Fast forward for mesenchymal cells in the vasculature
Here's my summary of a couple v. cool papers just published on powerful cells within blood vessels, with potential for tissue engineering and regenerative medicine. (We'll have it as a formal article next week)
Extra rolls of fat certainly come from extra calories, but where new fat cells come from has been far less certain. New research in mice shows that blood vessels within fat tissue harbour cells that have already committed to becoming fat cells and that give rise to most new fat cells.
Jonathan Graff and colleagues at the University of Texas Southwestern Medical Center, in Dallas, used a slew of genetic tricks to figure out when fat cell progenitors are produced and to track the descendents of these cells1. They found, surprisingly, a set of fat stem cells within the walls of blood vessels. "These cells lead to the formation of fat and likely are activated in obesity, so if you can interrupt that, you could block cells from forming or keep them from functioning," says Graff.
In particular, blood vessels could well regulate the formation of new fat tissue. Studies have hinted that blood vessels within many tissues house powerful progenitor cells that seem similar to the mesenchymal stem cell populations known to exist in bone marrow. A 20-member international team led by Bruno Péault at the University of Pittsburgh Medical School, in Pennsylvania, recently reported2 that the vasculature of multiple human organs contains cells “indistinguishable from classic mesenchymal stem cells.” These cells, says Péault, “should constitute an ubiquitous stem cell reserve in the body.”
Péault says Graff’s work is important because knowing what pericytes, which are also called mural cells, can do in culture is not the same as knowing how they normally function within animals. “We demonstrated the existence of a potential, but we have no clue as to how this potential is used.” Graff’s work “nicely confirms, in an elegant dynamic model, our basic statement regarding the role of mural cells as a stem cell reservoir,” says Péault.
Péault, who is also working on cell-tracking models, says an important next step is studying the role of pericytes in other tissues besides fat. “This obviously opens a broad field of investigation,” he says.
References
1. Tang, W. et al. White fat progenitor cells reside in the adipose vasculature. Science doi:10.1126/science.1156232 (published online 18 September 2008).
2. Crisan, M. A perivascular origin for mesenchymal stem cells in multiple human organs. Cell Stem Cell 3, 301–313 (2008). | Article |
Author affiliation
Monya Baker is editor of Nature Reports Stem Cells.
