Fight Aging! Newsletter, March 16th 2020

Researcher have developed a promising molecular tool that targets and inhibits one of cell immortality's underlying gears: the enzyme telomerase. This enzyme is found overexpressed in approximately 90% of human cancer cells and has become an important subject of study for cancer researchers. Normal cells have the gene for telomerase, but it typically is not expressed. "Telomerase is the primary enzyme that allows cancer cells to live forever. We want to short-circuit this immortality. Now we have designed a first-of-its-kind small molecule that irreversibly binds to telomerase, shutting down its activity. This mechanism offers a new pathway for treating cancer and understanding cellular aging."

The big idea for the small molecule design came from nature. A decade ago, the researchers were intrigued by the biological activity of chrolactomycin, which is produced by bacteria and has been shown to inhibit telomerase. The team used chrolactomycin as a starting point in the design of their small molecules. They produced more than 200 compounds over the years, and the compound they call NU-1 was the most effective of those tested. Its synthesis is very efficient, taking fewer than five steps. "NU-1 inhibits telomerase unlike anything that came before it. It does this by forming a covalent bond. Another advantage of NU-1 is that its molecular structure should enable scientists to add cargo, such as a therapeutic."

Telomerase is a ribonuceloprotein complex responsible for maintaining telomeres and protecting chromosomal integrity. The human telomerase reverse transcriptase (hTERT) is expressed in ∼90% of cancer cells where it confers the capacity for limitless proliferation. Along with its established role in telomere lengthening, telomerase also serves noncanonical extra-telomeric roles in oncogenic signaling, resistance to apoptosis, and enhanced DNA damage response. We report a new class of natural-product-inspired covalent inhibitors of telomerase that target the catalytic active site.

Researchers have discovered that reining in the expression of two epigenetic regulators could extend the "healthspan" - as opposed to merely the lifespan - of worms and mice. The scientists studied BAZ-2 and SET-6, proteins that read and write epigenetic signals, respectively. They found that levels of both proteins ramp up with age in both species, in turn dampening expression of genes involved in mitochondrial function. The resulting metabolic slowdown put worms off their food and they mated less, and it hastened memory loss in old mice. What about orthologs of these epigenetic proteins in humans? Their levels increased in the brain with age, and correlated with progression of Alzheimer's disease. The study reinforces current thinking that mitochondria are key to aging.

How do BAZ-2 and SET-6 hasten aging? The researchers found that the two proteins together bind to promoter regions of more than 2,000 genes, dampening their expression via histone methylation. Among these target genes were numerous nuclear-encoded mitochondrial genes. Through their repression of these genes, BAZ-2 and SET-6 sapped oxygen consumption and ATP production, and bungled critical stress responses that maintain mitochondrial proteostasis. The researchers extended their nematode findings to mammals, reporting that orthologs of BAZ-2 and SET-6 dampened expression of key mitochondrial genes in cultured mouse and human cells. Knocking out BAZ-2 in mice assuaged age-related decline in brain metabolism, weight gain, and spatial memory loss, but did not extend lifespan.

Next, the researchers accessed a gene-expression dataset of human prefrontal cortex samples from the Harvard Brain Tissue Resource Center, including 376 from people with late-onset Alzheimer's disease and 173 from nondemented elderly. Among the samples from cognitively normal people, levels of human homologs of BAZ-2 and SET-6 increased with age. Among those with Alzheimer's disease, the proteins correlated with Alzheimer's disease progression, and with reduced expression of mitochondrial genes.

Here we report a conserved epigenetic mechanism underlying healthy ageing. Through genome-wide RNA-interference-based screening of genes that regulate behavioural deterioration in ageing Caenorhabditis elegans, we identify 59 genes as potential modulators of the rate of age-related behavioural deterioration. Among these modulators, we found that a neuronal epigenetic reader, BAZ-2, and a neuronal histone 3 lysine 9 methyltransferase, SET-6, accelerate behavioural deterioration in C. elegans by reducing mitochondrial function, repressing the expression of nuclear-encoded mitochondrial proteins. This mechanism is conserved in cultured mouse neurons and human cells.

Examination of human databases shows that expression of the human orthologues of these C. elegans regulators, BAZ2B and EHMT1, in the frontal cortex increases with age and correlates positively with the progression of Alzheimer's disease. Furthermore, ablation of Baz2b, the mouse orthologue of BAZ-2, attenuates age-dependent body-weight gain and prevents cognitive decline in ageing mice. Thus our genome-wide RNA-interference screen in C. elegans has unravelled a set of conserved epigenetic negative regulators of ageing, suggesting possible ways to achieve healthy ageing.

Amyloid plaques in the brains of people with Alzheimer's disease have a heterogeneous composition; for instance, some may also contain sugars, lipids, or nucleic acids. Previously, researchers found that amyloid fibrils with nucleic acids, but not those without them, triggered immune cells in the blood to produce type 1 interferon (IFN). IFN is a potent cytokine produced when immune cells sense nuclei acids, such as those that come from viral particles, in their environment. IFN triggers a beneficial inflammatory response that is the first line of defense against viral infections.

Researchers found that the same mouse brains that had amyloid plaques with nucleic acids also showed a molecular signature mimicking an antiviral IFN response. Further experiments revealed that nucleic acids in the plaques activated brain microglia, which produced IFN that in turn triggered a cascade of inflammatory reactions that led to the loss of synapses, the junctions between neurons through which they communicate. Synapse loss is a key part of neurodegeneration and can lead to memory loss and eventually dementia.

The accumulation of amyloid plaques in human brains is known to poorly correlate with the severity or duration of dementia. There are people without signs of dementia who harbor significant amounts of both amyloid plaques and tau tangles in their brains, but remarkably lack the robust microglial activation and inflammatory response that is associated with loss of synapses and neurons. "Our findings in mouse models suggest that it is plausible that plaques that accumulate in Alzheimer's disease patients and those in non-demented individuals differ in their content of nucleic acids. It is thus of great interest to examine more closely the molecular constituents of amyloid plaques in the brains of cognitively resilient individuals and compared them to those of Alzheimer's disease cases."

Type I interferon (IFN) is a key cytokine that curbs viral infection and cell malignancy. Previously, we have demonstrated a potent IFN immunogenicity of nucleic acid (NA)-containing amyloid fibrils in the periphery. Here, we investigated whether IFN is associated with β-amyloidosis inside the brain and contributes to neuropathology. An IFN-stimulated gene (ISG) signature was detected in the brains of multiple murine Alzheimer disease (AD) models, a phenomenon also observed in wild-type mouse brain challenged with generic NA-containing amyloid fibrils.

In vitro, microglia innately responded to NA-containing amyloid fibrils. In AD models, activated ISG-expressing microglia exclusively surrounded NA-positive amyloid β plaques, which accumulated in an age-dependent manner. Brain administration of recombinant IFNβ resulted in microglial activation and complement C3-dependent synapse elimination in vivo. Conversely, selective IFN receptor blockade effectively diminished the ongoing microgliosis and synapse loss in AD models. Moreover, we detected activated ISG-expressing microglia enveloping NA-containing neuritic plaques in post-mortem brains of AD patients. Gene expression interrogation revealed that IFN pathway was grossly upregulated in clinical AD and significantly correlated with disease severity and complement activation.

Having now gone through several significant investment rounds, Eric Marcotulli, CEO of Elysium Health is ideally positioned to comment on whether investors are yet seeing longevity as an investment category and we raised this with him during our recent interview. Considering the question, he recalls seeing Elizabeth Blackburn, a Nobel Prize winner for her work on telomeres, giving a talk on investment. "She said if she walked up and down Sand Hill Road saying that her work had discovered the cure for a very specific form of cancer, she would probably be able to get a blank check from anybody she sat with. But if she walked in there and said her work could potentially impact on cancer, Alzheimer's, diabetes, cardiovascular disease, and so on, she'd be laughed out of the room. And I think that was a really great encapsulation of the State of the Union, not just on her research, but on aging itself."

Marcotulli concurs that much of the investment community is perhaps "a little behind" when it comes to longevity and anti-aging, although he points out that there are those who are ahead of the field. "Those types of people will have the ultimate advantage. But, broadly speaking, the investor community thinks the way that consumers and patients think. At the end of the day they want to see the data so that, in less than 10 seconds, they can see what the benefit of the products your company are developing will be. We've made great progress in identifying and agreeing the key pillars of aging. However, what we still haven't shown conclusively, especially in humans, is are there discrete impacts, how interconnected they are, are certain ones more or greater contributors than others? And, more importantly, how do we measure the impact of changes to the different processes, what does it take to actually change those processes, and what does changing those processes mean?"

What is the so-called "Longevity Hype"?

Back in 2013, Silicon Valley tech giant Google promised the world that it will solve the problem of death. We have entered a new decade now, however, in my opinion, the progress in actual, practical life extension of humans is not far away from where it was back in 2013. There is lots of positive hype on the subject: many people ranging from the general public to scientists, entrepreneurs and investors are confident that we are on the brink of creating actual human life extension techniques which will soon translate into real-world, accessible applications. These claims need to be validated and a set of guidelines used to help separate hype from reality around this hypothesis in a concrete, logical and tangible way.

There has been tangible progress in the field, though?

Absolutely. A number of longevity-focused scientists have achieved a rather significant progress over the last decade with respect to stalling the aging process and in some cases even rejuvenation (restoring a young phenotype) in certain model organisms such as yeast, worms, flies and mice, including Maria Blasco and colleagues managing to extend the lifespan of mice by 24% by breeding a set of chimeric mice using embryonic stem cells with telomeres twice as long as usual.

So what happens next?

Undoubtedly, gaining a sufficient understanding of the nature of human aging and longevity as well as the necessary scope of technologies required for practical human life extension to the point of achieving Longevity Escape Velocity (the point where more years are added onto the human lifespan than are taken away due to aging) would require substantial resources. However, compared with the amount of funds being spent even on general aging research, not to mention the myriad of diseases that have their root causes in aging, we are not talking about unthinkable numbers. We estimate that 100bn per year over 10 years would be more than enough to get a real understanding and implementation of the technologies necessary for practical extension of healthy human longevity, which is vastly less than the amounts currently being spent on cancer research or on FinTech, for example.

The rapid increase in our understanding of the molecular mechanisms that underlie ageing has created new opportunities to intervene in the ageing process. Two notable findings have emerged from these early studies. First, the number of genes that can extend lifespan is much larger than expected, which suggests a much higher level of plasticity in the ageing process than expected. Second, genes that control ageing - which define cellular pathways such as the TOR and insulin signalling pathways - are remarkably conserved in yeast, worms, fruit flies and humans. The conservation of these pathways across wide evolutionary distances and the fact that targeting these pathways in model organisms increases both lifespan and healthspan has brought to the fore the idea of interventions in humans.

Rapidly ageing societies across the world are seeing an increasing healthcare burden attributable to both morbidity and cost of age-related diseases, such as heart disease, stroke, cancer, neurodegeneration, osteoarthritis, and macular degeneration. However, current medical care is highly segmented as well as organ- and disease-based, and ignores the fact that age and the ageing process are the strongest risk factor for each of these diseases. According to the concept of geroscience, targeting conserved ageing pathways is anticipated to protect against multiple diseases and represents a different approach to tackling the rapidly growing burden of diseases worldwide.

The concept of geroscience predicts that conserved ageing pathways are part of the pathophysiology of many age-related conditions and diseases. For example, multimorbidity is seen as the multisystem expression of an advanced stage of ageing rather than a coincidence of unrelated diseases. Targeting conserved ageing pathways should, therefore, prevent or ameliorate multiple clinical problems. This hypothesis remains to be tested in clinical trials, but is supported by several lines of evidence. A wide range of animal models of specific diseases can be affected by manipulating a single ageing mechanism (such as NAD+) or senescent cells in the laboratory. Rates of individual age-related diseases and of multimorbidity increase nonlinearly with age, and the rate of acquiring new chronic diseases may be higher in people who have an existing chronic disease.

We are now entering an exciting era for research on ageing. This era holds unprecedented promise for increasing human healthspan: preventing, delaying or - in some cases - reversing many of the pathologies of ageing based on new scientific discoveries. Whether this era promises to increase the maximum life span of humans remains an open question. What is clear is that, 30 years after the fundamental discoveries that link unique genes to ageing, a solid foundation has been built and clinical trials that directly target the ageing process are being initiated. Although considerable difficulties can be expected as we translate this research to humans, the potential rewards in terms of healthy ageing far outweigh the risks.

Adipose tissue derived stem cells (ADSCs) are mesenchymal stem cells identified within subcutaneous tissue at the base of the hair follicle (dermal papilla cells), in the dermal sheets (dermal sheet cells), in interfollicular dermis, and in the hypodermis tissue. These cells are expected to play a major role in regulating skin regeneration and aging-associated structural deficits. ADSCs are known to proliferate and differentiate into skin cells to repair damaged or dead cells, but also act by an autocrine and paracrine pathway to activate cell regeneration and the healing process.

During wound healing, ADSCs have a great ability in migration to be recruited rapidly into wounded sites added to their differentiation towards dermal fibroblasts (DF), endothelial cells, and keratinocytes. Additionally, ADSCs and DFs are the major sources of the extracellular matrix (ECM) proteins involved in maintaining skin structure and function. Their interactions with skin cells are involved in regulating skin homeostasis and during healing.

The evidence suggests that their secretomes ensure: (i) The change in macrophages inflammatory phenotype implicated in the inflammatory phase, (ii) the formation of new blood vessels, thus promoting angiogenesis by increasing endothelial cell differentiation and cell migration, and (iii) the formation of granulation tissues, skin cells, and ECM production, whereby proliferation and remodeling phases occur. These characteristics would be beneficial to therapeutic strategies in wound healing and skin aging and have driven more insights in many clinical investigations. ADSCs fulfill the general accepted criteria for cell-based therapies, but nonetheless still need further investigations into their efficiency, taking into consideration the host-environment and patient-associated factors.

Scientists have shown one way in which visceral fat is bad for brains is by enabling easy, excessive access for the proinflammatory protein signal interleukin-1 beta. The brain typically does not see much of this interleukin-1 beta, but researchers have found that visceral adiposity generates high, chronic levels of the signal that in turn over-activate the usually protective microglia, the resident immune cells in our brain. A bit like a smoldering pot, this chronic inflammation from visceral fat prompts formation of inflammasome complexes that further amplify the immune response and inflammation. The protein NLRP3 is a core component of the inflammasome complex in the fat, and it's what promotes the production and release of interleukin-1 beta by fat cells, and stokes the inflammation fire. It was known these reactions were causing problems in the body, and now the scientists have evidence they are causing problems in the brain.

To explore brain effects, the scientists knocked NLRP3 out of mice and found the mice were protected against obesity-induced inflammation of the brain and the cognitive problems that can result. They also transplanted visceral adipose tissue from obese mice and obese mice missing NLRP3 into lean mice recipients and found the transplant from the NLRP3 knockout mouse had essentially no effect. But the transplant from the obese but genetically intact mice increased levels of interleukin-1 beta in the hippocampus, a center of learning and memory in the brain, and impaired cognition.

Microglia typically function as watchdogs, constantly surveilling and roaming the brain, eliminating dead cells and other debris as well as a myriad of other tasks like forming and pruning connections between neurons. Microglia also have receptors for interleukin-1 beta, and the protein, whose many actions include promoting inflammation, easily passes through the protective blood brain barrier. Microglia's helpful - or harmful - actions likely result from signals they are exposed to, and another thing interleukin-1 beta appears to do is prompt microglia to wrap around synapses, possibly exerting damaging pressure and/or releasing substances that actually interfere with conversations between neurons. In the absence of disease, microglia also are known to embrace synapses but to release good things like brain-derived neurotrophic factor, which is like fertilizer for these invaluable connections.

Researchers analysed all available academic literature on sex chromosomes and lifespan - and they tried to establish whether there was a pattern of one sex outliving the other that was repeated across the animal kingdom. Specifically, they wanted to test the 'unguarded X hypothesis' which suggests that the Y chromosome in heterogametic sexes - those with XY (male) sex chromosomes rather than XX (female) sex chromosomes - is less able to protect an individual from harmful genes expressed on the X chromosome. The hypothesis suggests that, as the Y chromosome is smaller than the X chromosome, and in some cases absent, it is unable to 'hide' an X chromosome that carries harmful mutations, which may later expose the individual to health threats. Conversely, there is no such problem in a pair of homogametic chromosomes (XX), where a healthy X chromosome can stand in for another X that has deleterious genes to ensure those harmful genes aren't expressed, thus maximising the length of life for the organism.

After examining the lifespan data available on a wide range of animal species, it appears that the unguarded X hypothesis stacks up. This is the first time that scientists have tested the hypothesis across the board in animal taxonomy; previously it was tested only within a few groups of animals. "We looked at lifespan data in not just primates, other mammals and birds, but also reptiles, fish, amphibians, arachnids, cockroaches, grasshoppers, beetles, butterflies, and moths, among others. And we found that across that broad range of species, the heterogametic sex does tend to die earlier than the homogametic sex, and it's 17.6 per cent earlier on average."

Interestingly, the researchers observed this same pattern in the classes of animals possessing their own unique pair of sex chromosomes that are the reverse of all other animals. In birds, butterflies and moths, it is the male of the species that has the homogametic sex chromosomes (denoted by ZZ) while the female has the heterogametic chromosomes (ZW). Female birds, butterflies, and moths were usually found to die earlier than their male counterparts, giving credence to the unguarded X hypothesis - although strictly speaking, it's an unguarded Z in this case.

The cells of the body use a chemical compound called adenosine triphosphate (ATP) for fuel. Much of this ATP is made by cellular power plants called mitochondria. In spinal cord nerves, mitochondria can be found along the axons. When axons are injured, the nearby mitochondria are often damaged as well, impairing ATP production in injured nerves. "Nerve repair requires a significant amount of energy. Our hypothesis is that damage to mitochondria following injury severely limits the available ATP, and this energy crisis is what prevents the regrowth and repair of injured axons."

Adding to the problem is the fact that, in adult nerves, mitochondria are anchored in place within axons. This forces damaged mitochondria to remain in place while making it difficult to replace them, thus accelerating a local energy crisis in injured axons. One of the leading groups studying mitochondrial transport previously created genetic mice that lack the protein - called Syntaphilin - that tethers mitochondria in axons. In these "knockout mice" the mitochondria are free to move throughout axons.

When the researchers looked in three injury models in the spinal cord and brain, they observed that Syntaphilin knockout mice had significantly more axon regrowth across the injury site compared to control animals. The newly grown axons also made appropriate connections beyond the injury site. When the researchers looked at whether this regrowth led to functional recovery, they saw some promising improvement in fine motor tasks in mouse forelimbs and fingers. This suggested that increasing mitochondrial transport and thus the available energy to the injury site could be key to repairing damaged nerve fibers. To test the energy crisis model further, mice were given creatine, a bioenergetic compound that enhances the formation of ATP. Both control and knockout mice that were fed creatine showed increased axon regrowth following injury compared to mice fed saline instead. More robust nerve regrowth was seen in the knockout mice that got the creatine.

This investigation evaluated physical activity levels of 1,262 participants from the ongoing Framingham Offspring Study. Participants were an average age of 69 (54% women), and they were instructed to wear a device that objectively measured physical activity for at least 10 hours a day, for at least four days a week between 2011 and 2014. Participants were 67% less likely to die of any cause if they spent at least 150 minutes per week in moderate to vigorous physical activity - a goal recommended by the American Heart Association - compared to those who did not engage in more than 150 minutes per week of moderate to vigorous physical activity.

However, this investigation observed that, among the participants with an average age of 69, physical activity doesn't have to be strenuous to be effective. The researchers observed that each 30-minute interval of light-intensity physical activities - such as doing household chores or casual walking - was associated with a 20% lower risk of dying from any cause. Conversely, every additional 30-minutes of being sedentary was related to a 32% higher risk of dying from any cause.

The homeostatic regulation of protein folding (proteostasis), which is monitored in specific subcellular compartments, is an integral player in stress resistance and longevity. The endoplasmic reticulum (ER), in particular, is a central regulator of stress monitoring as it controls nearly a third of the cell's proteins, provides an internal medium for lipid homeostasis and cell signaling, and communicates directly with all other organelles to maintain cellular secretion. Thus, cells have evolved numerous quality control machineries dedicated to protecting the ER both under basal and stressed conditions.

Notably, the ER has evolved three primary branches of its unfolded protein response (UPRER) to maintain proper secretion, protein folding, and lipid homeostasis. While these pathways have been intensively studied for the past two decades, much less is known about the adaptive responses of the ER under long-lived conditions. Work with the nematode C. elegans has shown that its cells become less capable in protein folding and also less able to induce stress responses to proteotoxicity with advanced age. Overexpression of xbp-1, specifically in neurons, extends organismal life span and increases ER stress tolerance in a cell nonautonomous manner. While the precise, small ER stress signal was not identified, small clear vesicles are required for this beneficial effect, which could be host to numerous neurotransmitters.

We hypothesized that induction of the UPRER in neurons, which reverses the age-dependent loss of ER proteostasis, also enacts a marked restructuring of ER morphology, which, in turn, imparts a beneficial metabolic change and promotes longevity. Although whole-organismal metabolic restructuring has been a topic of intense study in the aging field, much less is known about the adaptive responses of organelles in long-lived conditions. Here, we find that neuronal xbp-1 animals have notable ER restructuring and lipid depletion, and that these changes are distinct from chaperone induction. Thus, we argue that the beneficial effects of nonautonomous UPRER are dependent on two independent, yet equally important, arms of UPRER: the protein homeostasis arm, including chaperone induction, and the metabolic arm, which induces ER remodeling and lipophagy.

Experiences in early life may lay the foundation for age-related non-communicable disease (NCD) suseptibility. The developmental origins of health and disease (DOHaD) hypothesis postulates that many common NCDs originate in utero by re-programming fetal physiological and metabolic responses with lifelong consequences on organ and tissue function. The biological signatures linked to early life adversity are also transmitted across generations. Natural disaster and nutritional birth cohorts as well as experimental studies have demonstrated that remote ancestral adverse experiences increase the risk of metabolic, cardiac, and renal disease, and mental illness with a sex-specific bias. These adverse health outcomes are linked to epigenetic regulation, including altered microRNA (miRNA) expression.

Here, we performed a longitudinal rat cohort study to examine the impact of recurrent stress reaching back across four generations (F0-F3) on lifetime health trajectories. We hypothesized that multigenerational prenatal stress (MPS) in the F4 generation would lead to a behavioural phenotype of sex-specific stress vulnerability and resilience at young and old age. Moreover, we proposed particular vulnerability to NCDs in old age in association with up-stream epigenetic and down-stream metabolic biomarker signatures.

Unbiased deep sequencing of frontal cortex revealed that MPS altered expression of microRNAs and their target genes involved in synaptic plasticity, stress regulation, immune function, and longevity. Multi-layer top-down deep learning metabolite enrichment analysis of urine markers revealed altered metabolic homeodynamics in MPS males. Thus, peripheral metabolic signatures may provide sensitive biomarkers of stress vulnerability and disease risk. Programming by MPS appears to be a significant determinant of lifetime mental health trajectories, physical wellbeing, and vulnerability to NCDs through altered epigenetic regulation.

Due to the lack of effective treatment to at least slow down the neurodegenerative process, neurodegenerative diseases (NDDs) are still an unmet medical need. Most high-profile clinical trials for NDDs led to inefficacious results, suggesting that novel approaches to treat these pathologies are needed. Targeting NDDs through the prism of aging is one of such approach. Indeed, the primary risk factor associated with NDDs, including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, or Huntington's disease is aging. Consequently, it is tempting to study age-related dysfunctions that could favor or be instrumental in the neurodegenerative process.

Reduced nicotinamide adenine dinucleotide (NAD) levels might be one of these age-related dysfunctions influencing neurodegeneration. Indeed, NAD levels were found to decrease as a consequence of aging, including in the human brain and cerebrospinal fluid (CSF), while NAD was found to be a potent neuroprotective and anti-inflammatory molecule. The reason as to why NAD levels are reduced as a consequence of aging remained elusive until the discovery in 2016 that expression of CD38, the main enzyme responsible for NAD degradation, increased as a consequence of aging, thus explaining age-related NAD decline. Moreover, CD38 deletion was found to repress neurodegeneration and neuroinflammation in experimental models of NDDs.

However, CD38 biology is complex and not restricted to its NAD-degrading ability. The aims of this review are to summarize the physiological role played by CD38 in the brain, present the arguments indicating the involvement of CD38 in neurodegeneration and neuroinflammation, and to discuss these observations in light of CD38 complex biology.

Scientists began their experiments with a fibroblast - a connective tissue cell - taken from a person with type 1 diabetes. Reprogrammed fibroblasts function as stem cells, with the potential to give rise to all tissues in the body, including blood vessels. The team reprogrammed the fibroblast stem cells to revert to a state that is even more primitive than that of conventional human induced pluripotent stem cells - more like the state of embryonic cells about six days after fertilization. This is when cells are the most "naive," or more capable of developing into any specialized type of cell with a much higher efficiency than conventional human induced pluripotent stem cells.

Researchers used a cocktail mixture of two drugs that other scientists previously used to reprogram stem cells: GSK3β inhibitor CHIR99021, which blocks carbohydrate storage in cells, and MEK inhibitor PD0325901, an experimental anti-cancer drug that can block cancer cell growth. The team had also looked at the potential of a third drug, a PARP inhibitor - a popular anticancer drug used to treat a variety of cancers including those of the ovaries and breast. The team calls the cocktail 3i, named for the three inhibitors.

The research team tracked the reprogrammed stem cells' molecular profile, including measures of proteins such as NANOG, NR5A2, DPPA3 and E-cadherin that guide cell differentiation. That profile appeared similar to that found in so-called naive epiblast cells, the primitive cells that make up an approximately six day-old human embryo. The scientists also found that the stem cells reprogrammed with the 3i cocktail did not have abnormal changes in factors that can alter core DNA, called epigenetics, that typically plague other lab-made versions of naive stem cells. "Interestingly, the 3i cocktail appeared to erase disease-associated epigenetics in the donor cells, and brought them back to a healthy, pristine non-diabetic stem cell state."

Finally, the research team injected cells called vascular progenitors, which were made from the naive stem cells and are capable of making new blood vessels, into the eyes of mice bred to have a form of diabetic retinopathy that results from blood vessels closing off in the retina. They found that the naive vascular progenitors migrated into the retina's innermost tissue layer that encircles the eye, with higher efficiencies than have been reported with vascular cells made from conventional stem cell approaches. The naive vascular cells took root there, and most survived in the retina for the duration of the four-week study.

CEACAM1 contributes to angiogenesis by induction of vascular sprouting, but has not been associated with the vascular aging process until recently. It has been known for a long time that the pro-inflammatory cytokine TNF-α is upregulated within the wall of aging vasculature and contributes to endothelial dysfunction that in turn predicts cardiovascular events. Since we showed previously that CEACAM1 is critically involved in TNF-α-mediated endothelial barrier breakdown via adherens junction disassembly, we wondered whether CEACAM1 might also contribute to vascular aging.

As a first hint, we observed re-expression of CEACAM1 in the murine and human vasculature with progressive age. This upregulation of vascular CEACAM1 expression is of great importance since we demonstrated that the presence of CEACAM1 is necessary for age-associated vascular upregulation of TNF-α using a murine CEACAM1 knockout model. Reversely, TNF-α induced the expression of CEACAM1 in cultured endothelial cells, indicating the establishment of a vicious cycle within aging vessels.

A hallmark of vascular aging is the increased deposition of collagen fibers within the media of larger vessels. Intriguingly, we found that only in the presence of CEACAM1 vascular aging in mice was accompanied by vascular fibrosis presumably due to enhanced TGF-β/TGF-βR1 signaling whereas genetic deletion of CEACAM1 completely prevented aortic collagen accumulation. Age-related CEACAM1-dependent vascular collagen accumulation might increase arterial stiffness, which is known to augment cardiac afterload permanently resulting in concentric ventricular hypertrophy and cardiomyopathy.

Finally, we found that CEACAM1 contributes to the age-related increase in oxidative stress within the vasculature which promotes endothelial barrier impairment. It is well-known that oxidative stress is also critically involved in processes that promote angiopathies like atherosclerosis. Although there are some hints pointing to a role of CEACAM1 in atherosclerosis the exact contribution of CEACAM1 in these processes is yet to be defined.

In summary, we identified CEACAM1 as an important player in the process of vascular aging. Identification of mechanisms of vascular aging in detail that are regulated by endothelial and vascular presence of CEACAM1 might therefore open up new therapeutic strategies to slow-down the vascular aging process thereby reducing the risk of life-threatening cardiovascular events.