So that 2014 study found functional mitochondria outside cells (released) from platelets used for transfusions. So they do respire:
"
Quite unexpectedly, significant O2 consumption was detected even in the absence of detergent. These observations suggest that, in addition to active mitoMPs, platelets may also release respiration-competent free mitochondria (freeMito) into the extracellular milieu."
And they (and mitochondrial DNA fragments) modulate immune cell (neutrophil) behaviour, stimulate cortisol release and promote inflammation. Elevated cell free mitochondria seem problematic:
"
we established that platelet concentrates that had been associated with adverse transfusion reactions in human recipients contain higher concentrations of extracellular mitochondria."
Danger and possible wound healing, I would say.
Sure, well, that paper describes platelets releasing mitochondria when activated. So cell free mitos will presumably be much more highly concentrated at sites of tissue damage where platelets have accumulated.
I wonder if the the background level of free mitos seen in the new study could be accounted for by ongoing (healthy) platelet activity (or similar processes)...? Also, if mitos might be able to migrate to and concentrate in certain areas themselves...?
But even at much higher concentrations, I doubt their purpose would be providing energy through respiration. Maybe producing ROS for "oxidative shielding", as well as promoting inflammatory responses...?
ATP has a very different purpose inside the cell and outside the cell. [...]
Thus, when a muscle cell is stressed, it may suffer a micro-tear, releasing ATP outside the cell.
Yeah. I was going to point at Naviaux's
paper(s) on
Cell Danger Response.
Intact cells can also release ATP, and other purinergic molecules, for danger signalling, to other cells. And Naviaux's found success treating autism (and potentially ME/CFS) via the anti-purinergic drug suramin. (2016 write-up on these by Cort,
here.)
But what if their energy production capability is impaired in a similar way to that of whole cells from serum?
I meant to be more explicit in saying: could these extra-cellular mitos be helpful for diagnostic testing? Or research? If it's not too hard to isolate them. Like, would there be advantages over looking at whole cells from blood (in the nano-needle), because those are inevitably immune cells, who's behaviour can complicate interpretation...? (No point re-inventing the wheel there though.)
Also, I meant to ponder if this new population of mitochondria might potentially be significant in developing (pathological) auto-antibodies against mitochonria...? If they're always in contact with immune system. Or more so at site of injury/infection...?
