Several in vitro studies reported increased expression of CCL5 in co-cultures of breast cancer cells (mainly triple-negative MDA-MB-231 cells) and mesenchymal stromal cells such as ASCs, but also bone marrow-derived mesenchymal stromal cells (BMSCs), but these studies have so far only been conducted in standard 2D co-cultures [9,17,18,22,23]. Here, CCL5 is linked to breast cancer.