Gestational Hypoxia and Developmental Plasticity.

Hypoxia is one of the most common and severe challenges to the maintenance of homeostasis. Oxygen sensing is a property of all tissues, and the response to hypoxia is multidimensional involving complicated intracellular networks concerned with the transduction of hypoxia-induced responses. Of all the stresses to which the fetus and newborn infant are subjected, perhaps the most important and clinically relevant is that of hypoxia. Hypoxia during gestation impacts both the mother and fetal development through interactions with an individual's genetic traits acquired over multiple generations by natural selection and changes in gene expression patterns by altering the epigenetic code. Changes in the epigenome determine "genomic plasticity," i.e., the ability of genes to be differentially expressed according to environmental cues. The genomic plasticity defined by epigenomic mechanisms including DNA methylation, histone modifications, and noncoding RNAs during development is the mechanistic substrate for phenotypic programming that determines physiological response and risk for healthy or deleterious outcomes. This review explores the impact of gestational hypoxia on maternal health and fetal development, and epigenetic mechanisms of developmental plasticity with emphasis on the uteroplacental circulation, heart development, cerebral circulation, pulmonary development, and the hypothalamic-pituitary-adrenal axis and adipose tissue. The complex molecular and epigenetic interactions that may impact an individual's physiology and developmental programming of health and disease later in life are discussed.

The origin and role of the renal stroma.

The postnatal kidney is predominantly composed of nephron epithelia with the interstitial components representing a small proportion of the final organ, except in the diseased state. This is in stark contrast to the developing organ, which arises from the mesoderm and comprises an expansive stromal population with distinct regional gene expression. In many organs, the identity and ultimate function of an epithelium is tightly regulated by the surrounding stroma during development. However, although the presence of a renal stromal stem cell population has been demonstrated, the focus has been on understanding the process of nephrogenesis whereas the role of distinct stromal components during kidney morphogenesis is less clear. In this Review, we consider what is known about the role of the stroma of the developing kidney in nephrogenesis, where these cells come from as well as their heterogeneity, and reflect on how this information may improve human kidney organoid models.

Combination therapy of insulin-like growth factor I and BTP-2 markedly improves lipopolysaccharide-induced liver injury in mice.

Acute liver injury is a common disease without effective therapy in humans. We sought to evaluate a combination therapy of insulin-like growth factor 1 (IGF-I) and BTP-2 in a mouse liver injury model induced by lipopolysaccharide (LPS). We chose this model because LPS is known to increase the expression of the transcription factors related to systemic inflammation (i.e., NFκB, CREB, AP1, IRF 3, and NFAT), which depends on calcium signaling. Notably, these transcription factors all have pleiotropic effects and account for the other observed changes in tissue damage parameters. Additionally, LPS is also known to increase the genes associated with a tissue injury (e.g., NGAL, SOD, caspase 3, and type 1 collagen) and systemic expression of pro-inflammatory cytokines. Finally, LPS compromises vascular integrity. Accordingly, IGF-I was selected because its serum levels were shown to decrease during systemic inflammation. BTP-2 was chosen because it was known to decrease cytosolic calcium, which is increased by LPS. This current study showed that IGF-I, BTP-2, or a combination therapy significantly altered and normalized all of the aforementioned LPS-induced gene changes. Additionally, our therapies reduced the vascular leakage caused by LPS, as evidenced by the Evans blue dye technique. Furthermore, histopathologic studies showed that IGF-I decreased the proportion of hepatocytes with ballooning degeneration. Finally, IGF-I also increased the expression of the hepatic growth factor (HGF) and the receptor for the epidermal growth factor (EGFR), markers of liver regeneration. Collectively, our data suggest that a combination of IGF-I and BTP-2 is a promising therapy for acute liver injury.

The Challenge of Intermediate-Risk Pulmonary Embolism.

BACKGROUND: Intermediate-risk pulmonary embolism is a common disease that is associated with significant morbidity and mortality; however, a standardized treatment protocol is not well-established. AREAS OF UNCERTAINTY: Treatments available for intermediate-risk pulmonary embolisms include anticoagulation, systemic thrombolytics, catheter-directed therapies, surgical embolectomy, and extracorporeal membrane oxygenation. Despite these options, there is no clear consensus on the optimal indication and timing of these interventions. THERAPEUTIC ADVANCES: Anticoagulation remains the cornerstone of treatment for pulmonary embolism; however, over the past 2 decades, there have been advances in the safety and efficacy of catheter-directed therapies. For massive pulmonary embolism, systemic thrombolytics and, sometimes, surgical thrombectomy are considered first-line treatments. Patients with intermediate-risk pulmonary embolism are at high risk of clinical deterioration; however, it is unclear whether anticoagulation alone is sufficient. The optimal treatment of intermediate-risk pulmonary embolism in the setting of hemodynamic stability with right heart strain present is not well-defined. Therapies such as catheter-directed thrombolysis and suction thrombectomy are being investigated given their potential to offload right ventricular strain. Several studies have recently evaluated catheter-directed thrombolysis and embolectomies and demonstrated the efficacy and safety of these interventions. Here, we review the literature on the management of intermediate-risk pulmonary embolisms and the evidence behind those interventions. CONCLUSIONS: There are many treatments available in the management of intermediate-risk pulmonary embolism. Although the current literature does not favor 1 treatment as superior, multiple studies have shown growing data to support catheter-directed therapies as potential options for these patients. Multidisciplinary pulmonary embolism response teams remain a key feature in improving the selection of advanced therapies and optimization of care.

Synthesis of a photocleavable bola-phosphatidylcholine.

Phosphatidylinositol transfer proteins (PITPs) are ubiquitous in eukaryotes and are involved in the regulation of phospholipid metabolism, membrane trafficking, and signal transduction. Sec14 is a yeast PITP that has been shown to transfer phosphatidylinositol (PI) or phosphatidylcholine (PC) from the endoplasmic reticulum to the Golgi. It is now believed that Sec14 may play a greater role than just shuttling PI and PC throughout the cell. Genetic evidence suggests that retrieval of membrane-bound PI by Sec14 also manages to present PI to the phosphatidylinositol-4-kinase, Pik1, to generate phosphatidylinositol-4-phosphate, PI(4)P. To test this hypothetical model, we designed a photocleavable bolalipid to span the entire membrane, having one phosphatidylcholine or phosphatidylinositol headgroup on each leaflet connected by a photocleavable diacid. Sec14 should not be able to present the bola-PI to Pik1 for phosphorylation as the head group will be difficult to lift from the bilayer as it is tethered on the opposite leaflet. After photocleavage the two halves would behave as a normal phospholipid, thus phosphorylation by Pik1 would resume. We report here the synthesis of a photocleavable bola-PC, a precursor to the desired bola-PI. The mono-photocleavable bola-PC lipid was designed to contain two glycerol molecules with choline head groups connected through a phosphodiester bond at the sn3 position. Each glycerol was acylated with palmitic acid at the sn1 position. These two glycerol moieties were then connected through their respective sn2 hydroxyls via a photocleavable dicarboxylic acid containing a nitrophenyl ethyl photolabile protecting group. The bola-PC and its precursors were found to undergo efficient photocleavage when irradiated in solution or in vesicles with 365 nm light for two minutes. Treatment of the bola-PC with a mutant phospholipase D and myo-inositol produced a mono-inositol bola-PC-PI.

Improved Workflow for Analysis of Vascular Myocyte Time-Series and Line-Scan Ca2+ Imaging Datasets.

Intracellular Ca2+ signals are key for the regulation of cellular processes ranging from myocyte contraction, hormonal secretion, neural transmission, cellular metabolism, transcriptional regulation, and cell proliferation. Measurement of cellular Ca2+ is routinely performed using fluorescence microscopy with biological indicators. Analysis of deterministic signals is reasonably straightforward as relevant data can be discriminated based on the timing of cellular responses. However, analysis of stochastic, slower oscillatory events, as well as rapid subcellular Ca2+ responses, takes considerable time and effort which often includes visual analysis by trained investigators, especially when studying signals arising from cells embedded in complex tissues. The purpose of the current study was to determine if full-frame time-series and line-scan image analysis workflow of Fluo-4 generated Ca2+ fluorescence data from vascular myocytes could be automated without introducing errors. This evaluation was addressed by re-analyzing a published "gold standard" full-frame time-series dataset through visual analysis of Ca2+ signals from recordings made in pulmonary arterial myocytes of en face arterial preparations. We applied a combination of data driven and statistical approaches with comparisons to our published data to assess the fidelity of the various approaches. Regions of interest with Ca2+ oscillations were detected automatically post hoc using the LCPro plug-in for ImageJ. Oscillatory signals were separated based on event durations between 4 and 40 s. These data were filtered based on cutoffs obtained from multiple methods and compared to the published manually curated "gold standard" dataset. Subcellular focal and rapid Ca2+ "spark" events from line-scan recordings were examined using SparkLab 5.8, which is a custom automated detection and analysis program. After filtering, the number of true positives, false positives, and false negatives were calculated through comparisons to visually derived "gold standard" datasets. Positive predictive value, sensitivity, and false discovery rates were calculated. There were very few significant differences between the automated and manually curated results with respect to quality of the oscillatory and Ca2+ spark events, and there were no systematic biases in the data curation or filtering techniques. The lack of statistical difference in event quality between manual data curation and statistically derived critical cutoff techniques leads us to believe that automated analysis techniques can be reliably used to analyze spatial and temporal aspects to Ca2+ imaging data, which will improve experiment workflow.

Calcium released by osteoclastic resorption stimulates autocrine/paracrine activities in local osteogenic cells to promote coupled bone formation.

A major cause of osteoporosis is impaired coupled bone formation. Mechanistically, both osteoclast-derived and bone-derived growth factors have been previously implicated. Here, we hypothesize that the release of bone calcium during osteoclastic bone resorption is essential for coupled bone formation. Osteoclastic resorption increases interstitial fluid calcium locally from the normal 1.8 mM up to 5 mM. MC3T3-E1 osteoprogenitor cells, cultured in a 3.6 mM calcium medium, demonstrated that calcium signaling stimulated osteogenic cell proliferation, differentiation, and migration. Calcium channel knockdown studies implicated calcium channels, Cav1.2, store-operated calcium entry (SOCE), and calcium-sensing receptor (CaSR) in regulating bone cell anabolic activities. MC3T3-E1 cells cultured in a 3.6 mM calcium medium expressed increased gene expression of Wnt signaling and growth factors platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), and bone morphogenic protein-2 (BMP 2). Our coupling model of bone formation, the receptor activator of nuclear factor-κΒ ligand (RANKL)-treated mouse calvaria, confirmed the role of calcium signaling in coupled bone formation by exhibiting increased gene expression for osterix and osteocalcin. Critically, dual immunocytochemistry showed that RANKL treatment increased osterix-positive cells and increased fluorescence intensity of Cav1.2 and CaSR protein expression per osterix-positive cell. The above data established that calcium released by osteoclasts contributed to the regulation of coupled bone formation. CRISPR/Cas-9 knockout of Cav1.2 in osteoprogenitor cells cultured in basal calcium medium caused a >80% decrease in the expression of downstream osteogenic genes, emphasizing the large magnitude of the effect of calcium signaling. Thus, calcium signaling is a major regulator of coupled bone formation.

Cellular extrusion bioprinting improves kidney organoid reproducibility and conformation.

Directed differentiation of human pluripotent stem cells to kidney organoids brings the prospect of drug screening, disease modelling and the generation of tissue for renal replacement. Currently, these applications are hampered by organoid variability, nephron immaturity, low throughput and limited scale. Here, we apply extrusion-based three-dimensional cellular bioprinting to deliver rapid and high-throughput generation of kidney organoids with highly reproducible cell number and viability. We demonstrate that manual organoid generation can be replaced by 6- or 96-well organoid bioprinting and evaluate the relative toxicity of aminoglycosides as a proof of concept for drug testing. In addition, three-dimensional bioprinting enables precise manipulation of biophysical properties, including organoid size, cell number and conformation, with modification of organoid conformation substantially increasing nephron yield per starting cell number. This facilitates the manufacture of uniformly patterned kidney tissue sheets with functional proximal tubular segments. Hence, automated extrusion-based bioprinting for kidney organoid production delivers improvements in throughput, quality control, scale and structure, facilitating in vitro and in vivo applications of stem cell-derived human kidney tissue.

Suction-based catheter retrieval of right ventricular clot-in-transit.

Right ventricular clot-in-transit (CIT) is a rare finding in venous thromboembolic disease and carries a high mortality rate. Its optimal treatments have yet to be established in the literature. Here we describe the usage of a suction-based catheter, the INARI FlowTriever® system (INARI Medical Inc.) to successfully retrieve a CIT from the right ventricle of a patient with coronavirus disease 2019 acute respiratory distress syndrome on veno-veno extracorporeal membrane oxygenation.

Comparison of clinical outcomes between use of overexpanding an undersized versus nominal-sized SAPIEN 3 ultra transcatheter heart valve in patients with borderline annulus area.

BACKGROUND: For patients with borderline annulus areas that fall between two valve sizes, overinflating a smaller balloon-expandable transcatheter heart valve (THV) may be preferable to nominal sizing of a larger THV. OBJECTIVES: To evaluate the outcomes of nominal preparation versus over-expanding an under-sized SAPIEN 3 Ultra (S3U) transcatheter heart valve (OE-THV) in cases with borderline annuli. METHODS: 958 patients that underwent TAVR with the S3U at four high-volume TAVR centers between January 2017 and December 2020 were retrospectively reviewed. 336 patients were identified as borderline annuli size, of which 146 (44%) received OE-THVs and 190 (56%) received nominal-sized THVs. The primary composite endpoint included: in-hospital mortality, aortic injury, moderate/severe paravalvular leak (PVL), permanent pacemaker implant (PPM), stroke, or conversion to surgery. RESULTS: Baseline characteristics were similar except for a larger percentage of females in the OE-THV (53.42% vs. 42.11%, p = 0.04). TAVR with OE-THV resulted a reduction in the primary composite endpoint (13.69% vs. 22.63%, p = 0.04). On subgroup analysis, there was no difference between 20 mm OE-THV versus 23 mm nominal or 23 mm OE-THV versus 26 mm nominal, but there was a reduction in the primary composite endpoint in patients with larger annuli that received a 26 mm OE-THV compared to the 29 mm nominally sized THV (9.7% vs. 27.4%, p = 0.02). At 1 month and 1 year follow-up, there was no significant difference in mortality, PVL rates, NYHA class, and/or KCCQ score. CONCLUSION: Overinflating a smaller-sized S3U THV may be a safer option in comparison to nominal sizing in patients with borderline annular area.

Prosthetic valve endocarditis after transcatheter aortic valve replacement in low-risk patients.

OBJECTIVES: We sought to report details of the incidence, organisms, clinical course, and outcomes of prosthetic valve endocarditis (PVE) after transcatheter aortic valve replacement (TAVR) in low-risk patients. BACKGROUND: PVE remains a rare but devastating complication of aortic valve replacement. Data regarding PVE after TAVR in low-risk patients are lacking. METHODS: We performed a detailed review of all patients in the low-risk TAVR trials who underwent TAVR from 2016 to 2020 and were adjudicated to have definitive PVE by the independent Clinical Events Committee. RESULTS: We analyzed 396 low-risk patients who underwent TAVR (including 72 with bicuspid valves). PVE occurred in 11 patients at a median 379 days (210, 528) from TAVR. The incidence within the first 30 days was 0%; days 31-365, 1.5%; and after day 365, 2.8%. The most common organism identified was Streptococcus (n = 4/11). Early PVE (≤ 365 days) occurred in five patients, of whom three demonstrated evidence of embolic stroke and two underwent surgical aortic valve re-intervention. Late PVE (> 365 days) occurred in six patients, of whom thee demonstrated evidence of embolic stroke and only one underwent surgical aortic valve re-intervention. Of the six patients with evidence of embolic stroke, two died, two were discharged to rehabilitation, and two were discharged home with home care. CONCLUSIONS: PVE was infrequent following TAVR in low-risk patients but was associated with substantial morbidity and mortality. Embolic stroke complicated the majority of PVE cases, contributing to worse outcomes in these patients. Efforts must be undertaken to minimize PVE in TAVR.

Malaria care-seeking and treatment ideation among gold miners in Guyana.

BACKGROUND: Although miners are a priority population in malaria elimination in Guyana, scant literature exists on the drivers of malaria-related behaviour. This study explores the relationship between gold miners' malaria-related ideation and the adoption of malaria care-seeking and treatment behaviours including prompt care-seeking, malaria testing, and self-medication. METHODS: Data are from a cross-sectional quantitative survey of 1685 adult miners between the ages of 18-59 years who live in mining camps in Regions 1, 7, and 8. The analysis focused on miners who reported an episode of fever in the past year (n = 745). Malaria care-seeking and treatment ideation was defined as a composite additive score consisting of the following variables: general malaria knowledge, perceived severity, perceived susceptibility, beliefs, perceived self-efficacy, perceived norms, interpersonal communication, and perceived response efficacy. Multivariable logistic regressions explored the relationship between ideation on care-seeking/treatment behaviours, controlling for confounding variables. RESULTS: Most miners with a recent episode of fever had perceived risk (92%), self-efficacy (67%), susceptibility (53%) and high malaria knowledge (53%). Overall, miners' care-seeking/treatment ideation score ranged from 0 to 8 with a mean of 4.1. Ideation scores were associated with higher odds of care-seeking for fever (aOR: 1.19; 95% CI 1.04-1.36), getting tested for malaria (aOR: 1.22; 95% CI 1.07-1.38) and lower odds of self-medication (aOR: 0.87; 95% CI 0.77-0.99). CONCLUSIONS: A national community case management initiative is using study findings as part of its scale-up, using volunteers to make testing and treatment services more accessible to miners. This is complemented by a multi-channel mass media campaign to improve miners' ideation. Communication messages focus on increasing miners' knowledge of malaria transmission and symptoms, encourage positive beliefs about malaria testing and volunteer testers, promote evidence about the effectiveness of testing, and reminders of how quick and easy it is to get a malaria test with the community case management initiative. Study findings also have implications for efforts to eliminate malaria across the Guiana Shield.

Defective bone repletion in aged Balb/cBy mice was caused by impaired osteoblastic differentiation.

INTRODUCTION: This study was undertaken to gain mechanistic information about bone repair using the bone repletion model in aged Balb/cBy mice. MATERIALS AND METHODS: one month-old (young) mice were fed a calcium-deficient diet for 2 weeks and 8 month-old (adult) and 21-25 month-old (aged) female mice for 4 weeks during depletion, which was followed by feeding a calcium-sufficient diet for 16 days during repletion. To determine if prolonged repletion would improve bone repair, an additional group of aged mice were repleted for 4 additional weeks. Control mice were fed calcium-sufficient diet throughout. In vivo bone repletion response was assessed by bone mineral density gain and histomorphometry. In vitro response was monitored by osteoblastic proliferation, differentiation, and senescence. RESULTS:  There was no significant bone repletion in aged mice even with an extended repletion period, indicating an impaired bone repletion. This was not due to an increase in bone cell senescence or reduction in osteoblast proliferation, but to dysfunctional osteoblastic differentiation in aged bone cells. Osteoblasts of aged mice had elevated levels of cytosolic and ER calcium, which were associated with increased Cav1.2 and CaSR (extracellular calcium channels) expression but reduced expression of Orai1 and Stim1, key components of Stored Operated Ca2+ Entry (SOCE). Activation of Cav1.2 and CaSR leads to increased osteoblastic proliferation, but activation of SOCE is associated with osteoblastic differentiation. CONCLUSION: The bone repletion mechanism in aged Balb/cBy mice is defective that is caused by an impaired osteoblast differentiation through reducedactivation of SOCE.

Survival and readmission among patients with advanced cardiomyopathy undergoing transcatheter edge-to-edge mitral valve repair: Are we applying COAPT findings too broadly?

OBJECTIVE: Transcathether edge-to-edge mitral valve repair (TEER) has been shown to be an effective treatment for secondary mitral regurgitation (MR). However, the outcomes of TEER in patients with severe cardiomyopathy is less clear. The objective of this study is to determine the outcomes of such patients who underwent TEER at our institution. METHODS: A retrospective review of patients with severe cardiomyopathy, defined as ejection fraction ≤30% or the requirement of inotropic support preoperatively, undergoing TEER for secondary MR at our institution from 11/2016 to 11/2020 was performed. Univariate analysis associating preoperative characteristics with our primary endpoint of 1-year death or orthotopic heart transplant (OHT) was performed. Kaplan-Meier analysis was conducted for the composite outcome of death or OHT, as well as for heart failure-related readmission. Finally, an assessment of changes in MR severity from the preoperative, to immediate postoperative period, to 30-day postoperative period was conducted. RESULTS: There were 48 patients identified. Median age was 74.5 years (IQR 65.5-79.5), median ejection fraction was 21.5% (IQR 16.0-27.5), and 81.4% of patients had severe or torrential mitral regurgitation preoperatively. The composite endpoint of 1-year mortality or OHT occurred in 15 of 48 patients (31.3%, 14 deaths and 1 OHT). One-year heart failure readmission rate was 47.9%. Mortality or OHT at 2 years occurred in 45.8%. CONCLUSION: Patients at extremes of heart failure who underwent TEER had poor outcomes when assessed at 1-year. Our study may suggest that the results of cardiovascular outcomes assessment of the mitraclip percutaneous therapy for heart failure patients with secondary mitral regurgitation may not be applicable to patients with severe cardiomyopathy.

Transcatheter heart valve selection in patients with low ejection fraction and aortic stenosis.

OBJECTIVE: The aim of this study was to compare outcomes of transcatheter heart valve (THV) choice in patients with left ventricular (LV) systolic dysfunction. BACKGROUND: The management congestive heart failure with combined LV systolic dysfunction and severe aortic stenosis (AS) is challenging, yet transcatheter aortic valve replacement (TAVR) has emerged as a suitable treatment option in such patients. Head-to-head comparisons among the balloon-expandable (BEV) and self-expandable (SEV) THV remain limited in this subgroup of patients. METHODS: In this retrospective study, we included patients with severe AS with LV systolic dysfunction (LVEF ≤40%) who underwent TAVR at four high volume centers. Two thousand and twenty-eight consecutive patients were analyzed, of which 335 patients met inclusion criteria. One hundred fourty-six patients (43%) received a SEV, and 189 patients (57%) received a BEV. RESULTS: Baseline characteristics were similar except for a higher proportion of females in the SEV group. The primary composite endpoint of in-hospital mortality, moderate or greater paravalvular (PVL), stroke, conversion to open surgery, aortic valve reintervention, and/or need for permanent pacemaker (PPM) was no different among THV choice. There was more PVL in the SEV group, but higher transaortic gradients in the BEV group. Clinical outcomes and quality of life measures were similar up to 1 year follow-up. CONCLUSION: The choice of THV in patients with severe AS and systolic dysfunction must be weighed on a case-by-case basis.

Validation of 2 Novel and Complementary Training Platforms for Small Joint Arthroscopy.

PURPOSE: We developed 2 complementary low-fidelity models to be used to create the tool skills needed to perform small joint arthroscopy. The purpose of the study was to establish the face and construct validity of the 2 models. METHODS: The "foundation model" was constructed from lemon and radish sections, and the "advanced model" was constructed from a chicken knee. Using both models, novice, intermediate, and experienced participants were asked to perform specific tasks and were timed and scored on their performance. The experienced surgeons were given a 16-item survey to rate how closely each model emulated reality to determine face validity. RESULTS: For the foundation model, the mean total time for the completion of tasks was 1,138 seconds for novices, 1,059 seconds for intermediates, and 631 seconds for experienced, with significant differences between the groups for time to complete 2 of the tasks. With a maximum possible score of 50 points for the correct performance of all tasks, the mean total performance score was 23 for novices, 31.8 for intermediates, and 42.2 for experienced operators. For the advanced model, the mean total time for completion was 266 seconds for novices, 147 seconds for intermediates, and 72 seconds for experienced participants. With a maximum possible score of 31 points for the correct performance of all tasks, the mean total performance score was 1.9 for novices, 15.0 for intermediates, and 24.3 for experienced participants. The average scores for the face validity surveys using a 5-point Likert scale were 4.2 and 4.5 of 5 possible points for the foundation and advanced models, respectively. CONCLUSIONS: Experienced operators completed the tasks more quickly and had higher performance scores than the operators in other groups. This correlation between experience and performance suggests that both models have construct validity. The face validity scores were on the upper end of the scale, suggesting that both models emulate reality for experienced operators. CLINICAL RELEVANCE: These novel models provide low-cost, available and valid simulations conducive to high-repetition training.

Gestational long-term hypoxia induces metabolomic reprogramming and phenotypic transformations in fetal sheep pulmonary arteries.

Gestational long-term hypoxia increases the risk of myriad diseases in infants including persistent pulmonary hypertension. Similar to humans, fetal lamb lung development is susceptible to long-term intrauterine hypoxia, with structural and functional changes associated with the development of pulmonary hypertension including pulmonary arterial medial wall thickening and dysregulation of arterial reactivity, which culminates in decreased right ventricular output. To further explore the mechanisms associated with hypoxia-induced aberrations in the fetal sheep lung, we examined the premise that metabolomic changes and functional phenotypic transformations occur due to intrauterine, long-term hypoxia. To address this, we performed electron microscopy, Western immunoblotting, calcium imaging, and metabolomic analyses on pulmonary arteries isolated from near-term fetal lambs that had been exposed to low- or high-altitude (3,801 m) hypoxia for the latter 110+ days of gestation. Our results demonstrate that the sarcoplasmic reticulum was swollen with high luminal width and distances to the plasma membrane in the hypoxic group. Hypoxic animals were presented with higher endoplasmic reticulum stress and suppressed calcium storage. Metabolically, hypoxia was associated with lower levels of multiple omega-3 polyunsaturated fatty acids and derived lipid mediators (e.g., eicosapentaenoic acid, docosahexaenoic acid, α-linolenic acid, 5-hydroxyeicosapentaenoic acid (5-HEPE), 12-HEPE, 15-HEPE, prostaglandin E3, and 19(20)-epoxy docosapentaenoic acid) and higher levels of some omega-6 metabolites (P < 0.02) including 15-keto prostaglandin E2 and linoleoylglycerol. Collectively, the results reveal broad evidence for long-term hypoxia-induced metabolic reprogramming and phenotypic transformations in the pulmonary arteries of fetal sheep, conditions that likely contribute to the development of persistent pulmonary hypertension.

Patient-iPSC-Derived Kidney Organoids Show Functional Validation of a Ciliopathic Renal Phenotype and Reveal Underlying Pathogenetic Mechanisms.

Despite the increasing diagnostic rate of genomic sequencing, the genetic basis of more than 50% of heritable kidney disease remains unresolved. Kidney organoids differentiated from induced pluripotent stem cells (iPSCs) of individuals affected by inherited renal disease represent a potential, but unvalidated, platform for the functional validation of novel gene variants and investigation of underlying pathogenetic mechanisms. In this study, trio whole-exome sequencing of a prospectively identified nephronophthisis (NPHP) proband and her parents identified compound-heterozygous variants in IFT140, a gene previously associated with NPHP-related ciliopathies. IFT140 plays a key role in retrograde intraflagellar transport, but the precise downstream cellular mechanisms responsible for disease presentation remain unknown. A one-step reprogramming and gene-editing protocol was used to derive both uncorrected proband iPSCs and isogenic gene-corrected iPSCs, which were differentiated to kidney organoids. Proband organoid tubules demonstrated shortened, club-shaped primary cilia, whereas gene correction rescued this phenotype. Differential expression analysis of epithelial cells isolated from organoids suggested downregulation of genes associated with apicobasal polarity, cell-cell junctions, and dynein motor assembly in proband epithelial cells. Matrigel cyst cultures confirmed a polarization defect in proband versus gene-corrected renal epithelium. As such, this study represents a "proof of concept" for using proband-derived iPSCs to model renal disease and illustrates dysfunctional cellular pathways beyond the primary cilium in the setting of IFT140 mutations, which are established for other NPHP genotypes.

Transcatheter aortic valve replacement in low-risk patients: 2-year results from the LRT trial.

BACKGROUND: Previous studies from the Low Risk TAVR (LRT) trial demonstrated that transcatheter aortic valve replacement (TAVR) is safe and feasible in low-risk patients, with excellent 30-day and 1-year outcomes. The objective of this study was to report clinical outcomes and the impact of 30-day hypoattenuated leaflet thickening (HALT) on structural valve deterioration (SVD) 2 years after TAVR. METHODS: The LRT trial was the first Food and Drug Administration-approved Investigational Device Exemption trial in the United States to evaluate the safety and feasibility of TAVR in low-risk patients with symptomatic severe tricuspid aortic stenosis (AS). Valve hemodynamics and SVD by echo were recorded 30 days, 1 year, and 2 years post-TAVR. RESULTS: The LRT trial enrolled 200 low-risk patients to receive TAVR. Their mean age was 73.6 years and 61.5% were men. At 2-year follow-up, the mortality rate was 4.2%; the cardiovascular death rate was 1.6%. The disabling stroke rate was 1.1%, permanent pacemaker implantation rate was 8.6%, and 4 patients (2.2%) presented with endocarditis (2 between years 1 and 2). Of the 14% of TAVR subjects who had evidence of HALT at 30 days, there was no impact on valve hemodynamics, endocarditis or stroke at 2 years. CONCLUSIONS: TAVR for low-risk patients with symptomatic severe tricuspid AS is safe at 2 years. The presence of HALT at 30 days did not impact the early hemodynamic improvements nor the durability of the valve structure.

Reporter-based fate mapping in human kidney organoids confirms nephron lineage relationships and reveals synchronous nephron formation.

Nephron formation continues throughout kidney morphogenesis in both mice and humans. Lineage tracing studies in mice identified a self-renewing Six2-expressing nephron progenitor population able to give rise to the full complement of nephrons throughout kidney morphogenesis. To investigate the origin of nephrons within human pluripotent stem cell-derived kidney organoids, we performed a similar fate-mapping analysis of the SIX2-expressing lineage in induced pluripotent stem cell (iPSC)-derived kidney organoids to explore the feasibility of investigating lineage relationships in differentiating iPSCs in vitro Using CRISPR/Cas9 gene-edited lineage reporter lines, we show that SIX2-expressing cells give rise to nephron epithelial cell types but not to presumptive ureteric epithelium. The use of an inducible (CreERT2) line revealed a declining capacity for SIX2+ cells to contribute to nephron formation over time, but retention of nephron-forming capacity if provided an exogenous WNT signal. Hence, while human iPSC-derived kidney tissue appears to maintain lineage relationships previously identified in developing mouse kidney, unlike the developing kidney in vivo, kidney organoids lack a nephron progenitor niche capable of both self-renewal and ongoing nephrogenesis.