Multistep Nature of Microvascular Recruitment of Ex Vivo–expanded Embryonic Endothelial Progenitor Cells during Tumor Angiogenesis

Tissue neovascularization involves recruitment of circulating endothelial progenitor cells that originate in the bone marrow. Here, we show that a class of embryonic endothelial progenitor cells (Tie-2+, c-Kit+, Sca-1+, and Flk-1−/low), which were isolated at E7.5 of mouse development at the onset of vasculogenesis, retain their ability to contribute to tumor angiogenesis in the adult. Using intravital fluorescence videomicroscopy, we further defined the multistep process of embryonic endothelial progenitor cell (eEPC) homing and incorporation. Circulating eEPCs are specifically arrested in “hot spots” within the tumor microvasculature, extravasate into the interstitium, form multicellular clusters, and incorporate into functional vascular networks. Expression analysis and in vivo blocking experiments provide evidence that the initial cell arrest of eEPC homing is mediated by E- and P-selectin and P-selectin glycoprotein ligand 1. This paper provides the first in vivo insights into the mechanisms of endothelial progenitor cell recruitment and, thus, indicates novel ways to interfere with pathological neovascularization

Rare and low-frequency coding variants alter human adult height

Height is a highly heritable, classic polygenic trait with ~700 common associated variants identified so far through genome - wide association studies . Here , we report 83 height - associated coding variants with lower minor allele frequenc ies ( range of 0.1 - 4.8% ) and effects of up to 2 16 cm /allele ( e.g. in IHH , STC2 , AR and CRISPLD2 ) , >10 times the average effect of common variants . In functional follow - up studies, rare height - increasing alleles of STC2 (+1 - 2 cm/allele) compromise d proteolytic inhibition of PAPP - A and increased cleavage of IGFBP - 4 in vitro , resulting in higher bioavailability of insulin - like growth factors . The se 83 height - associated variants overlap genes mutated in monogenic growth disorders and highlight new biological candidates ( e.g. ADAMTS3, IL11RA, NOX4 ) and pathways ( e.g . proteoglycan/ glycosaminoglycan synthesis ) involved in growth . Our results demonstrate that sufficiently large sample sizes can uncover rare and low - frequency variants of moderate to large effect associated with polygenic human phenotypes , and that these variants implicate relevant genes and pathways

Embryonic endothelial progenitor cells armed with a suicide gene target hypoxic lung metastasis after intravenous delivery.

We show that mouse embryonic endothelial progenitor cells (eEPCs) home preferentially to hypoxic lung metastases when administered intravenously. This specificity is inversely related to the degree of perfusion and vascular density in the metastasis and directly related to local levels of hypoxia and VEGF. Ex vivo expanded eEPCs that were genetically modified with a suicide gene specifically and efficiently eradicated lung metastases with scant patent blood vessels. eEPCs do not express MHC I proteins, are resistant to natural killer cell-mediated cytolysis, and can contribute to tumor vessel formation also in nonsyngeneic mice. These results indicate that eEPCs can be used in an allogeneic setting to treat hypoxic metastases that are known to be resistant to conventional therapeutic regimes

Neuregulin-1β regulation of embryonic endothelial progenitor cell survival

Endothelial progenitor cells (EPCs) are mobilized into the vascular space and home to damaged tissues, where they promote repair in part through a process of angiogenesis. Neuregulins (NRGs) are ligands in the epidermal growth factor family that signal through type I receptor tyrosine kinases in the erbB family (erbB2, erbB3, and erbB4) and regulate endothelial cell biology, promoting angiogenesis. Stimuli such as ischemia and exercise that promote EPC mobilization also induce cleavage and release of transmembrane NRG from cardiac microvascular endothelial cells (CMECs). We hypothesized that NRG/erbB signaling may regulate EPC biology. Using an embryonic (e)EPC cell line that homes to and repairs injured myocardium, we were able to detect erbB2 and erbB3 transcripts. Identical receptor expression was found in EPCs isolated from rat bone marrow and human whole blood. NRG treatment of eEPCs induces phosphorylation of kinases including Akt, GSK-3β, and Erk1/2 and the nuclear accumulation and transcriptional activation of β-catenin. NRG does not induce eEPC proliferation or migration but does protect eEPCs against serum deprivation-induced apoptosis. These results suggest a role for tissue-derived NRG in the regulation of EPC survival

Early peak and rapid decline of SARS-CoV-2 seroprevalence in a Swiss metropolitan region

Serological assays can detect anti-SARS-CoV-2 antibodies, but their sensitivity often comes at the expense of specificity. Here we developed a Tripartite Automated Blood Immunoassay (TRABI) to assess the IgG response against SARS-CoV-2. Calibration was performed with 90 prepandemic and 55 virologically and clinically confirmed COVID-19 samples. Posterior probabilities were calculated from 3×8 measurements of logarithmically diluted samples against the ectodomain and the receptor-binding domain of the spike protein and the nucleocapsid protein. We then performed 948’528 assays on 5’503 prepandemic and 34’019 copandemic samples from hospital patients and healthy blood donors. The seroprevalence increased in March 2020 (0.3%; CI95%: 0.1% - 0.5%) among hospital patients but plateaued in April at 1.1-1.3%, and dropped to 0.3-0.7% in July. A dynamic transmission model describing SARS-CoV-2 transmission and seroconversion in the general population of the Canton of Zurich yielded an infection fatality ratio of 0.6% (CI95%: 0.4%-0.8%), similarly to other European areas. While the evolution of seroprevalence points to a high effectiveness of containment measures, our data highlight that antibody waning warrants a continuous seromonitoring to reliably estimate the prevalence in a population

Protein-coding variants implicate novel genes related to lipid homeostasis contributing to body-fat distribution.

Body-fat distribution is a risk factor for adverse cardiovascular health consequences. We analyzed the association of body-fat distribution, assessed by waist-to-hip ratio adjusted for body mass index, with 228,985 predicted coding and splice site variants available on exome arrays in up to 344,369 individuals from five major ancestries (discovery) and 132,177 European-ancestry individuals (validation). We identified 15 common (minor allele frequency, MAF ≥5%) and nine low-frequency or rare (MAF <5%) coding novel variants. Pathway/gene set enrichment analyses identified lipid particle, adiponectin, abnormal white adipose tissue physiology and bone development and morphology as important contributors to fat distribution, while cross-trait associations highlight cardiometabolic traits. In functional follow-up analyses, specifically in Drosophila RNAi-knockdowns, we observed a significant increase in the total body triglyceride levels for two genes (DNAH10 and PLXND1). We implicate novel genes in fat distribution, stressing the importance of interrogating low-frequency and protein-coding variants

Continuous population-level monitoring of SARS-CoV-2 seroprevalence in a large metropolitan region

Effective public-health measures and vaccination campaigns against SARS-CoV-2 require granular knowledge of population-level immune responses. We developed a Tripartite Automated Blood Immunoassay (TRABI) to assess the IgG response against the ectodomain and the receptor-binding domain of the spike protein as well as the nucleocapsid protein of SARS-CoV-2. We used TRABI for continuous seromonitoring of hospital patients and healthy blood donors (n=72’222) in the canton of Zurich from December 2019 to December 2020 (pre-vaccine period). Seroprevalence peaked in May 2020 and rose again in November 2020 in both cohorts. Validations of results included antibody diffusional sizing and Western Blotting. Using an extended Susceptible-Exposed-Infectious-Removed model, we found that antibodies waned with a half-life of 75 days, whereas the cumulative incidence rose from 2.3% in June 2020 to 12.2% in mid-December 2020 in the population of the canton of Zurich. A follow-up health survey indicated that about 10% of patients infected with wildtype SARS-CoV-2 sustained some symptoms at least twelve months post COVID-19 and up to the timepoint of survey participation. Crucially, we found no evidence for a difference in long-term complications between those whose infection was symptomatic and those with asymptomatic acute infection. The cohort of asymptomatic SARS-CoV-2- infected subjects represents a resource for the study of chronic and possibly unexpected sequelae