Liposome Calibration for EV Surface Marker Quantitation
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Solution Overview
Problem
Current methods for analyzing extra-cellular vesicle (EV) surface markers lack standardization, particularly in quantitating the number of molecules or antibodies bound, leading to challenges in inter-laboratory comparisons due to variations in instrument setups and fluorescent antibody vendors.
Innovation Solution
A method involving a liposome calibration composition with fluorescently labeled liposomes of known fluorophore numbers is used to create a calibration plot, allowing for conversion of mean fluorescence intensity (MFI) values of EV samples into standardized MESF values, independent of instrument variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If commercial flow cytometers are used to measure relative fluorescence of surface markers, then EV surface markers can be detected, but the MFI values cannot be compared across different instruments and laboratories due to instrument variations
Solution Approach 1:
The patent introduces fluorescently labeled liposomes with known fluorophore numbers as intermediary calibration particles. These liposomes serve as a universal reference standard that mediates between different flow cytometers and laboratories, enabling conversion of instrument-specific MFI values into standardized MESF values that can be compared across platforms
Solution Approach 2:
The patent transforms the measurement parameter from relative MFI (instrument-dependent) to absolute MESF (standardized). By establishing a calibration curve that relates MFI to known fluorophore numbers, the system changes the measurement scale to enable quantitative comparison across different instruments and laboratories
2Adaptability or versatility
If fluorescent antibodies from different vendors are used, then EV surface markers can be stained, but quantitation of the number of molecules or antibodies bound becomes unreliable
Solution Approach 1:
The calibration liposomes act as an intermediary reference that decouples the measurement from antibody-specific variations. By comparing all samples (regardless of which fluorescent antibody was used) against the same liposome standard, the system enables quantitation that is independent of vendor or antibody batch differences
3Productivity
If current EV analysis methods are used, then EV particles can be enumerated, but standardization for surface marker quantitation is lacking
Solution Approach 1:
The patent creates a universal calibration system using fluorescent liposomes that can be applied to all EV surface marker quantitation experiments regardless of the specific marker or instrument used. This single calibration approach serves multiple functions: it standardizes measurements, enables inter-laboratory comparison, and works with any fluorescent antibody
Solution Approach 2:
The patent implements preliminary calibration using fluorescent liposomes with known fluorophore numbers before actual EV sample analysis. This pre-established calibration curve (relating MFI to MESF) is then used to convert measurements from all subsequent experiments, ensuring standardized quantitation from the outset
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables accurate and standardized quantitation of EV surface markers, improving inter-laboratory consistency and reliability by converting MFI values into MESF values, thereby overcoming previous limitations in EV research.
Implementation Method 1
fluorescently labeled liposomes with a known number of fluorophores attached to their surfaces
Data Source
AI summary
Methods of quantitating extra-cellular vesicle surface markers are provided. Aspects of the methods include comparing: a mean fluorescence intensity of a surface marker of interest (surface marker MFI) of a labeled extra-cellular vesicle (EV) sample with a calibration plot obtained from a liposome calibration composition to quantitate the surface marker on extra-cellular vesicles of the EV sample. Also provided are compositions that find use in practicing embodiments of the invention.