Dying Organs Restored to Life in Novel Experiments | Hacker News Reader

Dying Organs Restored to Life in Novel Experiments

nytimes.com

120 pointsThomPete32 comments

It occurs to me that mitochondrial decline also seems to be an important aspect of aging. If you can just infuse mitochondria through the blood and "the organelles will gravitate almost magically to the injured cells that need them and take up residence", that suggests a rather obvious rejuvenation approach.

And do different cross have different mitochondria? I would be tempted to say no but I'm not sure

All the cells in the body have the same mitochondrial DNA, which is inherited from the maternal side (egg cells have them, sperm cells don’t).

(Edit: except for cells that have no mitochondria, of course)

Yes but do they differentiate across different cell types?

IANABiologist, but my understanding is that they don’t differentiate; they have too simplistic a structure for that, and rely on the host cells for many of their functions. The main differences seen across cell types is whether they are present or not.

My girlfriend is a biologist. She is saying that all cells that have mitochondrias in a human body have the same mitochondrial DNA.

Truly, they are the powerhouse of the cell

But where do we get those new mitochondria from? I'm almost afraid to ask.

Maybe from cloning one's own cells, then carefully dismantling them to free up mitochondria without damaging them? I don't think a lot of the tissue should be required (that is, ounces, not pounds).

mitachondria are living organelles, they could simply be induced to replicate until the desired quantity is reached.

If I recall bio from school, they are super adapted to living in animal cells -- they probably couldn't survive on their own.

It's true that they very much rely on a nuclear genome, because some of their genes required for independent replciation have been lost. But surely there's a framework that enables the mass replication of mitochondria using our own cells as a source material.

I doubt blood would work because red blood cells contain effectively very minimal, if not zero, mitochondria (depending on stage of cycle).

Funny enough, the best bet might be taking mitochondria from sperm or egg. Human sperm have ~50-75 mitochondria per cell. There's on average 50 million sperm cells per ml of ejaculant and the average is 2.5ml per ejaculation, so 125 million mitochondria could potentially be harvested from an average guy in a single go, provided the extraction is an unrealistic 100% efficiency.

50 million/ml x 2.5 ml x 50 = 6.25 billion, is what I get the number to be.

Ah yes, I totally botched the math. Thanks for that.

So 6.25 billion potentially harvestable mitochondria per average sperm donation.

Hard to say how much might be needed for a rejuvination test, but those seem like viable numbers.

If adipose cells could be used for this purpose, a small amount of liposuctioned fat would be adequate.

And if pounds are needed, well... let's just say there should be plenty of eager donors for those who don't have enough.

http://www.lifeextension.com/magazine/2010/ss/rejuvenate-you...

http://www.lifeextension.com/Magazine/2010/2/Reverse-Mitocho...

Yup. It is a very promising area of rejuvenation research. I think right now most dollars are allocated to understanding basic mitochondrial function. As well as cures for the pernicious degenerative diseases associated with malfunctioning mitochondria that cruelly tend to develop in young children. But there is no question: further research activities and clinical trials have a high probability of bearing fruit. Cryo-EM visualization of metabolic pathways. Even understanding function and purpose of the THC cannabinoid receptors found on their outer membranes could unlock their mysterious hidden potential.

Yeah, Mitochondria are a big deal in aging. Animals of a given size with larger mitochondria populations, like hummingbirds, tend to live a lot longer than other animals of similar size. Though hummingbirds lose their ability to hover and hence feed normally in the wild long before they die of old age.

Nick Lane wrote about book about mitochondria I'd heartily recommend: Power, Sex, Suicide: Mitochondria and the Meaning of Life.

EDIT: And Aubrey de Grey of course has a typically audacious/crazy plan for dealing with mitochondrial mutations. http://www.sens.org/research/introduction-to-sens-research/m...

A brief search shows that mitochondrial transplantation for myocardial infarction was described in 2008. Astonishing work. This is starting to become more mainstream in the last couple of years.

https://www.ncbi.nlm.nih.gov/pubmed/18978192

Wait, how do the mitochondria get back into the cells? Presumably the cell membrane somehow permits them to pass but how are they recognized? If a mechanism exists to recognize and permit them to move into a cell, doesn’t that either suggest they can move out of cells as well and/or confirm the theory that mitochondria were symbiotes? That is, there’s something in cell DNA that encodes a mechanism for foreign symbiotes to cross the cell membrane?

I was also surprised by this. In the papers where they did this work, they discuss many previously-known mechanisms for intercellular mitochondrial transfer - apparently cells can form nanotubes and exchange organelles, and that's relatively well-studied. That's not what's happening here, though, and they state that the mechanism at play is unknown.

It would be hard to convince me to sign up for such a study, if there’s a 50% chance they give me a placebo and I die.

You would rather not sign up and go for the 100% percent chance they give you nothing and you die?

In clinical trials, pure placebos are very rarely used (only in mild conditions or where no treatment exists). Commonly novel therapies are compared against the current treatment of choice.

I was about to ask how ethical it could be to give a pure placebo in cases as serious as heart failure, when simply telling the patient (or the patient's family) that they received some other more conventional procedure should produce similar results.

I think this is never done. I suppose both groups receive two therapies, one of them being the best available therapy for the condition, and the other either the new therapy, or a placebo.

This requires new and old therapies to be compatible, though.

Studies will also be suspended if it becomes clear that one treatment is so obviously better as to be unethical to continue with the other.

Maybe in those cases, if the treatment, if it shows promise, should be given also to the people that were given placebo (after the study)

At that point it's far from certain that the medicine will give you higher chances of survival though.

I'm very excited about this stuff ... but as a relatively healthy person, I'm gonna wait for v1.1 :)

From Edward Tufte’s book “Data Analysis for Politics and Policy”:

“One day when I was a junior medical student, a very important Boston surgeon visited the school and delivered a great treatise on a large number of patients who had undergone successful operations for vascular reconstruction. At the end of the lecture, a young student at the back of the room timidly asked, “Do you have any controls?” Well, the great surgeon drew himself up to his full height, hit the desk, and said, “Do you mean did I not operate on half of the patients?” The hall grew very quiet then. The voice at the back of the room very hesitantly replied, “Yes, that’s what I had in mind.” Then the visitor’s fist really came down as he thundered, “Of course not. That would have doomed half of them to their death.” It was quiet then, and one could scarcely hear the small voice ask, “Which half?””

https://www.edwardtufte.com/tufte/dapp/DAPP1.pdf

(further attributed to Dr. E. E. Peacock, Jr, as quoted in Medical World News, September 1, 1972, p. 45)

It!!!

Could!!!

Work!!!!!!

(Apologies to Mel Brooks/Young Frankenstein)

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