Investigations into the cancer stem cell niche using in-vitro 3-D tumor models and microfluidics.

The concept of Cancer Stem Cells (CSCs) and the CSC Niche/Tumor Microenvironment (TME) as the central driving force behind tumor progression and maintenance has garnered much attention in recent years. Concomitantly, the widespread adoption of 3D tissue models, organotypic co-cultures, and the revolutionary microfluidic technology has resulted in a plethora of ground-breaking fundamental discoveries and has enabled investigations which were previously unfeasible. A large number of existing review papers concern themselves with either a broad look at the TME and CSC Niche, or on the studies undertaken on a particular niche component alone. In this article, we attempt to bring out a harmonic, expansive look at the concept of CSCs, the TME, and the various advancements in answering key biological queries enabled by these emerging new technologies. Our primary goal is to present a fundamental understanding of CSCs, as well as the CSC niche, and elucidate note-worthy examples of investigations being carried out with regard to each of the major TME components, along with our insights into the potential for further research. We hope that this serves as an impetus to new, as well as existing researchers in this area, to gain fresh perspectives on the CSC niche, as well as provide them with a glimpse at the kind of progress being made using 3D tumor models and microfluidic devices.