Retinoids regulate a wide spectrum of cellular functions from the embryo throughout adulthood, including cell differentiation, metabolic regulation, and inflammation. These traits make retinoids very ...attractive molecules for medical purposes. In light of some of the physicochemical limitations of retinoids, the development of drug delivery systems offers several advantages for clinical translation of retinoid-based therapies, including improved solubilization, prolonged circulation, reduced toxicity, sustained release, and improved efficacy. In this Review, we discuss advances in preclinical and clinical tests regarding retinoid formulations, specifically the ones based in natural retinoids, evaluated in the context of regenerative medicine, brain, cancer, skin, and immune diseases. Advantages and limitations of retinoid formulations, as well as prospects to push the field forward, will be presented.
The ability to quantify differentiation potential of single cells is a task of critical importance. Here we demonstrate, using over 7,000 single-cell RNA-Seq profiles, that differentiation potency of ...a single cell can be approximated by computing the signalling promiscuity, or entropy, of a cell's transcriptome in the context of an interaction network, without the need for feature selection. We show that signalling entropy provides a more accurate and robust potency estimate than other entropy-based measures, driven in part by a subtle positive correlation between the transcriptome and connectome. Signalling entropy identifies known cell subpopulations of varying potency and drug resistant cancer stem-cell phenotypes, including those derived from circulating tumour cells. It further reveals that expression heterogeneity within single-cell populations is regulated. In summary, signalling entropy allows in silico estimation of the differentiation potency and plasticity of single cells and bulk samples, providing a means to identify normal and cancer stem-cell phenotypes.
Altered cell metabolism is inherently connected with pathological conditions including cancer and viral infections. Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiological agent of Kaposi's ...sarcoma (KS). KS tumour cells display features of lymphatic endothelial differentiation and in their vast majority are latently infected with KSHV, while a small number are lytically infected, producing virions. Latently infected cells express only a subset of viral genes, mainly located within the latency-associated region, among them 12 microRNAs. Notably, the metabolic properties of KSHV-infected cells closely resemble the metabolic hallmarks of cancer cells. However, how and why KSHV alters host cell metabolism remains poorly understood. Here, we investigated the effect of KSHV infection on the metabolic profile of primary dermal microvascular lymphatic endothelial cells (LEC) and the functional relevance of this effect. We found that the KSHV microRNAs within the oncogenic cluster collaborate to decrease mitochondria biogenesis and to induce aerobic glycolysis in infected cells. KSHV microRNAs expression decreases oxygen consumption, increase lactate secretion and glucose uptake, stabilize HIF1α and decreases mitochondria copy number. Importantly this metabolic shift is important for latency maintenance and provides a growth advantage. Mechanistically we show that KSHV alters host cell energy metabolism through microRNA-mediated down regulation of EGLN2 and HSPA9. Our data suggest that the KSHV microRNAs induce a metabolic transformation by concurrent regulation of two independent pathways; transcriptional reprograming via HIF1 activation and reduction of mitochondria biogenesis through down regulation of the mitochondrial import machinery. These findings implicate viral microRNAs in the regulation of the cellular metabolism and highlight new potential avenues to inhibit viral latency.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Aging is associated with reduced fitness and increased myeloid bias of the hematopoietic stem cell (HSC) compartment, causing increased risk of immune compromise, anemia, and malignancy. We show that ...mitochondrial membrane potential (MMP) can be used to prospectively isolate chronologically old HSCs with transcriptional features and functional attributes characteristic of young HSCs, including a high rate of transcription and balanced lineage-affiliated programs. Strikingly, MMP is a stronger determinant of the quantitative and qualitative transcriptional state of HSCs than chronological age, and transcriptional consequences of manipulation of MMP in HSCs within their native niche suggest a causal relationship. Accordingly, we show that pharmacological enhancement of MMP in old HSCs in vivo increases engraftment potential upon transplantation and reverses myeloid-biased peripheral blood output at steady state. Our results demonstrate that MMP is a source of heterogeneity in old HSCs, and its pharmacological manipulation can alter transcriptional programs with beneficial consequences for function.
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•HSCs from old and young mice are heterogeneous for mitochondrial activity (MMP)•MMPhigh HSCs from old mice have young-like transcriptional and functional features•MMP of HSCs can be manipulated in vivo with consequences for function•Mitochondrial potentiation can prevent or ameliorate onset of hematopoietic aging
HSC aging is clinically associated with risk of anemia, immune compromise, and malignancy. Mansell et al. show that mitochondrial activity is directly linked to age-related performance of HSCs and that its perturbation has direct consequences for HSC function, resulting in alleviation or prevention of hematopoietic aging.
Single-cell analysis is a rapidly evolving approach to characterize genome-scale molecular information at the individual cell level. Development of single-cell technologies and computational methods ...has enabled systematic investigation of cellular heterogeneity in a wide range of tissues and cell populations, yielding fresh insights into the composition, dynamics, and regulatory mechanisms of cell states in development and disease. Despite substantial advances, significant challenges remain in the analysis, integration, and interpretation of single-cell omics data. Here, we discuss the state of the field and recent advances and look to future opportunities.
ObjectivesTo estimate the impact of the COVID-19 pandemic on cancer care services and overall (direct and indirect) excess deaths in people with cancer.MethodsWe employed near real-time weekly data ...on cancer care to determine the adverse effect of the pandemic on cancer services. We also used these data, together with national death registrations until June 2020 to model deaths, in excess of background (pre-COVID-19) mortality, in people with cancer. Background mortality risks for 24 cancers with and without COVID-19-relevant comorbidities were obtained from population-based primary care cohort (Clinical Practice Research Datalink) on 3 862 012 adults in England.ResultsDeclines in urgent referrals (median=−70.4%) and chemotherapy attendances (median=−41.5%) to a nadir (lowest point) in the pandemic were observed. By 31 May, these declines have only partially recovered; urgent referrals (median=−44.5%) and chemotherapy attendances (median=−31.2%). There were short-term excess death registrations for cancer (without COVID-19), with peak relative risk (RR) of 1.17 at week ending on 3 April. The peak RR for all-cause deaths was 2.1 from week ending on 17 April. Based on these findings and recent literature, we modelled 40% and 80% of cancer patients being affected by the pandemic in the long-term. At 40% affected, we estimated 1-year total (direct and indirect) excess deaths in people with cancer as between 7165 and 17 910, using RRs of 1.2 and 1.5, respectively, where 78% of excess deaths occured in patients with ≥1 comorbidity.ConclusionsDramatic reductions were detected in the demand for, and supply of, cancer services which have not fully recovered with lockdown easing. These may contribute, over a 1-year time horizon, to substantial excess mortality among people with cancer and multimorbidity. It is urgent to understand how the recovery of general practitioner, oncology and other hospital services might best mitigate these long-term excess mortality risks.
•COVID-19 lung failure specifically correlates with a marker of peripheral blood cell immune activation.•Our findings suggest its use as a prognostic test for hypoxia.•Novel insight into COVID-19 ...related lung damage prompts possibilities for new treatment strategies.
The reasons why some patients with COVID-19 develop pneumonia and others do not are unclear. To better understand this, we used multiparameter flow cytometry to profile circulating leukocytes from non-immunocompromised adult patients with PCR-proven COVID-19 and specifically compared those with mild symptoms with those who had developed pneumonia.
Using clinically validated antibody panels we studied leukocytes from 29 patients with PCR-proven COVID-19. Ten were hypoxic requiring ventilatory support, eleven were febrile but otherwise well, and eight were convalescing having previously required ventilatory support. Additionally, we analysed patients who did not have COVID-19 but received ventilatory support for other reasons. We examined routine Full Blood Count (FBC) specimens that were surplus to routine diagnostic requirements; normal ranges were established in a historic group of healthy volunteers.
We observed striking and unexpected differences in cells of the innate immune system. Levels of CD11b and CD18, which together comprise Complement Receptor 3 (CR3), were increased in granulocytes and monocytes from hypoxic COVID-19 patients, but not in those with COVID-19 who remained well, or in those without COVID-19 but ventilated for other reasons. Granulocyte and monocyte numbers were unchanged, however Natural Killer (NK) cell numbers were two-fold higher than normal in COVID-19 patients who remained well.
CR3 is central to leukocyte activation and subsequent cytokine release in response to infection. It is also a fibrinogen receptor, and its over-expression in granulocytes and monocytes of patients with respiratory failure tables it as a candidate effector of both the thrombotic and inflammatory features of COVID-19 pneumonia, and both a biomarker of impending respiratory failure and potential therapeutic target. NK cells are innate immune cells that retain immunological memory. Rapid expansion of memory NK cells targeting common antigens shared with other Coronaviruses may explain why most patients with COVID-19 do not develop respiratory complications. Understanding the innate immune response to SARS-CoV-may uncover why most infected individuals experience mild symptoms, and inform a preventive approach to COVID-19 pneumonia in the future.
Umbilical cord blood (UCB) has had considerable impact in pediatric stem cell transplantation, but its wider use is limited in part by unit size. Long-term ex vivo culture offers one approach to ...increase engraftment capacity by seeking to expand stem and progenitor cells. Here, we show brief incubation (8 h) of UCB CD34+ cells with the matricellular regulator Nov (CCN3) increases the frequency of serially transplantable hematopoietic stem cells (HSCs) 6-fold. This rapid response suggests recruitment rather than expansion of stem cells; accordingly, in single-cell assays, Nov increases the clonogenicity of phenotypic HSCs without increasing their number through cell division. Recruitment is associated with both metabolic and transcriptional changes, and tracing of cell divisions demonstrates that the increased clonogenic activity resides within the undivided fraction of cells. Harnessing latent stem cell potential through recruitment-based approaches will inform understanding of stem cell state transitions with implications for translation to the clinic.
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•NOV rapidly increases the number of functional HSCs in a single cord blood unit•This is by direct recruitment without expansion or self-renewal ex vivo•NOV reduces C-MYC and ROS but increases glycolytic enzymes in HSCs•Manipulating non-dividing stem cells can alter their state and functional potential
Umbilical cord blood (UCB) HSCs offer several clinical advantages, but many units are too small for use. NOV rapidly increases the number of functional HSCs in single UCB units by recruitment rather than expansion. Manipulation of stem cell state transitions offers an alternative approach to enhance HSC activity.
Tumor relapse is associated with dismal prognosis, but responsible biological principles remain incompletely understood. To isolate and characterize relapse-inducing cells, we used genetic ...engineering and proliferation-sensitive dyes in patient-derived xenografts of acute lymphoblastic leukemia (ALL). We identified a rare subpopulation that resembled relapse-inducing cells with combined properties of long-term dormancy, treatment resistance, and stemness. Single-cell and bulk expression profiling revealed their similarity to primary ALL cells isolated from pediatric and adult patients at minimal residual disease (MRD). Therapeutically adverse characteristics were reversible, as resistant, dormant cells became sensitive to treatment and started proliferating when dissociated from the in vivo environment. Our data suggest that ALL patients might profit from therapeutic strategies that release MRD cells from the niche.
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•Patients' ALL cells growing in mice contain a rare unfavorable subpopulation•Unfavorable cells display treatment resistance, dormancy, and stemness•Unfavorable cells mimic patients' primary cells at minimal residual disease•Retrieving unfavorable cells from their environment sensitizes them for treatment
Ebinger et al. identify a rare subpopulation of acute lymphoblastic leukemia (ALL) cells that have the combined properties of long-term dormancy, treatment resistance, and leukemia initiation. RNA sequencing results show that these cells are similar to ALL cells isolated from patients at minimal residual disease.
We postulate that exit from pluripotency involves intermediates that retain pluripotency while simultaneously exhibiting lineage-bias. Using a MIXL1 reporter, we explore mesoderm lineage-bias within ...the human pluripotent stem cell compartment. We identify a substate, which at the single cell level coexpresses pluripotent and mesodermal gene expression programmes. Functionally these cells initiate stem cell cultures and exhibit mesodermal bias in differentiation assays. By promoting mesodermal identity through manipulation of WNT signalling while preventing exit from pluripotency using lysophosphatidic acid, we 'trap' and maintain cells in a lineage-biased stem cell state through multiple passages. These cells correspond to a normal state on the differentiation trajectory, the plasticity of which is evidenced by their reacquisition of an unbiased state upon removal of differentiation cues. The use of 'cross-antagonistic' signalling to trap pluripotent stem cell intermediates with different lineage-bias may have general applicability in the efficient production of cells for regenerative medicine.
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