Found this very interesting article in "The Age" newspaper today regarding cells. The link at the end shows and interesting relationship between mesenchymal stem cells and mitochondria.
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Scientists film real-time footage inside a human cell
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Under the microscope, they look like little red bubbles, swelling with green slime. The bubbles stretch, and then burst in a shower of goo.
This never-before-seen process may be a crucial trigger for autoimmune diseases like arthritis.
It was midnight when Professor Benjamin Kile first saw the vision, sitting awake at midnight at his computer in the Monash Biomedicine Discovery Institute.
“I felt like I was part of NASA, getting pictures from the dark side of the moon”, he said. “It was obvious immediately that this was something no one had ever seen before.”
The footage was shot by Professor Kile’s PhD student Dr Kate McArthur at the Janelia Research Campus in the USA, using a remarkable new microscope that can take images of living cells. She later confirmed the images using a similar microscope at the Walter and Eliza Hall Institute in Melbourne.
As scientists, we are taught to be quite sceptical when we see something unexpected, so I think my initial reaction was ‘no way’,” she said.
The vision is real-time footage from inside a human cell. The red structures are mitochondria, the cell’s powerhouse. The green is mitochondrial DNA.
What the footage captures is the exact moment a mitochondria ruptures, spraying its innards throughout the cell.
Two mitochondria, in red, undergoing herniation - the release of DNA (in green). If you look really closely you will see that the left half of the lower mitochondria has two membranes, but on the right, there is only one left as the mitochondria disintegrates.
Photo: Credit: Dr Kate McArthur, Monash Biomedicine Discovery Institute
Scientists suspected mitochondrial ruptures might happen – they are one of the leading theorised causes for autoimmune diseases. But no one had ever been able to prove their existence.
“We think some of those cells die in an aberrant fashion, and bits of the cell that should stay inside – like the mitochondrial DNA – get out into the blood. And that’s when your immune system fires up,” Professor Kile said.
This image shows two cells that have undergone programmed cell death. The nucleus of the cell in each is the black hole surrounded by coloured dots. The colored dots are mitochondria that have undergone herniation. If you look closely at each structure you will see mitochondria that have blown.
Photo: Dr Kate McArthur, Monash Biomedicine Discovery Institute
In nearly every single cell in your body lives an ancient organism.
This organism, known as mitochondria, is an ancient bacterial relative that was consumed by a cell long ago. It struck a symbiotic relationship: it manufactures energy, and in return, cells keep it alive.
But despite the fact we could not survive without mitochondria, they are not human – they contain their own set of DNA. If it makes it into the blood, this ‘foreign’ DNA triggers a big immune reaction.
Luckily, in most cases, when a cell dies, its mitochondrial DNA stays inside the carcass – otherwise our immune system would be constantly attacking our own tissue.
This is a 3D reconstruction showing a single mitochondria in the act of herniating. The team calls it the “great escape”.
Photo: Dr Kate McArthur, Monash Biomedicine Discovery Institute
What Professor Kile and Dr McArthur demonstrated, in a paper published Friday in
Science, was evidence of that DNA being violently ejected from the mitochondria into the cell when the cell dies.
It is thought some of this ejected DNA makes its way outside the cell and into the blood.
This might explain why the immune system in some people seems to go haywire, causing illnesses like rheumatoid arthritis and diabetes. Possibly, Professor Kile suggests, the immune system is reacting to the presence of the foreign mitochondrial DNA.
The find, a “fundamental discovery”, will be used by researchers studying the cause of – and treatments for – autoimmune diseases, says Professor Kile.
But Professor Kile has a more radical idea: tuning the system to fight cancer.
If you could get somehow get cancerous cells to release their mitochondrial DNA, you could provoke an enormous immune response against the cells in the tumour.
“This horrible autoimmune response we want to prevent in healthy people, that could be triggered to fight cancer,” he says.
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Mitochondria in mesenchymal stem cell biology and cell therapy: From cellular differentiation to mitochondrial transfer.
https://www.ncbi.nlm.nih.gov/m/pubmed/26868759/
Two important points which relate to Mesoblast.
1. MSCs can serve as a vehicle to transfer mitochondria into cells after cell transplantation.
2. Accumulating evidence has substantiated that the therapeutic potential of MSCs is conferred not only by cell replacement and paracrine effects but also by transferring mitochondria into injured tissues or cells to modulate the cellular metabolism in situ. Therefore, elucidation of the underlying mechanisms in the regulation of mitochondrial metabolism of MSCs may ultimately improve therapeutic outcomes of stem cell therapy in the future.
(20min delay)
