Extracellular vesicles, including large translating vesicles called midbody remnants, are released during the cell...

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Extracellular vesicles (EVs) are key mediators of intercellular communication.
• The biogenesis of large EVs, particularly those exceeding 800 nm, remains poorly understood.
• Current understanding of EV markers and isolation methods may be confounded by other cellular components.

Purpose of the Study:

• To elucidate the biogenesis pathway of large EVs.
• To identify the cellular origin and characteristics of large EVs.
• To reassess the specificity of canonical EV markers and the impact of isolation methods on EV research.

Main Methods:

• Cell cycle and cytokinesis inhibition (genetic and chemical).
• Characterization of large EVs using microscopy and marker analysis (MKLP1, CD9, CD63, CD81).
• Evaluation of EV isolation techniques and assessment of MBR translation activity.

Main Results:

• Large EVs (>800 nm-2 µm) are predominantly midbody remnants (MBRs) formed during cytokinesis.
• Inhibition of cell division significantly reduces the production of all sizes of EVs.
• Canonical EV markers (CD9, CD63, CD81) are found on MBRs, not exclusively on EVs.
• Common EV isolation methods retrieve MBRs, potentially confounding previous findings.
• Isolated MBRs exhibit translation activity.

Conclusions:

• A significant population of large EVs originates from mitotic cells as MBRs.
• The presence of MBRs in EV preparations necessitates re-evaluation of existing EV research.
• MBRs represent a unique class of translating EVs with potential applications in cancer diagnostics and therapeutic delivery.