Investigating the effects of indirect coculture of human mesenchymal stem cells on the migration of breast cancer cells: a systematic review and meta-analysis

Purpose: Breast cancer is the most diagnosed cancer and the leading cause of cancer death in women globally, and mesenchymal stem cells have been widely implicated in tumour progression. This systematic review and meta-analysis seeks to identify and summarise existing literature on the effects of human mesenchymal stem cells (hMSCs) on the migration of breast cancer cells (BCCs) in vitro, to determine the direction of this relationship according to existing research and to identify the directions for future research. Methods: A systematic literature search was conducting using a collection of databases, using the following search terms: in vitro AND mesenchymal stem cells AND breast cancer. Only studies that investigated the effects of human, unmodified MSCs on the migration of human, unmodified BCCs in vitro were included. Standardised mean differences (SMDs) were calculated to determine pooled effect sizes. Results: This meta-analysis demonstrates that hMSCs (different sources combined) increase the migration of both MDA-MB-231 and MCF-7 cell lines in vitro (SMD = 1.84, P =.03 and SMD = 2.69, P <.00001, respectively). Importantly, the individual effects of hMSCs from different sources were also analysed and demonstrated that MSCs derived from human adipose tissue increase BCC migration (SMD = 1.34, P =.0002) and those derived from umbilical cord increased both MDA-MB-231 and MCF-7 migration (SMD = 3.93, P <.00001 and SMD = 3.01, P <.00001, respectively). Conclusions: To our knowledge, this is the first systematic review and meta-analysis investigating and summarising the effects of hMSCs from different sources on the migration of BCCs, in vitro.