How long would effects like this last? I mean, let's say a bunch of children donated blood for the cause, and we used it to replace the blood of a senior citizen.
I don't know how to phrase this properly, but how long does the blood maintain the youthful qualities? Do you constantly need new blood coming in from a young donor? Do you receive it once and you're good for a week? A year?
Current thinking I've been privy to is that the factors in question are short-lived.
In any case, this will never turn into cross-generation blood transplants on a regular basis. The present system of medical regulation is heavily biased towards demonstrating mechanisms. If you can't explain your mechanism you are not getting approved by the FDA, or at least not until such time as everyone else in the world is already doing it and the bureaucrats are made to look bad - see the last decade of stem cell transplants for the way in which that happens.
So the attempts at therapies that result from this will likely be delivery of proteins or interference with proteins to put a thumb on the scales of metabolic machinery. At which point it lasts for the period of time in which you are getting regular injections.
Most of the parabiotic procedures on mice had two organisms almost always connected to each other. Not sure if the case you described above is feasible in near future.
It seems like it would be relatively easy to test out. People donate blood all the time. I'm sure the effects are known of how much blood you can replace at once without causing issues. Without a doubt some elderly people would volunteer. Why can't we start giving them new blood once a week from donors, and see the results on their health or illnesses? I'm all for testing, but this seems like one of those things you could quickly move to human trials.
Should be done outside the normal blood donor system. There's not that much donor blood around, so it would be unethical to use it. Not a practical problem, but it would look and feel bad.
Anyway, yes, why not try this on humans? Sounds perfectly reasonable.
Well, many people seem to be suggesting (including the researchers themselves) that there is a possibility of the older person dying of insta-cancer after receiving the blood because their cancerous stem cells would immediately be told to start multiplying. That's why I think it's a good idea to test this in animals first.
As foreshadowed by Heinlein in Methuselah's Children...in 1958
"Yes, yes," agreed Hardy. "Naturally---but what is the basic process?"
"It consists largely in replacing the entire blood tissue in an old person with new, young blood..."
You have to be very careful when you say "reverses aging." That is a very different thing from "reverses a couple of measurable aspects associated with aging." In the former case you are making an assertion that will immediately lead you to having to define the cause and mechanisms of aging and defend your point that it is, as a process, reversed - and the definition of aging is a contentious topic at the present time. But the press is lazy and in search of clicks, etc, etc.
The mainstream of the aging research community theorizes on the basis of mountainous evidence that aging is accumulated damage. What that damage consists of is pretty much settled, but there is a lot of argumentation over how it all hooks together, what is important, what is primary versus secondary, and how in detail it connects to visible pathologies of aging.
Outside that mainstream, the present day accepted heresy, in the sense that the minority population of heretics are engaged with rather than cast out of the cathedral, is that aging is an evolved genetic program. It is a selected adaptation and where there is damage that damage is a consequence of epigenetic changes, not the cause of them. There are factions within this heresy too, and a lot of argumentation. If you want to learn more, look for the hyperfunction theory of aging and related thoughts as representative of the field. [1]
The damage view of epigenetic and signaling changes in tissues that occur with aging is that these changes are reactions to damage. Altering them may lead to short term benefits and be worthy of use as treatments but that doesn't do anything about the underlying damage - which will grow and kill you. In the case of stem cell decline with aging, this process is thought to be a cancer suppression mechanism, and thus forcing all the dormant stem cells back to work is going to mean cancer everywhere. Equally it may turn out that evolution has produced an overcompensation and some of the benefits of doing this might be effectively free. The fastest way to find out is to conduct animal studies in something other than mice (which are little cancer factories and have telomere dynamics that are very dissimilar to that of humans).
In contrast the programmed aging view is that reversing signaling and epigenetic changes is exactly reversal of aging, and is thus a great thing to be doing and we should be making full steam ahead on this front. I think they are wrong, and that the balance of evidence clearly points in the other direction, but as I said this is a heresy with enough advocates that they are not just ignored.
(Bizarrely, most of that portion of the mainstream who work towards enhancing longevity and slowing aging actually spend their time on potential treatments that make much more sense as goals for programmed aging enthusiasts. Look at sirtuin or calorie restriction mimetic work - all about altering protein levels and signals. All too few researchers take the sensible approach of looking for means of damage repair. But that's a whole different topic. I blame regulation of medicine as a force steering research into marginal channels).
Anyway, on to the heterochronic parabiosis, which is what you call the linking of circulatory systems in two individuals, one old, one young. This has been used for some years as a way of studying what might be going on in old tissues, especially in connection with the decline in stem cell tissue maintenance activity that leads to organ dysfunction and death. The end goal is to figure out the differences and use that knowledge to produce the part of the complete map of the molecular biology of the progression of aging that covers tissue signaling - most researchers in the field have no declared interest in doing anything other than looking at what is going on.
Along the way, however, someone will produce prospective treatments based on identifying signals to stem cells involved in the choice between activity and quiescence. No-one is going to be shifting blood around as a basis for treatments between young and old when you can instead figure out what exactly it is in the blood that is causing changes - this is a change likely to occur in the stem cell transplant field also, in which much of the benefits seem to depend on the alteration of signals caused by the transplanted cells rather than any cell maintenance they are doing directly. Why sling cells around if you can just manufacture proteins that have the same beneficial effects?
One of the signals is apparently GDF11, which has been explored for a couple of years now. [2] It is interesting to see that it is more general than simply localized to heart tissue. Given the large number of quite different stem cell populations in the body it would be unexpected to find much in the way of commonality between the signaling systems that they use. Apparently there is some commonality after all. Though I wouldn't hold out for much more. In general I'm expecting the exploration of cell signaling to be every bit as complicated as the hunt-and-peck approach taken to finding ways to interfere with cancer: a lot of proteins, different in most tissues.
Aging is more than just accumulated dammage, menopause is a clear counter example to this idea. However, dammage does accumulate so like most complex systems there are no simple answers.
Menopause is an oddity and a puzzle. It isn't easily used to support any of the various points of view in aging research, partially because it is a human peculiarity that doesn't seem to be present in anything like a similar form in other primates or mammals. Theorizing has it linked with the grandmother hypothesis viewpoint on why humans are so much longer lived than other primates, and the evolutionary track by which we got here. You might look at these papers:
What ? This is not true at all. Menopause is present in all mammals. The reason you don't see it in most mammals is simple : the normal maximum age for most mammals is less than half of humans. Most animals grow to about 30-35 "dog-years", and die. Dogs and cats in captivity, some long-lived races, do experience menopause. If humans died at 30-35, which is about the expected age for humans in the natural habitat, it would be a very rare woman indeed that experience menopause. (Keep in mind that 35 is the average age of death for humans in nature. But at that age most deaths are still accidental, meaning there is a large deviation. A lot of kids would "naturally" die 5 years or younger (like 30-50%, depending on environment), then there is a certain chance of dying every year. IF a human can avoid nature, infection, fights (or you know, win them all), poisoning, famine, ... a male human would age to about 40-45 years in nature, a woman a little older. But no more than 2% or so will ever see their 45th birthday in a natural human population)
Here's the key, when a female baby takes her first breath (oxygen in the lungs), a mechanism is set off that causes the ovi to cut off all connections to the mother body. To put it simple: before a baby girl takes her first sip of mother's milk, all the baby's children have become independent lifeforms, no longer connected to the mother's body. The baby's DNA will sabotage and boobytrap it's own ability to create new ovi at that point. This of course means, among other things, that their numbers are 100% fixed at this point. This means that at that point the number of fertility cycles her body will go through is a constant from that point forward. There is a similar, but more complex, process set off in men (in men, too, the cells that form the reproductive cells are very isolated from the rest of the body).
When a human is disconnected from the umbilical, a number of changes happen as a result of that in order to switch to what you might call internal power if it were a robot. The immune system wakes up. The lungs inflate. The heart starts actually pumping blood around (yes it beats in babies, but a baby would survive without a beating heart as diffusion will actually happen fast enough. This is really sad when it happens since the baby is alive at that point, but growing will kill it). Cell reproduction rates are massively cut, and are moving towards replacement-only (a 2 year old is -almost- no longer making extra tissue. An adult is simply a 2 year old with "stretched" cells, not more cells)
Essentially nature is trying to protect the next generation from DNA alterations by external influences. Menopause is just a side-effect that evolution doesn't care about because women are unlikely to have viable children at that age.
Isn't menopoause caused by running out of eggs? Actually this is the same mechanism as reported in this story - a lack of stem cells. The interesting thing about this is the stem cells can be reactivated.
That's an oversimplification - menopause results from decreased levels of hormones that would normally be secreted during the process of egg maturation, among other potential causes [see ref 1].
Further, all the eggs a woman will ever have are created while she is developing in her own mother. This is totally distinct from stem cells, many of which are able to generate new stem cells throughout our lives, albeit at an ever-decreasing rate.
I dug into this a bit. A good metric by which to measure exciting (and very controversial) papers like the one referenced by that link is to see whether the papers have been replicated by others in well-regarded journals.
While the principal author of that article published an equally-controversial paper in 2005, follow-up studies suggest that there are no newly-generated egg cells in mammals [1]. I think it's fair to say, again, that stem cells don't play a role in maturation of adult egg cells.
Everything when it comes to reproduction is an oversimplification, but the basic problem is the same a lack of active stem cells (there are still stem cells present). Once all the eggs are used up then the ovary stops producing oestrogen and the other hormones.
Menopause is not a clear counter example. For all intents and purposes it is a symptom of biological aging and thus the result of "accumulated damage" (assuming that is indeed the overarching mechanism).
Menopause usually starts around 51 but there is a lot of variability and around 1 percent of women experience menopause before age 40. So it's not a direct result of cell damage. Now, if your suggesting that it's an evolutionary response to cell damage that's possible however as fixing the damage would not remove that response the difference is somewhat meaningless.
Changes in brain chemistry are another thing that's probably not directly damage related as the declines start around mid 20's.
Details of the procedure: "To do so, they joined rats in pairs by stitching together the skin on their flanks. After this procedure, called parabiosis, blood vessels grew and joined the rats’ circulatory systems. "
So the old and new rats were basically sewn together.
How is this bad science? I cannot argue about the cruelty part, as that is a completely subjective qualification (on which I don't agree at all), but if this ends providing results that improve our scientific knowledge and the lives of future generations, I don't believe it can be called bad science.
It's long been known that replacing the blood of an elderly person with that of a youth will make the codger feel like a million bucks. It really does work and, if I were a wealthy old guy, I would definitely have a stable of donors on hand and get weekly treatments.
There is a Brazilian book for teens that has the story of a group of criminals kidnapping children between 12-14 in order to harvest their blood. Of course, it's more a satirical and comedic book, with the usual gang of boys and girls solving the problem.
The second one sounds more serious, but "wow time to start talking about the ethics of immortality" doesn't engage with anything in this article; it's simply an immediate leap to something generic and obvious. That is not what HN discussions need.
I've wondered about this because I've done the same thing and gotten downvoted. There's nothing about not making jokes in the guidelines. Personally I like a little humor mixed with my HN.
Is there some unspoken guideline that HN is supposed to be humorless?
And on a semi-serious note, isn't mildly interesting that one of the most common cultural myths (vampires) may have some scientific validity?
HN isn't against humor per se. Personally, when I read Reddit, I'm in awe of how good the best jokes are. The problem is that you can't have everything; with a culture of humor comes a flood of lame humor. HN's tradeoff is to optimize for signal-noise ratio, so that stuff tends to get hammered.
There are other places to get lots of internet humor. HN is never going to be one of those, not because people don't like to laugh, but because the signal/noise problem is hard.
I do occasionally up vote posts that I find funny. I just down vote several times that. The real issue is HN has an older audience which does not find obvious one liners interesting.
Sometimes a really clever one-can contain an amazing amount of information (laconic humour is a good example of this[0]). The signal-to-noise ratio can be very high here.
Would it be that bad if one of the best places for intelligent tech discussion online didn't include humour? There's an abundance of humour everywhere else.
Isn't there a way to store your own bone marrow( or the cells that could make blood ) when you're young, and then generate your own blood in a laboratory.
Only tangential to the ethics of immortality, more about possible consequences of immortality for a given individual is "All Men Are Mortal" by Simone de Beauvoir, highly recommended.
The parent shouldn't be downvoted, as it is exactly true. Hypocritical even in its two sentences, but true. It is fashionable to look away, and necessary for our own health and progress in medicine to do these things, but that doesn't make it anything other than what it is.
However, what happens within the scientific community is a drop in the ocean of what happens on farms and in the wild.
If you feel strongly about animal suffering, then the following are logical things to advocate and aid:
1) Veganism, now that we are at a point in our mastery of agriculture at which this is a viable choice if everyone made it.
2) Tissue engineered meat and other animal products, made without any form of suffering.
3) Simulational approaches to animal research. Ultimately animals will be sacrificed only for calibration, at rates far lower than is presently the case.
4) The removal of all natural wildlife, to be replaced by managed systems in which there is no death or violence, only the simulation of it.
Obviously these, especially (4), are long term projects. They are not impossible, but will require progressively greater levels of technology in the order in which they are presented. If you think they are valuable, you should help these causes.
The Hedonistic Imperative is an interesting set of ideas to look into with regards to (4). [1]
If thats your concern, hope you stop having drugs when sick. Almost all allopathic drugs are tested on animals first and the conditions in which they live in arent great.
Scientists do a lot of grotesque things to mice, rats and insects all the time. We have to test stuff on someone, and humans are not really acceptable, even with consent.
Choice is an interesting question for the ethicists, but there are also many more reasons to use mice, rats, fruit flies and other animals: you can easily get thousands of genetically similar ones, you can get ones bred with specific properties, they have shorter life cycles, so you can test what happens during life time, you can test to destruction/death, you can test before consent be given, you can test multiple generations, you can keep them in controlled conditions. All of those are things that are either impossible to get consent for or prohibitively time consuming or expensive with humans.
There are other reasons why test animals are not that useful, mostly because they aren't human, and what works in them might not work on people, and what doesn't work in them won't be tested on people.
Over time animal testing has been decreasing and will continue to decrease while cell cultures become easier to create and closer to the cell structures that need to be tested, but for now they are needed in many fields of science.
I don't know how to phrase this properly, but how long does the blood maintain the youthful qualities? Do you constantly need new blood coming in from a young donor? Do you receive it once and you're good for a week? A year?