High content cellular assays can offer more physiologically relevant assay results compared to biochemical assays. Broader adoption of cellular assays has been hindered in part by costly reagents and limited availability of cells. This issue has been especially acute for assays requiring primary or stem cells. It is further exacerbated when multi-step staining procedures require large amounts of labeled antibody.

DropArray™ ensures that cells are retained throughout all assay procedures and wash steps. Each assay in a 384-well DropArray microplate uses only 100 – 2,000 cells per data point, compared to the 3,000 – 10,000 cells per data point needed for conventional microplates. For a typical siRNA screen using an immuno-assay readout, the reduced sample and reagent volumes of the DropArray platform provide at least a 75% cost-savings.

Reagents and consumables Costs for a conventional
microtiter plate (25µL/well)
Costs for the DropArray 384-well plate (2µL/well)
Transfection reagent (eg. HiPerfect) $ 10,750 $ 1,075
Plate cost (for 160 plates) $ 824 $ 4,320
Commercial primary antibody for whole screen $12,900 $ 1,290
Total $ 24,474 $ 6,685

Cost savings of approximatlely 76% achieved on DropArray 384 over traditional 384 well micropaltes for a siRNA genome wide screen. Data courtesy IMCB.

To further facilitate high content assays, DropArray microplates provide the surface and optical properties needed for growing and imaging cells, even for assays requiring high (40x) magnification. The cyclic olefin copolymer (COC) used in DropArray microplates provides almost the same high-quality imaging that glass does, allowing even sub-cellular structural changes to be imaged. The flat surface of the DropArray microplate and the lack of meniscus effects offer superior optical properties than traditional microplates. DA-HCS is offered with the following coated formats:

DA-HCS Plate Format (96- or 384-well) Application
Tissue culture treated plates A polystyrene plate specially treated for increased hydrophilic surface for enhancing cell attachment
Poly-D-lysine or Poly-L-lysine coated plates Poly-D-lysine and Poly-L-lysine are well known for increasing the adherence of certain cell types by mediating the negative charges of the cell membrane and surface of plate
Collagen coated plates Extracellular matrix proteins such as collagen provide an attachment matrix for the adhesion and growth of certain cell types and is used for cell attachment to plate surfaces
Fibronectin coated plates Fibronectin is an extracellular matrix (ECM) component and is one of the primary cell adhesion molecules and offers improved adherence of certain cell types

A. Control

B. Blebbistatin

C. Cytochalasin D

COS7 cells were treated with 50µM -(-)Blebbistatin, control medium or 0.4µM Cyto. D overnight. The cells were then fixed with 4% PFA and stained with phalloidin-FITC (green) to visualize the actin cytoskeleton and Hoechst (blue) for nuclei. Both Blebbistatin and Cyto. D caused drastic changes to the actin cytoskeleton as was expected. Scale bar = 70µm, 40X Images shown. Images courtesy of Genentech.

DMSO

33 nM Wortmanin

40× Images of Hela cells (control) and Wortmanin treated cells. GFP-LC3 (green); ToPro-3 dye nucleus stain (red).

IPS Cells

Human tissue-derived iPS (induced pluripotent stem) cardiomyocytes and hepatocytes present molecular and physiological features very similar to native cardiac or hepato-cells, making them more functionally relevant for research and screening efforts. However, the high cost of iPS cells limits their use with high-content screening assays.

The Curiox DropArray™ platform reduces the amount of cells needed for screening assays by 3-10X, providing a cost-effective pathway for use of iPS cells with high-content cellular assays. This is accomplished via gentle, low velocity liquid exchange during assay procedures that allows iPS cells to be retained. Compared to conventional 384-well microplates that need 5000-7500 cells per well, 384-well DropArray Microplates only require 900-1500 cells per well.