ADAMTS-7 Modulates Atherosclerotic Plaque Formation by Degradation of TIMP-1.

BACKGROUND: The ADAMTS7 locus was genome-wide significantly associated with coronary artery disease. Lack of the ECM (extracellular matrix) protease ADAMTS-7 (A disintegrin and metalloproteinase-7) was shown to reduce atherosclerotic plaque formation. Here, we sought to identify molecular mechanisms and downstream targets of ADAMTS-7 mediating the risk of atherosclerosis. METHODS: Targets of ADAMTS-7 were identified by high-resolution mass spectrometry of atherosclerotic plaques from Apoe-/- and Apoe-/-Adamts7-/- mice. ECM proteins were identified using solubility profiling. Putative targets were validated using immunofluorescence, in vitro degradation assays, coimmunoprecipitation, and Förster resonance energy transfer-based protein-protein interaction assays. ADAMTS7 expression was measured in fibrous caps of human carotid artery plaques. RESULTS: In humans, ADAMTS7 expression was higher in caps of unstable as compared to stable carotid plaques. Compared to Apoe-/- mice, atherosclerotic aortas of Apoe-/- mice lacking Adamts-7 (Apoe-/-Adamts7-/-) contained higher protein levels of Timp-1 (tissue inhibitor of metalloprotease-1). In coimmunoprecipitation experiments, the catalytic domain of ADAMTS-7 bound to TIMP-1, which was degraded in the presence of ADAMTS-7 in vitro. ADAMTS-7 reduced the inhibitory capacity of TIMP-1 at its canonical target MMP-9 (matrix metalloprotease-9). As a downstream mechanism, we investigated collagen content in plaques of Apoe-/- and Apoe-/-Adamts7-/- mice after a Western diet. Picrosirius red staining of the aortic root revealed less collagen as a readout of higher MMP-9 activity in Apoe-/- as compared to Apoe-/- Adamts7-/- mice. To facilitate high-throughput screening for ADAMTS-7 inhibitors with the aim of decreasing TIMP-1 degradation, we designed a Förster resonance energy transfer-based assay targeting the ADAMTS-7 catalytic site. CONCLUSIONS: ADAMTS-7, which is induced in unstable atherosclerotic plaques, decreases TIMP-1 stability reducing its inhibitory effect on MMP-9, which is known to promote collagen degradation and is likewise associated with coronary artery disease. Disrupting the interaction of ADAMTS-7 and TIMP-1 might be a strategy to increase collagen content and plaque stability for the reduction of atherosclerosis-related events.

Molecular anatomy of adult mouse leptomeninges.

Leptomeninges, consisting of the pia mater and arachnoid, form a connective tissue investment and barrier enclosure of the brain. The exact nature of leptomeningeal cells has long been debated. In this study, we identify five molecularly distinct fibroblast-like transcriptomes in cerebral leptomeninges; link them to anatomically distinct cell types of the pia, inner arachnoid, outer arachnoid barrier, and dural border layer; and contrast them to a sixth fibroblast-like transcriptome present in the choroid plexus and median eminence. Newly identified transcriptional markers enabled molecular characterization of cell types responsible for adherence of arachnoid layers to one another and for the arachnoid barrier. These markers also proved useful in identifying the molecular features of leptomeningeal development, injury, and repair that were preserved or changed after traumatic brain injury. Together, the findings highlight the value of identifying fibroblast transcriptional subsets and their cellular locations toward advancing the understanding of leptomeningeal physiology and pathology.

Leukocytes carrying Clonal Hematopoiesis of Indeterminate Potential (CHIP) Mutations invade Human Atherosclerotic Plaques.

Background: Leukocyte progenitors derived from clonal hematopoiesis of undetermined potential (CHIP) are associated with increased cardiovascular events. However, the prevalence and functional relevance of CHIP in coronary artery disease (CAD) are unclear, and cells affected by CHIP have not been detected in human atherosclerotic plaques. Methods: CHIP mutations in blood and tissues were identified by targeted deep-DNA-sequencing (DNAseq: coverage >3,000) and whole-genome-sequencing (WGS: coverage >35). CHIP-mutated leukocytes were visualized in human atherosclerotic plaques by mutaFISH™. Functional relevance of CHIP mutations was studied by RNAseq. Results: DNAseq of whole blood from 540 deceased CAD patients of the Munich cardIovaScular StudIes biObaNk (MISSION) identified 253 (46.9%) CHIP mutation carriers (mean age 78.3 years). DNAseq on myocardium, atherosclerotic coronary and carotid arteries detected identical CHIP mutations in 18 out of 25 mutation carriers in tissue DNA. MutaFISH™ visualized individual macrophages carrying DNMT3A CHIP mutations in human atherosclerotic plaques. Studying monocyte-derived macrophages from Stockholm-Tartu Atherosclerosis Reverse Networks Engineering Task (STARNET; n=941) by WGS revealed CHIP mutations in 14.2% (mean age 67.1 years). RNAseq of these macrophages revealed that expression patterns in CHIP mutation carriers differed substantially from those of non-carriers. Moreover, patterns were different depending on the underlying mutations, e.g. those carrying TET2 mutations predominantly displayed upregulated inflammatory signaling whereas ASXL1 mutations showed stronger effects on metabolic pathways. Conclusions: Deep-DNA-sequencing reveals a high prevalence of CHIP mutations in whole blood of CAD patients. CHIP-affected leukocytes invade plaques in human coronary arteries. RNAseq data obtained from macrophages of CHIP-affected patients suggest that pro-atherosclerotic signaling differs depending on the underlying mutations. Further studies are necessary to understand whether specific pathways affected by CHIP mutations may be targeted for personalized treatment.

The Impact of Exercise on Immunity, Metabolism, and Atherosclerosis.

Physical exercise represents an effective preventive and therapeutic strategy beneficially modifying the course of multiple diseases. The protective mechanisms of exercise are manifold; primarily, they are elicited by alterations in metabolic and inflammatory pathways. Exercise intensity and duration strongly influence the provoked response. This narrative review aims to provide comprehensive up-to-date insights into the beneficial effects of physical exercise by illustrating the impact of moderate and vigorous exercise on innate and adaptive immunity. Specifically, we describe qualitative and quantitative changes in different leukocyte subsets while distinguishing between acute and chronic exercise effects. Further, we elaborate on how exercise modifies the progression of atherosclerosis, the leading cause of death worldwide, representing a prime example of a disease triggered by metabolic and inflammatory pathways. Here, we describe how exercise counteracts causal contributors and thereby improves outcomes. In addition, we identify gaps that still need to be addressed in the future.

Quo Vadis? Immunodynamics of Myeloid Cells after Myocardial Infarction.

Myocardial infarction (MI), a major contributor to worldwide morbidity and mortality, is caused by a lack of blood flow to the heart. Affected heart tissue becomes ischemic due to deficiency of blood perfusion and oxygen delivery. In case sufficient blood flow cannot be timely restored, cardiac injury with necrosis occurs. The ischemic/necrotic area induces a systemic inflammatory response and hundreds of thousands of leukocytes are recruited from the blood to the injured heart. The blood pool of leukocytes is rapidly depleted and urgent re-supply of these cells is needed. Myeloid cells are generated in the bone marrow (BM) and spleen, released into the blood, travel to sites of need, extravasate and accumulate inside tissues to accomplish various functions. In this review we focus on the "leukocyte supply chain" and will separately evaluate different myeloid cell compartments (BM, spleen, blood, heart) in steady state and after MI. Moreover, we highlight the local and systemic kinetics of extracellular factors, chemokines and danger signals involved in the regulation of production/generation, release, transportation, uptake, and activation of myeloid cells during the inflammatory phase of MI.

Colchicine Impacts Leukocyte Trafficking in Atherosclerosis and Reduces Vascular Inflammation.

Background: Inflammation strongly contributes to atherosclerosis initiation and progression. Consequently, recent clinical trials pharmacologically targeted vascular inflammation to decrease the incidence of atherosclerosis-related complications. Colchicine, a microtubule inhibitor with anti-inflammatory properties, reduced cardiovascular events in patients with recent acute coronary syndrome and chronic coronary disease. However, the biological basis of these observations remains elusive. We sought to explore the mechanism by which colchicine beneficially alters the course of atherosclerosis. Methods and Results: In mice with early atherosclerosis (Apoe-/- mice on a high cholesterol diet for 8 weeks), we found that colchicine treatment (0.25 mg/kg bodyweight once daily over four weeks) reduced numbers of neutrophils, inflammatory monocytes and macrophages inside atherosclerotic aortas using flow cytometry and immunohistochemistry. Consequently, colchicine treatment resulted in a less inflammatory plaque composition and reduced plaque size. We next investigated how colchicine prevented plaque leukocyte expansion and found that colchicine treatment mitigated recruitment of blood neutrophils and inflammatory monocytes to plaques as revealed by adoptive transfer experiments. Causally, we found that colchicine reduced levels of both leukocyte adhesion molecules and receptors for leukocyte chemoattractants on blood neutrophils and monocytes. Further experiments showed that colchicine treatment reduced vascular inflammation also in post-myocardial infarction accelerated atherosclerosis through similar mechanisms as documented in early atherosclerosis. When we examined whether colchicine also decreased numbers of macrophages inside atherosclerotic plaques by impacting monocyte/macrophage transitioning or in-situ proliferation of macrophages, we report that colchicine treatment did not influence macrophage precursor differentiation or macrophage proliferation using cell culture experiments with bone marrow derived macrophages. Conclusions: Our data reveal that colchicine prevents expansion of plaque inflammatory leukocytes through lowering recruitment of blood myeloid cells to plaques. These data provide novel mechanistic clues on the beneficial effects of colchicine in the treatment of atherosclerosis and may inform future anti-inflammatory interventions in patients at risk.

Interleukin-1ß suppression dampens inflammatory leucocyte production and uptake in atherosclerosis.

AIMS: Targeting vascular inflammation represents a novel therapeutic approach to reduce complications of atherosclerosis. Neutralizing the pro-inflammatory cytokine interleukin-1ß (IL-1ß) using canakinumab, a monoclonal antibody, reduces the incidence of cardiovascular events in patients after myocardial infarction (MI). The biological basis for these beneficial effects remains incompletely understood. We sought to explore the mechanisms of IL-1ß-targeted therapies. METHODS AND RESULTS: In mice with early atherosclerosis (ApoE-/- mice on a high-cholesterol diet for 6 weeks), we found that 3 weeks of NACHT, LRR, and PYD domains-containing protein 3 (NLRP3)-inflammasome inhibition or anti-IL-1ß treatment (using either MCC950, an NLRP3-inflammasome inhibitor which blocks production and release of active IL-1ß, or a murine analogue of canakinumab) dampened accumulation of leucocytes in atherosclerotic aortas, which consequently resulted in slower progression of atherosclerosis. Causally, we found that endothelial cells from atherosclerotic aortas lowered expression of leucocyte chemoattractants and adhesion molecules upon NLRP3-inflammasome inhibition, indicating that NLRP3-inflammasome- and IL-1ß-targeted therapies reduced blood leucocyte recruitment to atherosclerotic aortas. In accord, adoptive transfer experiments revealed that anti-IL-1ß treatment mitigated blood myeloid cell uptake to atherosclerotic aortas. We further report that anti-IL-1ß treatment and NLRP3-inflammasome inhibition reduced inflammatory leucocyte supply by decreasing proliferation of bone marrow haematopoietic stem and progenitor cells, demonstrating that suppression of IL-1ß and the NLRP3-inflammasome lowered production of disease-propagating leucocytes. Using bone marrow reconstitution experiments, we observed that haematopoietic cell-specific NLRP3-inflammasome activity contributed to both enhanced recruitment and increased supply of blood inflammatory leucocytes. Further experiments that queried whether anti-IL-1ß treatment reduced vascular inflammation also in post-MI accelerated atherosclerosis documented the operation of convergent mechanisms (reduced supply and uptake of inflammatory leucocytes). In line with our pre-clinical findings, post-MI patients on canakinumab treatment showed reduced blood monocyte numbers. CONCLUSIONS: Our murine and human data reveal that anti-IL-1ß treatment and NLRP3-inflammasome inhibition dampened vascular inflammation and progression of atherosclerosis through reduced blood inflammatory leucocyte (i) supply and (ii) uptake into atherosclerotic aortas providing additional mechanistic insights into links between haematopoiesis and atherogenesis, and into the beneficial effects of NLRP3-inflammasome- and IL-1ß-targeted therapies.

Acute mental stress drives vascular inflammation and promotes plaque destabilization in mouse atherosclerosis.

AIMS: Mental stress substantially contributes to the initiation and progression of human disease, including cardiovascular conditions. We aim to investigate the underlying mechanisms of these contributions since they remain largely unclear. METHODS AND RESULTS: Here, we show in humans and mice that leucocytes deplete rapidly from the blood after a single episode of acute mental stress. Using cell-tracking experiments in animal models of acute mental stress, we found that stress exposure leads to prompt uptake of inflammatory leucocytes from the blood to distinct tissues including heart, lung, skin, and, if present, atherosclerotic plaques. Mechanistically, we found that acute stress enhances leucocyte influx into mouse atherosclerotic plaques by modulating endothelial cells. Specifically, acute stress increases adhesion molecule expression and chemokine release through locally derived norepinephrine. Either chemical or surgical disruption of norepinephrine signalling diminished stress-induced leucocyte migration into mouse atherosclerotic plaques. CONCLUSION: Our data show that acute mental stress rapidly amplifies inflammatory leucocyte expansion inside mouse atherosclerotic lesions and promotes plaque vulnerability.

Whole genome DNA sequencing provides an atlas of somatic mutagenesis in healthy human cells and identifies a tumor-prone cell type.

BACKGROUND: The lifelong accumulation of somatic mutations underlies age-related phenotypes and cancer. Mutagenic forces are thought to shape the genome of aging cells in a tissue-specific way. Whole genome analyses of somatic mutation patterns, based on both types and genomic distribution of variants, can shed light on specific processes active in different human tissues and their effect on the transition to cancer. RESULTS: To analyze somatic mutation patterns, we compile a comprehensive genetic atlas of somatic mutations in healthy human cells. High-confidence variants are obtained from newly generated and publicly available whole genome DNA sequencing data from single non-cancer cells, clonally expanded in vitro. To enable a well-controlled comparison of different cell types, we obtain single genome data (92% mean coverage) from multi-organ biopsies from the same donors. These data show multiple cell types that are protected from mutagens and display a stereotyped mutation profile, despite their origin from different tissues. Conversely, the same tissue harbors cells with distinct mutation profiles associated to different differentiation states. Analyses of mutation rate in the coding and non-coding portions of the genome identify a cell type bearing a unique mutation pattern characterized by mutation enrichment in active chromatin, regulatory, and transcribed regions. CONCLUSIONS: Our analysis of normal cells from healthy donors identifies a somatic mutation landscape that enhances the risk of tumor transformation in a specific cell population from the kidney proximal tubule. This unique pattern is characterized by high rate of mutation accumulation during adult life and specific targeting of expressed genes and regulatory regions.

CRISPR-Knockout Screen Identifies Dmap1 as a Regulator of Chemically Induced Reprogramming and Differentiation of Cardiac Progenitors.

Direct in vivo reprogramming of cardiac fibroblasts into myocytes is an attractive therapeutic intervention in resolving myogenic deterioration. Current transgene-dependent approaches can restore cardiac function, but dependence on retroviral delivery and persistent retention of transgenic sequences are significant therapeutic hurdles. Chemical reprogramming has been established as a legitimate method to generate functional cell types, including those of the cardiac lineage. Here, we have extended this approach to generate progenitor cells that can differentiate into endothelial cells and cardiomyocytes using a single inhibitor protocol. Depletion of terminally differentiated cells and enrichment for proliferative cells result in a second expandable progenitor population that can robustly give rise to myofibroblasts and smooth muscle. Deployment of a genome-wide knockout screen with clustered regularly interspaced short palindromic repeats-guide RNA library to identify novel mediators that regulate the reprogramming revealed the involvement of DNA methyltransferase 1-associated protein 1 (Dmap1). Loss of Dmap1 reduced promoter methylation, increased the expression of Nkx2-5, and enhanced the retention of self-renewal, although further differentiation is inhibited because of the sustained expression of Cdh1. Our results hence establish Dmap1 as a modulator of cardiac reprogramming and myocytic induction. Stem Cells 2019;37:958-972.

Assessment of acute kidney injury in rhabdomyolytic mice by transcutaneous measurement of sinistrin excretion.

BACKGROUND: Early and accurate assessment of renal function is required for the successful detection and treatment of acute kidney injury (AKI). However, only retention parameters such as plasma urea and creatinine, and the indirect estimation of glomerular filtration rate are commonly available. METHODS: Here, we measured the kinetics of plasma fluorescein isothiocyanate (FITC)-sinistrin excretion to detect alterations of renal function over time in a murine model of rhabdomyolysis-induced AKI. The half-life of FITC-sinistrin was evaluated using a transcutaneous device at different time points in conscious mice, from 4 days before renal damage up to 30 days after. Retention markers were also evaluated, in parallel. RESULTS: Evaluation of the FITC-sinistrin half-life revealed early reduction of renal filtration, observed as early as 6 h after renal damage, and maintained up to 12 h following AKI. Plasma creatinine and urea levels correlated with the transcutaneous measurements of sinistrin excretion. Evaluation of sinistrin excretion also demonstrated that glycerol-treated animals did not develop AKI. Finally, histological analysis showed the presence of renal parenchymal lesions, which developed following the reduced renal filtration and persisted over time, highlighting the causative role of vascular dysfunction and myoglobin toxicity on the subsequent induction of tissue damage. CONCLUSIONS: Taken together, the results of this study provide important insights into the pathophysiology of kidney injury in rhabdomyolytic mice, and indicate that the transcutaneous measurement of FITC-sinistrin is an efficient and simple method to assess renal function precisely. This method also allows reduction of the required number of experimental animals by monitoring the same mouse over time.

The effects of glomerular and tubular renal progenitors and derived extracellular vesicles on recovery from acute kidney injury.

BACKGROUND: Mesenchymal stromal cells (MSCs) and renal stem/progenitors improve the recovery of acute kidney injury (AKI) mainly through the release of paracrine mediators including the extracellular vesicles (EVs). Several studies have reported the existence of a resident population of MSCs within the glomeruli (Gl-MSCs). However, their contribution towards kidney repair still remains to be elucidated. The aim of the present study was to evaluate whether Gl-MSCs and Gl-MSC-EVs promote the recovery of AKI induced by ischemia-reperfusion injury (IRI) in SCID mice. Moreover, the effects of Gl-MSCs and Gl-MSC-EVs were compared with those of CD133+ progenitor cells isolated from human tubules of the renal cortical tissue (T-CD133+ cells) and their EVs (T-CD133+-EVs). METHODS: IRI was performed in mice by clamping the left renal pedicle for 35 minutes together with a right nephrectomy. Immediately after reperfusion, the animals were divided in different groups to be treated with: Gl-MSCs, T-CD133+ cells, Gl-MSC-EVs, T-CD133+-EVs or vehicle. To assess the role of vesicular RNA, EVs were either isolated by floating to avoid contamination of non-vesicles-associated RNA or treated with a high dose of RNase. Mice were sacrificed 48 hours after surgery. RESULTS: Gl-MSCs, and Gl-MSC-EVs both ameliorate kidney function and reduce the ischemic damage post IRI by activating tubular epithelial cell proliferation. Furthermore, T-CD133+ cells, but not their EVs, also significantly contributed to the renal recovery after IRI compared to the controls. Floating EVs were effective while RNase-inactivated EVs were ineffective. Analysis of the EV miRnome revealed that Gl-MSC-EVs selectively expressed a group of miRNAs, compared to EVs derived from fibroblasts, which were biologically ineffective in IRI. CONCLUSIONS: In this study, we demonstrate that Gl-MSCs may contribute in the recovery of mice with AKI induced by IRI primarily through the release of EVs.

Histamine type 1-receptor activation by low dose of histamine undermines human glomerular slit diaphragm integrity.

Histamine has been reported to decrease the ultrafiltration coefficient, which inversely correlates with glomerular permselectivity, however the mechanism(s) underling this effect have never been investigated. This study aimed to assess whether histamine could exert a direct detrimental effect on podocyte permeability and the possible involvement of two key proteins for the glomerular slit diaphragm (SD) integrity, zonula occludens-1 (ZO-1) and P-cadherin. The effect of histamine (100 pM-1000nM) on coloured podocytes junctional integrity was evaluated functionally by a transwell assay of monolayer permeability and morphologically by electron microscopy. Histamine receptor (H1-4R) presence was evaluated at both mRNA (RT-PCR) and protein (immunofluorescence) levels. The Kd and Bmax values for [3H]mepyramine were determined by saturation binding analysis; IP1 and cAMP production evoked by histamine were measured by TR-FRET. ZO-1, P-cadherin and vimentin expression was assessed by qRT-PCR and quantitative immunoblotting. Histamine elicited a time- and sigmoidal dose-dependent (maximum effect at 8h, 10nM) increase in podocyte paracellular permeability widening the paracellular spaces. Only H1R was predominantly localised to the podocyte membrane. Consistently, histamine elicited a sigmoidal dose-dependent increase in IP1, but not in cAMP. Histamine exposure evoked a concentration-dependent reduction in both ZO-1 and P-cadherin and a parallel induction of vimentin mRNA expression with a maximum effect after 6h, and protein expression with a maximum effect after 8h. These effects were prevented by the selective H1R antagonist chlorpheniramine. In conclusion, our data demonstrate that histamine, via the H1R, modifies SD morphological and functional integrity, in part, by decreasing the expression of ZO-1 and P-cadherin.

Histamine receptor expression in human renal tubules: a comparative pharmacological evaluation.

OBJECTIVE AND DESIGN: The aim of this study is to evaluate the expression of the histamine receptors, particularly focusing on the H4R in human renal tubules. MATERIAL: The ex vivo evaluation was carried on specimens from human renal cortex. Primary and immortalized tubular epithelial cells (TECs) and the HK-2 cell line were used as in vitro models. TREATMENT: Cells were pretreated for 10 min with chlorpheniramine maleate 10 µM (H1R antagonist), ranitidine 10 µM (H2R antagonist), GSK189254 1 µM (H3R antagonist) or JNJ7777120 10 µM (H4R antagonist), and then exposed to histamine (3 pM-10 nM) for 30 min. METHODS: The ex vivo evaluation on specimens from human renal cortex was performed by immunohistochemistry. The expression of histamine receptors on primary and immortalized TECs and the HK-2 cell line was evaluated at both gene (RT-PCR) and protein (immunocytofluorescence) levels. The pharmacological analysis was performed by TR-FRET measurements of second messenger (IP3 and cAMP) production induced by histamine with or without the selective antagonists. RESULTS: Our data revealed the presence of all histamine receptors in human tubules; however, only TECs expressed all the receptors. Indeed, histamine elicited a sigmoid dose-response curve for IP3 production, shifted to the right by chlorpheniramine maleate, and elicited a double bell-shaped curve for cAMP production, partially suppressed by the selective H2R, H3R and H4R antagonists when each added alone, and completely ablated when combined together. CONCLUSIONS: Herein, we report the identification of all four histamine receptors in human renal tubules.

H3 receptor renal expression in normal and diabetic rats.

INTRODUCTION: To extend our previous observation of H4R upregulation in the kidney of diabetic rats, we evaluated in the same specimens the presence of the H3R. MATERIALS AND METHODS: Kidney specimens from 24 8-week-old male Wistar rats (12 non-diabetic and 12 diabetic animals) were processed for both immunohistochemical and immunofluorescence analyses. RESULTS AND CONCLUSION: H3R is expressed in the apical membrane by collecting duct cells in the kidney of rats and it is significantly increased in diabetic animals. These data support the hypothesis that H3R could also mediate non-neuronal histamine effects, suggesting its involvement in fluid homeostasis.

Protective effect and localization by optical imaging of human renal CD133+ progenitor cells in an acute kidney injury model.

Abstract Recent approaches of regenerative medicine can offer a therapeutic option for patients undergoing acute kidney injury. In particular, mesenchymal stem cells were shown to ameliorate renal function and recovery after acute damage. We here evaluated the protective effect and localization of CD133(+) renal progenitors from the human inner medulla in a model of glycerol-induced acute tubular damage and we compared the results with those obtained with bone marrow-derived mesenchymal stem cells. We found that CD133(+) progenitor cells promoted the recovery of renal function, preventing tubular cell necrosis and stimulating resident cell proliferation and survival, similar to mesenchymal stem cells. In addition, by optical imaging analysis, CD133(+) progenitor cells accumulated within the renal tissue, and a reduced entrapment in lung, spleen, and liver was observed. Mesenchymal stem cells were detectable at similar levels in the renal tissue, but a higher signal was present in extrarenal organs. Both cell types produced several cytokines/growth factors, suggesting that a combination of different mediators is involved in their biological action. These results indicate that human CD133(+) progenitor cells are renotropic and able to improve renal regeneration in acute kidney injury.

Concise review: stem/progenitor cells for renal tissue repair: current knowledge and perspectives.

The kidney is a specialized low-regenerative organ with several different types of cellular lineages; however, the identity of renal stem/progenitor cells with nephrogenic potential and their preferred niche(s) are largely unknown and debated. Most of the therapeutic approaches to kidney regeneration are based on administration of cells proven to enhance intrinsic reparative capabilities of the kidney. Endogenous or exogenous cells of different sources were tested in rodent models of ischemia-reperfusion, acute kidney injury, or chronic disease. The translation to clinics is at the moment focused on the role of mesenchymal stem cells. In addition, bioproducts from stem/progenitor cells, such as extracellular vesicles, are likely a new promising approach for reprogramming resident cells. This concise review reports the current knowledge about resident or exogenous stem/progenitor populations and their derived bioproducts demonstrating therapeutic effects in kidney regeneration upon injury. In addition, possible approaches to nephrogenesis and organ generation using organoids, decellularized kidneys, and blastocyst complementation are surveyed.

Renal CD133(+)/CD73(+) progenitors produce erythropoietin under hypoxia and prolyl hydroxylase inhibition.

The identity of the peritubular population of cells with mesenchymal phenotype thought responsible for producing erythropoietin in humans remains unclear. Here, renal CD133(+)/CD73(+) progenitor cells, isolated from the human renal inner medulla and described as a population of mesenchymal progenitors, released erythropoietin under hypoxic conditions. CD133(-) cells did not synthesize erythropoietin, and CD133(+) progenitor cells stopped producing erythropoietin when they differentiated and acquired an epithelial phenotype. Inhibition of prolyl hydroxylases, using either dimethyloxalylglycine or a small hairpin RNA against prolyl hydroxylase-2, increased both hypoxia-inducible factor-2α (HIF-2α) expression and erythropoietin transcription. Moreover, under hypoxic conditions, inhibition of prolyl hydroxylase significantly increased erythropoietin release by CD133(+) progenitors. Finally, blockade of HIF-2α impaired erythropoietin synthesis by CD133(+) progenitors. Taken together, these results suggest that it is the renal CD133(+) progenitor cells that synthesize and release erythropoietin under hypoxia, via the prolyl hydroxylase-HIF-2α axis, in the human kidney. In addition, this study provides rationale for the therapeutic use of prolyl hydroxylase inhibitors in the setting of acute or chronic renal injury.

Sorafenib inhibits growth, migration, and angiogenic potential of ectopic endometrial mesenchymal stem cells derived from patients with endometriosis.

OBJECTIVE: To characterize the proliferation, migration, and angiogenic properties of mesenchymal stem cells (MSC) from ectopic and eutopic endometrial tissue and to investigate the effect of the tyrosine kinase inhibitor sorafenib. DESIGN: In vitro studies. SETTING: University hospital and research center. PATIENT(S): Patients receiving surgical treatment of endometriosis (n = 4) and control patients without endometriosis (n = 2) undergoing surgery for benign gynecologic diseases. INTERVENTION(S): Mesenchymal stem cell lines were isolated from ectopic and eutopic endometrial tissue, and sorafenib was administered to them. MAIN OUTCOME MEASURE(S): Proliferation, migration, invasion of endometrial MSC, and expression of ezrin, vascular endothelial growth factor, and hypoxia-inducible factor-1α (HIF-1α) were measured. RESULT(S): Ectopic endometrial MSC from patients with endometriosis showed a higher proliferation, migration, and angiogenic ability than eutopic MSC from the same patient or control MSC from patients without endometriosis. Sorafenib reduced the proliferation, motility, ezrin phosphorylation, vascular endothelial growth factor release, and HIF-1α expression of ectopic MSC. CONCLUSION(S): The increased proliferative, migratory, and angiogenic phenotype of ectopic MSC may be reverted by treatment with sorafenib. Targeting of the MSC population involved in sustaining the ectopic lesions might be useful in eradicating endometriotic implants.

Efficient stem cell isolation from under vacuum preserved tissue samples.

Different approaches for the isolation of stem/progenitor cells have been reported, including stem cell selection in stringent culture conditions. We evaluated the possibility of isolating human progenitor cells from surgical specimens preserved by under vacuum sealing and cooling, a clinical practice approached by several hospitals as alternative to formalin. Renal tissue samples (n = 20) maintained under vacuum from 6 to 48 h at 4°C were used to isolate human renal CD133(+) progenitor cells. We obtained CD133(+) progenitors from unsorted cells derived from disaggregated tissues from each sample. Phenotypic characterization as well as in vitro and in vivo differentiation of the obtained CD133(+) lines showed results comparable with sorted CD133(+) cells obtained from fresh tissue. These results indicate that the process of sealing under vacuum and cooling appears as a suitable tissue treatment to isolate hypoxia resistant cells, such as human stem/progenitor cells, and that this procedure can be exploited to render the extraction of stem cells from human samples more practical and feasible.