SRU Biosystems - BIND Reader >> BIND SCANNER

BIND Readers >> BIND SCANNER

Designed for Primary & Stem Cell Applications

Cytotoxicity
Differentiation
Chemotaxis
Low Cell Number Assays

The BIND® SCANNER is a first-of-its-kind, plate-based instrument capable of monitoring cellular responses at an individual cell resolution using label-free assays. The BIND SCANNER is based on the same underlying photonic crystal technology as SRU’s other BIND Readers. Limited cell numbers currently prevent widespread use of primary and stem cells in screening and profiling applications. The SCANNER’s high resolution and throughput capabilities enable the use of primary cultured cells in physiologically relevant assays earlier in the drug discovery process. For example, it can be used to monitor individual stem cell growth, adhesion, invasion, and differentiation profiles. Additionally, the SCANNER’s high resolution allows researchers to investigate and quantify individual cellular responses within a heterogeneous population. Because BIND assays utilize cells in their native state without the introduction of labels or tags, the SCANNER enables researchers to quickly develop new cell-based assays, and run higher throughput validated assays with biorelevant cell types that were previously difficult or impossible to run.

SCANNER Features

Low cell number applications using well below 1,000 cells/well
Compatible with recombinant cell lines, endogenous systems, primary cells and stem cells
Label-free measurement of individual cell responses within a heterogeneous population
Miniaturized assays using low cell numbers and rapid read times enabling high throughput formats

Cellular Migration Imaging

The BIND SCANNER is able to monitor the migration of individual cells using high resolution, label-free readings. These video clips display the power of the SCANNER to view cellular changes over time of both stimulated and unstimulated cell populations.


Unstimulated HFF-1 cells in a serum-free environment	HFF-1 cells stimulated with 20 ng/ml PDGF-BB
Video Clips: HFF-1 (human foreskin fibroblast) cells are seeded onto fibronectin-coated biosensors and grown in serum-free conditions overnight. Cells are then stimulated with PDGF-BB (20 ng/ml) or incubated further in serum-free media (unstimulated) and images are captured every 20 minutes for 20 hours on the BIND SCANNER at 3.75 um/pixel resolution. In the unstimulated wells, cells can be observed remaining largely stationary, although there is a very dynamic process of lamellipodial and filopodial extension and retraction that occurs at the cell surface. In contrast, HFF-1 cells stimulated with PDGF-BB can be observed traversing the biosensor surface to great lengths. The data is represented as a heat map with the darker colors reflecting greater cell adhesion between the cell and biosensor surface. The resulting data output is rich in information with measurements such as migration velocity, directional persistence, and differential subcellular adhesion all recordable.

Low Cell Number Stem Cell Assays

Figure 1 - Rat mesenchymal stem cells (MSCs) were seeded at 100 cells/well in a 384-well BIND® Biosensor plate. Cells were incubated at 37°C for 16 hours. PWVs were measured at a 7.5 µm resolution following attachment and used as baseline values. Cells were then stimulated with 500nM SDF-1α and PWVs collected over time.

The BIND SCANNER enables low cell number GPCR assays using a variety of cell types including recombinant cell lines, endogenous systems and primary cells (including stem cells). The SDF-1α/CXCR4 mesenchymal stem cell assay shown in Figure 1 required as few as 100 cells/well for robust measurement of receptor activation. The assay results are displayed as a colorized image (7.5µm resolution/pixel) of the changes in peak wavelength values (PWVs) over baseline. Black and green represents negative and positive PWV changes respectively, while blue represents no change in PWV.

Stimulation of MSCs with SDF-1α resulted in significant changes in PWV that increased over time (Figure 1) and were concentration-dependent. These BIND responses were mediated via CXCR4 as responses were lost upon pretreatment with two different CXCR4 blocking antibodies or a small molecule inhibitor, AMD3100 (data not shown).

Chemotaxis Assay

A. Chemotaxis Assay Schematic

Figure 2 - A). Chemotaxis assay schematic. B). HT10.80 cells were seeded on a 384-well BIND biosensor and media containing 10% FBS added above the collagen layer. PWV shifts were measured and results displayed as a colorized image (7.5µm resolution/pixel) with negative PWV shifts shown in black. C). PDGF-BB mediated migration of MSCs (2K cells/well) with an EC50

The BIND SCANNER is able to assess cell migration using the BIND chemotaxis assay. This highly sensitive, label-free assay is transwell-free, reproducible and requires low cell numbers.

The BIND chemotaxis assay is run by plating cells on a BIND biosensor followed by deposition of a layer of collagen atop the cells (Figure 2A). Media containing chemoattractants is added and cell migration monitored on the BIND SCANNER. As cells migrate from the biosensor surface towards the chemoattractant, cells detach from the sensor surface and a decrease in PWV is observed.

Figure 2B is a colorized image of PWV shifts. Within this image, black represents the loss of cell-sensor interactions and cellular migration towards the upper media containing FBS. Figure 2C demonstrates the robust, dose-dependent chemotaxis of mesenchymal stem cells (MSCs) upon addition of PDGF.

Stem Cell Differentiation

Figure 3 - Rat MSCs were seeded at 100 cells/well and incubated with media alone (Undiff.), osteoblast differentiation media (Diff.) or differentiation media containing a GSK3β inhibitor. Daily images of a single well/condition were acquired on the BIND SCANNER and normalized to the Day 0 signal. Parallel wells were stained with alirazin red as a measure of bone deposition.

A. GSK3β Inhibitor

B. PWV vs. Staining Method

Figure 4 - The results of figure 3 were plotted (PWV versus time). A). Results for cells incubated with media, stimulation media and/or GSK3β inhibitor. B). PWV readings overlaid with alizarin red staining results.

Differentiation of stem cells into bone-producing osteoblasts can be monitored in real time and in a non-destructive manner using the label-free BIND SCANNER.

MSCs are readily propagated on BIND biosensors. Upon addition of a differentiation cocktail, MSCs differentiate into bone-producing osteoblasts as measured by standard staining reagents (Alizarin Red) and biochemical analyses. Daily measurements on the BIND SCANNER reveal gradual but robust PWV shifts as differentiating osteoblasts secrete collagen and mineralized deposits onto the sensor surface (Figure 3 & 4). The change in PWVs is accelerated by the addition of an inhibitor of glycogen synthase kinase 3 (GSK3β) which is consistent with previous reports. Additionally, the BIND assay was shown to be more sensitive than traditional mineralization staining as the PWV shifts precede Alizarin Red staining by 3-4 days (Figure 3 & 4).

BIND PWV shifts can be quantified and expressed as a differentiation time course. Because BIND is a label-free, non-destructive assay, daily measurements from a single well of a 384-well biosensor can be taken which provide for higher assay throughput.