features with freshly isolated or cultured MSCs. In this mini-review, results from our and other laboratories are summarized and suggest that MSCs originate from tissue sites where pericytes reside, although we do not rule out the possibility that only a small portion of pericytes give rise to MSCs. Understanding the MSC niches can definitely help us to take many parameters into account when designing isolation, expansion, and differentiation protocols for using these cells in future therapeutic applications.