Aged Animals Research Articles

Spontaneous type II cell-derived bronchioloalveolar adenoma in a young ICR mouse.

Although pulmonary adenomas have been reported in ICR mice, spontaneous adenomas have not been reported in mice aged ≤10 weeks. Here, we report a well-circumscribed nodule (1 mm × 1 mm) in the peripheral lesion of the left lateral lobe of a 10-week-old male ICR mouse. Histopathologic evaluation revealed a well-demarcated nodule compressing the surrounding tissue. The neoplastic cells were polygonal with indistinct cellular borders, round/oval nuclei and abundant cytoplasm. These characteristics led to the diagnosis of type II cell-derived bronchioloalveolar adenoma. Given that they are generally observed in aged laboratory animals, this case represents a rare manifestation of a spontaneous tumor in young laboratory mice before puberty.

Extreme Body Condition Index Values in Small Mammals.

The body condition index (BCI) values in small mammals are important in understanding their survival and reproduction. The upper values could be related to the Chitty effect (presence of very heavy individuals), while the minimum ones are little known. In this study, we analyzed extremes of BCI in 12 small mammal species, snap-trapped in Lithuania between 1980 and 2023, with respect to species, animal age, sex, and participation in reproduction. The proportion of small mammals with extreme body condition indices was negligible (1.33% with a BCI < 2 and 0.52% with a BCI > 5) when considering the total number of individuals processed (n = 27,073). When compared to the expected proportions, insectivores and herbivores were overrepresented, while granivores and omnivores were underrepresented among underfit animals. The proportions of granivores and insectivores were higher, while those of omnivores and herbivores were lower than expected in overfit animals. In several species, the proportions of age groups in underfit and overfit individuals differed from that expected. The male-female ratio was not expressed, with the exception of Sorex araneus. The highest proportion of overfit and absence of underfit individuals was found in Micromys minutus. The observation that individuals with the highest body mass are not among those with the highest BCI contributes to the interpretation of the Chitty effect. For the first time in mid-latitudes, we report individuals of very high body mass in three shrew species.

The Commerson's dolphin as Subantarctic sentinel of POPs: Insights into the pollutant status in one of the southernmost coastal areas of the globe

Persistent organic pollutants (POPs) are halogenated contaminants found globally. Cetaceans are impacted by these pollutants, and nowadays, it is essential to understand their presence to mitigate their impacts. This study aimed to establish baseline levels of POPs in the blubber of Commerson's dolphins (Cephalorhynchus commersonii) within the Subantarctic ecosystem. A wide range of POPs concentrations were measured among individuals: ΣPCBs from 289.5 to 15264 ng g−1 lw and ΣDDTs from 540.4 to 17657 ng g−1 lw. Levels of HCB and mirex ranged from 48 to 1703.7 ng g−1 lw and 5.1–1917.4 ng g−1 lw, respectively. The predominant POPs were mid-to high molecular weight PCBs (hexa-PCBs), consistent with other findings in cetaceans of the southern hemisphere. The mean ratio of ΣDDT/ΣPCB was 0.44, with p,p′-DDE/ΣDDT at 0.56, indicating p,p’-DDE as the dominant DDT isomer. Furthermore, differences in POP concentrations were observed based on sexual maturity, with mature males exhibiting higher levels of ƩPCBs, HCB, ƩDDT, and mirex. Age and total body length of animals were strongly correlated with POP concentrations. Our study provides valuable insights into the pollutant status of POPs in the Subantarctic population of Commerson's dolphins inhabiting the southernmost coastal regions of South America.

Comparative analysis of environmental adaptation and individual strategy choice in animal foraging behavior

Comparative analysis of environmental adaptation and individual strategy choice in animal foraging behavior

Cannot outrun the past: age, nutrition, and cohort influence horn size in pronghorn

AbstractIn North America, most ungulate species exhibit life‐history traits typical of long‐lived, iteroparous species wherein young males tend to prioritize essential life functions including body growth and maintenance that constrains allocation of resources to horn, antler, and pronghorn growth. As a result, males of most ungulate species require several years of growth before reaching asymptotic body size and thereafter, peak weapon size is attained. Unique among ungulate species in North America, pronghorn possess a suite of life‐history traits resulting in a precocious (i.e., unusually early development) pace of life relative to other North American ungulates. We tested the hypothesis that the fast pace of life of pronghorn extends to precocious development of large horns, and evaluated how horn size was affected by environmental conditions during the year they were grown and the potential for cohort effects associated with environmental signatures during the year of birth. We evaluated the influence of age and the environment on horn size of pronghorn using data collected from 1,789 male pronghorn harvested from 2019 to 2022 in Wyoming, USA. Pronghorn attained 95% of their peak horn size by 3.5 years old. Climatic conditions influenced horn growth through cohort effects and year of growth pathways. Snow depth during the year of birth positively influenced horn size, whereas the effects of environmental conditions during the year of horn growth were dependent on age. For young animals, snow depth and moderate drought positively influenced horn size during the year of horn growth, but the effect was negligible for prime aged and old animals. The precocious nature of pronghorn extended to their horn growth characteristics, resulting in early attainment of a large proportion of their peak horn size. The unique ecology of pronghorn and rapid attainment of size early in life can allow for greater flexibility to balance hunter opportunity and production of large‐horned males for pronghorn as compared with other ungulates.

ER-phagy drives age-onset remodeling of endoplasmic reticulum structure-function and lifespan.

The endoplasmic reticulum (ER) comprises an array of structurally distinct subdomains, each with characteristic functions. While altered ER-associated processes are linked to age-onset pathogenesis, whether shifts in ER morphology underlie these functional changes is unclear. We report that ER remodeling is a conserved feature of the aging process in models ranging from yeast to C. elegans and mammals. Focusing on C. elegans as an exemplar of metazoan aging, we find that as animals age, ER mass declines in virtually all tissues and ER morphology shifts from rough sheets to tubular ER. The accompanying large-scale shifts in proteomic composition correspond to the ER turning from protein synthesis to lipid metabolism. To drive this substantial remodeling, ER-phagy is activated early in adulthood, promoting turnover of rough ER in response to rises in luminal protein-folding burden and reduced global protein synthesis. Surprisingly, ER remodeling is a pro-active and protective response during aging, as ER-phagy impairment limits lifespan in yeast and diverse lifespan-extending paradigms promote profound remodeling of ER morphology even in young animals. Altogether our results reveal ER-phagy and ER morphological dynamics as pronounced, underappreciated mechanisms of both normal aging and enhanced longevity.

Anti-aging interventions in geriatric mice: insights into the timing of treatment, benefits, and limitations.

Studies aimed at preventing age-associated diseases are fundamental in addressing the challenges posed by an aging population. However, biomedical and technological advancements have now reached a stage where it appears increasingly possible to repair the damage caused by severe pathologies and reverse the functional decline that accompanies aging. This perspective highlights the significance of using aging models, specifically non-transgenic geriatric mice (aged over 24months), to study interventions aimed at reversing or ameliorating age-related pathologies. While most research typically utilizes young, adult, and mid-aged mice to investigate aging mechanisms and develop preventive strategies, geriatric models provide unique insights into the efficacy and safety of treatments in conditions that mimic the complexities of multiple concurrent diseases or syndromes. This manuscript highlights the importance of considering timing responses in aging interventions, illustrated by recent findings such as those involving canagliflozin. These studies reveal that the timing of intervention can significantly influence the outcomes, highlighting aspects often overlooked. Practical challenges and resource demands associated with geriatric mouse studies including concerns related to animal husbandry and aging phenotypes are also discussed. This perspective aims to foster a deeper understanding of the potential benefits and limitations of geriatric mice models in geroscience research and emphasizes the need for continued innovation in this field to meet the critical need to develop effective treatments for age-related diseases.

INTENSITY OF GREENHOUSE GAS FORMATION DUE TO LIVESTOCK FARMING ACTIVITIES – AS AN ENVIRONMENTAL FACTOR

According to numerous expert assessments by international organizations and specialists, animal husbandry makes a significant negative contribution to global climate change due to the emission of greenhouse gases (GHG), which are formed at different stages of livestock production as a result of various chemical and biological processes in the body of animals and in livestock waste. The domestic animal husbandry is developing mainly due to the intensification of production in the industry, but traditional farming methods as well as small-scale production in the individual sector also take place. Since the use of various technologies in animal husbandry has different effects on the level of environmental pollution and GHG emissions, the aim of the research was to study the differences in the intensity of GHG gas formation by one animal reared with individual features of animal rearing technologies and business activities. The intensity of gas formation and emission of CH4 and N2O in typical farms for pork production and milk production by one animal reared was determined, analyzed and substantiated. A significant variation in this indicator was found depending on the individual economic and technological features of the studied farms. The average weighted annual intensity of CH4 emission from animal manure in pig farms varied within the range of 0.95–25.71, in cattle farm – 2.74; CH4 from intestinal fermentation of dairy cows – 110.8–148.4; N2O (direct) in pig farms – 0.0–0.106, in cattle farm – 0.229; N2O (indirect) in pig farms – 0.071–0.097, in cattle farm – 0.174. The emission intensity is characterized separately in each age and sex group of animals in the herd structure of farms and the average weighted emission intensity in pork producing farms depending on the season. Based on the research results, it is proposed to use the generalized average annual indicator of greenhouse gas emissions per one average weighted animal reared (kg/head/year) as an indicator of the environmental load of livestock farms on the environment, which will allow planning production volumes with minimal environmental risks in the context of climate change.

Computational model for synthesizing auditory brainstem responses to assess neuronal alterations in aging and autistic animal models.

This study presents a novel computational model of the auditory brainstem, capable of synthesizing auditory brainstem response (ABR) traces by simulating large-scale neuronal activities. Addressing limitations of traditional ABR measurements, the model links ABR waveform features to underlying neuronal properties. Validated using empirical ABRs from animal models of autism and aging, the model accurately reproduced observed ABR alterations, revealing influences of myelin deficits and hyperexcitability in Fragile X syndrome, and degraded inhibitory activity in aging. These findings, supported by experimental data, demonstrate the model's potential for predicting changes in auditory brainstem physiology and guiding further physiological investigations, thus advancing our understanding of auditory neural processes.

Продуктивные особенности коров голштинской породы разных генетических линий

Abstract. The purpose of the study is to investigate the productive features of Holstein cows of different genetic lines. Methods. The research was carried out in two breeding enterprises of the Sverdlovsk region on the livestock of Holstein cows. Groups of animals were formed by the method of pairs of analogues, taking into account the age of animals in lactation, physiological condition, live weight, lines of breeding bulls. The coefficient of milk content was estimated by the calculation method. The lactose, fat and protein content in milk was determined using a “Bentley 150” device. Somatic cells were determined on the “Somatos-M” device. Bacterial contamination was studied using a reductase assay. Prolactin was determined by enzyme immunoassay, cortisol by immunochemiluminescent method. Results. In terms of milk yield for 305 days of lactation and protein content in milk, Montwick Chieftain cows had an advantage with a significant difference between the groups (P &lt; 0.05). The animals of the Reflection Sovering line were the best in terms of fat content, the difference between the groups was insignificant. The lowest content of somatic cells in milk and bacterial contamination was found in animals of the Reflection Sovering and Vis Back Idial lines. The best indicators of the leukocyte profile were determined in animals of the Vis Back Idial and Montwick Chieftain lines. In terms of glucose and total protein content in the blood, cows of the Montwick Chieftain line had an advantage, in terms of the amount of urea, animals of the Montwick Chieftain and Vis Back Idial line affiliation. The highest level of total lipids in the blood is typical for cows of the Reflection Sovering line. Scientific novelty. The research results indicate the relationship of biological characteristics and milk productivity with different lines of breeding bulls. The leukocyte profile of this herd of cows of different genetic lines in breeding enterprises of the Sverdlovsk region was studied for the first time. Practical significance. The results of the research can be used in breeding enterprises in order to increase the milk productivity of cows.

Highly regenerative species-specific genes improve age-associated features in the adult Drosophila midgut

BackgroundThe remarkable regenerative abilities observed in planarians and cnidarians are closely linked to the active proliferation of adult stem cells and the precise differentiation of their progeny, both of which typically deteriorate during aging in low regenerative animals. While regeneration-specific genes conserved in highly regenerative organisms may confer regenerative abilities and long-term maintenance of tissue homeostasis, it remains unclear whether introducing these regenerative genes into low regenerative animals can improve their regeneration and aging processes.ResultsHere, we ectopically express highly regenerative species-specific JmjC domain-encoding genes (HRJDs) in Drosophila, a widely used low regenerative model organism. Surprisingly, HRJD expression impedes tissue regeneration in the developing wing disc but extends organismal lifespan when expressed in the intestinal stem cell lineages of the adult midgut under non-regenerative conditions. Notably, HRJDs enhance the proliferative activity of intestinal stem cells while maintaining their differentiation fidelity, ameliorating age-related decline in gut barrier functions.ConclusionsThese findings together suggest that the introduction of highly regenerative species-specific genes can improve stem cell functions and promote a healthy lifespan when expressed in aging animals.

Abstract Or117: JNK2-mediated gut-heart crosstalk in aging-associated AF pathogenesis.

Introduction: Aging is an independent risk factor for atrial fibrillation (AF). We recently revealed a critical role of activated cardiac stress kinase JNK2 in AF risk. Yet, the mechanisms underlying JNK2 activation in the aged heart remain unclear. Emerging evidence suggests that organ crosstalk critically contributes to the development of heart diseases. Interestingly, increased AF episodes were clinically observed in patients with active gastrointestinal (GI) diseases (with a hallmark of enhanced intestinal epithelial barrier permeability (‘leaky gut’), but reduced AF during remission. While both GI dysfunction and enhanced AF risk are seen in aged humans and animal models, whether aging-associated leaky gut leads to AF pathogenesis through activated JNK2 remains unknown. Methods: To assess the leaky gut and AF link, young (Yg, 2 mo) wildtype (WT) and JNK2dn mice (cardiac-specific overexpression of inactive dominant negative (dn) JNK2) were used for aged fecal matter transplant (FMT), while aged (Ag, 24 mo) mice were transplanted with Yg fecal matter to rescue aging-associated AF. Atrial tachycardia/fibrillation (AT/AF) incidence was measured using our well-established protocol, and GI permeability was measured using a serum dextran (4-kDa) FITC fluorescence assay 7 days post-FMT. Results: Aged WT mice had an elevated FITC level (4.9±1.5 µg/ml vs 0.98±0.04 µg/ml; n=11,8; p&lt;0.01) with increased AT/AF inducibility compared to Yg mice (n=7,10; p&lt;0.05). Interestingly, Yg WT recipients subjected to aged FMT (Ag-to-Yg) exhibited an ~3-fold increase in GI permeability (n=14; p&lt;0.01) and significantly enhanced AT/AF inducibility relative to Yg sham controls (8 of 13 vs 0 of 10; p&lt;0.05), while Yg-to-Yg FMT did not alter GI permeability and AT/AF inducibility in Yg recipients (0 of 5, p=NS). Strikingly, cardiac-specific JNK2 inhibition prevented aged-FMT-caused AT/AF in Yg JNK2dn recipient mice (0 of 10; p&lt;0.01), suggesting that activated cardiac JNK2 underlies leaky gut-evoked AF in aging. Further, Yg-to-Ag FMT eliminated aged-associated AT/AF inducibility in aged recipients (0 of 6). Conclusion: Aging-associated GI dysfunction enhances cardiac JNK2 activation, which in turn drives AF risk. Targeting cardiac JNK2 could be a novel anti-AF therapeutic strategy.

The effect of hypochlorous acid inhalation on the activity of antioxidant system enzymes in rats of different ages

Hypochlorous acid HOCl is an effective disinfectant with a broad spectrum and high rate of microbicidal action. Its use for air treatment can be an effective tool for the prevention and therapy of infectious diseases. In this work, the in vivo study was conducted on 110 Wistar Han rats (12 and 72 weeks old) on the effect of a single inhalation of air containing gaseous HOCl on the activity of antioxidant system enzymes. For this, a special installation was designed to uniformly maintain the concentration of HOCl in the air and regulate it over a wide range. Inhalation exposure was carried out for 4 h at total chlorine concentrations in the air of approximately 2.0 mg/m3 and 5.0 mg/m3, after which the animals were observed for 14 days. The effect of inhalation on the antioxidant system activity varied significantly in animals of different ages. Catalase activity in young rats increased approximately 2-fold on days 1-2 after inhalation, regardless of the HOCl concentration, while in old animals a sharp dose-dependent decrease was initially observed. The glutathione peroxidase activity in animals of both ages increased upon inhalation of air with 5.0 mg/m3 HOCl, and in old animals this was more pronounced; when the HOCl concentration decreased to 2.0 mg/m3, this indicator increased slightly in old rats and remained virtually unchanged in young ones. The glutathione reductase activity when exposed to 2.0 mg/m3 HOCl did not change for both age groups, and with increasing HOCl concentration it increased by 1.5-2.0 times in all animals.

Effects of pre-treatment, historical age, and sample characteristics on the stable isotope analyses of killer whale (Orcinus orca) bone.

Stable isotope analysis of bone provides insight into animal foraging and allows for ecological reconstructions over time, however pre-treatment is required to isolate collagen. Pre-treatments typically consist of demineralization to remove inorganic components and/or lipid extraction to remove fats, but these protocols can differentially affect stable carbon (δ13C) and nitrogen (δ15N) isotope values depending on the chemicals, tissues, and/or species involved. Species-specific methodologies create a standard for comparability across studies and enhance understanding of collagen isolation from modern cetacean bone. Elemental analyzers coupled to isotope ratio mass spectrometers were used to measure the δ13C and δ15N values of powdered killer whale (Orcinus orca) bone that was intact (control) or subjected to one of three experimental conditions: demineralized, lipid-extracted, and both demineralized and lipid-extracted. Additionally, C:N ratios were evaluated as a proxy for collagen purity. Lastly, correlations were examined between control C:N ratios vs. historical age and control C:N ratios vs. sample characteristics. No significant differences in the δ15N values were observed for any of the experimental protocols. However, the δ13C values were significantly increased by all three experimental protocols: demineralization, lipid extraction, and both treatments combined. The most influential protocol was both demineralization and lipid extraction. Measures of the C:N ratios were also significantly lowered by demineralization and both treatments combined, indicating the material was closer to pure collagen after the treatments. Collagen purity as indicated via C:N ratio was not correlated with historical age nor sample characteristics. If only the δ15N values from killer whale bone are of interest for analysis, no pre-treatment seems necessary. If the δ13C values are of interest, samples should be both demineralized and lipid-extracted. As historical age and specimen characteristics are not correlated with sample contamination, all samples can be treated equally.

Reactive oxygen-scavenging polydopamine nanoparticle coated 3D nanofibrous scaffolds for improved osteogenesis: Toward an aging in vivo bone regeneration model.

Tissue engineered scaffolds aimed at the repair of critical-sized bone defects lack adequate consideration for our aging society. Establishing an effective aged in vitro model that translates to animals is a significant unmet challenge. The in vivo aged environment is complex and highly nuanced, making it difficult to model in the context of bone repair. In this work, 3D nanofibrous scaffolds generated by the thermally-induced self-agglomeration (TISA) technique were functionalized with polydopamine nanoparticles (PD NPs) as a tool to improve drug binding capacity and scavenge reactive oxygen species (ROS), an excessive build-up that dampens the healing process in aged tissues. PD NPs were reduced by ascorbic acid (rPD) to further improve hydrogen peroxide (H2O2) scavenging capabilities, where we hypothesized that these functionalized scaffolds could rescue ROS-affected osteoblastic differentiation in vitro and improve new bone formation in an aged mouse model. rPDs demonstrated improved H2O2 scavenging activity compared to neat PD NPs, although both NP groups rescued the alkaline phosphatase activity (ALP) of MC3T3-E1 cells in presence of H2O2. Additionally, BMP2-induced osteogenic differentiation, both ALP and mineralization, was significantly improved in the presence of PD or rPD NPs on TISA scaffolds. While in vitro data showed favorable results aimed at improving osteogenic differentiation by PD or rPD NPs, in vivo studies did not note similar improvements in ectopic bone formation an aged model, suggesting that further nuance in material design is required to effectively translate to improved in vivo results in aged animal models.

A comparative assessment of age-related nicotinamide adenine dinucleotide phosphate-diaphorase positivity in the spinal cord and medulla oblongata of pigeons, rats, and mice.

Nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase (N-d) positive neurons have been extensively studied across various animals, and N-d neurodegenerative neurites have been detected in some aged animal models. However, detailed knowledge on N-d positivity and aging-related alterations in the spinal cord and medulla oblongata of pigeons is limited. In this study, we investigated N-d positivity and age-related changes in the pigeon's spinal cord and medulla oblongata and compared them to those in rats and mice. Pigeons, had more N-d neurons in the dorsal horn, around the central canal, and in the column of Terni in the thoracic and lumbar segments, with scattered neurons found in the ventral horn of the spinal segments. N-d neurons were also present in the white matter of the spinal cord. Morphometric analysis revealed that the size of N-d soma in the lumbosacral, cervical, and thoracic regions was substantially altered in aged pigeons compared to young birds. Furthermore, the lumbar to sacral segments underwent significant morphological alterations. The main findings of this study were the presence of age-related N-d positive bodies (ANB) in aged pigeons, predominantly in the external cuneate nucleus (CuE) and occasionally in the gracilis and CuEs. ANBs were also identified in the gracile nuclei and spinal cord in the aged rats and mice, whereas in aged rats, ANBs were detected in the CuE spinal nucleus. Immunohistochemistry showed that the age-related alterations occurred in the cell types and neuropeptides in old animals. The results suggest weak inflammatory response and neuronal dysfunction in the spinal cord in aged pigeons. Our results suggested that the ANB could be a potential aging marker for the central nervous system.

Age dictates brain functional connectivity and axonal integrity following repetitive mild traumatic brain injuries in mice

Traumatic brain injuries (TBI) present a major public health challenge, demanding an in-depth understanding of age-specific symptoms and risk factors. Aging not only significantly influences brain function and plasticity but also elevates the risk of hospitalizations and death following TBIs. Repetitive mild TBIs (rmTBI) compound these issues, resulting in cumulative and long-term brain damage in the brain. In this study, we investigate the impact of age on brain network changes and white matter properties following rmTBI by employing a multi-modal approach that integrates resting-state functional magnetic resonance imaging (rsfMRI), graph theory analysis, diffusion tensor imaging (DTI), and neurite orientation dispersion and density imaging (NODDI). Our hypothesis is that the effects of rmTBI are worsened in aged animals, with this group showing more pronounced alterations in brain connectivity and white matter structure. Utilizing the closed-head impact model of engineered rotational acceleration (CHIMERA) model, we conducted rmTBIs or sham (control) procedures on young (2.5–3-months-old) and aged (22-months-old) male and female mice to model high-risk groups. Functional and structural imaging unveiled age-related reductions in communication efficiency between brain regions, while injuries induced opposhigh-risking effects on the small-world index across age groups, influencing network segregation. Functional connectivity analysis also identified alterations in 79 out of 148 brain regions by age, treatment (sham vs. rmTBI), or their interaction. Injuries exerted pronounced effects on sensory integration areas, including insular and motor cortices. Age-related disruptions in white matter integrity were observed, indicating alterations in various diffusion directions (mean diffusivity, radial diffusivity, axial diffusivity, and fractional anisotropy) and density neurite properties (dispersion index, intracellular and isotropic volume fraction). Neuroinflammation, assessed through Iba-1 and GFAP markers, correlated with higher dispersion in the optic tract, suggesting a neuroinflammatory response in injured aged animals compared to sham aged. These findings offer insight into the interplay between age, injuries, and brain connectivity, shedding light on the long-term consequences of rmTBI.

Age-related myelin deficits in the auditory brain stem contribute to cocktail-party deficits.

Age-related hearing loss is a global health problem of increasing importance. While the role of peripheral hearing loss is well understood and treatments are available, central hearing loss, the ability of the brain to make sense of sound, is much less well understood and no treatments are available. We report on age-related alterations in the auditory brain stem which compromise a listener's ability to isolate a sound from competing background noises, for example in a crowded restaurant. Sound localization depends on extreme temporal precision on the order of microseconds, and the sound localization pathway shows several specializations towards temporal precision. The pathway from the cochlear nucleus to the medial nucleus of the trapezoid body (MNTB) is heavily myelinated and terminates in the calyx of Held. Using auditory brain stem response measurements (ABRs), we found that the physiological properties of MNTB changes with age. The mechanism is that in older animals, MNTB afferents demyelinate to various degrees, resulting in larger variability in the timing of responses. Myelin is produced by oligodendrocytes, and we found that fewer mature, but more precursor and immature oligodendrocytes are present in MNTB of aged animals, suggesting that the demyelination is an age-related deficit in oligodendrocyte maturation.

Age and dose dependent changes to the bone and bone marrow microenvironment after cytotoxic conditioning with busulfan.

Preparative regimens before Hematopoietic Cell Transplantation (HCT) damage the bone marrow (BM) microenvironment, potentially leading to secondary morbidity and even mortality. The precise effects of cytotoxic preconditioning on bone and BM remodeling, regeneration, and subsequent hematopoietic recovery over time remain unclear. Moreover, the influence of recipient age and cytotoxic dose have not been fully described. In this study, we longitudinally investigated bone and BM remodeling after busulfan treatment with low intensity (LI) and high intensity (HI) regimens as a function of animal age. As expected, higher donor chimerism was observed in young mice in both LI and HI regimens compared to adult mice. Noticeably in adult mice, significant engraftment was only observed in the HI group. The integrity of the blood-bone marrow barrier in calvarial BM blood vessels was lost after busulfan treatment in the young mice and remained altered even 6weeks after HCT. In adult mice, the severity of vascular leakage appeared to be dose-dependent, being more pronounced in HI compared to LI recipients. Interestingly, no noticeable change in blood flow velocity was observed following busulfan treatment. Ex vivo imaging of the long bones revealed a reduction in the frequency and an increase in the diameter and density of the blood vessels shortly after treatment, a phenomenon that largely recovered in young mice but persisted in older mice after 6weeks. Furthermore, analysis of bone remodeling indicated a significant alteration in bone turnover at 6weeks compared to earlier timepoints in both young and adult mice. Overall, our results reveal new aspects of bone and BM remodeling, as well as hematopoietic recovery, which is dependent on the cytotoxic dose and recipient age.

Epigenetic aging studies of pair bonding in prairie voles

The quality of romantic relationships can predict health consequences related to aging. DNA methylation-based biomarkers of aging accurately estimate chronological age. We developed several highly accurate epigenetic aging clocks, based on highly conserved mammalian CpGs, for the socially monogamous prairie vole (Microtus ochrogaster). In addition, our dual-species human-vole clock accurately measured relative age and illustrates high species conservation of epigenetic aging effects. Next, we assessed how pair bonding impacts epigenetic aging. We did not find evidence that pair-bonded voles exhibit accelerated or decelerated epigenetic aging effects in blood, ear, liver, or brain tissue. Our epigenome wide association study identified CpGs in five genes strongly associated with pair bonding: Foxp4, Phf2, Mms22l, Foxb1, and Eif1ad. Overall, we present accurate DNA methylation-based estimators of age for a species of great interest to researchers studying monogamy in animals. We did not find any evidence that sex-naive animals age differently from pair-bonded animals.