Studying the biological functions of the aryl hydrocarbon receptor (AhR) other than its function in xenobiotic drug metabolism may answer the questions as to why AhR orthologues have long been conserved phylogenically widely in the animal kingdom, and why homologues have diverged from nonvertebrate species such as nematodes and drosophila to all the vertebrate species.
Neutrophils are major cells participants in innate host responses. They are short-lived leukocytes, although microbial products activate intracellular signaling cascades that prolong their survival by inhibiting constitutive apoptosis. To gain insight into the phylogeny of this important cell type, we examined the ability of toll-like receptor agonists to extend the lifespan of gilthead seabream (Sparus aurata L.) acidophilic granulocytes, which are the functional equivalent of mammalian neutrophils.
Cardiovascular (CV) diseases and related complications are the main causes of morbidity and mortality in the elderly. CV progenitor cells, including CD34+ cells, play a role in delaying the progression of atherosclerosis. In the present study we observed 100 octogenarians for seven years, in order to address the question of whether CD34+ cell number is a predictor of longevity in selected survivors.
Very small embryonic-like stem cells (VSELs) are a population of developmentally early stem cells residing in adult tissues. These rare cells, which are slightly smaller than red blood cells, i) become mobilized during stress situations into peripheral blood, ii) are enriched in the Sca1+Lin-CD45- cell fraction in mice and the CD133+ Lin-CD45- cell fraction in humans, iii) express markers of pluripotent stem cells (e.g., Oct4, Nanog, and SSEA), and iv) display a distinct morphology characterized by a high nuclear/cytoplasmic ratio and undifferentiated chromatin.
Self-renewal and multilineage differentiation of stem cells are keys to the lifelong homeostatic maintenance of tissues and organs. Hematopoietic aging, characterized by immunosenescence, proinflammation, and anemia, is attributed to age-associated changes in the number and function of hematopoietic stem cells (HSCs) and their microenvironmental niche. Genetic variants and factors regulating stem cell aging are correlatively or causatively associated with overall organismal aging and longevity.
Aging of the hematological system causes anemia, reduced immunity, and increased incidence of hematological malignancies. Hematopoietic stem cells (HSCs) play a crucial role in this process as their functions decline during aging. Sirtuins are a family of protein lysine modifying enzymes that have diverse roles in regulating metabolism, genome stability, cell proliferation, and survival, and have been implicated in mammalian aging and longevity.
Cellular quiescence is a reversible cell cycle arrest that is poised to re-enter the cell cycle in response to a combination of cell-intrinsic factors and environmental cues. In hematopoietic stem cells, a coordinated balance between quiescence and differentiating proliferation ensures longevity and prevents both genetic damage and stem cell exhaustion. However, little is known about how all these processes are integrated at the molecular level.
Immunodeficient mice bearing targeted mutations in the IL2rg gene and engrafted with human immune systems are effective tools for the study of human haematopoiesis, immunity, infectious disease and transplantation biology. The most robust human immune model is generated by implantation of human fetal thymic and liver tissues in irradiated recipients followed by intravenous injection of autologous fetal liver haematopoietic stem cells [often referred to as the BLT (bone marrow, liver, thymus) model].
The ability of hematopoietic stem cells (HSCs) to self-renew and differentiate into progenitors is essential for homeostasis of the hematopoietic system. The longevity of HSCs makes them vulnerable to accumulating DNA damage, which may be leukemogenic or result in senescence and cell death. Additionally, the ability of HSCs to self-renew and differentiate allows DNA damage to spread throughout the hematologic system, leaving the organism vulnerable to disease.
Hematopoietic stem cells (HSCs) have the immense task of supplying an organism with enough blood to sustain a lifespan. Much of what is known about how this scant population of cells can meet the varying demand of producing more than 10(11) cells per day comes from studies conducted in an animal that is a fraction of our size and lives roughly 1/30th of our lifespan. The differences in longevity can be expected to impose different demands on a cell essential for existence.