3D Human Tumor Tissues Cultured in Dynamic Conditions as Alternative In Vitro Disease Models.

The slow knowledge progression about cancer disease and the high drug clinical failure are mainly due to the inadequacy of the simplistic pre-clinical in vitro and in vivo animal tumor models. To overpass these limits, in recent years many 3D matrix-based cell cultures have been proposed as challenging alternatives, since they allow to better recapitulate the in vitro cells-cells and cells-matrix reciprocal interactions in a more physiological context. Among many natural polymers, alginate has been adopted as an extracellular matrix surrogate to mimic the 3D spatial organization. After their expansion, cancer cells are suspended in an alginate solution and dropped within a crosslinking solution enabling gelification. The result is the generation of a 3D hydrogel embedding a single cell suspension: Cells are equally distributed throughout the gel, and they are free to proliferate generating clonal spheroids. Moreover, according to the hydrogel matrix stiffness that can be easily tuned, tumor cells can spread within the 3D structure and migrate outside, where they may become circulating tumor cells and infiltrate secondary tumor sites when these 3D tumor tissues are cultured in a fluid dynamic environment (i.e., organ on chip).

A multi-organ-on-chip to recapitulate the infiltration and the cytotoxic activity of circulating NK cells in 3D matrix-based tumor model.

The success of immunotherapeutic approaches strictly depends on the immune cells interaction with cancer cells. While conventional in vitro cell cultures under-represent the complexity and dynamic crosstalk of the tumor microenvironment, animal models do not allow deciphering the anti-tumor activity of the human immune system. Therefore, the development of reliable and predictive preclinical models has become crucial for the screening of immune-therapeutic approaches. We here present an organ-on-chip organ on chips (OOC)-based approach for recapitulating the immune cell Natural Killer (NK) migration under physiological fluid flow, infiltration within a 3D tumor matrix, and activation against neuroblastoma cancer cells in a humanized, fluid-dynamic environment. Circulating NK cells actively initiate a spontaneous "extravasation" process toward the physically separated tumor niche, retaining their ability to interact with matrix-embedded tumor cells, and to display a cytotoxic effect (tumor cell apoptosis). Since NK cells infiltration and phenotype is correlated with prognosis and response to immunotherapy, their phenotype is also investigated: most importantly, a clear decrease in CD16-positive NK cells within the migrated and infiltrated population is observed. The proposed immune-tumor OOC-based model represents a promising approach for faithfully recapitulating the human pathology and efficiently employing the immunotherapies testing, eventually in a personalized perspective. An immune-organ on chip to recapitulate the tumor-mediated infiltration of circulating immune cells within 3D tumor model.