Vascular Wall-Resident Multipotent Stem Cells within the Process of Vascular Remodelling

Abstract

Processes of new vessel formation are central events in tissue development and repair. Therein, sprouting endothelial cells and/or endothelial progenitor cells form imma‐ ture blood vessels that lack coverage by pericytes and other mural cells. Subsequently, vascular remodelling takes place, in which association with mural cells (pericytes and smooth muscle cells, SMC) stabilizes these immature vessels resulting in normaliza‐ tion of the vascular structures. Vascular remodelling is a dynamic and strictly regulated process; an ordered remodelling seems to be critical for proper vascular development, maintenance and stability of the vessel wall. The molecular and cellular changes associated with this process and its importance for tumour growth remain elusive. Up to now, the origin of vascular wall cells in tumours and the molecular mechanisms that govern their recruitment and association with angiogenic endothe‐ lial cells (vascular stabilization) are not well understood. There is some evidence that pericytes and SMC might originate from multipotent mesenchymal stem cells. This chapter aims to explore the role of tissue-resident multipotent stem cells of mesen‐ chymal nature (VW-MPSCs) which putatively reside in the adventitia of adult blood vessels within the process of vascular remodelling of tumour blood vessels as well as of molecular factors that regulate VW-MPSC differentiation into pericytes and SMC.