Consistent Inclusion of Mesenchymal Stem Cells into In Vitro Tumor Models

Over recent years, the role of distinct mesenchymal stem cell populations in cancer progression has become increasingly evident. In this regard, developing in vitro preclinical tumor models capable of portraying tumor-associated mesenchymal stem cells (TA-MSCs) interactions with the tumor microenvironment (TME), cellular and extracellular components, would allow to improve the predictive potential of these platforms and expedite preclinical drug screening. Although recent studies successfully developed in vitro tumor models in which the biomolecular and cellular behaviors of TA-MSCs were recapitulated in the context of their interactions with specific TME components, no consensus has yet been reached regarding distinct TA-MSCs influence in the evolution of solid tumors. The paradoxical observations regarding the roles of MSCs on in vitro tumor models can in part be associated to a lack of standardization in how MSCs integration is performed. Herein, we summarize some of the main parameters linked to phenotypic variations established upon MSCs inclusion and interaction within in vitro tumor models. A critical overview of recent studies and how standardization of key parameters could improve the reproducibility and predictability of current preclinical validation models containing MSCs is also provided.