High Capacity Flow – Completing the Toolset in High Content Screening
Author: Joe Zock; Published: Nov 19, 2011
For the last decade and a half I have worked to take High Content Imaging (HCI) from an idea to a useful tool that is changing the way researchers approach the workflow of drug discovery and, more broadly, life science research. Turning fluorescence microscopy into a detection mode for screening cells took a leap of faith. Believing the hurdles of automating the manual process of finding the cells, reproducibly acquiring cell images across the visible spectrum, and algorithmically extracting biologically relevant information, could be overcome, we pushed on. Eventually, through the cross functional efforts of many gifted scientists and engineers, High Content Screening was born. The main characteristics of the high content approach that make it so compelling and unique compared to high throughput methods are:
- Individual, intact cell measurements
- Multiplexed assays per well and cell
- Morphological phenotyping
- Artifact rejection and subpopulation isolation
These features and their utility formed the basis for countless novel assays, creating new ways of assessing biology from cell inception to cell death and everything in between. I am extremely proud to have been a part of it.
There were, however, limitations to High Content Imaging. The underlying engine of microscopy meant that only cells associated with the bottom of the well, either growing on it like adherent cells or associated with it by settling, centrifuging, or immobilizing in a matrix (like suspension cells) could be focused on accurately enough to acquire the images needed. For suspension cells which are biologically sensitive to contact with the plate, this caused a great deal of variation, so adherent cells have become the norm in HCI assay formats. Another limitation of the approach lies in the battle between resolution of the objects and the number of objects collected. With imaging, you can’t have both, so you either end up with a compromise to collect a lot of low resolution objects (if your assay does not require higher resolution) or you end up collecting a lot of high resolution images in order to get enough objecst to statistically represent your biology. Unfortunately, there is a cost associated with storage and analysis of large number of images and many of you have multiple terabyte server farms of images and distributed processing engines whirring away to analyze those images.
But ‘high content’ is still fantastic because of the kinds of data that can be generated and cross correlated in the well and sometimes to the cell. But not having a high content screening tool optimized for suspension cells always bugged me…and by the number of inquiries about sticking cells down that I would get from the high content community, I guess it bugged you too.
But there is high content technology, as defined by the bullets above, for suspension cells that has been in use for the last 30+ years, and of course I am talking about flow cytometry. Flow cytometry has all the attributes of a high content approach, but was designed and optimized for suspension cells, beads, microbes, and mixtures of these objects. I have read many articles on our industry over the years and flow cytometry is always mentioned as a great technology, but lacking the capacity and simplicity to be a true screening tool. Imagine my delight when I found out, through the grapevine, that IntelliCyt, headed up by one of my early Cellomics colleagues, was commercializing technology that would overcome the limitations of current flow cytometry by combining their novel approach to high speed sample loading with a revolutionary, and widely accepted flow cytometer that dramatically reduced complexity, adjustments, and cost. As I discovered more about the potential and future directions this technology was about to take, it became apparent to me that I had found the missing link— a technology to fill the gap in the high content toolbox. All the projects to stick cells down, all the times we treated cells like “nails” because we only had a high content “hammer”, could be solved by the introduction of a high content suspension screening platform! After a lot of soul searching, I decided that this was too compelling of an opportunity to ignore, and I moved by family out to the desert of New Mexico and joined IntelliCyt as the Director of Product Management.
So, this new high content tool needed a name, something short and sweet that linked the technology to the high content family of tools but still retained the essence of what makes it special. High Capacity Flow (HCF) is the name we chose, because “capacity” is the value we bring to a technique that was high content years before we invented high content. Our vision at IntelliCyt is that HCF and HCI become a complementary set of tools used by the high content community, where suspension screening releases an entire class of cells, beads, microbes, and mixtures from the shackles of compromise.
More to come on the advantages of HCF and where it might be used to optimize your high content workflow….