Co-culture Microdevice with Oxygen Gradient for Tumor Microenvironment Model and Metastasis Imaging

Takahiro Shiwa,Kosuke Tsukada,Hideyuki Uchida

doi:10.5923/j.ajbe.20120204.04

Abstract

Tu mor hypoxia is a major therapeutic problem since it decreases radiation effects and leads to metastasis. Oxygen is delivered to tumor tissue via abnormal and dysfunctional microvessels, which forms heterogeneity of tissue oxygenation in the tumo r. Mimicking the o xygen gradient fo r cellu lar experiments in vitro is important to clarify the mechanis ms involved in tumor bio logy, but the only method to produce hypoxic conditions at a constant level is using gas-controlled incubators, because there is currently no technique for creating an o xygen gradient using culture dishes. We designed a polydimethylsilo xane (PDMS) microflu idic device integrated with microchannels for cell cultures that enables visualizat ion of cellu lar distribution under a microscope and co -culture to determine interactions between cancer and other cells. Phosphorescence-based partial o xygen measurements quantified the o xygen grad ient, which can be controlled by the gas pressure between the inlet and outlet of the device. A monoculture of end othelial cells with an oxygen gradient in the device showed an increase in cell death in the hypoxic area. In addition, Lewis lung carcino ma cells co -cultured with endothelial cells showed gradient-dependent migration through a membrane pore filter, indicating that the interaction between tumor and endothelial cells under hypo xia is crucial in metastasis. The results suggest that the developed microdevice can be used to study the mechanisms of tu mor metastasis under hypoxic conditions.

Highlights

Tumor cells consume o xygen during active division, and abnormal and dysfunctional microvessels form severe hypoxic conditions in the tu mors [1, 2]
The co-culture microdevice, as shown in the cross section in Fig. 1(a), consisted of polydimethylsilo xane (PDMS) with microchannels for gas flo w and a membrane pore filter for trans migrat ion of tu mor cells, which were located 1 mm above the PDMS coated with collagen for endothelial cell culture
Oxygen gradient in the co-culture microdevice The only oxygen supply to the co-culture microdevice was via the microchannels in PDMS, since the device was set in a chamber filled with nitrogen gas

Summary

Introduction

Tumor cells consume o xygen during active division, and abnormal and dysfunctional microvessels form severe hypoxic conditions in the tu mors [1, 2]. To clarify the mechani sms of tumor gro wth and metastasis and the effects of radiation under hypo xia, cellu lar experiments in an environment with a controlled o xygen concentration are required. Interactions between tumor and other types of cells, such as Recent microfluid ic devices fo r controlling themicroenvi ronment have been used in bio medical research. The absence of a technique for co-cultures in microdevices to study interactions between cells of different types, has delayed the understanding of mechanis ms that relate to tumor metastasis under hypoxic co n d it io n s

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Methods

Results

Conclusion