María Dolores Salinas, MSc
University of Murcia
Murcia, Spain
Rut Valdor, PhD
University of Murcia
Murcia, Spain
Declarations of interest: none.
What?
Pericytes are cells that surround the walls of small blood vessels and maintain the architecture of the endothelia in capillaries, venules and arterioles. Pericytes are a heterogeneous population in terms of origin, morphology and localization, presenting a different behaviour depending on the surrounding microenvironment. This cell type is not only involved in vessel contraction as smooth muscle cells would do in big vessels, but it also contributes in the angiogenesis process of new vessel formation. Importantly, pericytes are multipotent cells that present stem cell like-properties such as self-renewal, secretion of extracellular vesicles (EVs) with regenerative factors, release of cytokines and immunomodulation function. Pericytes act as defense cells with immune properties, phagocytic ability and, specifically in the central nervous system, pericytes are key components forming the neurovascular unit (NVU) to maintain and establish brain homeostasis through the integrity protection of the blood-brain barrier (BBB) (1–3).
Why?
Pericytes have the ability to filter substances, including drugs, thereby regulating what can pass through them to the tissue parenchyma. Moreover, due to their mesenchymal stromal cell (MSC) properties, pericytes have the capability to influence and modify the behaviour of the neighbouring cells in their immediate surroundings through their regenerative secretome with anti-inflammatory properties (1,4,5).
Who?
Carl Joseph Eberth and Charles Rouget are often credited as the first authors to describe pericytes in the 19th century. However the interest in this cell type has risen only in the last decade, due to their role in neurovascular coupling and cerebral blood flow deficits following cerebral ischemia and Alzheimer’s disease. In an in vivo glioblastoma (a very aggressive type of brain tumour) mouse model, pericytes deficient in a specific autophagy form, chaperone-mediated autophagy (CMA), presented the capacity and were sufficient to promote the elimination of glioblastoma cancer cells, by developing a pro-inflammatory phenotype that destabilizes the physical tumour cell interactions, increase the secretion of anti-tumour immune proteins and their ability to phagocytose tumour cell debris and present specific antigen to promote anti-tumour T cell responses (6,7).
When?
Pericytes are CD146+CD34- population isolated together with MSC from the vascular fraction of adipose tissue or other tissues (8). The manipulation of their CMA activity could be useful in the development of anti-tumour cell-based therapies for Glioblastoma treatment, provided that this type of cells is able to cross the BBB and reach tumour areas upon intravenous injection (7).
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