Isolation and Analysis of Plasma Lipoproteins by Ultracentrifugation
January 28th, 2021
Several methods have been used for analyzing plasma lipoproteins; however, ultracentrifugation is still one of the most popular and reliable methods. Here, we describe a method regarding how to isolate lipoproteins from plasma using sequential density ultracentrifugation and how to analyze the apolipoproteins for both diagnostic and research purposes.
Analysis of plasma lipoproteins is very important for the diagnosis of hyperlipidemia and the investigation of atherosclerosis. In is this protocol, we'll introduce the basic method using ultracentrifugation to isolate plasma lipoproteins. This method allows the researchers to use one milliliter of plasma to isolate seven lipoprotein fractions.
These fractions can be used for the of lipids, apolipoproteins, as well as well-functional studies This method can be applied for both human and animal samples for the diagnosis of dyslipidemia and the related disease. Begin by transferring one milliliter of plasma into each polycarbonate ultracentrifuge tube. Then load the tubes in a fixed angle rotor and centrifuge the plasma at 356, 000 times G for 2.5 hours at four degrees Celsius.
Adjust the position of the blade in the tube slicer to a level between the top fraction and the bottom fraction. Cut the tubes using a slicer and collect the top fraction, approximately 200 microliters, into a new micro tube. Collect the remaining bottom fraction into a new polycarbonate ultracentrifuge tube for the next separation.
Adjust the total volume to 800 microliters by adding the same density solution. Adjust the bottom fraction to a density of 1.02 grams per milliliter by adding 58.9 microliters of 1.21 grams per milliliter solution, and 141.1 microliters of 1.02 grams per milliliter solution for a total volume of one milliliter. Load these tubes in the fixed angle rotor and centrifuge at 356, 000 times G for 2.5 hours at four degrees Celsius.
Continue collecting top fractions, adjusting the density of bottom fractions, and centrifuging for fraction densities of 1.02, 1.04, 1.06, 1.08, 1.1, and 1.21 grams per milliliter. For the final ultracentrifugation, centrifuge at 513, 000 times G for four hours at four degrees Celsius. Lipoprotein profiles of rabbits fed either a normal standard diet or a high cholesterol diet are shown here.
Rabbits are herbivores, so their plasma TC, TG, and PL levels are generally lower than those of humans and mice. In normal standard diet-fed rabbits, TC is mainly distributed in HDL3 and LDL. In wild type rabbits on a normal standard diet, 39%of plasma TG are distributed in VLDLs, whereas 57%of plasma PL is contained in HDL3.
When rabbits were challenged with a high-cholesterol diet, they rapidly developed hypercholesterolemia. Their lipoprotein profiles were characterized by marked elevation of VLDLs. Seven lipoprotein fractions from wild type rabbits fed either a normal standard or a high-cholesterol diet were run on an SDS polyacrylamide gel and visualized with CBB staining.
On a high-cholesterol diet, both ApoB-100 and ApoE contents in VLDLs, IDLs, and LDLs were markedly elevated. Western blotting was used to compare apolipoproteins and lipoprotein profiles of three different hyperlipidemic rabbits:high-cholesterol diet-fed wild type rabbits, ApoE knockout rabbits, and Watanabe Heritable Hyperlipidemic rabbits with LDL receptor deficiency. The ApoB containing particles of high-cholesterol diet-fed wild type rabbits are characterized by increased ApoB-100 and ApoE contents, whereas ApoE knockout rabbits showed an increase of ApoB-48 along with the appearance of ApoA-1.
Watanabe Heritable Hyperlipidemic rabbits are genetically deficient in LDL receptor functions, so a marked increase of ApoB-100 in LDLs accompanied by reduced ApoA-1 in HDLs was observed, similar to human familial hypercholesterolemia patients. Sample recovery is the most critical in this procedure. To minimize sample loss, one should it be careful to collect fraction and completely dissolve viscous precipitation in the bottom fraction.
After the collection of seven lipoprotein fractions, dialysis is require for the sorting. Once dialysis is complete, the lipoproteins samples for analysis using SDS page, western blotting, and cell-based study. In the clinical setting, ultracentrifugation usually separates lipoproteins into four fractions.
The current method can isolate seven lipoproteins fractions, which provides more detail of lipoproteins for investigation of hyperlipidemia.
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Overview
This article describes a method for isolating plasma lipoproteins using sequential density ultracentrifugation. This technique is crucial for diagnosing hyperlipidemia and studying atherosclerosis.
Key Study Components
Area of Science
- Neuroscience
- Biochemistry
- Clinical Diagnostics
Background
- Plasma lipoproteins play a significant role in lipid metabolism.
- Understanding lipoprotein profiles is essential for diagnosing metabolic disorders.
- Ultracentrifugation is a reliable method for lipoprotein isolation.
- This method can be applied to both human and animal samples.
Purpose of Study
- To isolate lipoproteins from plasma for diagnostic purposes.
- To analyze apolipoproteins related to dyslipidemia.
- To provide a protocol for researchers in the field.
Methods Used
- Sequential density ultracentrifugation of plasma samples.
- Isolation of seven lipoprotein fractions from one milliliter of plasma.
- Centrifugation at 356,000 times G for 2.5 hours at 4°C.
- Analysis of lipids and apolipoproteins in the isolated fractions.
Main Results
- Successful isolation of multiple lipoprotein fractions.
- Ability to analyze apolipoproteins for diagnostic applications.
- Method applicable for both human and animal samples.
- Facilitates research into dyslipidemia and related diseases.
Conclusions
- Ultracentrifugation is an effective method for lipoprotein isolation.
- The protocol can aid in the diagnosis of lipid disorders.
- Further research can utilize these isolated fractions for various studies.
Frequently Asked Questions
Executive Industry Relevance
Sequential ultracentrifugation enables precise isolation of seven distinct plasma lipoprotein fractions, supporting advanced lipid metabolism research and translational studies in dyslipidemia and atherosclerosis. This method enhances predictive confidence in target validation and mechanistic de-risking for cardiovascular and metabolic disease portfolios. Its detailed fractionation and compatibility with downstream proteomic and functional assays position it as a reusable capability across discovery and preclinical pipelines.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Enables interrogation of lipid transport pathways and apolipoprotein function in disease-relevant models.
- Supports mechanistic de-risking by isolating fractions for functional and proteomic analysis.
- Facilitates target validation by quantifying apolipoprotein distribution across lipoprotein classes.
Screening & Assay Development
- Provides standardized, reproducible lipoprotein fractions for assay development and compound screening.
- Delivers quantitative outputs for comparative analysis of lipid and protein content.
- Enables platform reuse for both human and animal model systems.
Translational & Preclinical Research
- Aligns with translational biomarker strategies by enabling detailed lipoprotein and apolipoprotein profiling.
- Supports continuity from discovery through preclinical validation in hyperlipidemic and genetically modified models.
- Informs risk-adjusted advancement decisions by revealing mechanistic drivers of dyslipidemia.
Pipeline & Workflow Integration
This ultracentrifugation protocol integrates from early discovery through preclinical research, enabling robust hypothesis testing and mechanistic studies in lipid metabolism.
- Discovery Biology: Supports pathway clarification and biological de-risking by isolating functionally distinct lipoprotein fractions.
- Screening: Provides assay-ready, reproducible fractions for quantitative evaluation of lipid and protein content.
- Analytics: Enables SDS-PAGE and Western blotting for quantitative apolipoprotein measurement and comparative profiling.
- Translational Research: Facilitates biomarker alignment and disease model validation in hyperlipidemic animal studies.
- Enterprise Reuse: Establishes a standardized protocol adaptable across multiple disease models and research teams.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence and reduces mechanistic ambiguity in lipid metabolism research.
- Operational Value: Delivers standardized, scalable, and reproducible lipoprotein isolation for cross-team workflows.
- Strategic Value: Improves go/no-go decision quality and capital efficiency by enabling detailed mechanistic insight.
- Portfolio Impact: Supports risk-adjusted prioritization and advancement of cardiovascular and metabolic disease assets.
Implementation Considerations
- Requires expertise in ultracentrifugation and fraction collection to ensure sample integrity.
- Demands access to high-speed ultracentrifuges and analytical platforms for SDS-PAGE and Western blotting.
- Necessitates rigorous cross-team standardization for reproducible fractionation and analysis.
- Adaptable to both human and animal plasma but may require optimization for different species or disease models.
- Sample recovery and fraction purity are critical for downstream functional and proteomic studies.
