Functional extracellular mitochondria have been revealed to exist in the blood...
Functional extracellular mitochondria have been revealed to exist in the blood circulation

© Alain R. Thierry/Inserm

News • Functional extracellular mitochondria

Surprising discovery of a new blood component

Does the blood we thought to know so well contain elements that had been undetectable until now? The answer is yes, according to a team of researchers.

The scientists from Inserm, Université de Montpellier and the Montpellier Cancer Institute (ICM) working at the Montpellier Cancer Research Institute (IRCM), led by Inserm researcher Alain R. Thierry, have revealed the presence of whole functional mitochondria in the blood circulation. These organelles that are responsible for cellular respiration had hitherto only been found outside cells in very specific cases. The team’s findings, published in The FASEB Journal, will deepen our knowledge of physiology and open up new avenues for treatment.

Mitochondria are organelles that are found in the eukaryotic cells. A place of cellular respiration, they are the cells’ “batteries” and play a major role in energy metabolism and intercellular communication. Their particularity is to possess their own genome, transmitted solely by the mother and separate from the DNA contained in the nucleus. The mitochondria can sometimes be observed outside the cells in the form of fragments encapsulated within microvesicles. Under certain very specific conditions the platelets are also capable of releasing intact mitochondria into the extracellular space.

The researchers used previous findings which showed that the plasma of a healthy individual contains up to 50,000 times more mitochondrial DNA than nuclear DNA. They hypothesized that for it to be detectable and quantifiable in the blood in this manner, the mitochondrial DNA had to be protected by a structure of sufficient stability. In order to identify such a structure, plasma samples from around 100 individuals were analyzed. This analysis revealed the presence in the blood circulation of highly stable structures containing whole mitochondrial genomes. Following examination of their size and density, as well as the integrity of their mitochondrial DNA, these structures observed using electron microscopy (up to 3.7 million per ml of plasma) were revealed to be intact and functional mitochondria.

When we consider the sheer number of extracellular mitochondria found in the blood, we have to ask why such a discovery had not been made before

Alain R. Thierry

Throughout the seven-year research period, the scientists used as many technical and methodological approaches as possible to validate this presence of circulating extracellular mitochondria in the blood. “When we consider the sheer number of extracellular mitochondria found in the blood, we have to ask why such a discovery had not been made before”, notes Thierry. “Our team has built up expertise in the specific and sensitive detection of DNA in the blood, by working on the fragmentation of extracellular DNA derived from the mitochondria in particular”, he adds.

But what is the role of these extracellular mitochondria? The answer to that could be linked to the structure of the mitochondrial DNA, similar to that of bacterial DNA, which gives it the ability to induce immune and inflammatory responses. Based on this observation, the researchers hypothesize that these circulating mitochondria could be implicated in many physiological and/or pathological processes requiring communication between the cells (such as the mechanisms of inflammation). Indeed, recent studies have demonstrated the ability of certain cells to transfer mitochondria between themselves, such as the stem cells with damaged cells. “The extracellular mitochondria could perform various tasks as messenger for the entire body”, specifies Thierry. In addition to its importance to our knowledge of physiology, this discovery could lead to improvements in the diagnosis, monitoring and treatment of certain diseases. In fact, the research team is now devoting its attention to evaluating the extracellular mitochondria as biomarkers in non-invasive prenatal diagnosis and cancer. 


Source: Inserm

23.01.2020

More on the subject:
Read all latest stories

Related articles

Photo

News • Based on image-based flow cytometry

Rapid test to predict severe Covid-19 infections

Researchers have developed a method for assessing the number and structure of aggregated blood platelets (or thrombocytes) that can potentially help quantify the risk of a severe Covid-19 infection.…

Photo

News • Troponin assessment

Blood test aids emergency diagnosis of heart conditions

A high sensitivity blood test can improve diagnosis for one in five patients who have a heart muscle injury, according to new research.

Photo

News • VITT reseach

Cause for rare, but deadly vaccine-related blood clotting found

A mechanism that led some patients to experience cases of deadly clotting following some types of Covid-19 vaccination has been identified in new research.

Related products

Alsachim · Dosimmune immunosupressant Alsachim – kit (CE-IVD or RUO)

Clinical Chemistry

Alsachim · Dosimmune immunosupressant Alsachim – kit (CE-IVD or RUO)

Alsachim, a Shimadzu Group Company
Alsachim · Dosinaco anticoagulant reagent kit (RUO)

Clinical Chemistry

Alsachim · Dosinaco anticoagulant reagent kit (RUO)

Alsachim, a Shimadzu Group Company
Beckman Coulter · Access Procalcitonin (PCT)

Immunoassays

Beckman Coulter · Access Procalcitonin (PCT)

Beckman Coulter Diagnostics
Beckman Coulter · DxH 500 Series

Blood Cell Counter

· Beckman Coulter · DxH 500 Series

Beckman Coulter Diagnostics
Beckman Coulter · Early Sepsis Indicator

Blood Cell Counter

Beckman Coulter · Early Sepsis Indicator

Beckman Coulter Diagnostics
Beckman Coulter · PK7400 Automated Microplate System

Blood Cell Counter

· Beckman Coulter · PK7400 Automated Microplate System

Beckman Coulter Diagnostics
Subscribe to Newsletter