Adult stem cell niches for tissue homeostasis

Abstract

Adult stem cells are fundamental to maintain tissue homeostasis, growth, and regeneration. They reside in specialized environments called niches. Following activating signals, they proliferate and differentiate into functional cells that are able to preserve tissue physiology, either to guarantee normal turnover or to counteract tissue damage caused by injury or disease. Multiple interactions occur within the niche between stem cell-intrinsic factors, supporting cells, the extracellular matrix, and signaling pathways. Altogether, these interactions govern cell fate, preserving the stem cell pool, and regulating stem cell proliferation and differentiation. Based on their response to body needs, tissues can be largely classified into three main categories: tissues that even in normal conditions are characterized by an impressive turnover to replace rapidly exhausting cells (blood, epidermis, or intestinal epithelium); tissues that normally require only a basal cell replacement, though able to efficiently respond to increased tissue needs, injury, or disease (skeletal muscle); tissues that are equipped with less powerful stem cell niches, whose repairing ability is not able to overcome severe damage (heart or nervous tissue). The purpose of this review is to describe the main characteristics of stem cell niches in these different tissues, highlighting the various components influencing stem cell activity. Although much has been done, more work is needed to further increase our knowledge of niche interactions. This would be important not only to shed light on this fundamental chapter of human physiology but also to help the development of cell-based strategies for clinical therapeutic applications, especially when other approaches fail.

Cell Models and Omics Techniques for the Study of Nonalcoholic Fatty Liver Disease: Focusing on Stem Cell-Derived Cell Models

“…Human adult stem cells reside in specific niches inside tissues, and their multipotency allows them to differentiate into different tissue-specific somatic cells to contribute to tissue regeneration and renewal [ 84 ]. In fact, stem cells from different tissues, such as bone marrow, adipose tissue, or umbilical cord blood, have been differentiated into cells with the hepatic phenotype [ 85 ].…”

TrpA1 is a shear stress mechanosensing channel regulating intestinal homeostasis in Drosophila

“…The coordination of ISC division, EB differentiation, and physiological functions of EEs and ECs requires many evolutionarily conserved pathways (2,4,8,11). The investigation of these pathways in the adult Drosophila midgut as a model organism have provided important insights into intestinal regeneration and tissue wellness in mammalian systems (2,4,8,11).…”

“…Regulation of ISC activity and intestinal homeostasis involves physiological signals such as growth factors, hormones, and innervation of the nervous system, as well as external signals from interaction with commensal and ingested microbes, and ingested food particles and fluids (2,4,8,11). The intestinal epithelium is wrapped around by visceral muscle, and the rhythmic peristalsis propels ingested food particles and fluid down the gut lumen.…”

“…ISCs, precursor cells called enteroblasts (EBs), and enteroendocrine cells (EEs) are smaller cells that situated closer to the basal side of the midgut epithelium and serve to support various functions of the intestine (3,4,8). The coordination of ISC division, EB differentiation, and physiological functions of EEs and ECs requires many evolutionarily conserved pathways (2,4,8,11). The investigation of these pathways in the adult Drosophila midgut as a model organism have provided important insights into intestinal regeneration and tissue wellness in mammalian systems (2,4,8,11).…”

Role of the store-operated Ca𝟐+ channel in ATP-induced Ca𝟐+ signalling in mesenchymal stem cells and regulation of cell functions

“…Mesenchymal stem cells (MSC) are present in stem cell niches in many adult tissues, like bone marrow, adipose tissue and dental pulp, and play an essential role in the homeostasis of residing tissues [20]. They are multipotent stem cells and able to differentiate into several cell lineages [21,22].…”