Label-free characterization of an extracellular vesicle-based therapeutic

Journal of Extracellular Vesicles, 2021 · DOI: 10.1002/jev2.12156 · Published: September 23, 2021

Simple Explanation

This study introduces a method for characterizing extracellular vesicles (EVs) using quartz crystal microbalance (QCM), an immunosensing technique. It allows for the detection of EVs and differentiation from non-vesicular particles based on specific markers. Atomic force microscopy (AFM) is used to analyze the topography and elasticity of EVs. This helps in distinguishing EV sub-fractions and characterizing surface proteins with minimal sample preparation. The combination of QCM with impedance measurement (QCM-I) and AFM offers a robust multi-marker approach to improve the quality control of EV therapeutics.

Study Duration

Not specified

Participants

Human umbilical cord (UC)-derived MSCs

Evidence Level

Not specified

Key Findings

1
The study established QCM as a sensitive label-free method for characterizing clinically approved umbilical cord MSC-EVs, detecting EVs via specific EV and MSC markers.
2
Analysis of QCM dissipation versus frequency allows quantitative determination of the ratio of marker-specific EVs versus non-vesicular particles (NVPs), which is not achievable by other techniques.
3
AFM distinguished between EVs and NVPs by their elasticity, identifying EV sub-fractions and characterizing EV surface proteins with minimal sample preparation.

Research Summary

This study introduces a QCM-I and AFM-based protocol for characterizing EVs by elasticity and surface markers, tailored for reproducibility and integration in existing labs. The method utilizes specific recruitment of marker-positive particles by antibodies and distinguishes EVs from NVPs based on viscoelastic properties. The combined approach allows quantitative determination of marker-specific EV versus NVP ratios, providing insight into the complex composition of EV-based therapeutics.

Practical Implications

Improved Quality Control

The QCM-I and AFM combination provides a robust method for quality control of EV therapeutics.

Enhanced Characterization

The multi-marker approach enables detailed characterization of EV surface proteins and distinction from NVPs.

Accessible Technology

The method offers a label-free immunosensing technique that is easy to integrate in existing laboratory infrastructures.

Study Limitations

1
The method assumes viscoelastic properties of NVPs and EVs can be approximated by large proteins and pure vesicles, respectively.
2
The volumes of single NVPs and EVs are assumed to be approximately equal.
3
Future determination of exact values for the viscoelastic properties and volumes of NVPs and EVs would further improve the absolute values obtained through our formalism.

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