Immortalized CNS pericytes are quiescent smooth muscle actin-negative and pluripotent

Abstract

Despite their identification more than 100 years ago by the French scientist Charles-Marie Benjamin Rouget, microvascular pericytes have proven difficult to functionally characterize, due in part to their relatively low numbers and the lack of specific cell markers. However, recent progress is beginning to shed light on the diverse biological functions of these cells. Pericytes are thought to be involved in regulating vascular homeostasis and hemostasis as well as serving as a local source of adult stem cells. To further define the properties of these intriguing cells, we have isolated pericytes from transgenic mice (Immortomouse®) harboring a temperature-sensitive mutant of the SV40 virus target T-gene. This Immortopericyte (IMP) conditional cell line is stable for long periods of time and, at 33°C in the presence of interferon gamma, does not differentiate. Under these conditions IMPs are alpha muscle actin-negative and exhibit a pluripotent phenotype, but can be induced to differentiate along both mesenchymal and neuronal lineages at 37°C. Alternatively, differentiation of wild type pericytes and IMPs can be induced directly from capillaries in culture. Finally, the addition of endothelial cells to purified IMP cultures augments their rate of self-renewal and differentiation, possibly in a cell-to-cell contact dependent manner.

A Novel Population of α-Smooth Muscle Actin-Positive Cells Activated in a Rat Model of Stroke: An Analysis of the Spatio-Temporal Distribution in Response to Ischemia

“…The coexpression of aSMA + /GFAP + (Lecain et al, 1991) is consistent with expression by subpopulations of multipotential precursors of pericytes cultured in vitro (Dore- Duffy et al, 2011). For this reason, other markers of precursors (nestin) and pericytes were investigated and these included desmin (Kokovay et al, 2006) Figures 3G and 3H), aSMA + cells were negative for nestin.…”

“…Immortalized precursors of murine pericytes with proliferative potential express PDGFRb and NG2, but not aSMA (Dore- Duffy et al, 2011). With basic fibroblast growth factor immortalized pericytes form neurospheres and many cells appear to coexpress markers for pericytes (NG2), neurons (NF), astrocytes a-smooth muscle actin-positive cells in stroke V Sharma et al (GFAP), and oligodendrocytes (O4), suggesting an immature phenotype (Dore- Duffy et al, 2011).…”

“…With basic fibroblast growth factor immortalized pericytes form neurospheres and many cells appear to coexpress markers for pericytes (NG2), neurons (NF), astrocytes a-smooth muscle actin-positive cells in stroke V Sharma et al (GFAP), and oligodendrocytes (O4), suggesting an immature phenotype (Dore- Duffy et al, 2011). We had observed aSMA + cells (putative pericytes) some of which also expressed GFAP, which might also be consistent with an immature phenotype of cells that go on to differentiate into astrocytes (aSMAÀ).…”

“…Pericyte precursors have been found to be multipotential (Dore-Duffy et al, 2011) and furthermore, immortalized multipotential precursors were a-smooth muscle actin (aSMA)-negative in vitro (Dore- Duffy, 2008;Dore-Duffy et al, 2011). However, transforming growth factorb has been reported to induce aSMA in the brain (Verbeek et al, 1994) and retinal (Sieczkiewicz and Herman, 2003) pericytes, perhaps suggesting that aSMA-expression (aSMA + ) can be associated with a more mature phenotype.…”

“…, NG2(Kokovay et al, 2006;Dore-Duffy et al, 2011), PDGFRb(Lindahl et al, 1997;Dore-Duffy et al, 2011) and FLVCR2(Thomas et al, 2010). At day 3 in Areas A and B, Histogram representing the quantification of aSMA + cell numbers.…”