Silicon Microchips for Manipulating Cell-cell Interaction

Summary

This article describes an experimental approach for dynamic regulation of cell-cell interactions between adherent cells on a micrometer scale. Manipulation of intercellular communication between hepatocytes and stromal cell is demonstrated. The developed platform enables investigation of cell-cell interactions in a variety of biological processes, including development and pathogenesis.

Abstract

The role of the cellular microenvironment is recognized as crucial in determining cell fate and function in virtually all mammalian tissues from development to malignant transformation.  In particular, interaction with neighboring stroma has been implicated in a plethora of biological phenomena; however, conventional techniques limit the ability to interrogate the spatial and dynamic elements of such interactions.

In Micromechanical Reconfigurable Culture (RC), we employ a micromachined silicon substrate with moving parts to dynamically control cell-cell interactions through mechanical repositioning. Previously, this method has been applied to investigate intercellular communication in co-cultures of hepatocytes and non-parenchymal cells, demonstrating time-dependent interactions and a limited range for soluble signaling ¹.

Here, we describe in detail the preparation and use of the RC system. We begin by demonstrating the handling of the device parts using tweezers, including actuating between the gap and contact configurations (cell populations separated by a narrow 80-µm gap, or in direct intimate contact). Next, we detail the process of preparing the substrates for culture, and the multi-step cell seeding process required for obtaining confluent cell monolayers. Using live microscopy, we then illustrate real-time manipulation of cells between the different possible experimental configurations. Finally, we demonstrate the steps required in order to regenerate the device surface for reuse: toluene and piranha cleaning, polystyrene coating, and oxygen plasma treatment.

Protocol

Preparation of cell cultures:

1. Start with silicon parts coated with plasma-treated polystyrene.
2. Coat parts with appropriate extracellular matrix proteins to support attachment of desired cell type. For hepatocytes, incubate in 50 g/ml Collagen-1 solution at 37°C for 45 min. For 3T3 fibroblasts, no matrix is needed.
3. Lock parts with complementary parts in contact configuration.
4. Soak in 70% ethanol for a minimum of 10 min to sterilize. Rinse 2x in ddH₂O, and 1x in cell culture media.
5. Seed cells at a concentration of 500,000 cells/ml in the appropriate culture medium. Use 1 ml in each well of a 12-well cultu....

Discussion

This system is unique in that it enables the spatial organization of tissue to be dynamically manipulated at the cellular level. Consequently, this device has enabled a number of novel biological experiments, spanning topics such as intercellular signaling dynamics, contact-mediated versus soluble signaling, cell fate decisions, toxicology, and cellular crosstalk. This device should be widely generalizable since the culture substrate is standard tissue culture plastic, and the system is compatible with standard culture m.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Silicon Comb Substrates	Tool	N/A	N/A	Parts are available for collaborative research projects. Please contact Elliot Hui (eehui @ alum . mit . edu) or Sangeeta Bhatia (sbhatia @ mit . edu).