Fight Aging! Newsletter, October 7th 2019

Methionine restriction (MetR) extends lifespan across different species and exerts beneficial effects on metabolic health and inflammatory responses. In contrast, certain cancer cells exhibit methionine auxotrophy that can be exploited for therapeutic treatment, as decreasing dietary methionine selectively suppresses tumor growth. Thus, MetR represents an intervention that can extend lifespan with a complementary effect of delaying tumor growth.

Beyond its function in protein synthesis, methionine feeds into complex metabolic pathways including the methionine cycle, the transsulfuration pathway, and polyamine biosynthesis. Manipulation of each of these branches extends lifespan; however, the interplay between MetR and these branches during regulation of lifespan is not well understood. In addition, a potential mechanism linking the activity of methionine metabolism and lifespan is regulation of production of the methyl donor S-adenosylmethionine, which, after transferring its methyl group, is converted to S-adenosylhomocysteine. Methylation regulates a wide range of processes, including those thought to be responsible for lifespan extension by MetR.

Although the exact mechanisms of lifespan extension by MetR or methionine metabolism reprogramming are unknown, it may act via reducing the rate of translation, modifying gene expression, inducing a hormetic response, modulating autophagy, or inducing mitochondrial function, antioxidant defense, or other metabolic processes. Although it is clear that each of the three branches of methionine metabolism - the methionine cycle, the transsulfuration pathway, and polyamine biosynthesis - plays a significant role in lifespan extension, how these branches crosstalk during regulation of lifespan is unknown. Moreover, how activity in these different branches of methionine metabolism change with age in different tissues and organs remains to be elucidated.

Microglia cells are the main immunocompetent cells in the brain. They colonize the brain in the early prenatal period, but contrary to other tissue resident macrophages, they remain secluded within the central nervous system (CNS) throughout life and self-renew at slow pace. Should the brain homeostasis be compromised, microglia change their phenotype and initiate a defense program. Thus, under pathological conditions, they adopt reactive states characterized by multiple morphological and functional changes including but not limited to increased phagocytosis and increased expression of receptors, cytokines, chemokines, and additional inflammation related molecules.

Alzheimer's disease (AD) classical hallmarks include brain atrophy, extracellular amyloid-beta (Aβ) deposits, intracellular aggregated phosphorylated tau, dystrophic neurites, synapses, and neurons loss. The presence of reactive glial cells within the neuritic plaques was described by Alois Alzheimer himself and further studies identified both reactive astrocytes and microglia in the vicinity of the Aβ deposits. Long considered as a consequence of the pathology, reactive glia and associated neuroinflammation are now regarded as playing key roles in both disease initiation and progression. Evidence strongly supports a causal involvement of microglial cells in AD pathogenesis and generated a strong interest for studying these cells. Yet, the roles of microglia in AD initiation and progression are unclear and heavily debated, with conflicting reports regarding their detrimental or protective contribution to the disease.

The involvement of microglia in AD is a relatively new area of research, but it is growing at a fast pace. Recent genome-wide association studies have established that the majority of AD risk loci are found in or near genes that are highly and sometimes uniquely expressed in microglia. This leads to the concept of microglia being critically involved in the early steps of the disease and identified them as important potential therapeutic targets.

Over the recent years, several technological breakthroughs have been achieved, allowing scientists to address new challenging questions. These technical developments now allow studying microglia roles with medium or high throughput workflows, and perform fine analysis of their functions in preserved environments. A better understanding of the contribution of microglia cells to AD initiation and progression is expected to renew the interest of big pharma to re-invest in the field and will pave the way toward better designed strategies.

The SENS Research Foundation (SRF) has formulated seven practical repair strategies to the common drivers of aging. Whereas some of these strategies are now widely researched by the scientific establishment the MitoSENS strategy for dealing with mitochondrial damage is among the most novel. Our theory is, through allotopic expression, that is by placing functional copies of critical mitochondrial DNA (mtDNA) genes in the nucleus of the cell one could alleviate defects arising due to mutations in mtDNA.

When it was proposed, this unique and ambitious strategy was perhaps too daring for mainstream labs and funding agencies to contemplate. Consequently, the MitoSENS approach has been an in house project for SENS that would not have been possible without community support. So far, this community-funded approach has an excellent track record leading to groundbreaking discoveries. In 2013 SENS organized its first crowdfunding campaign specific to MitoSENS in partnership with LongeCity. The small initiative seeded significant research momentum and paved the way for a larger fundraiser in 2015 at Lifespan.io. Breakthrough discoveries followed and a proof-of-principle for the MitoSENS approach was established for the first time in human cells. Here, the MitoSENS team in collaboration with scientists from the Buck Institute showed that allotopic expression of two mtDNA genes could bring back several functions in a patient cell line with a severe mutation in one of the mtDNA genes, namely ATP8.

To move this strategic advancement toward the clinic, SRF then created the "maximally modifiable mouse model". This mouse has a unique modification in their nuclear genome to allow a targeted insertion of new genes at a specific location. Using this mouse, we are ready to take the next step and pursue mitochondrial gene therapy in an animal model.

Mice of the C57/BL6MT-FVB strain (let's call them "SickMice") have a mitochondrial gene defect, a mutation in the mitochondrial ATP8 gene, and exhibit several age-related symptoms including lower fertility, arthritis, type II diabetes, and neurological impairments. Since mitochondria are only inherited from the mother, cross-breeding female SickMice with male mice from other models will result in the same mitochondrial dysfunction.

We will use the maximally modifiable model to create a new transgenic mouse (the "allotopic ATP8 transgenic mouse - Mitomouse"). This mouse will have the ATP8 gene that is important for mitochondrial function hidden in the cell nucleus and thus capable of being passed on to offspring irrespective of gender. Our hypothesis is that both male and female offspring from SickMice x MitoMice will result in rescued mitochondrial function. This would prove the viability of the MitoSENS strategy by showing that functional backup copies of mitochondrial DNA genes in the nucleus can replace their mutated counterparts in live animals.

Since T cells must be continuously produced throughout life, the accelerated atrophy of the thymus with age is enigmatic, especially given its latent regenerative potential. Age-associated atrophy is common to many tissues (for instance, muscle, central nervous system, skin, and testes), and can be a consequence of cell loss (death), but often is associated with the shrinkage (atrophy) of individual cells, collectively resulting in tissue atrophy. Likewise, regeneration may be attributed to proliferation of stem or end stage cells (hyperplasia), but can also result from growth of existing cells (hypertrophy) that is independent of proliferation. Despite the magnitude of atrophy and regeneration in the thymus, the underlying mechanisms for these processes have remained obscure, although our previous findings show that both are attributable to changes in cortical thymic epithelial cells (cTEC). Our non-presumptive analysis of global gene expression in young cTEC, aged cTEC, or aged cTEC in the regenerating thymus suggested that genes associated with cell size and shape dominated the dynamic landscape. However, the size and shape of individual cTEC has been difficult to discern using conventional methods, thus obscuring any changes that might occur during age atrophy or regeneration.

In other tissues, epithelial cells exhibit distinctive morphologies, and are polarized (with respect to a basement membrane) in either a single simple layer or in multiple stratified layers. In the thymus, with the exception of a small proportion of conventional epithelial cells lining the capsule and blood vessels, most TEC lack classical epithelial morphology. Instead, they are defined as epithelial mainly based on biochemical features, such as the appearance of desmosomes or keratin filaments. Various histochemical markers indicate that cTEC, in particular, form an extensive network of finely branched cell processes, but the morphology and number of individual cells in this network has been very difficult to define, due to this elaborate branching morphology and their relatively uniform staining with various antibody markers. Medullary thymic epithelial cells (mTEC) appear to be less dense, and therefore more easily defined as individual cells, but extensive heterogeneity among lineage markers has rendered the morphology of individual mTEC vague as well. Consequently, defining the size, shape, and interconnectivity of these essential cells has remained enigmatic.

Given the need for continuous T cell production during life, the thymus is paradoxically the most rapidly aging tissue in the body. It reaches peak tissue mass (in all species studied) prior to the onset of adolescence, and exhibits rapid and progressive atrophy afterwards, such that by mid-life most healthy mass is lost. Except at very late age, thymic lymphocytes are essentially unchanged in the atrophied thymus, while these age related changes are primarily manifest in stromal cells, particularly cortical. Niche availability provided by cTEC is the rate limiting feature for lymphoid cellularity and thymus size. Thus, as cTEC deteriorate during aging, the thymus becomes proportionally smaller. Since new T cells are produced proportionally to thymic mass, peripheral homeostasis thus becomes more dependent on homeostatic expansion of existing T cells, with the repertoire gradually drifting towards immunologic memory, with diminished broad spectrum immunity as a result.

Remarkably, the atrophied thymus retains potent regenerative capacity, and can be induced to attain its full peak size by stimuli such as androgen ablation. Quite logically, albeit without much evidence, thymic atrophy is assumed to result from senescence-associated cell death among TEC, while regeneration is believed to result from proliferative expansion from an epithelial stem cell or progenitor cell population. Consistent with these concepts, experimental loss of cTEC does result in decreased thymus size, while induction of cTEC proliferation results in a larger thymus. However, the fact that thymus size changes in response to TEC number (and resulting lymphoid capacity) does not mean that atrophy or regeneration, under physiologic conditions, necessarily involve changes in TEC number.

The present study stems from a large temporal database of stromal transcriptional profiles during aging and regeneration. Non-presumptive analysis indicates that dynamic changes in genes associated with cell size and cell morphology dominated the regeneration response. Here we use two different conditional reporter models to morphologically define and enumerate TEC in young, aged, or regenerated thymuses. Both models confirm the predictions of informatic analysis, showing that age atrophy of the thymus represents contraction of unique cell projections that characterize cTEC, while regeneration involves their regrowth. Both atrophy and regeneration occur independently of changes in cTEC number, and appear to solely reflect changes in projection morphology. Although mTEC morphology does not change appreciably with age, dynamic analysis suggests that medullary stroma may play an important role in modulation of cTEC morphology via paracrine production of known morphogens and growth factors. Our findings reconcile diverse existing concepts, and provide a revised view of atrophy and regeneration based on structural remodeling of a novel cTEC morphology that is unique among metazoan tissues.

Skeletal muscles have a tremendous capacity to make new muscles from special muscle stem cells. These "blank" cells are not only good at making muscles but also at generating more of themselves, a process called self-renewal. But their amazing abilities diminish with age, resulting in poorer muscle regeneration from muscle trauma. A research team figured out that a protein called GAS1 is the culprit for this age-related decline.

The protein is found in only a small number of young muscle stem cells, but is present in all aged muscle stem cells, they discovered. Tinkering with muscle stem cells to express GAS1 in the entire young stem cell population resulted in diminished regeneration. By contrast, removing GAS1 from aged muscle stem cells rejuvenated them to a youthful state that supported robust regeneration. They also discovered that GAS1 inhibits another protein, a cell-surface receptor called RET, which they showed to be necessary for muscle stem cell renewal. The more GAS1 protein is present, the more RET's function is reduced. The inhibition of RET by GAS1 could be reversed by the third protein called GDNF, which binds to and activates RET. Indeed, when the researchers injected GDNF directly into the muscles of aged mice, muscle stem cell function and muscle regeneration were restored.

Muscle undergoes progressive weakening and regenerative dysfunction with age due in part to the functional decline of skeletal muscle stem cells (MuSCs). MuSCs are heterogeneous, but whether their gene expression changes with age and the implication of such changes are unclear. Here we show that in mice, growth arrest-specific gene 1 (Gas1) is expressed in a small subset of young MuSCs, with its expression progressively increasing in larger fractions of MuSCs later in life. Overexpression of Gas1 in young MuSCs and inactivation of Gas1 in aged MuSCs support that Gas1 reduces the quiescence and self-renewal capacity of MuSCs. GAS1 reduces RET signalling, which is required for MuSC quiescence and self-renewal. Indeed, we show that the RET ligand, glial-cell-line-derived neurotrophic factor can counteract GAS1 by stimulating RET signalling and enhancing MuSC self-renewal and regeneration, thus improving muscle function. We propose that strategies aimed at targeting this pathway can be exploited to improve the regenerative decline of MuSCs.

Vascular calcification (VC) constitutes a major risk factor for cardiovascular (CV) morbidity and mortality and involves a complex regulated process of biomineralization that resembles osteogenesis. This process is mainly driven by the vascular smooth muscle cells (VSMCs), and includes the transformation of these cells into an osteoblastic phenotype.

Chronic kidney disease (CKD) is a major risk factor for CV disease (CVD) and is a clinical scenario closely related to the development of VC. In addition to the traditional CV risk factors, subjects with CKD are also exposed to other non-traditional factors predisposing for this pathology. Fibroblast growth factor (FGF) 23 is the most potent phosphatonin. This is an osteocyte-derived hormone produced in response to phosphate levels which, in combination with its cofactor Klotho, reduces the reabsorption of phosphate and the synthesis of active vitamin D in the kidneys. In patients with CKD, FGF23 concentrations increase with declining renal function and reach extremely high levels in end-stage renal disease. Clinical epidemiological studies have shown that FGF23 strongly predicts mortality in patients with CKD independently of other risk factors. These results suggest that FGF23 may causally be related to the high mortality observed in CKD patients and, importantly, that may exert direct effects on CV system besides its function as a phosphaturic hormone.

FGF23 binds to its cognate receptors (FGFRs), which are activated in the presence of the co-receptor Klotho. Our group and others described the expression of FGFR and Klotho in the human vascular wall, allowing to speculate that vascular tissue may be an objective for the actions of FGF23. Moreover, the synthesis of FGF23 by calcified vascular tissues and its contribution to CVD is an intriguing question not adequately studied. Only two previous works have explored the expression of FGF23 in calcified tissues, although solely coronary arteries and carotid atheroma plaques were analyzed. Moreover, the relationships of vascular FGF23 gene and protein expression levels with soluble FGF23 concentration and with the expression of Klotho and FGFRs in the vessels have not been previously established.

In this work, we determined the levels of both intact and fragmentary circulating FGF23 in 133 patients with established cardiovascular disease, the expression of FGF23, its receptors, and its co-receptor Klotho in vascular fragments of aorta, carotid, and femoral in 43 out of this group of patients, and in a control group of 20 organ donors. Patients with atherosclerosis and vascular calcification presented increased levels of FGF23 respect to the control group. Vascular immunoreactivity for FGF23 was also significantly increased in patients with vascular calcification as compared to patients without calcification and to controls. Finally, gene expression of FGF23 and RUNX2 were also higher and directly related in vascular samples with calcification. Conversely, expression of Klotho was reduced in patients with cardiovascular disease when comparing to controls. In conclusion, our findings link the calcification of the vascular tissue with the expression of FGF23 in the vessels and with the elevation of circulating levels this hormone.

They've been called the "special forces" of the immune system: invariant natural killer T cells. Although there are relatively few of them in the body, they are more powerful than many other immune cells. Scientists have hypothesized that iNKT cells could be a useful weapon against cancer because it has been shown that they are capable of targeting many types of cancer at once - a difference from most immune cells, which recognize and attack only one particular type of cancer cell at a time. But most people have very low quantities of iNKT cells; less than 0.1% of blood cells are iNKT cells in most cases. Still, previous clinical studies have shown that cancer patients with naturally higher levels of iNKT cells generally live longer than those with lower levels of cells.

The researchers' goal was to create a therapy that would permanently boost the body's ability to naturally produce more iNKT cells. They started with hematopoietic stem cells - cells found in the bone marrow that can duplicate themselves and can become all types of blood and immune cells, including iNKT cells. The researchers genetically engineered the stem cells so that they were programmed to develop into iNKT cells.

They tested the resulting cells, called hematopoietic stem cell-engineered invariant natural killer T cells, or HSC-iNKT cells, on mice with both human bone marrow and human cancers - either multiple myeloma (a blood cancer) or melanoma (a solid tumor cancer) - and studied what happened to the mice's immune systems, the cancers and the HSC-iNKT cells after they had integrated into the bone marrow. They found that the stem cells differentiated normally into iNKT cells and continued to produce iNKT cells for the rest of the animals' lives, which was generally about a year.

While mice without the engineered stem cell transplants had nearly undetectable levels of iNKT cells, in those that received engineered stem cell transplants, iNKT cells made up as much as 60% of the immune systems' total T cell count. Plus, researchers found they could control those numbers by how they engineered the original hematopoietic stem cells. Finally, the team found that in both multiple myeloma and melanoma, HSC-iNKT cells effectively suppressed tumor growth.

Over the past several years, scientists have identified four genetic and molecular biomarkers that potentially predict human and animal longevity. The first is the rate at which an individual's telomeres shorten in length. There is increasing evidence from both human and animal studies that the slower the rate of telomere shortening, the longer that individual is likely to live. The second is the rate of gene methylation, indicating an increased level of methylation was correlated with shortened longevity. The third is the polygenic risk. A recently reported genetic analysis can identify "10 percent of people with the most protective genes, who will live an average of five years longer than the least protected 10 percent," according to a statement from a scientist who developed the method.

The fourth approach was described in a study this year that identified 14 blood-based biomarkers of metabolism that when combined into a predictive score was statistically associated with predicting the end of life. Screening individuals using these metabolite profiles appeared to be predictive of a high risk of mortality within 10 years. In this study, scientists included more 44,000 people from 12 cohorts who were followed between three and 17 years to establish a correlation with these blood metabolites and longevity. There are no comparable studies that have examined such a large population using telomere length or gene methylation as longevity predictors.

Each of the four approaches to predicting longevity raises several scientific and ethical concerns that need to be addressed. The blood-based biomarker studies differ from current clinical end-of-life predictors, such as blood pressure and cholesterol levels, because there are established behavioral and drug interventions to reduce blood pressure and cholesterol levels. Were biomarkers to be developed for clinical applications, we propose that they should only be used if they provide actionable results. We should be cautious in applying both premature and unproven longevity results in a clinical situation that has such serious implications.

Several companies are already offering consumers tests to assay their telomere length. We would not be surprised if in the future companies will use other biological or genetic predictors to assess human longevity or offer ways to reverse our biological clocks. We also caution consumers against seeking out such longevity predictions should they be offered direct to the public, unless companies present the results to the consumer by a certified genetic counselor, as the psychological effect from these data could be devastating. Furthermore, the unintended consequences of using end-of-life predictions based on these preliminary studies can be unsettling. Do we want our life insurance agents canceling any policy or raising rates based on our biomarkers? In conclusion, we have not reached the point when it is ethical and scientifically valid to use biomarkers to predict longevity.

Cardiovascular disease (CVD) remains the leading cause of death in the elderly, and treatment is costly. The reduced endothelial function with aging contributes to the development of CVD, so maintaining the normal endothelial integrity is an important therapeutic approach to reduce the age-related risk of CVD. Endothelial progenitor cells (EPCs) are thought to promote postnatal neovascularization and maintain endothelial integrity and function. These cells have aroused the interest of researchers, especially given the limited regenerative capacity of mature endothelial cells. It has been suggested that EPCs not only foster the continuous recovery of the endothelium after injury/damage, but also stimulate angiogenesis.

The function and number of circulating EPCs decreases with aging. Aging impairs the ability of EPCs to regenerate and migrate to damaged blood vessels and ischemic areas to repair the vasculature and promote angiogenesis. Aging EPCs exhibit reduced capacities. Therefore, therapeutic interventions that stimulate EPCs to enhance endothelial repair in elderly individuals have important clinical implications for the aging population. Different mechanisms of EPC senescence have been reported, including telomere shortening, age-related declines in pro-angiogenic factors, increased oxidative stress, reduced nitric oxide (NO) bioavailability and chronic low-grade inflammation. However, the complex molecular network responsible for EPC senescence requires further investigation.

We explored the effects of nuclear factor (erythroid-derived 2)-like 2 (NRF2) on EPC activity during aging. Both in vitro and in vivo, the biological functioning of EPCs decreased with aging. The expression of NRF2 and its target genes also declined with aging, while Nod-like receptor protein 3 (NLRP3) expression increased. Aging was associated with oxidative stress, as evidenced by increased reactive oxygen species and malondialdehyde levels and reduced superoxide dismutase activity. Nrf2 silencing impaired the functioning of EPCs and induced oxidative stress in EPCs from young mice. On the other hand, NRF2 activation in EPCs from aged mice protected these cells against oxidative stress, ameliorated their biological dysfunction and downregulated the NLRP3 inflammasome. These findings suggest NRF2 can prevent the functional damage of EPCs and downregulate the NLRP3 inflammasome through NF-κB signaling.

Sarcopenia is defined as the combined loss of skeletal muscle strength, function, and/or mass with aging. This degenerative loss of muscle mass is associated with poor quality of life and early mortality in humans. The loss of muscle mass occurs due to acute changes in daily muscle net protein balance (NPB). It is generally believed a poor NPB occurs due to reduced muscle protein synthetic responses to exercise, dietary amino acid availability, or an insensitivity of insulin to suppress breakdown. Hence, aging muscles appear to be resistant to the anabolic action of exercise and protein (amino acids or hormonal) when compared to their younger counterparts.

The mechanisms that underpin anabolic resistance to anabolic stimuli (protein and resistance exercise) are multifactorial and may be partly driven by poor lifestyle choices (increased sedentary time and reduced dietary protein intake) as well as an inherent dysregulated mechanism in old muscles irrespective of the environmental stimuli. The insulin like growth factor 1 (IGF-1), Akt/Protein Kinase B and mechanistic target of rapamycin (mTOR) pathway is the primary driver between mechanical contraction and protein synthesis and may be a site of dysregulation between old and younger people.

Therefore, our review aims to describe and summarize the differences seen in older muscle in this pathway in response to resistance exercise (RE) and describe approaches that researchers have sought out to maximize the response in muscle. Furthermore, this review will present the hypothesis that inositol hexakisphosphate kinase 1 (IP6K1) may be implicated in IGF-1 signaling and thus sarcopenia, based on recent evidence that IGF-1 and insulin share some intracellular bound signaling events and that IP6K1 has been implicated in skeletal muscle insulin resistance.

Researchers report that when microglia spat out damaged mitochondria, these cast-offs inflamed astrocytes, which in turn expelled their own mitochondrial fragments. Jetsam from either cell sickened neurons as well, limiting their energy production. Conversely, an inhibitor of mitochondrial fission protected astrocytes and neurons from the effect of externally added mitochondrial fragments, suggesting that mitochondrial fragmentation cascades from cell to cell. Curiously, adding whole, functional mitochondria to neuronal cultures mitigated the damage from fragmented organelles. Mitochondria are ancient bacterial invaders of eukaryotic cells, but are tolerated by the body because they are sequestered inside cells. Once released, their proteins and other macromolecules may trigger inflammation.

In mouse models of neurodegenerative conditions, P110 improved survival and motor skills. Exactly how P110 protected neurons in these mouse models was unclear. Researchers added the inhibitor to microglia expressing a 73-amino-acid polyglutamine expansion (Q73) that causes mitochondria to malfunction and fragment. P110 treatment reduced mitochondrial fission, boosted ATP production, and lowered reactive oxygen species. How might microglia in these models affect other cell types? The authors added media from Q73 microglia to mouse primary astrocyte cultures. In response, the astrocytes pumped out TNF-α and IL-1β. Their mitochondria became dysfunctional and fragmented, and 75 percent more astrocytes died. Adding P110 directly to astrocytes also protected them from the Q73 microglia-conditioned media.

Taken together, the data implied that fragmentation of mitochondria causes microglia and astrocytes to release factors that can somehow damage mitochondria in other cell types. The authors wondered if those released "factors" might be mitochondria themselves. Confirming this, the authors found intact functional mitochondria in media from healthy microglial cultures. Media from Q73 microglia cultures contained the same total number of mitochondria as media from the healthy cultures, but only half as many were whole and functional. At the same time, the amount of free-floating mitochondrial proteins in Q73 culture medium rose, suggesting the organelles were leaking contents. Treating Q73 microglial cultures with P110 bumped the number of functional mitochondria almost back to that of control cultures.

While the damaged organelles may trigger inflammation by activating microglia or astroglia, their direct effect on neurons remains puzzling, as does the effect of whole mitochondria. Researchers are investigating the idea that neurons take up whole or fragmented organelles, with the former bolstering cellular respiration and the latter spreading damage.

Oxidative stress is a consequence of the use of oxygen in aerobic respiration by living organisms and is denoted as a persistent condition of an imbalance between the generation of reactive oxygen species (ROS) and the ability of the endogenous antioxidant system (AOS) to detoxify them. The oxidative stress theory has been confirmed in many animal studies, which demonstrated that the maintenance of cellular homeostasis and biomolecular stability and integrity is crucial for cellular longevity and successful aging.

Mitochondrial dysfunction, impaired protein homeostasis (proteostasis) network, alteration in the activities of transcription factors such as Nrf2 and NF-κB, and disturbances in the protein quality control machinery that includes molecular chaperones, ubiquitin-proteasome system (UPS), and autophagy/lysosome pathway have been observed during aging and age-related chronic diseases. The accumulation of ROS under oxidative stress conditions results in the induction of lipid peroxidation and glycoxidation reactions, which leads to the elevated endogenous production of reactive aldehydes and their derivativesm, giving rise to advanced lipoxidation and glycation end products (ALEs and AGEs, respectively).

Both ALEs and AGEs play key roles in cellular response to oxidative stress stimuli through the regulation of a variety of cell signaling pathways. However, elevated ALE and AGE production leads to protein cross-linking and aggregation resulting in an alteration in cell signaling and functioning which causes cell damage and death. This is implicated in aging and various age-related chronic pathologies such as inflammation, neurodegenerative diseases, atherosclerosis, and vascular complications of diabetes mellitus. In the present review, we discuss experimental data evidencing the impairment in cellular functions caused by AGE/ALE accumulation under oxidative stress conditions. We focused on the implications of ALEs/AGEs in aging and age-related diseases to demonstrate that the identification of cellular dysfunctions involved in disease initiation and progression can serve as a basis for the discovery of relevant therapeutic agents.

A normal intervertebral disc (IVD) consists of an outer annulus fibrosus (AF) that forms a ring structure to enclose the central nucleus pulposus (NP) and is connected to adjacent vertebral bodies by the cartilaginous endplates. The NP is crucial to maintain biomechanical function of IVD by counteracting and dissipating compressive loads, which depends on the extracellular matrix (ECM) secreted by nucleus pulposus cells (NPCs). However, the NP changes from a gel-like substance into a fibrous tissue with age, resulting in the structural and functional failure of IVD. Although the molecular mechanism of these pathological changes has not been fully understood, the apoptosis and senescence of NPCs are proven to be crucial to the development of intervertebral disc degeneration (IDD).

At present, increasing studies have demonstrated that reactive oxygen species (ROS) is closely related to the apoptosis and senescence of NPCs, contributing to the initiation and progression of IDD. As the main site of intracellular ROS generation, mitochondrion is also adversely influenced by ROS. Mitochondrial dysfunction is regarded as an important factor in NPC apoptosis and senescence, and accelerates disc degeneration. Thus, the strategies that aim at antioxidation and maintenance of mitochondrial homeostasis are promising to prevent or retard IDD.

Here we present evidence that a lower level of Nrf2 is closely associated with higher grade of IDD. The apoptosis and senescence of nucleus pulposus cells (NPCs) were exacerbated by Nrf2 knockdown, but suppressed by Nrf2 overexpression under oxidative stress. Based on findings that Kinsenoside could exert multiple pharmacological effects, we found that Kinsenoside rescued the NPC viability under oxidative stress and protected against apoptosis, senescence, and mitochondrial dysfunction in a Nrf2-dependent way. Further experiments revealed that Kinsenoside activated a signaling pathway of AKT-ERK1/2-Nrf2 in NPCs. Moreover, in vivo study showed that Kinsenoside ameliorated IDD in a puncture-induced model. Together, the present work suggests that Nrf2 is involved in the pathogenesis of IDD and shows the protective effects as well as the underlying mechanism of Kinsenoside on Nrf2 activation in NPCs.

Let's spend a little bit of time talking about your therapy. Let's say I hop into a time machine and go to the future, to whatever time it may be for it to have fully hit the market. What's your procedure going to look like?

So let's start with the present. Today, when a person needs a new liver, then a major transplantation surgery is their last option. This is an expensive and major operation - if you ever search online for "liver transplantation," you really do want to brace yourself. And then there's our approach, which uses endoscopic ultrasound to engraft cells into a patient's lymph nodes, and transforms the transplantation process into an outpatient procedure. That's one of the fundamental value propositions of our technology. The patient would be put under light sedation, the endoscope would be moved into a place where it can access your lymph nodes - the mesentery, in your abdominal region - and thirty minutes later you'd have multiple ectopic cell clusters placed there, engrafted by a cellular therapy, and you'd potentially even be able to leave the same day. Over the course of the next few weeks and months your lymph nodes would serve as bioreactors to grow multiple ectopic organs - a process called 'organogenesis' - that would begin filtering your blood and providing life-saving support. That's our vision of the future for our lead candidate in liver regeneration.

So the question that follows from that is: is this a therapy that would be a final procedure? Or is it a stopgap for those who are waiting on a transplant list for a full replacement?

One group of patients, for whom we hope this will be a single procedure and a curative therapy, are the many people with end stage liver disease. Those who have gradually and progressively lost liver function over time. Right now, once you get to a certain threshold where you've lost enough liver function, if you're healthy enough (and don't have any contraindicated medical comorbidities) you might make it onto the liver transplant list. Once you've made it on there you'll wait, oftentimes hundreds of days, or even longer, to receive an organ. And that's if you're lucky. So there's a huge unmet need. Patients need a new liver, but they're too ill and that prevents them from being eligible for a full organ transplantation. Right now there's no viable therapy for these people. So we think our therapy will be the first in line therapy for those patients.

How many lymph nodes, on average, would you need to use for this to work? Are there going to be any side effects from this process?

Right now, our best guess is that we will be grafting ectopic livers into, probably, three to five lymph nodes. You spread the mass of the ectopic organs across multiple lymph nodes, not just a single lymph node. That's our best guess and clinical development plan right now. In the research we've been doing for almost decade now, we've tried everything from a single lymph node to twenty lymph nodes or more, in the different animal models. And we've seen no adverse effects in terms of the transition from the lymph node to an ectopic organ. One thing we stress is that when you look at what happens over time, the lymph node disappears. The lymph node acts like a bioreactor in this process - once it's kicked the organ growth into gear, the organ takes over and the lymph node disappears. And because our bodies have hundreds of lymph nodes distributed throughout, we don't expect that losing a handful of them will produce any untoward effects.

How could this enhance people's longevity going forward?

Another great regenerative medicine story from our platform is based on our work on the thymus, which is fascinating. So, we have proof-of-concept data showing that we can regenerate the thymus ectopically inside the lymph nodes, as well. The thymus, as you may know, has a complicated biology; it does a lot of different things. But there is some indication that one of the effects of rebooting the thymus is to reboot the immune system - which absolutely could have regenerative, and therefore potential longevity, effects. We have try to be very careful about this, lots of things work in small animals that do not translate to people - there are jokes that the medical field has cured cancer in mice so many times over by now. We have to be careful when talking about longevity. Here's this dream of man since the beginning of time, to live longer. I think with some of the regenerative medicine and our understanding of biology we can start to make some inroads but, for what it's worth, I'm very careful not to promise that we're unlocking the fountain of youth. That's not the case. We're trying to develop science-based, FDA-regulated therapies to address unmet medical needs - even though, admittedly, the famous one would be potential downstream effects on aging and longevity.

There's no question that as body weight increases, so too does blood pressure. Now, in a study of mice, researchers have revealed exactly which molecules are likely responsible for the link between obesity and blood pressure. Nearly a third of American adults have high blood pressure, and only about half of those people have their blood pressure under control through medications and lifestyle changes. Hypertension can be especially difficult to treat in obese patients.

The new work revolves around leptin, a molecule that controls appetite and metabolism in response to food. Obese people often become resistant to leptin, so rising levels of the molecule after a meal no longer boost metabolism or cause a feeling of fullness. In response to this resistance, leptin levels continue to rise with obesity. Leptin has also been shown to increase blood pressure and, surprisingly, obesity doesn't change that link - even when people are resistant to leptin's effects on metabolism and appetite, their blood pressure rises in response to the molecule. Until now, researchers weren't sure why.

Previous studies had revealed that there were high levels of leptin receptors in the carotid bodies - tiny clusters of cells along the carotid arteries on either side of the throat that respond to changing levels of oxygen and carbon dioxide in the blood. Researchers wondered whether this could be where leptin affects blood pressure, completely separate from its effects on appetite and metabolism in the brain.

Researchers first confirmed that giving high doses of leptin to lean mice triggered a rise in blood pressure of 10.5 to 12.2 mm Hg, while having no effect on heart rate or food intake. Then, they repeated the experiment in mice without functioning carotid bodies. This time, the animals' blood pressure didn't change in response to leptin. Next, the team studied obese mice that had no leptin receptors - despite their weight, they had normal blood pressure. But when the researchers injected the genes for leptin receptors directly into the carotid bodies of these mice, the animals' blood pressure readings rose by 9.4 to 12.5 mm Hg.