A major focus at NIST is to apply measurement assurance tools to improve the performance of any cell-based assay to achieve a high-end, high-quality documentary standard. As part of this focus, NIST is developing an innovative measurement assurance technology through the establishment of the Prototype Cell Assay Measurement Platform (P-CAMP) for high quality assay validation and evidence based protocol development. This unique automated platform enables multimodal analysis of large parameter spaces and guides the development of measurement assurance strategies for assays used for characterization and testing of biological products and processes. The system design is centered on automation that can set up thousands of experiments for the purpose of identifying sources of variability in bioassays, designing fit-for-purpose and on-demand reference materials, and generating specifications that assure confidence in an assay measurement system.
Any assay can be considered as a measurement process that comprises of a series of discrete steps wherein each step can introduce a potential source of variability. A key to developing a cell assay into a high-quality documentary standard where you have confidence in your measurement, is to adapt the process quality tools to the cell assay. This process of measurement assurance involves prioritizing the sources of variability through inter laboratory comparisons, developing reference materials or protocols, using design of experiments or introducing in-process controls and specifications. Identifying the parameters that are the most important sources of variability and determining the range over which the parameters can vary without significantly changing the result is possible with design of experiment. Design of experiment involves setting a large number of experiments to vary individual factors and track the assay performance over time. To achieve this, we have developed an automation-based cellular measurement system that facilitates understanding the sources of variability and reduce the time required to develop a high-quality assay protocol.
Our automation-based system called Prototype Cell Assay Measurement Platform (P-CAMP) is designed such that it can systematically and exhaustively explore the measurement factor space and identify the sources of variability, their magnitudes and their interactions. It is built to mimic the assay protocols but rather than merely automating the assay to make it high throughput, the automated protocol will introduce variability in individual steps as per a high order partial factorial experimental design to include comprehensive factor and level changes. Thanks to the robot’s capability to set 1000s of parallel experiments and generate data reports and trails suitable for high resolution provenance development, we can map out the complex assay factor space in intricate details to prioritize the factors that are critical in changing a measurement. With that in mind, following are some detailed features of the P-CAMP.
The Prototype Cell Assay Measurement Platform (P-CAMP) is an integration of a Hamilton MicroLab Star Plus robotic pipetting workstation and a modular instrument cabinet. It is built with flexible design strategy with an idea to have:
The deck on the P-CAMP with the largest possible deck capability (71 tracks) to maximize the number of plates per experiment looks as follows and is equipped with:
Our modularly designed instrument cabinet is currently equipped with the following instruments:
An open design software- Venus 4 controls all the on-deck liquid handling and plate transfers, ODTC, incubator, centrifuge, plate reader/imager and nucleofector. Venus is also equipped with all the tools needed for worklist handling, LIMS adaption, database- and server controls, scheduling or third-party component control.
First Use Case:
Generation of Short-Lived Reference Conditions for The Viability Assay Sensitivity/Robust Analysis
For cell-based therapies and similar cellular applications, the properties of cells being exploited, such as protein expression, secretion, target identification, migration, communication and proliferation, are all dependent on the cells being alive and healthy. Measurement of live cell properties requires some live cell reference materials. However, live cell features have limited stability and therefore a live cell reference material will need to be generated “on-demand” for an experiment. With P-CAMP, we can generate short-lived reference conditions composed of different proportions of live and dead Jurkat cells, for the viability assay sensitivity/robustness analysis. The next step is to characterize the stability and reproducibility of the materials and the sources of variability in the methods.
The diagram below shows a schematic workflow of the steps involved in generating short-lived live/dead-cell reference material: