Selective initial in vivo homing pattern of 5T2 multiple myeloma cells in the C57BL/KalwRij mouse

One of the main characteristics of multiple myeloma cells is their predomin ant localization in the bone marrow. It is, however, unclear whether this i s due to a selective initial entry, or whether this entry is more random an d other processes like survival and/or growth stimulation, only present in the medullar microenvironment, are unique. To investigate this, in vivo hom ing kinetics of murine 5T2MM cells shortly after injection were assessed in bone marrow, liver, spleen, lungs, heart, intestines, kidney and testis by tracing of radiolabelled cells, by immunostaining of isolated cells and by polymerase chain reaction analysis. We demonstrated the presence of 5T2MM cells in bone marrow, spleen and liver with all other organs being negative . Adhesion assays of 5T2MM cells to different types of endothelial cells de monstrated a selective adhesion of 5T2MM cells to bone marrow and liver and not to lung endothelial cells. We here demonstrate that the specific in vi vo localization of the 5T2MM cells is a result of the combination of a sele ctive entry/adhesion of the 5T2MM cells in the bone marrow, spleen and live r, and a selective survival and growth of these tumour cells in the bone ma rrow and spleen but not in the liver. (C) 2000 Cancer Research Campaign.