Search

This chapter covers the basics of fluid homeostasis and fluids that are employed to maintain homeostasis in the perioperative setting. It begins with a basic review of human physiology in relation to fluids, age, and gender. Historical background is also provided on the 4–2–1 rule, the method of choice for determining fluid rate administration that has been passed on from generation to generation of physicians. Then it transitions into how the homeostasis is maintained in the perioperative setting. Particular emphasis is given to the most commonly administered fluids, such as PlasmaLyte, lactated Ringer’s, normal saline (crystalloids), and albumin (colloids). The reader will learn what these fluids are made of, what makes them different, as well as how and why certain fluids should be given and when they could be potentially dangerous.

Fibrogenesis is part of a normal protective response to tissue injury that can become irreversible and progressive, leading to fatal diseases. Senescent cells are a main driver of fibrotic diseases through their secretome, known as senescence-associated secretory phenotype (SASP). However, the mechanisms involved in the conversion of damaged cells into senescent cells remain incompletely understood. Here, we report that multiple types of fibrotic diseases in mice and humans are characterized by the accumulation of iron. We show that vascular and hemolytic injuries, through the release of iron, are efficient in triggering senescence and fibrosis. Interestingly, the accumulation of iron is an intrinsic property of senescent cells that does not require an abnormal surge in extracellular iron. Upon damage, cells initiate an iron accumulation response with abundant ferritin-bound iron within lysosomes and high levels of labile iron, the latter being a main driver of senescence-associated ROS and SASP. Finally, we demonstrate that detection of iron by magnetic resonance imaging (MRI) is a powerful non-invasive method to assess fibrotic burden in the kidneys of mice and patients with renal fibrosis. Our findings establish a central role for iron accumulation in senescence and fibrogenesis.

Senescent cells accumulate in tissues over time, favoring the onset and progression of multiple age-related diseases. Senescent cells present a remarkable increase in lysosomal mass and elevated autophagic activity. Here, we report that two main autophagic pathways macroautophagy (MA) and chaperone-mediated autophagy (CMA) are constitutively upregulated in senescent cells. Proteomic analyses of the subpopulations of lysosomes preferentially engaged in each of these types of autophagy revealed profound quantitative and qualitative changes in senescent cells, affecting both lysosomal resident proteins and cargo proteins delivered to lysosomes for degradation. These studies have led us to identify resident lysosomal proteins that are highly augmented in senescent cells and can be used as novel markers of senescence, such as arylsulfatase ARSA. The abundant secretome of senescent cells, known as SASP, is considered their main pathological mediator; however, little is known about the mechanisms of SASP secretion. Some secretory cells, including melanocytes, use the small GTPase RAB27A to perform lysosomal secretion. We found that this process is exacerbated in the case of senescent melanoma cells, as revealed by the exposure of lysosomal membrane integral proteins LAMP1 and LAMP2 in their plasma membrane. Interestingly, a subset of SASP components, including cytokines CCL2, CCL3, CXCL12, cathepsin CTSD, or the protease inhibitor SERPINE1, are secreted in a RAB27A-dependent manner in senescent melanoma cells. Finally, proteins previously identified as plasma biomarkers of aging are highly enriched in the lysosomes of senescent cells, including CTSD. We conclude that the lysosomal proteome of senescent cells is profoundly reconfigured, and that some senescent cells can be highly active in lysosomal exocytosis.© 2022 The Authors. Aging Cell published by Anatomical Society and John Wiley & Sons Ltd.

Senescence is a state of permanent cell cycle arrest. Cellular senescence can promote tissue remodelling but can negatively affect regenerative capacities of tissues and contribute to inflammation and the progression of cancer and ageing-related diseases. This Review highlights the chemical characteristics of senescence and how we can target senescent cells with small molecules to induce senescence in hyperproliferative tissues. Alternatively, these small molecules can also be administered to inhibit senescence or eliminate senescent cells as the basis of a promising strategy to treat ageing-related diseases. We also describe advances in detecting senescence in in vitro and in vivo models, such that we can evaluate response to treatments intended to induce or eliminate senescent cells. Senescence is a state of permanent cell cycle arrest. This Review highlights the chemical characteristics of senescence and how we can use small molecules to target, detect or eliminate senescent cells, as well as to induce or inhibit senescence.

Palbociclib is a selective inhibitor of cyclin-dependent kinases 4 and 6 (CDK4/6) approved for the treatment of some cancers. The main mechanism of action of palbociclib is to induce cell cycle arrest and senescence on responsive cells. Here, we report that palbociclib concentrates in intracellular acidic vesicles, where it can be readily observed due to its intrinsic fluorescence, and it is released from these vesicles upon dilution or washing out of the extracellular medium. This reversible storage of drugs into acidic vesicles is generally known as lysosomal trapping and, based on this, we uncover novel properties of palbociclib. In particular, a short exposure of cells to palbociclib is sufficient to produce a stable cell-cycle arrest and long-term senescence. Moreover, after washing out the drug, palbociclib-treated cells release the drug to the medium and this conditioned medium is active on susceptible cells. Interestingly, cancer cells resistant to palbociclib also accumulate and release the drug producing paracrine senescence on susceptible cells. Finally, other lysosomotropic drugs, such as chloroquine, interfere with the accumulation of palbociclib into lysosomes, thereby reducing the minimal dose of palbociclib required for cell-cycle arrest and senescence. In summary, lysosomal trapping explains the prolonged temporal activity of palbociclib, the paracrine activity of exposed cells, and the cooperation with lysosomotropic drugs. These are important features that may help to improve the therapeutic dosing and efficacy of palbociclib. Finally, two other clinically approved CDK4/6 inhibitors, ribociclib and abemaciclib, present a similar behavior as palbociclib, suggesting that lysosomal trapping is a property common to all three clinically-approved CDK4/6 inhibitors.

Cellular senescence is a state of stable cell cycle arrest that can negatively affect the regenerative capacities of tissues and can contribute to inflammation and the progression of various aging-related diseases. Advances in the in vivo detection of cellular senescence are still crucial to monitor the action of senolytic drugs and to assess the early onset or accumulation of senescent cells. Here, we describe a naphthalimide-styrene-based probe (HeckGal) for the detection of cellular senescence both in vitro and in vivo. HeckGal is hydrolyzed by the increased lysosomal β-galactosidase activity of senescent cells, resulting in fluorescence emission. The probe was validated in vitro using normal human fibroblasts and various cancer cell lines undergoing senescence induced by different stress stimuli. Remarkably, HeckGal was also validated in vivo in an orthotopic breast cancer mouse model treated with senescence-inducing chemotherapy and in a renal fibrosis mouse model. In all cases, HeckGal allowed the unambiguous detection of senescence in vitro as well as in tissues and tumors in vivo. This work is expected to provide a potential technology for senescence detection in aged or damaged tissues.

[EN] Cellular senescence is a state of stable cell cycle arrest that can negatively affect the regenerative capacities of tissues and can contribute to inflammation and the progression of various aging-related diseases. Advances in the in vivo detection of cellular senescence are still crucial to monitor the action of senolytic drugs and to assess the early onset or accumulation of senescent cells. Here, we describe a naphthalimide-styrene-based probe (HeckGal) for the detection of cellular senescence both in vitro and in vivo. HeckGal is hydrolyzed by the increased lysosomal beta-galactosidase activity of senescent cells, resulting in fluorescence emission. The probe was validated in vitro using normal human fibroblasts and various cancer cell lines undergoing senescence induced by different stress stimuli. Remarkably, HeckGal was also validated in vivo in an orthotopic breast cancer mouse model treated with senescence-inducing chemotherapy and in a renal fibrosis mouse model. In all cases, HeckGal allowed the unambiguous detection of senescence in vitro as well as in tissues and tumors in vivo. This work is expected to provide a potential technology for senescence detection in aged or damaged tissues., R.M. laboratory members thank the financial support from the Spanish Government (project RTI2018-100910-B-C41) and the Generalitat Valenciana (project PROMETEO 2018/024). B.L.-T. is grateful to the Spanish Ministry of Economy for their PhD grants (FPU15/02707). I.G. thanks her contract from IDM. J.F.-B. thanks to his postdoctoral fellowship (CD19/00038). J.A.L.-D. thanks the financial support from the Ministry of Science/MICINN (IJCI-2017-33047). Work in the laboratory of M.S. was funded by the IRB and by grants from the Spanish Ministry of Economy cofunded by the European Regional Development Fund (ERDF) (SAF201348256-R), the European Research Council (ERC-2014-AdG/669622), and the "laCaixa" Foundation. The D.M.-E. laboratory is supported by the Cancer Research U.K. (CRUK), Cambridge Centre Early Detection Programme, by a CRUK Early Detection OHSU project award (C62187/A26989), by a Medical Research Council (MRC) New Investigators Research Grant (NIRG, MR/R000530/1).

Planar cell polarity (PCP), the coordinated and consistent orientation of cells in the plane of epithelial sheets, is a fundamental and conserved property of animals and plants. Up to now, the smallest unit expressing PCP has been considered to be an entire single cell. We report that, in the larval epidermis of Drosophila, different subdomains of one cell can have opposite polarities. In larvae, PCP is driven by the Dachsous/Fat system; we show that the polarity of a subdomain within one cell is its response to levels of Dachsous/Fat in the membranes of contacting cells. During larval development, cells rearrange (Saavedra et al., 2014) and when two subdomains of a single cell have different types of neighbouring cells, then these subdomains can become polarised in opposite directions. We conclude that polarisation depends on a local comparison of the amounts of Dachsous and Fat within opposing regions of a cell's membrane.

Rationale: Cellular senescence is a key mechanism implicated in the pathogenesis of pulmonary fibrosis. Objective: To test if the inoculation of senescent human fibroblasts in mice generates lung fibrosis, and whether this model is useful to assess antifibrotic or senolytic drugs in vivo. Methods: Immunodeficient mice were inoculated intratracheally with proliferating human lung fibroblasts (IMR90), senescent human lung fibroblasts induced by γ-irradiation (gIR-IMR90), or bleomycin as control. After 21 days, lung fibrosis was determined by immunohistochemistry (IHC), and quantified by hydroxyproline assay and Ashcroft score. Gene expression analysis was performed using senescence markers. Furthermore, a group of mice with established fibrosis were treated with pirfenidone, nintedanib or placebo administrated orally for 14 days. Another group was treated with navitoclax (ABT-263) or vehicle. Collagen deposition was measured by hydroxyproline assay and IHC. Results: Inoculation of gIR-IMR90 elicited a progressive lung remodeling process characterized by increased score of fibrosis (Ashcroft score, p Conclusion: Intratracheal inoculation of gIR-IMR90 generates progressive lung fibrosis in mice that is reduced by antifibrotic drugs. This model can be used to test novel drugs for pulmonary fibrosis in vivo.

[EN] Pharmacologically active compounds with preferential cytotoxic activity for senescent cells, known as senolytics, can ameliorate or even revert pathological manifestations of senescence in numerous preclinical mouse disease models, including cancer models. However, translation of senolytic therapies to human disease is hampered by their suboptimal specificity for senescent cells and important toxicities that narrow their therapeutic windows. We have previously shown that the high levels of senescence-associated lysosomal beta-galactosidase (SA-beta-gal) found within senescent cells can be exploited to specifically release tracers and cytotoxic cargoes from galactose-encapsulated nanoparticles within these cells. Here, we show that galacto-conjugation of the BCL-2 family inhibitor Navitoclax results in a potent senolytic prodrug (Nav-Gal), that can be preferentially activated by SA-beta-gal activity in a wide range of cell types. Nav-Gal selectively induces senescent cell apoptosis and has a higher senolytic index than Navitoclax (through reduced activation in nonsenescent cells). Nav-Gal enhances the cytotoxicity of standard senescence-inducing chemotherapy (cisplatin) in human A549 lung cancer cells. Concomitant treatment with cisplatin and Nav-Gal in vivo results in the eradication of senescent lung cancer cells and significantly reduces tumour growth. Importantly, galacto-conjugation reduces Navitoclax-induced platelet apoptosis in human and murine blood samples treated ex vivo, and thrombocytopenia at therapeutically effective concentrations in murine lung cancer models. Taken together, we provide a potentially versatile strategy for generating effective senolytic prodrugs with reduced toxicities., Royal Society, Grant/Award Number: RG160806; Medical Research Council, Grant/Award Number: MR/R000530/1; Cancer Research UK, Grant/Award Number: C62187/A26989 and C62187/A29760; CRUK Cambridge Centre Early Detection Programme, Grant/Award Number: RG86786

Flow cytometry is a powerful multiparametric technology, widely used for the identification, quantification, and isolation of defined populations of cells based on the expression of target proteins. It also allows for the use of surrogate reporters, either enzymatic or fluorescent, to indirectly monitor the expression of these target proteins. In this work, we optimised the dissociation protocol for the detection of the enzymatic reporter LacZ using the FACS-Gal detection system with the fluorogenic substrate FDG to compare cis- versus trans-positioned reporters efficiency. Particularly, for the FACS-Gal optimization, we studied lung and haematopoietic tissues, focusing on cell recovery, viability, FDG loading conditions and distribution of cellular populations. Reporter genes such as LacZ can be placed together with the gene of interest in the same polycistronic mRNA (in cis), or in independent alleles (in trans), which can strongly affect the correlation with the reporter readout. To address this issue, we generated a mouse model containing both types of reporters for the same gene, and compared them. Our results clearly indicate that trans-positioned reporters can be misleading, and that using a reporter gene in cis rather than trans is a much more specific method to sort for cells undergoing Cre-mediated recombination. © 2017 International Society for Advancement of Cytometry.

[EN] A naphthalimide-based two-photon probe (AHGa) for the detection of cell senescence is designed. The probe contains a naphthalimide core, an L-histidine methyl ester linker, and an acetylated galactose bonded to one of the aromatic nitrogen atoms of the L-histidine through a hydrolyzable N-glycosidic bond. Probe AHGa is transformed into AH in senescent cells resulting in an enhanced fluorescent emission intensity. In vivo detection of senescence is validated in mice bearing tumor xenografts treated with senescence-inducing chemotherapy., The authors thank the financial support from the Spanish Government (Projects MAT2015-64139-C4-1-R) and the Generalitat Valenciana (Project PROMETEOII/2014/047). B.L-T. is grateful to the Spanish Ministry of Economy for her PhD grant. I.G. thanks the Generalitat Valenciana for her PhD grant. A.B. thanks the Spanish Government for the financial support "Juan de la Cierva-Incorporacion". M.R. is grateful to "La Caixa" foundation for his PhD scholarship. Work in the M.S. group was funded by the CNIO and by grants from Spanish Ministry of Economy, the European Regional Development Fund (SAF project) the European Research Council (ERC Advanced Grant), and the Botin Foundation and Banco Santander (Santander Universities Global Division). D.M.-E. was funded by a "Ramon y Cajal" Programme Senior Grant and the "RETOS" National Programme for Research (MINECO), Cancer Research UK, and the CRUK Cambridge Centre Early Detection Programme.

For cell reprogramming, context matters Differentiated cells in a culture dish can assume a new identity when manipulated to express four transcription factors. This “reprogramming” process has sparked interest because conceivably it could be harnessed as a therapeutic strategy for tissue regeneration. Mosteiro et al. used a mouse model to study the signals that promote cell reprogramming in vivo. They found that the factors that trigger reprogramming in vitro do the same in vivo; however, they also inflict cell damage. The damaged cells enter a state of senescence and begin secreting certain factors that promote reprogramming, including an inflammatory cytokine called interleukin-6. Thus, in the physiological setting, cell senescence may create a tissue context that favors reprogramming of neighboring cells. Science , this issue p. 10.1126/science.aaf4445