Mesenchymal stem cells (MSC) are a heterogeneous subset of stromal stem
cells that can be isolated from many adult tissues. They can differentiate into cells of the
mesodermal lineage, such as adipocytes, osteocytes and chondrocytes, providing a
promising tool for tissue repair. MSC can interact with cells of both the innate and
adaptive immune systems, leading to the modulation of several effector functions. The
immunoregulatory functions of human MSC, coupled with their low immunogenicity,
provide a rationale for the use of allogeneic MSC to treat severe graft-versus-host disease
(GvHD) and, possibly, autoimmune disorders. In addition, MSC exhibit tropism for sites
of tissue damage as well as for the tumor microenvironment, where they integrate into the
tumor-associated stroma supporting cancer growth. However, studies investigating the in
vivo and in vitro effects mediated by MSC on tumor growth provided conflicting results,
depending on the experimental model tested. This chapter reviews the role of MSC in
different angiogenic processes and underlying mechanisms. In particular, we discuss the
involvement of MSC in angiogenesis in ischemic brain and heart after stroke, wound
healing, tumor angiogenesis and maintenance of hematopoietic stem cell niche.
