Fig. 1.

Endosteal and perivascular niches. Myeloma cells thrive in the bone marrow by utilising important communication pathways within their microenvironment via direct interactions, soluble factors, and exosome release. Myeloma cells settle on the endosteal surface where long-term multipotent cells reside, cells, such as HSCs, MSCs and bone-lining cells alongside osteoblasts and osteoclasts, where they maintain a dormant like state. Once MM cells become displaced from the bone surface, they move into the nutrient-rich perivascular niches where they are exposed to different cell types, such as adipocytes and endothelial cells, which release growth factors promoting proliferation and expansion.

Some of the elements in this illustration were adapted from Servier Medical Art, provided by Les Laboratoires Servier (available at: https://smart.servier.com)