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A Review of Immunosenescence – Article by Steve Hill

A Review of Immunosenescence – Article by Steve Hill

Steve Hill


Editor’s Note: In this article, Steve Hill discusses some of the reasons for the decline of the immune system.  This article was originally published by the Life Extension Advocacy Foundation (LEAF).

                   ~ Kenneth Alum, Director of  Publication, U.S. Transhumanist Party, January 9, 2018

Immunosenescence is the age-related decline of the immune system. The reason why our immune systems start to fail and weaken as we age is not fully understood, and, indeed, there are a variety of hypotheses as to why this happens.

Inflammaging

Inflammation certainly plays a role in this process, and it is well documented that inflammation has a considerable effect on immune cells such as macrophages, causing them to become dysfunctional and stop cleaning house. This is in line with the proposed concept of “inflammaging”, which describes an ever-increasing chronic background of inflammation from sources such as senescent cells, cell debris, and changes in the gut microbiota. This inflammaging then drives immune system dysfunction, which then creates more inflammation, continuing a downward spiral.

We recently learned that inflammation can cause problems with weight control by causing nerve-associated macrophages to stop signaling fat cells to release their stored energy[1]. We also know that macrophage dysfunction occurs in other tissues due to inflammation, and so it seems clear that inflammation plays at least a partial role in immune system decline.

Cellular Senescence

Some research suggests that the immune system declines due to its cells becoming senescent, just as other cell populations do. Over time, our cells reach their maximum number of divisions, or they are damaged and enter senescence and destroy themselves via apoptosis, a kind of programmed self-destruct sequence.

However, sometimes these cells resist apoptosis and cling on to life, but in doing so, they prevent fresh cells replacing them while generating inflammatory signals that cause nearby cells to become dysfunctional, too. It is proposed that the immune system experiences the same senescence as our other cells, leading to immune system failure.

Stem-cell depletion

Another player in immune system decline is stem-cell depletion; for example, the thymus begins to shrink from an early age and eventually stops producing new T cells to help defend us from invading pathogens. The production of T cells is facilitated by thymic stem cells, which are gradually depleted over our lifetime, and eventually, we have so few T cells that we cannot fight off diseases such as flu and pneumonia, which often kill the elderly. Some attempts are currently being made to rejuvenate the thymus and have enjoyed some success.

A review of immunosenescence

It is likely the case that immunosenescence is a combination of all of these proposed things and more, and each plays a role in the resulting decline of our immune systems as we age. When it comes to establishing the exact chain of events that leads to immunosenescence, it will take reversing each of those causes to see what happens.

Today, we wanted to bring your attention to an open-access paper that reviews the current knowledge of immunosenescence and provides a good introduction to the topic[2].

Conclusion

Developing the therapies that target the aging processes directly is likely the most expedient path to understanding immunosenescence, as these therapies will give us the tools with which to discover what drives the process. Approaches such as thymic rejuvenation or creating a replacement thymus, replacing lost stem-cell populations such as hematopoietic stem cells that create all immune cells, removing overspecialized immune cells, and removing senescent cells are all valid approaches towards discovering how immunosenescence works.

Our knowledge is growing rapidly by the passing month, and more and more is being understood about the aging processes and how we might directly target them to prevent or reverse age-related diseases. It is almost certain that medicine is going to change dramatically in the next decade or two as our understanding grows.

Literature

[1] Camell, C. D., Sander, J., Spadaro, O., Lee, A., Nguyen, K. Y., Wing, A., … & Rodeheffer, M. S. (2017). Inflammasome-driven catecholamine catabolism in macrophages blunts lipolysis during ageing. Nature, 550(7674), 119-123.

[2] Ventura, M. T., Casciaro, M., Gangemi, S., & Buquicchio, R. (2017). Immunosenescence in aging: between immune cells depletion and cytokines up-regulation. Clinical and Molecular Allergy, 15(1), 21.

About Steve Hill

As a scientific writer and a devoted advocate of healthy longevity technologies, Steve has provided the community with multiple educational articles, interviews, and podcasts, helping the general public to better understand aging and the means to modify its dynamics. His materials can be found at H+ Magazine, Longevity Reporter, Psychology Today, and Singularity Weblog. He is a co-author of the book Aging Prevention for All – a guide for the general public exploring evidence-based means to extend healthy life (in press).

About LIFE EXTENSION ADVOCACY FOUNDATION (LEAF)

In 2014, the Life Extension Advocacy Foundation was established as a 501(c)(3) non-profit organization dedicated to promoting increased healthy human lifespan through fiscally sponsoring longevity research projects and raising awareness regarding the societal benefits of life extension. In 2015 they launched Lifespan.io, the first nonprofit crowdfunding platform focused on the biomedical research of aging.

They believe that this will enable the general public to influence the pace of research directly. To date they have successfully supported four research projects aimed at investigating different processes of aging and developing therapies to treat age-related diseases.

The LEAF team organizes educational events, takes part in different public and scientific conferences, and actively engages with the public on social media in order to help disseminate this crucial information. They initiate public dialogue aimed at regulatory improvement in the fields related to rejuvenation biotechnology.

The Link Between Cellular Senescence and Cellular Reprogramming – Article by Steve Hill

The Link Between Cellular Senescence and Cellular Reprogramming – Article by Steve Hill

Steve Hill


Editor’s Note: In this article, Steve Hill discusses the link between Cellular Senescence and Cellular Reprogramming.  This article was originally published by the Life Extension Advocacy Foundation (LEAF).

            ~ Kenneth Alum, Director of  Publication, U.S. Transhumanist Party, January 8, 2018

The reprogramming of cells is a well-established technique in medicine and has been for over a decade now. It allows the en masse creation of patient-matched cells and is the basis for multiple current therapies.

Cellular Senescence and Cellular Reprogramming share mechanisms

Induced pluripotent stem cells (also known as iPS cells or iPSCs) can be created directly from adult cells. The iPSC technology was pioneered by Shinya Yamanaka, who demonstrated in 2006 that the introduction of four specific genes encoding transcription factors could convert adult cells into pluripotent stem cells[1]. These factors are Oct4, Sox2, Klf4, and c-Myc (OSKM), or as many call them, the Yamanaka factors.

Today, we have a new paper that discusses how induced pluripotency and cellular senescence, two of several possible cellular states, share similarities[2]. It is likely no surprise that the two states are closely related and that some of the mechanisms for one process are shared by the other. It appears that certain key signaling molecules are important in determining both cell fate and senescence.

Controlling cell behavior in living animals

As our understanding of guiding cell fate grows rapidly by the passing year, it has huge implications for therapies that seek to control cellular activities and encourage certain types of cells to be created. Research is now starting to move beyond the petri dish and to where cells are being programmed in situ in living animals.

In 2013, the Hallmarks of Aging proposed that epigenetic changes are a primary reason we age, but, at the time, the evidence in living animals was lacking[3]. All this changed in late 2015 when researchers induced pluripotency in living animals using the OSKM reprogramming factors, in much the same way as iPSC technology creates on-demand cell types outside the body. In this case, they only very briefly induced OSKM so that the aging markers in cells were reset but not long enough to cause the cells to revert to a developmental state.

The results of this first attempt to reprogram cells in living animals resulted in the cells of the mice becoming functionally younger in many ways and increased their healthy lifespan[4]. These results lend yet more support for the hypothesis that epigenetic alterations are one of the reasons we age and that reversing those changes is a path to maintaining health and tissue function as we age. A number of research teams are now exploring cellular reprogramming in living animals with a view to translating this to humans. We discussed the findings of this paper during our monthly Journal Club here.

Conclusion

This paper may be of interest to those wishing to delve deeper into the world of cell fate and understand the connection between cellular senescence and induced pluripotency. This builds on the knowledge we already have, and it is not difficult to imagine a time in the near future when we will have a very high level of control over our cells via reprogramming techniques.

If the hypothesis of epigenetic alterations being one of the causes of aging turns out to be correct, then that would be a real game changer. We are likely not too far off from determining if this is the case or not, and we may have the answer in the next few years, given the current pace of progress.

Literature

[1] Takahashi, K., & Yamanaka, S. (2006). Induction of pluripotent stem cells from mouse embryonic and adult fibroblast cultures by defined factors. cell, 126(4), 663-676.

[2] Mosteiro, L., Pantoja, C., Martino, A., & Serrano, M. (2017). Senescence promotes in vivo reprogramming through p16INK4a and IL‐6. Aging cell.

[3] López-Otín, C., Blasco, M. A., Partridge, L., Serrano, M., & Kroemer, G. (2013). The hallmarks of aging. Cell, 153(6), 1194-1217.

[4] Ocampo, A., Reddy, P., Martinez-Redondo, P., Platero-Luengo, A., Hatanaka, F., Hishida, T., … & Araoka, T. (2016). In vivo amelioration of age-associated hallmarks by partial reprogramming. Cell, 167(7), 1719-1733.

About Steve Hill

As a scientific writer and a devoted advocate of healthy longevity technologies, Steve has provided the community with multiple educational articles, interviews, and podcasts, helping the general public to better understand aging and the means to modify its dynamics. His materials can be found at H+ Magazine, Longevity Reporter, Psychology Today, and Singularity Weblog. He is a co-author of the book Aging Prevention for All – a guide for the general public exploring evidence-based means to extend healthy life (in press).

About LIFE EXTENSION ADVOCACY FOUNDATION (LEAF)

In 2014, the Life Extension Advocacy Foundation was established as a 501(c)(3) non-profit organization dedicated to promoting increased healthy human lifespan through fiscally sponsoring longevity research projects and raising awareness regarding the societal benefits of life extension. In 2015 they launched Lifespan.io, the first nonprofit crowdfunding platform focused on the biomedical research of aging.

They believe that this will enable the general public to influence the pace of research directly. To date they have successfully supported four research projects aimed at investigating different processes of aging and developing therapies to treat age-related diseases.

The LEAF team organizes educational events, takes part in different public and scientific conferences, and actively engages with the public on social media in order to help disseminate this crucial information. They initiate public dialogue aimed at regulatory improvement in the fields related to rejuvenation biotechnology.

SENS: Progress in the Fight Against Age-Related Diseases – Article by Nicola Bagalà and Steve Hill

SENS: Progress in the Fight Against Age-Related Diseases – Article by Nicola Bagalà and Steve Hill

Nicola Bagalà

Steve Hill


Editor’s Note: In this article, Mr. Nicola Bagalà and Steve Hill discuss the progress that the SENS Research Foundation has made in tackling the aging processes. Below is a brief summary of some of the highlights of their research efforts.  This article was originally published by the Life Extension Advocacy Foundation (LEAF).

                   ~ Kenneth Alum, Director of  Publication, U.S. Transhumanist Party, December 8, 2017

 

 

Today, there are many drugs and therapies that we take for granted. However, we should not forget that what is common and easily accessible today didn’t just magically appear out of thin air; rather, at some point, it used to be an unclear subject of study on which “more research was needed”, and even earlier, it was just a conjecture in some researcher’s head.

Hopefully, one day not too far into the future, rejuvenation biotechnologies will be as normal and widespread as aspirin is today, but right now, we’re in the R&D phase, so we should be patient and remind ourselves that the fact that we can’t rejuvenate people today doesn’t mean that nothing is being done or has been achieved to that end. On the contrary, we are witnessing exciting progress in basic research—the fundamental building blocks without which rejuvenation, or any new technology at all, would stay a conjecture.

In particular, SENS Research Foundation (SRF), a pioneering organization of the field, is sometimes unjustly accused by skeptics for failing to produce results. But produce results it has, and many at that. Skeptics either decide to ignore them or do not have access to reliable sources. For the benefit of the latter, we’ll discuss below what has been achieved by SRF over the past few years, in relation to the infamous “seven deadly things”, the seven categories of damage that aging causes as described in the SENS repair approach.

Mitochondrial mutations

In a nutshell, a mitochondrion is a cell component that is in charge of converting food nutrients into ATP (adenosine triphosphate), a chemical that powers cellular function. Your DNA is contained within the nucleus of each of your cells, but this isn’t the only DNA in your body; mitochondria have their own DNA (known as mtDNA), likely because, at the dawn of life, they were independent organisms that eventually entered a symbiotic relationship with eukaryotic cells, such as those found in our bodies.

Unfortunately, as mitochondria produce ATP, they also produce so-called free radicals as a byproduct—atoms with unpaired electrons that seek to “pair up” with other electrons, and to do so, they’ll gladly snatch them from other molecules nearby, damaging them. As free radicals are created by mitochondria, they’re very close to mtDNA, which is thus very susceptible to being damaged and undergoing mutations.

Mitochondria with damaged DNA may become unable to produce ATP or even produce large amounts of waste that cells cannot get rid of. To add insult to injury, mutant mitochondria have a tendency to outlive normal ones and take over the cells in which they reside, turning them into waste production facilities that increase oxidative stress—one of the driving factors of aging.

MitoSENS: How to solve this problem, and how far we’ve got

Cell nuclei are far less exposed to free-radical bombardment than mitochondria, which makes nuclear DNA less susceptible to mutations. For this reason, the cell nucleus would be a much better place for mitochondrial genes, and in fact, evolution has driven around 1000 of them there. Through a technique called allotopic expression, we could migrate the remaining genes to the nucleus and solve the problem of mitochondrial mutations.

Human-made allotopic expression was a mere theory until late 2016, when, thanks to the successful MitoSENS crowdfunding campaign on Lifespan.io, a proof of concept was finally completed. Dr. Matthew O’Connor and his team managed to achieve stable allotopic expression of two mitochondrial genes in cell culture, as reported in the open-access paper[1] they published in the journal Nucleic Acids Research. As Aubrey de Grey himself explains in this video, of the 13 genes SRF is focusing on, it’s now managed to migrate almost four. This had never been done before and is a huge step towards addressing this aspect of aging in humans. In the past few months, the MitoSENS team has presented its results around the world and worked on some problems encountered in the project.

A list of SRF-funded papers on the topic of mitochondrial mutations can be found here. A more detailed description of its intramural MitoSENS research can be found here.

Lysosomal dysfunction

Lysosomes are digestive organelles within cells that dispose of intracellular garbage—harmful byproducts that would otherwise harm cells. Enzymes within lysosomes can dispose of most of the waste that normally accumulates within cells, but some types of waste, collectively known as lipofuscin, turn out to be impossible to break down. As a result, this waste accumulates within the lysosomes, eventually making it harder for them to degrade even other types of waste; in a worst-case scenario, overloaded lysosomes can burst open and spread their toxic contents around.

This eventuality is especially problematic for cells that replicate little or not at all, such as heart and nerve cells—they’ve got all the time in the world to become swamped in waste, which eventually leads to age-related pathologies, such as heart disease and age-related macular degeneration.

LysoSENS: How to solve this problem, and how far we’ve got

As normal lysosomal enzymes cannot break down lipofuscin, a possible therapy could equip lysosomes with better enzymes that can do the job. The approach suggested by SRF originates with ERT—enzyme replacement therapy—for lysosomal storage diseases. This involves identifying enzymes capable of breaking down different types of intracellular junk, identifying genes that encode for these enzymes, and finally delivering the enzymes in different ways, depending on the tissues and cell types involved.

SRF funded a preliminary research project on lipofuscin clearance therapeutics at Rice University[2] and another project relating to atherosclerosis and the clearance of 7-ketocholesterol[3] (a lipofuscin subtype), which eventually spun into Human Rejuvenation Biotechnologies, an early-stage private startup funded by Jason Hope.

A LysoSENS-based approach is currently being pursued by Dr. Kelsey Moody, who used to work at SRF. Dr. Moody has been working on an ERT treatment for age-related macular degeneration. The treatment consists in providing cells of the macula (a region of the eye’s retina) with an enzyme capable of breaking down a type of intracellular waste known as A2E. The treatment, called LYSOCLEAR, is being worked on by Moody’s company Ichor Therapeutics, which earlier this year has announced a series A offering to start Phase I clinical trials of its product.

If LYSOCLEAR proves successful, it could pave the way for future LysoSENS-based therapies to treat lysosomal dysfunction in different tissues.

A list of SRF-funded papers on the topic can be found here.

Cellular senescence

As cells divide, their telomeres—the end-parts of chromosomes protecting them from damage—shorten. Once a critical length has been reached, cells stop dividing altogether and enter a state known as senescence. Senescent cells are known to secrete a cocktail of chemicals called SASP (Senescence Associated Secretory Phenotype), which promotes inflammation and is associated with several age-related conditions.

However, senescent cells are a bit of a double-edged sword; as explained by Professor Judy Campisi during RB2016, as long as they’re not too numerous, senescent cells carry out an anti-cancer function and may promote wound healing; however, too many of them have the opposite effect, and on top of that, they induce neighboring cells to undergo senescence themselves, starting a dangerous spiral.

Normally, senescent cells destroy themselves via programmed cell death, known as apoptosis, and are then disposed of by the immune system, but some of them manage to escape destruction, and as the immune system declines with age, this gets worse.

The result is that late in life, senescent cells have accumulated to unhealthy amounts and significantly contribute to the development of age-related diseases. Osteoarthritis, cardiovascular diseases, cancer, metabolic disorders such as diabetes, and obesity are all linked to the chronic age-related inflammation to which senescent cells contribute.

ApoptoSENS: How to solve this problem, and how far we’ve got

The proposed SENS solution is straightforward: if senescent cells become too numerous, then they need to be purged. Since they are useful in small amounts, the optimal solution would be periodically removing excess senescent cells without eradicating them entirely—and more importantly, leaving other cells unharmed.

This could potentially be achieved by either senolytic drugs or gene therapies that selectively target senescent cells and trigger programmed cell death. Indeed, a great deal of recent focus by researchers have been on finding ways to remove senescent cells using senolytic therapies.

Another approach that could complement senolytics is to address why the immune system stops clearing senescent cells effectively in the first place. This approach focuses on macrophages and other immune cells involved in clearing senescent cells, aiming to reduce inflammation so that these cells begin to function properly again. The irony is that as inflammation rises with age, the immune system that is supposed to clear senescent cells and keep inflammation levels down actually starts to create more inflammation and becomes part of the problem by not doing its job properly.

SRF has funded a number of studies on the subject of cellular senescence, and it’s recently begun working on a project in collaboration with the Buck Institute for Research on Aging, which is focusing on the immune system and its role in clearing senescent cells. Another extramural project, again with the Buck Institute, is focussed on SASP inhibition.

Senescent cell clearance has been all the rage for the past two years or so; Lifespan.io has hosted the MMTP project, which focused on testing senolytics in mice, and this was later followed by CellAge’s project to design synthetic biology-based senolytics.

There are other companies that have joined the race to add senescent cell clearance to the standard toolkit of doctors, such as Unity Biotechnology and Oisin Biotechnologies.

Unity’s approach uses a drug-based approach to senolytics and is scheduled to enter human clinical trials in 2018. A number of other research teams are also developing drug-based approaches to removing senescent cells, and the competition looks set to be fierce in this area in the coming years.

Oisin’s approach, which we discussed here, makes use of suicide genes and hopefully will be tested in clinical trials not too far into the future, thanks to venture funding presently being collected. If this system can be made to work, it will allow very selective targeting of senescent cells by destroying only those giving off a target gene or genes. Thus, if a unique gene expression profile for senescent cells is determined, it would mean only those cells were destroyed, with less risk of off-target effects.

Oisin owes its existence to the SENS Research Foundation and the Methuselah Foundation, which provided the necessary seed funding. Kizoo Technology Ventures has also invested in Oisin.

Extracellular crosslinks

The so-called extracellular matrix is a collection of proteins that act as scaffolding for the cells in our body. This scaffolding is rarely if ever replaced, and a really bad consequence of this is that its parts eventually end up being improperly linked to each other through a process called glycation—the reaction of (mainly) blood sugar with the proteins that make up the extracellular matrix itself.

The resulting cross-links impair the function and movement of the linked proteins, ultimately stiffening the extracellular matrix, which makes organs and blood vessels more rigid. Eventually, this leads to hypertension, high blood pressure, loss of skin elasticity, and organ damage, among other problems.

While there are different types of cross-links—known as AGEs, short for advanced glycation end-products—glucosepane is arguably the worst, being the most common and long-lasting of all, and the body is very ill-equipped to break it down.

GlycoSENS: How to solve this problem, and how far we’ve got

In order to eliminate unwanted cross-links, the SENS approach proposes to develop AGE-breaking molecules that may indeed sever the linkages and return tissues to their original flexibility. Of course, in order to do so, crosslink molecules need to be available for research to attempt to combat them with drugs, and especially in the case of glucosepane, this has been a problem for years.

Glucosepane is a very complex molecule, and very little of it can be extracted from human bodies, and not even in its pure form. This has been greatly hampering the progress of research against glucosepane, but thankfully, this problem is now solved thanks to a collaboration between the Spiegel Lab at Yale University and the SENS Research Foundation, which financially supported the study. It is now possible to fully synthesize glucosepane, allowing for researchers to create it on demand and at a cost-effective price.

The Spiegel Lab’s scientists are now developing anti-glucosepane monoclonal antibodies to cleave unwanted cross-links. The collaboration between the Spiegel Lab and SRF dates all the way back to 2011, but it was in 2015 that the Lab announced its success and published a related paper [4] in the journal Science.

Further information on glucosepane cross-link breakers can be found in this interview with Dr. David Spiegel from Yale University on Fight Aging!; a list of studies on the subject funded or otherwise supported by the SRF is available here.

SRF also worked with the Babraham Institute on a cross-link quantification project.

Let’s help SRF move forward

Readers who wish to donate to SRF to help the organization in its crusade against the ill health of old age can do so by contributing to its winter fundraiser or even becoming SRF patrons. Have a look at SRF’s donation page to find out more.

NB: Dr. Aubrey de Grey (Chief Science Officer and Co-founder of SENS Research Foundation) himself held an AMA (“ask me anything”) on Reddit on December 7, at 14:00 PST (22:00 UTC, 17:00 EST). The questions and Dr. de Grey’s responses can be found here.

Literature

[1] Boominathan, A., Vanhoozer, S., Basisty, N., Powers, K., Crampton, A. L., Wang, X., … & O’Connor, M. S. (2016). Stable nuclear expression of ATP8 and ATP6 genes rescues a mtDNA Complex V null mutant. Nucleic acids research, 44(19), 9342-9357.

[2] Gaspar, J., Mathieu, J., & Alvarez, P. (2016). A rapid platform to generate lipofuscin and screen therapeutic drugs for efficacy in lipofuscin removal. Materials, Methods and Technologies, 10, 1-9.

[3] Mathieu, J. M., Wang, F., Segatori, L., & Alvarez, P. J. (2012). Increased resistance to oxysterol cytotoxicity in fibroblasts transfected with a lysosomally targeted Chromobacterium oxidase. Biotechnology and bioengineering, 109(9), 2409-2415.

[4] Draghici, C., Wang, T., & Spiegel, D. A. (2015). Concise total synthesis of glucosepane. Science, 350(6258), 294-298.

 

About Steve Hill

As a scientific writer and a devoted advocate of healthy longevity technologies, Steve has provided the community with multiple educational articles, interviews, and podcasts, helping the general public to better understand aging and the means to modify its dynamics. His materials can be found at H+ Magazine, Longevity Reporter, Psychology Today, and Singularity Weblog. He is a co-author of the book Aging Prevention for All – a guide for the general public exploring evidence-based means to extend healthy life (in press).

About Nicola Bagalà

Nicola Bagalà has been an enthusiastic supporter and advocate of rejuvenation science since 2011. Although his preferred approach to treating age related diseases is Aubrey de Grey’s suggested SENS platform, he is very interested in any other potential approach as well. In 2015, he launched the blog Rejuvenaction to advocate for rejuvenation and to answer common concerns that generally come with the prospect of vastly extended healthy lifespans. Originally a mathematician graduated from Helsinki University, his scientific interests range from cosmology to AI, from drawing and writing to music, and he always complains he doesn’t have enough time to dedicate to all of them which is one of the reasons he’s into life extension. He’s also a computer programmer and web developer. All the years spent learning about the science of rejuvenation have sparked his interest in biology, in which he’s planning to get a university degree.

About LIFE EXTENSION ADVOCACY FOUNDATION (LEAF)

In 2014, the Life Extension Advocacy Foundation was established as a 501(c)(3) non-profit organization dedicated to promoting increased healthy human lifespan through fiscally sponsoring longevity research projects and raising awareness regarding the societal benefits of life extension. In 2015 they launched Lifespan.io, the first nonprofit crowdfunding platform focused on the biomedical research of aging.

They believe that this will enable the general public to influence the pace of research directly. To date they have successfully supported four research projects aimed at investigating different processes of aging and developing therapies to treat age-related diseases.

The LEAF team organizes educational events, takes part in different public and scientific conferences, and actively engages with the public on social media in order to help disseminate this crucial information. They initiate public dialogue aimed at regulatory improvement in the fields related to rejuvenation biotechnology.