Cancer metastasis on chip

Most breast cancer related deaths are not caused directly by the primary tumor, but by secondary tumors formed through metastasis to other organs [1]. Current in-vitro models rarely mimic the initial phase of metastasis: invasion. Hence, we focus on modeling breast cancer invasion and the relevant microenvironment on a chip. We develop microfluidic Cancer-on-a-Chip (CoC) devices to recapitulate essential cues in cancer microenvironment, namely (1) Extracellular Matrix (ECM) heterogeneity and (2) microvasculature. To generate the cancer niche, we use cell-embedded hydrogel encapsulation [2]. A water in oil flow-focusing device was used to encapsulate cancer cells in Matrigel beads. Next, Matrigel beads were cultured in collagen I hydrogel, mimicking the stromal ECM. This way we recapitulate the pre-invasive condition where cancer cells initially reside in a soft basement membrane before invading the fibrous and stiffer stromal ECM. Beside encapsulation method, we use alternative techniques like sugar-printing in CoC models to create the interface between two different materials. The model of ECM heterogeneity can potentially lead to better understanding of pre-invasive and invasive breast cancer.Moreover, we use sugar-printing technology to create perfusion lumens, cast directly in ECM [3]. When seeded with endothelial cells, these form the (micro) vasculature. Combined with a neighboring channel for cancer cell culture, the process of cancer invasion, migration through ECM, and intravasation can be studied. This way we avoid using artificial materials like Polydimethylsiloxane (PDMS) which usually have drawbacks for cellular experiments.<br/

An in vitro model of cancer invasion with heterogeneous ECM created with droplet microfluidics

Metastasis is a multi-step process that is critically affected by cues from the tumor micro-environment (TME), such as from the extracellular matrix (ECM). The role of the ECM in the onset of metastasis, invasion, is not yet fully understood. A further complicating factor is that the ECM in the TME is mostly heterogeneous, in particular presenting a basement membrane (BM) directly enveloping the tumor, which acts as a barrier to invasion into the surrounding stromal ECM. To systematically investigate the role of ECM in invasion, appropriate in vitro models with control over such ECM heterogeneity are essential. We present a novel high-throughput microfluidic approach to build such a model, which enables to capture the invasion of cancer cells from the tumor, through the BM and into the stromal tissue. We used a droplet-maker device to encapsulate cells in beads of a primary hydrogel mimicking BM, Matrigel, which were then embedded in a secondary hydrogel mimicking stromal ECM, collagen I. Our technology ultimately provides control over parameters such as tissue size, cell count and type, and ECM composition and stiffness. As a proof-of-principle, we carried out a comparative study with two breast cancer cell types, and we observed typical behavior consistent with previous studies. Highly invasive MDA-MB-231 cells showed single cell invasion behavior, whereas poorly invasive MCF-7 cells physically penetrated the surrounding matrix collectively. A comparative analysis conducted between our heterogeneous model and previous models employing a single type of hydrogel, either collagen I or Matrigel, has unveiled a substantial difference in terms of cancer cell invasion distance. Our in vitro model resembles an in vivo heterogeneous cancer microenvironment and can potentially be used for high throughput studies of cancer invasion.</p

Lumen-based microfluidics for cancer-on-chip devices

INTRODUCTION:Most breast cancer related deaths are not caused directly by primary tumor, but by secondary tumors formedthrough metastasis to other organs [1]. Metastasis is a complex cascade that we still poorly understand due to the limitations ofcurrent in-vitro models. Hence, we focus on modeling cancer metastasis on a chip, via introducing the relevant physiologicalfactors in the tumor microenvironment. To obtain such a model, we exploit our 3D sugar-printing technology to create luminalchannels with circular cross section to mimic (micro) vasculature and breast duct in ductal carcinoma. METHODS:We use 3D sugar printing technology [2] to create sugar glass structures that subsequently form perfusable lumens.These carbohydrate glass structures can be cast either in Extra Cellular Matrix (ECM), or synthetic polymers; after the ECMmaterial or synthetic polymer is cross-linked and the sugar glass is selectively dissolved, hollow perfusable lumens are obtained.When the lumens are seeded with endothelial cells, they form the (micro) vasculature. Combined with either a neighboring lumenfor cancer cell culture, the process of cancer invasion, migration through ECM, and intravasation can be studied. Furthermore,neighboring lumens can be filled with different types of hydrogels or cell types to mimic the pre-invasive and invasive cancermicroenvironment. RESULTS:We have developed a vessel and duct with 3D luminal geometry where cell-cell tight junctions are present, as a basisfor further study to recapitulate metastatic cascade. DISCUSSION & CONCLUSIONS:Cancer-on-Chip devices enable us to mimic key biophysical characteristics of the breast cancermicroenvironment. We use 3D sugar printing to create lumens directly in the ECM which enables us to study the invasion andsubsequent intravasation. This way, we avoid using synthetic materials which often have drawbacks for cellular experiments.However, casting lumens or other circular structures in synthetic polymers, is still a feasible option. Lumen channels with roundcross section provide more biophysical-alike perfusion. ECM structure and properties are expected to play a role in breast cancerinvasion, and our model composed of multiple cell types and different concentrations of hydrogels can potentially lead to betterunderstanding of pre-invasive and invasive breast cancer. Our model has also the capability to add more components of the in vivocancer microenvironment, such as immune cells or oxygen gradients

Breast cancer metastasis on chip

Most breast cancer related deaths are not caused directly by the primary tumor, but by secondary tumors formed through metastasis to other organs. Current in-vitro models rarely mimic the initial phase of metastasis: invasion and intravasation, which are strongly modulated by the tumor microenvironment. Hence, we focus on modeling a relevant microenvironment on a chip, namely (1) Extracellular Matrix (ECM) heterogeneity and (2) microvasculature. For (1), we use a flow-focusing device to encapsulate cancer cells in Matrigel beads that mimic the basement membrane. Next, Matrigel beads are cultured in collagen I hydrogel, mimicking the stromal ECM. This way we recapitulate the pre-invasive condition where cancer cells initially reside in a soft basement membrane before invading the fibrous and stiffer stromal ECM. Moreover, modeling vascular network (2) is required to mimic cancer intravasation. We use our 3D sugar-printing technology to create perfusion lumens embedded in matrix, in which endothelial cells can be seeded to recapitulate blood vessels in vitro. Combined with a neighboring channel for cancer cell culture, it is possible to study cancer-vasculature interaction on a single chip. In conclusion, our model of cancer metastasis potentially leads to better understanding of pre-invasive and invasive breast cancer. Furthermore, it has also the capability to add more components of the in vivo cancer microenvironment, such as immune cells or an oxygen gradient