Inhibition of the TOR signalling pathway by genetic or pharmacological intervention extends lifespan in invertebrates, including yeast, nematodes and fruitflies; however, whether inhibition of mTOR signalling can extend lifespan in a mammalian species was unknown. Here we report that rapamycin, an inhibitor of the mTOR pathway, extends median and maximal lifespan of both male and female mice when fed beginning at 600 days of age. On the basis of age at 90% mortality, rapamycin led to an increase of 14% for females and 9% for males. The effect was seen at three independent test sites in genetically heterogeneous mice, chosen to avoid genotype-specific effects on disease susceptibility. Disease patterns of rapamycin-treated mice did not differ from those of control mice. In a separate study, rapamycin fed to mice beginning at 270 days of age also increased survival in both males and females, based on an interim analysis conducted near the median survival point. Rapamycin may extend lifespan by postponing death from cancer, by retarding mechanisms of ageing, or both. To our knowledge, these are the first results to demonstrate a role for mTOR signalling in the regulation of mammalian lifespan, as well as pharmacological extension of lifespan in both genders. These findings have implications for further development of interventions targeting mTOR for the treatment and prevention of age-related diseases.

https://escholarship.org/content/qt1sj26154/qt1sj26154.pdf?t=qakeas

Rapamycin fed late in life extends lifespan in genetically heterogeneous mice

Acute tumor lysis syndrome (ATLS) is characterized by severe metabolic abnormalities and organ dysfunction resulting from rapid destruction of neoplastic cells. Metabolic disturbances are thought to be the primary cause of clinical ATLS symptoms, which include renal dysfunction, seizures, and cardiac arrhythmias. The histopathologic lesions associated with organ dysfunction are largely unknown because of the low rate of mortality of ATLS in humans and the few cases of ATLS identified in laboratory animals. Here, we describe histologic, immunohistochemical, and electron microscopic analyses of thirty-one ATLS cases from a cohort of 499 mice that are prone to spontaneous lymphoblastic lymphoma owing to genetic defects in DNA replication fidelity. Seventy-three percent of our cohort died with lymphoblastic lymphoma, and 8% of affected mice died with diffuse microthromboemboli consistent with ATLS. Mice with ATLS had a high spontaneous mortality rate (>50%), a large tumor burden with disseminated disease, and evidence of leukemia. Blood vessels in the lung, kidney, and other organs were occluded by microthromboemboli composed of chromatin, cellular debris, fibrin, platelets, and entrapped erythrocytes and malignant cells. This case series suggests that ATLS can occur at high frequency in mice with disseminated lymphoblastic lymphoma and leads to a high rate of spontaneous death from microthromboemboli.

https://journals.sagepub.com/doi/pdf/10.1177/0192623310362249

Case series: acute tumor lysis syndrome in mutator mice with disseminated lymphoblastic lymphoma.

The mammalian circadian system is a complex hierarchical temporal network which is organized around an ensemble of uniquely coupled cells comprising the principal circadian pacemaker in the suprachiasmatic nucleus of the hypothalamus. This central pacemaker is entrained each day by the environmental light/dark cycle and transmits synchronizing cues to cell-autonomous oscillators in tissues throughout the body. Within cells of the central pacemaker and the peripheral tissues, the underlying molecular mechanism by which oscillations in gene expression occur involves interconnected feedback loops of transcription and translation. Over the past 10 years, we have learned much regarding the genetics of this system, including how it is particularly resilient when challenged by single-gene mutations, how accessory transcriptional loops enhance the robustness of oscillations, how epigenetic mechanisms contribute to the control of circadian gene expression, and how, from coupled neuronal networks, emergent clock properties arise. Here, we will explore the genetics of the mammalian circadian system from cell-autonomous molecular oscillations, to interactions among central and peripheral oscillators and ultimately, to the daily rhythms of behavior observed in the animal.

/pdf/genetics-of-circadian-rhythms-in-mammalian-model-organisms-3cduvvkc4q.pdf

Genetics of circadian rhythms in Mammalian model organisms.

The microbiological quality of experimental animals can critically influence animal welfare and the validity and reproducibility of research data. It is therefore important for breeding and experimental facilities to establish a laboratory animal health monitoring (HM) programme as an integrated part of any quality assurance system. FELASA has published recommendations for the HM of rodent and rabbit colonies in breeding and experimental units (Nicklas et al. Laboratory Animals, 2002), with the intention of harmonizing HM programmes. As stated in the preamble, these recommendations need to be adapted periodically to meet current developments in laboratory animal medicine. Accordingly, previous recommendations have been revised and shall be replaced by the present recommendations. These recommendations are aimed at all breeders and users of laboratory mice, rats, Syrian hamsters, guinea pigs and rabbits as well as diagnostic laboratories. They describe essential aspects of HM, such as the choice of agents, selection of animals and tissues for testing, frequency of sampling, commonly used test methods, interpretation of results and HM reporting. Compared with previous recommendations, more emphasis is put on the role of a person with sufficient understanding of the principles of HM, opportunistic agents, the use of sentinel animals (particularly under conditions of cage-level containment) and the interpretation and reporting of HM results. Relevant agents, testing frequencies and literature references are updated. Supplementary information on specific agents and the number of animals to be monitored and an example of a HM programme description is provided in the appendices.

https://journals.sagepub.com/doi/pdf/10.1177/0023677213516312

FELASA recommendations for the health monitoring of mouse, rat, hamster, guinea pig and rabbit colonies in breeding and experimental units.

Development of a human embryonic stem cell (hESC)-based therapy for type 1 diabetes will require the translation of proof-of-principle concepts into a scalable, controlled, and regulated cell manufacturing process. We have previously demonstrated that hESC can be directed to differentiate into pancreatic progenitors that mature into functional glucose-responsive, insulin-secreting cells in vivo. In this study we describe hESC expansion and banking methods and a suspension-based differentiation system, which together underpin an integrated scalable manufacturing process for producing pancreatic progenitors. This system has been optimized for the CyT49 cell line. Accordingly, qualified large-scale single-cell master and working cGMP cell banks of CyT49 have been generated to provide a virtually unlimited starting resource for manufacturing. Upon thaw from these banks, we expanded CyT49 for two weeks in an adherent culture format that achieves 50–100 fold expansion per week. Undifferentiated CyT49 were then aggregated into clusters in dynamic rotational suspension culture, followed by differentiation en masse for two weeks with a four-stage protocol. Numerous scaled differentiation runs generated reproducible and defined population compositions highly enriched for pancreatic cell lineages, as shown by examining mRNA expression at each stage of differentiation and flow cytometry of the final population. Islet-like tissue containing glucose-responsive, insulin-secreting cells was generated upon implantation into mice. By four- to five-months post-engraftment, mature neo-pancreatic tissue was sufficient to protect against streptozotocin (STZ)-induced hyperglycemia. In summary, we have developed a tractable manufacturing process for the generation of functional pancreatic progenitors from hESC on a scale amenable to clinical entry.

/pdf/a-scalable-system-for-production-of-functional-pancreatic-2mtr2782x3.pdf

A Scalable System for Production of Functional Pancreatic Progenitors from Human Embryonic Stem Cells

The Mouse in biomedical research , The Mouse in biomedical research , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Muriel T. Davisson

Papers

The Mouse in biomedical research

Chapter 3 – Biology and Diseases of Mice