Extracellular vesicles release by cardiac telocytes: electron microscopy and electron tomography

Area of Science:

• Cardiovascular Biology
• Cell Biology
• Extracellular Vesicles Research

Background:

• Telocytes facilitate long-distance heterocellular communication in the heart via direct contact and extracellular vesicles (EVs).
• EVs, including exosomes and ectosomes, are key paracrine mediators in cellular signaling.

Purpose of the Study:

• To characterize the types of EVs released by telocytes using advanced microscopy techniques.
• To investigate the potential role of these EVs in cardiac physiology and regeneration.

Main Methods:

• Electron microscopy (EM) and electron tomography (ET) were employed to visualize and analyze telocyte-derived EVs.
• Telocytes in culture and tissue were examined to identify and quantify EV subtypes.

Main Results:

• Telocytes release three distinct EV types: exosomes (45 ± 8 nm), ectosomes (128 ± 28 nm), and a novel multivesicular cargo (MVC; 1 ± 0.4 μm).
• MVCs contain tightly packed endomembrane-bound vesicles (145 ± 35 nm) released as a plasma membrane-enclosed cargo.
• Electron tomography confirmed the release of these EVs, including MVCs, from telocytes in both culture and tissue.

Conclusions:

• Telocytes secrete a diverse range of EVs, including a previously undescribed MVC type.
• These EVs, particularly MVCs, represent a significant mode of paracrine secretion by telocytes.
• Telocyte-derived EVs are likely integral to heart function and regenerative processes.