Are pericytes stem cells?
"It all depends on how stringent your definition is of a stem cell, but I
do believe they behave in a similar manner with related endpoints.
Pericytes act as a plastic support cells with a primary goal of
stabilizing vascular perfusion and function, much the same way that stem
cells can adapt to different tissue needs to establish tissue
homeostasis. " - Amanda Jo LeBlanc, Assistant Professor, University of Louisville
"As a
pericyte purist, I would have previously said 'Pericytes are absolutely NOT
stem cells." But recently seeing some live imaging of pericyte migration,
I was surprised to see a subset of presumptive pericytes migrate off
capillaries into the interstitium. Do they assume a 'stem cell' phenotype?
We don't have concrete evidence, but I am not as resolute as I was
before." - John C. Chappell, Assistant Professor, Virginia Tech Carilion Research
Institute
"I think cell lineage-tracing
studies in mice and novel dynamic imaging approaches are beginning to reveal
that lots of different cells —pericytes included — possess previously
unrecognized (trans) differentiation potential in vivo. This
potential is likely heightened under conditions of injury and
inflammation." - Shayn Peirce-Cottler, Professor, University of Virginia
"My simple answer is, no.
Pericytes have an established function within the vasculature and are essential
in that function to the health of microvascular structures. However, pericytes
do exhibit high plasticity with, at least, tri-liniage capabilities. They
have been demonstrated to express CD146, CD24 and Stro-1, and to transition
into adipocytes, myofibroblasts and osteocytes. In pathological states
pericytes have been shown to migrate away from the vessel and contribute to the
reactive microglia population. So, while we don't consider them to be stem
cells as traditionally defined, they are certainly stem cell-like under the
appropriate conditions.” - Anjelica
Gonzales, Associate professor, Yale University
"I think pericytes
have the potential to be stem cells, but I’m not sure to what extent they
differentiate into and act as another cell type in vivo, particularly in
non-disease states. Maybe our definition of stem cell is inadequate. We tend to
think of cells in general as being either a differentiated cell or a stem cell,
but maybe pericytes are stem cells incognito as differentiated cells. Perhaps
they are never fully committed to differentiation and are on some continuum
between these two states based on the priming conditions of the environment."
- Jamie Mayo, Research Fellow, The
University of Melbourne
"Pericytes
are a jack of all trades, master of none. In the sense that, these cells are
capable of mimicking the action of others cells within the vasculature without
the need to differentiate." - Albert
Gonzales, Postdoctoral Fellow, University of Vermont
"I think yes, but I
do not know of definitive proof. It all depends on how you define a perciyte. I
look at pericytes along capillaries under the microscope all day long and I do
not know of any evidence to suggest that those cells transdifferentiate into
another cell type. I will not be surprised, however, when we do discover that
they can migrate off vessels, become interstitial cells, and differentiate into
a nerve, endothelial cell, or another cell type. Maybe the question should be -
Are pericytes macrophages?” - Lee Murfee, Associate Professor, Tulane
University
"Given the challenges of identifying
a definitive marker set for pericytes (markers often vary by tissue and/or are
shared by other cells types) and the dynamic nature of the many different cell
types within and around the microvascular niche, our group tends to use the
"pericyte” label to refer to those non-endothelial and vascular smooth muscle
cells associated with the microvessel that perform homeostatic activities (i.e.
anti-inflammatory, pro-healing, microvessel stability, etc.) as opposed to a
bona fide, single defined cell type.” - Jay
Hoying, Professor, University of Louisville
"Using the broadest
definition of a stem cell, which is defined as a cell that can self-renew and give
rise to terminally differentiated cell(s) types, pericytes certainly have been
demonstrated in multiple publications to fulfill these criteria. It is evident
that the migration and "differentiation” of pericytes is markedly influenced by
tissue injury, disease and inflammation. However, in the absence of definitive
cell-specific markers and lineage tracing studies I think there is no absolute
answer to this question at the present time.” - Bruce Bunnell, Professor, Tulane University
"I have yet to see evidence that pericytes
can become any cell in the body – a pre-requisite for being classified as stem
cells. That said, I believe they can acquire a new phenotype with different
functions in special circumstances (such as when activated or in pathological
conditions); which may make them be perceived as a different cell type
altogether." - Sara S. Nunes de
Vasconcelos, Assistant Professor, University of Toronto