Autologous human immunocompetent white adipose tissue-on-chip

Abstract

Obesity and associated diseases, such as diabetes, have reached epidemic proportions globally. In the era of 'diabesity' and due to its central role for metabolic and endocrine processes, adipose tissue (specifically white adipose tissue; WAT) has become a target of high interest for therapeutic strategies. To gain insights in cellular and molecular mechanisms of adipose (patho-)physiology, researchers traditionally relied on animal models since in vitro studies on human WAT are challenging due to the large size, buoyancy, and fragility of mature white adipocytes. Leveraging the Organ-on-Chip technology, we introduce a next-generation microphysiological in vitro model of human WAT based on a tailored microfluidic platform featuring vasculature-like perfusion. The platform integrates a 3D tissue comprising all major WAT-associated cellular components in an autologous manner, including not only mature adipocytes but also organotypic endothelial barriers and stromovascular cells featuring tissue-resident innate immune cells, specifically adipose tissue macrophages. This microphysiological tissue model recapitulates pivotal WAT functions, such as energy storage and mobilization as well as endocrine and immunomodulatory activities. The combination of all individual cell types with extra cellular matrix-like hydrogels in a precisely controllable bottom-up approach enables the generation of a multitude of replicates from the same donors circumventing issues of inter-donor variability and paving the way for personalized medicine. Moreover, it allows to adjust the model's degree of complexity to fit a specific purpose via a flexible mix-and-match approach with different cell component modules. This novel WAT-on-chip system constitutes a human- based, autologous and immunocompetent in vitro model of adipose tissue that recapitulates almost full tissue heterogeneity. In the future, the new WAT-on-chip model can become a powerful tool for human-relevant research in the field of metabolism and its associated diseases as well as for compound testing and personalized- and precision medicine applications.

Vascularized adipose tissue engineering: moving towards soft tissue reconstruction

“…The group later published an improved version of this bottom-up approach in a system that integrates autologous mature adipocytes, ECs, and AT macrophages (figures 9(C) and (D)) [334]. This system recapitulates WAT functions such as energy storage and release as well as endocrine and immunomodulatory activities.…”

Solid tumor-on-chip model for efficacy and safety assessment of CAR-T cell therapy

“…The tumor-on-chip consists of two stacked microfluidic channels separated by an isoporous, semipermeable polyethylene terephthalate (PET) membrane (5 µm poresize: r P \=\5\µm; ρ P \=\6\×\10 5 pores per cm 2 ; TRAKETCH® PET 5.0 p S210\×\300, SABEU GmbH & Co. KG, Northeim, Germany), which was functionalized by a plasma-enhanced, chemical vapor deposition (PECVD) process as previously described 40 . The tumor chambers (1 mm in diameter, 0.3 mm in height, six chambers per chip) branch off a main injection channel (0.2 mm in height) at a 45° angle and a highresistance channel towards the outlet port, which forces the aggregates/organoids to sequentially enter the tumor chambers during the injection process, utilizing an injection mechanism previously successfully established in other organ-on-chip model 11 . This concept and design enable the integration of any aggregate/organoid below 0.2 mm in size.…”

“…This ensures the placement of the cells into the tumor chambers during the injection instead of flowing out towards the outlet. The media channel is situated right above the tumor chambers and is separated by a porous PET membrane that serves multiple functions: during the cell injection step, it enables the entrapment of the tumor aggregates/PDOs and provides a growth surface for the endothelial barrier formation, whereas during the culture period, its 5 µm pore size allows T cell trafficking and passive diffusion of diluted species 11 .…”

“…For the replica molding, PDMS was homogeneously mixed in a 10:1 (elastomer base:curing agent) mass ratio and then degassed in a desiccator to remove air bubbles. Afterwards, two different replica molding approaches were conducted as previously described 11 . Standard molding approach was used by pouring the PDMS prepolymer solution onto the silicon wafer master mold to obtain 3\mm thick PDMS pieces with channel structures for the media layer.…”

“…Such models should translate to human immunity, recapitulate tumor heterogeneity, its microenvironment and should therefore be able to better predict clinical safety and efficacy outcomes 7 . Organ-on-Chip(OoC)technologies already demonstrated the potential to fulfil those requirements, specifically by recapitulating tumor microenvironmental aspects 9 and the integration of human immune components 10,11 .…”