Reproducibility and Harmonization in Research Using Biological Standards: The Example of Platelet Agonist Collagen-Related Peptide
August 4th, 2023
Here we present a method to standardize the platelet agonist collagen-related peptide cross-linked (CRP-XL) using light transmission aggregometry. While the protocol is targeted at platelet function, the experimental process can be applied to most biological molecules and bioassays to ensure scientific rigor and reproducibility.
Researchers at the MHRA South Mimms Laboratories have been developing manufacturing biological standards for over 60 years, and these reference reagents are used to ensure the quality, consistency, and safety of biological medicines and diagnostics. NIBSC standards from the MHRA support translation of cutting-edge therapeutic products, as well as the control of established medicines. At the MHRA South Mimms Laboratories, we use state-of-the-art technologies to produce materials that support the development and regulation of novel therapeutic innovations.
Biological standards remain underutilized by academics in the biological sciences due to a lack of knowledge exchange. This negatively impacts the quality of research and contributes to the reproducibility crisis. Biological standardization ensures experiments are reproducible, regardless of where or when they are performed.
A lack of proper knowledge in basic metrological principles and training compromises scientific rigor and negatively impacts reproducibility. Although our protocol focuses on standardizing platelet function measurement, the practice can be applied to any biological system. Applying biological standardization to research practices will not only standardize biological experiments, but also help to address inconsistencies and the lack of harmonization that undermines research.
To begin the assay, using the platelet receptor agonist, collagen-related peptide cross-linked, or CR-PXL, dilute an appropriate amount of the CR-PXL stock in the assay buffer to a concentration suitable to induce maximum platelet aggregation. The result in solution will be henceforth referred to as the standard. Next, starting from the same highest prepared concentrations, sequentially perform twofold serial dilutions for both the standard and the test reagent.
Prepare a six to eight-point dilution series for both the test and the standard in assay buffer that generates aggregation responses from 100%down to 0%When the platelet-rich plasma or PRP is ready to use, add an aliquot of PRP into the light transmission aggregometry cuvette. Allow the samples to warm to 37 degrees Celsius in the holding wells for a couple of minutes. Once appropriately warmed, place the cuvettes in the aggregometer to start recording the traces.
With constant stirring, add the agonist, and record the data. Perform data collection for each prepared dilution of the standard and the test reagent. Use GraphPad Prism or any suitable software package to check if the concentration curves for the standard and test are parallel.
Enter the data such that the X axis contains the concentrations, and the Y-axis contains the responses indicated, by either the percentage of maximum aggregation or the area under the curve. Next, transform the concentration values to the corresponding logarithms or log concentration. Select Nonlinear regression from the Analysis functions and use the equation for dose response stimulation.
Select log agonist vs. response Variable slope, and use a three or four-way fit, depending on which is best for the data. Determine if the curves generated are parallel by clicking the Compare tab and comparing the data sets.
Ensure that the slope and asymptotes of the test and the standard curves are equivalent. If these conditions are met, proceed to calculate the potency or EC50 using nonlinear regression curve fitting. Calculate the relative potency by dividing the EC50 value of the standard by that of the test.
Adjust the mass per volume concentration of the test reagent to account for the difference in potency with respect to the standard. The platelet aggregation traces for the standard and the test reagent revealed the difference between the two aggregation responses. At 0.075 micrograms per milliliter, there was a clear response to the standard, while for the test, the corresponding concentration showed no response.
The EC50 values of the standard and test reagent were calculated by plotting the concentration response curve.
Overview
This study presents a method for standardizing the platelet agonist collagen-related peptide cross-linked (CRP-XL) using light transmission aggregometry. The protocol, while focused on platelet function, can be applied to various biological molecules and bioassays to enhance scientific rigor and reproducibility.
Key Study Components
Area of Science
- Platelet function measurement
- Biological standardization
- Light transmission aggregometry
Background
- Biological standards ensure quality and safety in biological medicines.
- Standardization is crucial for reproducibility in research.
- There is a lack of knowledge exchange regarding biological standards among academics.
- Improper training in metrological principles can compromise scientific rigor.
Purpose of Study
- To standardize platelet function measurement using CRP-XL.
- To promote the application of biological standardization in research practices.
- To address inconsistencies in biological experiments.
Methods Used
- Dilution of CRP-XL in assay buffer to induce platelet aggregation.
- Preparation of a dilution series for both standard and test reagents.
- Use of light transmission aggregometry to record platelet aggregation responses.
- Data analysis using nonlinear regression to determine potency (EC50).
Main Results
- Clear aggregation response observed at 0.075 micrograms per milliliter for the standard.
- No response for the test reagent at the corresponding concentration.
- EC50 values calculated for both standard and test reagents.
- Relative potency determined by comparing EC50 values.
Conclusions
- Standardization improves reproducibility in biological experiments.
- Proper training in metrology is essential for scientific rigor.
- Application of the protocol can enhance the quality of research across various biological systems.
Frequently Asked Questions
Executive Industry Relevance
Standardization using biological reference materials is critical for ensuring reproducibility and harmonization across discovery and translational research pipelines. The application of metrological principles to platelet agonist assays, such as CRP-XL in light transmission aggregometry, directly addresses the reproducibility crisis and supports robust data comparability across sites and time. This capability underpins confidence in early discovery findings and enables reliable cross-functional decision-making in biopharma R&D portfolios.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Enables rigorous comparison of biological activity between test and standard reagents for target validation.
- Reduces mechanistic ambiguity by quantifying potency differences using EC50 values.
- Supports predictive confidence in pathway interrogation and functional assay outputs.
Screening & Assay Development
- Facilitates preparation of validated dilution series for reproducible assay performance.
- Standardizes quantitative readouts, ensuring assay comparability across batches and sites.
- Enables reliable benchmarking of new agonists or test materials against established standards.
Translational & Preclinical Research
- Promotes harmonization of bioassay data for translational continuity from discovery to preclinical studies.
- Supports risk-adjusted advancement by providing robust potency assignments for candidate molecules.
- Addresses inter-lab variability, strengthening the foundation for biomarker alignment and preclinical modeling.
Pipeline & Workflow Integration
This standardization protocol integrates at the interface of early discovery, assay development, and translational research, providing a foundation for reliable lead identification and preclinical validation.
- Discovery Biology: Supports hypothesis testing and biological de-risking by enabling direct potency comparisons.
- Screening: Delivers reproducible, quantitative outputs for assay readiness and compound evaluation.
- Analytics: Provides EC50-based measurements and parallelism checks to ensure data integrity.
- Translational Research: Facilitates continuity of biological activity assignments across research phases.
- Enterprise Reuse: Establishes a reusable framework for standardizing diverse bioassays beyond platelet function.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence and reduces mechanistic uncertainty in functional assays.
- Operational Value: Drives assay standardization, reproducibility, and harmonization across teams and sites.
- Strategic Value: Enables informed go/no-go decisions and capital-efficient portfolio management.
- Portfolio Impact: Supports risk-adjusted prioritization and advancement of discovery and translational assets.
Implementation Considerations
- Requires expertise in metrology, assay design, and nonlinear regression analysis.
- Needs access to validated reference materials and analytical instrumentation for aggregometry.
- Demands cross-team agreement on standardization protocols and data analysis workflows.
- Adaptable to various biological systems and assay platforms with appropriate validation.
- Dependent on consistent training and knowledge exchange to maximize reproducibility benefits.
