Applications of Flow Assays

• Long-Term Cell Culture Under Flow
• Rolling and Adhesion Assays
• Defined Liquid Exchange
• 3D Cell Culture
• ECIS Flow Assays

Long-Term Cell Culture Under Flow

Principle

In vivo, endothelial cells develop and differentiate under shear stress conditions. When starting cell-based assays with endothelial cells, you should consider the possible influence of this mechanical force on cell morphology and physiology. To bring the cells to a more physiological, in vivo-like state, they are cultured under flow for hours up to several weeks, generating more relevant results. In other words, flow conditioning is crucial for any kind of investigations using cells that are physiologically underlying flow conditions.

Application Examples

• Investigating the influence of shear stress on endothelial cell physiology with various experimental readouts, such as immunofluorescence, western blot, qPCR, and FACS
• Preparing the cell layer for subsequent functional assays, such as rolling and adhesion or transmigration assays

Flow characteristics	Continuous laminar flow, Non-uniform flow, Oscillatory flow (needed for disturbed flow simulation), Pulsatile flow
Experiment duration	Hours, up to several weeks
Recommended pumps	ibidi Pump System
Recommended μ-Slides	μ-Slide I Luer Family, μ-Slide VI 0.4, μ-Slide y-shaped

Rolling and Adhesion Assays

Principle

In a rolling and adhesion assay, leukocytes and/or platelets are perfused over a surface with a protein coating or a cell layer. Their adhesion to and their interaction with the surface can be analyzed under various conditions (e.g., after gene knockdown or drug treatment).

Application Examples

• Investigating the adhesion of platelets and leukocytes on endothelial cells or matrix protein layers

Schulz C, et al. (2009) Novel Methods for Assessment of Platelet and Leukocyte Function Under Flow - Application of Epifluorescence and Two-Photon Microscopy in a Small Volume Flow Chamber Model. Open Biol J 2(1):130–136.
read abstract

Flow characteristics	Continuous laminar flow
Experiment duration	Minutes to hours
Recommended pumps	ibidi Pump System, syringe pump, peristaltic pump
Recommended μ-Slides	μ-Slide I Luer Family, μ-Slide VI 0.4, μ-Slide y-shaped

Defined Liquid Exchange

Principle

A channel slide and a pump are used to supply the cells with exactly defined amounts of culture medium and/or any supplement of interest.

Application Examples

• Defined exchange of the cell culture medium
• Live Ca²⁺-imaging
• Live cell imaging of drug-stimulated adherent cells
• Live cell imaging of cellular stainings

Flow characteristics	Short periods of laminar flow
Duration	Minutes to hours
Recommended pumps	Manual liquid delivery, syringe pump, peristaltic pump
Recommended μ-Slides	μ-Slide VI 0.4, μ-Slide I Luer Family

3D Cell Culture

Principle

Cells are cultured in a 3D gel matrix. An interstitial flow is applied directly to the gel to supply the cells with nutrients, O₂, and CO₂ to maintain optimal conditions.

Application Examples

• 3D culture of single cells, spheroids or organoids in a gel matrix (e.g., with hepatocytes, fibroblasts, muscle cells, kidney cells, and stem cells)

Flow Characteristics	Very low interstitial flow
Duration	Hours, up to several weeks
Recommended pumps	ibidi Pump System
Recommended μ-Slides	μ-Slide VI 0.4, μ-Slide I Luer Family

ECIS Flow Assays

ECIS (Electric Cell-substrate Impedance Sensing) is a platform to measure morphological and physiological changes in an adherent cell layer by means of impedance. Living cells can be measured directly in the vessel without any disturbance, and without requiring any staining. The ECIS Flow Array enables the researcher to combine any type of flow assay with parallel impedance measurement.

Find more details about ECIS flow assays here.