What surfaces are available for cell-based assays?

Two surfaces are commercially available: uncoated and fibronectin-coated cell assay microplates.

Can I detect the direct binding of a ligand to a cell? What do I measure in a cell-based assay?

In cell based assays Epic technology does not measure the direct binding of ligand to receptor. The technology measures the downstream, integrated physiological response of the cell to the binding/activation of the biological target within a sensing region of ~150 nm from the sensor surface. We refer to the movement of intracellular components in response to a cellular stimulus, the Dynamic Mass Redistribution (DMR). Responses are measured as wavelength shifts (units of pm) in the reflected light from the bottom of the optical biosensor.

What is DMR?

DMR stands for Dynamic Mass Redistribution and refers to the movement of intracellular components in response to a cellular stimulus.

Can I test multiple cell lines on a single plate?

Yes, as long as the cell culture conditions are similar. We have successfully cultured multiple cell lines in adjacent columns on a single plate and tested their response to various stimuli.

What are the important parameters to optimize in a cell-based assay?

The most important parameters to optimize for each new cell assay are: 1) cell seeding density; 2) microplate type (uncoated, fibronectin-coated, or self-coated); 3) culture conditions; 4) liquid handling parameters for compound dispensing and mixing.

How do I choose the correct plate for a cell-based assay?

For loosely-adherent cells, we recommend fibronectin-coated microplates. For strongly adherent cells and suspension cells, we recommend that you evaluate both fibronectin-coated and uncoated microplates.

What is the minimum receptor expression level for which a reliable signal can be detected?

The minimum receptor expression level for which a reliable signal can be detected is dependent upon the cell line, the specific receptor biology, and the signaling network.

Can Epic Technology be used to study suspension cells?

Yes. Epic Technology has successfully been used to study both adherent and non-adherent (suspension) cells. Liquid handling parameters for compound addition may require optimization when working with suspension cells.

Can I directly use frozen cells?

Yes. Frozen cells can be directly seeded into Epic microplates.

Can Epic microplates be used with an optical microscope?

Yes. The bottom of the Epic microplate is transparent and can be used with optical microscopes.

Are Epic cell-based assays sensitive to cell density?

Yes. In general we recommend running assays with a confluent monolayer. For both adherent and non-adherent cells, the optimal seeding density should be empirically determined during assay optimization.

Does the Epic signal depend upon the expression level of the receptor?

Yes. However, for a given cell type, there is a maximal signal one can obtain for a particular receptor. The expression threshold required to reach the maximal signal is dependent on (1) the receptor; (2) the cell type; (3) the ligand; (4) the signaling capacity of the receptor; and (5) the interaction of the receptor with other proteins.

Can Epic Technology be used for cytotoxicity or viral lysis assays?

Yes. As the Epic response is sensitive to mass movement within a sensing region of ~150 nm from the bottom of the sensor, mass degradation due to cytotoxic events or viral lysis will result in large negative responses.

Can downstream cellular signaling pathway biology be revealed with Epic Technology?

Yes. Through the use of receptor, kinase, and downstream signaling component inhibitors, specifics detailing the signaling pathway biology can be identified.

Can cell-based assays be performed at 37°C?

The Epic BT System can placed inside a non-humidified incubator for running assays at 37°C.