key: cord-0791319-naw6y602
authors: Huang, Xiaojia; Zhang, Xianming; Machireddy, Narsa; Mutlu, Gökhan M.; Fang, Yun; Wu, David; Zhao, You-Yang
title: Decitabine Reactivation of FoxM1-Dependent Endothelial Regeneration and Vascular Repair for Potential Treatment of Elderly ARDS and COVID-19 Patients
date: 2021-04-30
journal: bioRxiv
DOI: 10.1101/2021.04.29.442061
sha: ac0f99a76a30dd10c19a182798f826516eb2586d
doc_id: 791319
cord_uid: naw6y602

Aging is a major risk factor of high incidence and increased mortality of acute respiratory distress syndrome (ARDS) and COVID-19. We repot that aging impairs the intrinsic FoxM1-dependent endothelial regeneration and vascular repair program and causes persistent lung injury and high mortality following sepsis. Therapeutic gene transduction of FOXM1 in vascular endothelium or treatment with FDA-approved drug Decitabine was sufficient to reactivate FoxM1-dependent lung endothelial regeneration in aged mice, reverse aging-impaired resolution of inflammatory injury, and promote survival. In COVID-19 lung autopsy samples, FOXM1 expression was not induced in vascular endothelial cells of elderly patients in contrast to mid-age patients. Thus, Decitabine reactivation of FoxM1-dependent vascular repair represents a potential effective therapy for elderly COVID-19 and non-COVID-19 ARDS patients.

The global COVID-19 pandemic has signified the urgency and importance of understanding the molecular and cellular mechanisms of endothelial regeneration and vascular repair in the pathogenesis of acute respiratory distress syndrome (ARDS).

ARDS is a form of acute-onset hypoxemic respiratory failure with bilateral pulmonary infiltrates, which is caused by acute inflammatory edema of the lungs not attributable to left heart failure (1-3). The common causes of ARDS include sepsis, pneumonia, inhalation of harmful substance, burn, major trauma with shock and massive transfusion. Sepsis with annual U.S. incidence of over 750,000 is the most common cause. In the current COVID-19 pandemic, COVID-19 has also found to be the major cause of ARDS. Endothelial injury characterized by persistently increased lung microvascular permeability resulting in protein-rich lung edema is a hallmark of acute lung injury (ALI)/ARDS (4) (5) (6) (7) . Despite recent advances on the understanding of the pathogenesis, there are currently no effective pharmacological or cell-based treatment of the disease and the mortality remains as high as 40% (1-3). Compared to young adult patients, the incidence of ARDS resulting from sepsis and pneumonia in elderly patients ( 65 yr) is as much as 19-fold greater and the mortality is up to 10fold greater (1, [8] [9] [10] [11] . Similarly, the hospitalization and mortality rates of elderly COVID-19 patients are much higher than young adults (12) (13) (14) (15) . In one study, it has been shown that 43% of COVID-19 patients aged ≥ 70 years died compared to 8.7%

of 40-59 years old and 2.8% of 20-39 years old patients died (14) . Severe vascular endothelial injury derived from direct viral effects and perivascular inflammation is a characteristic feature of COVID-19 lung injury (16) (17) (18) (19) and COVID-19 ARDS is considered as a vascular endotype of ARDS (20-22). However, little is known about how aging influences mechanisms of endothelial regeneration and resulting restoration of vascular homeostasis. The underlying causes of aging-related high incidence and mortality of ARDS and COVID-19 are poorly understood and thus there is no effective therapy to prevent and treat COVID-19 and non-COVID-19

ARDS.

Here we sought to define the cell source of origin mediating lung endothelial regeneration following sepsis injury by genetic lineage tracing, determine how aging affects this process and resolution of inflammatory lung injury, and delineate the underlying molecular mechanisms. Our studies demonstrate that aging impairs the intrinsic endothelial regeneration and vascular repair program and thus resolution of inflammation. Forced expression of the forkhead transcription factor FoxM1 (23-26) in lung ECs (transgenic or non-viral delivery of plasmid DNA) in aged mice is sufficient to re-activate lung endothelial regeneration and vascular repair and promote survival following sepsis. FoxM1 expression was induced in pulmonary vascular ECs of mid-aged COVID-19 patients but not in elderly patients. Importantly, repurposing an FDA-approved drug Decitabine could reactivate FoxM1-dependent endothelial regeneration and promote survival in aged mice. Thus, our studies demonstrate repurposing Decitabine to activate FoxM1-dependent endothelial regeneration and vascular repair represents a potential novel and effective therapy of ARDS and severe COVID-19 in elderly patients.

The major pathogenic feature of ALI/ARDS leading to deterioration of vascular barrier function is the precipitous loss of ECs (27-30). To trace the changes of pulmonary ECs following sepsis challenge, we performed lineage tracing on pulmonary ECs using a tamoxifen-inducible mTmG/EndoSCL-Cre ERT2 mouse ( fig.   S1A ). 95% of lung ECs (CD45 -CD31 + ) were labeled with green fluorescent protein (GFP) after tamoxifen treatment ( fig. S1 , B and C) whereas 5% of GFP + cells were either CD45 + cells (leukocytes) or CD31cells (non-ECs) ( fig. S1, D 

Fluorescence imaging revealed GFP + ECs in capillaries and along the inner surfaces of blood vessels but not bronchioles (Fig. 1A) . In young adult mice (3-5 mos. old), at 48h post-cecal ligation and puncture (CLP), which causes lethal peritonitis and polymicrobial sepsis, a well-recognized clinically relevant murine model of sepsis (31, 32) , the presence of GFP + ECs was noticeably disrupted along the blood vessel inner surfaces, consistent with loss of ECs seen in patients and animal models; by 144h post-CLP, the blood vessel inner wall was nicely lined with GFP + ECs again ( fig. S2) . To quantify the changes of pulmonary EC numbers over the course of sepsis-induced injury and recovery, we measured the percentage of CD45 -GFP + cells in the whole lung by flow cytometry analysis (FACS) in young adult mice. In sham animals, 40% of pulmonary CD45cells were GFP + . At 48h post-CLP, this number had dropped to 25%, but was followed by a steady return to baseline levels by 144h ( Fig. 1, B and C) . However, the CD45 + GFP + cell population was remained at steady minimal levels at various times ( fig. S3) , indicating CD45 + GFP + cells were not involved in endothelial regeneration. Bone marrow cell transplantation study further demonstrated that bone marrow-derived cells were not attributable to endothelial regeneration as the transplanted GFP + population remained steady ( fig. S4 ). Together, these data demonstrate that lung resident ECs are the cell source for endothelial regeneration in young adult mice following sepsis-induced injury.

FACS analysis revealed that the lung GFP + EC population was markedly decreased at 48h post-CLP in aged (19-21 mos.) mice as observed in young adult mice (Fig. 1D) . However, in contrast to young adult mice (Figure 1C) , the GFP + EC population in aged mice failed to recover and remained low at 144h post-CLP (Fig.   1D ). Thus, aging impaired the intrinsic endothelial regeneration program following sepsis challenge.

We next employed bromodeoxyuridine (BrdU) pulse assay to assess cell proliferation. Anti-BrdU immunostaining revealed defective lung endothelial proliferation in aged mice in contrast to young adult mice during the recovery phase (e.g., 72 and 96h post-CLP) (Fig. 1, E and F) . Accordingly, Evans blue-conjugated albumin (EBA) assay, a measurement of vascular permeability to protein showed persistent vascular leak indicating impaired vascular repair in the lungs of aged mice whereas vascular permeability returned to basal levels at 96h post-CLP in young adult mice (Fig. 1G) . The aged lungs also exhibited marked edema measured by greater lung wet/dry weight ratio at 72h post-CLP (Fig. 1H) and impaired resolution of inflammation during the recovery phase evident by persistently elevated lung myeloperoxidase (MPO) activity (Fig. 1I) , indicative of neutrophil sequestration, and increased expression of proinflammatory cytokines in lung tissue ( fig. S5 ).

To determine if aged mice also exhibit impaired vascular repair following endotoxemia, aged (19-21 mos.) and young (3-5 mos.) mice were challenged with lipopolysaccharide (LPS). Given that aged mice exhibited greater lung injury indicated by greater EBA flux and MPO activity at 24h post-LPS compared to young adult mice in response to the same dose of LPS (data not shown), we challenged the aged mice with a lower dose of LPS (e.g., 1.0 mg/kg) to induce a similar degree of injury during the injury phase (e.g., 24h) as seen in young adult mice with 2.5 mg/kg of LPS ( Fig. 2A) . EBA flux in young adult mice was reduced at 48h and returned to basal levels at 72h post-LPS whereas it remained elevated in aged lungs demonstrating defective vascular repair in aged lungs ( Fig. 2A) . Consistently, aged lungs exhibited edema at 72h post-LPS, which was not observed in young adult mice ( Fig. 2B) . MPO activity remained elevated in aged lungs at 72h post-LPS (Fig. 2C) . To further determine how aging affects vascular repair and inflammation resolution, we challenged the mice at various ages (3 to 21 mos. old) with LPS and assessed EBA flux and MPO activity at 72h post-LPS. As shown in Fig. 2D , EBA flux in mice at age of 6 mos. or younger returned to basal levels whereas it did not fully recover and maintained at marginally increased levels in 9 and 12 mos. old mice.

EBA flux was markedly elevated in 15 mos. old mice and greatly exaggerated in aged mice (18 and 21 mos. old). We also observed similar changes in MPO activity. Lung MPO activity did not return to basal levels at 72h post-LPS in mice starting at age 12 mos. and remained markedly increased in lungs of mice at age 15 mos. or older, indicating impaired resolution of inflammation (Fig. 2E) . Thus, mice at age 18 mos. or older exhibited severely impaired vascular repair and resolution of inflammation.

Anti-BrdU immunostaining shows a marked increase of endothelial proliferation in the lungs of young adult mice at 72h post-LPS whereas endothelial proliferation in lungs of aged mice was largely inhibited (Fig. 2F) , indicating impaired endothelial regeneration in aged lungs following LPS challenge. As FoxM1 is a critical reparative transcriptional factor (27, 33, 34), we assessed FoxM1 expression in mouse lungs.

Foxm1 was markedly induced in the lungs of young adult mice during the recovery phase but not in aged lungs following LPS challenge (Fig. 2G) . Accordingly, Foxm1 target genes essential for cell cycle progression were not induced in aged lungs ( fig.   S7 ).

To determine if failure of FoxM1 induction is responsible for the impaired vascular repair and inflammation resolution in aged mice, we employed the Foxm1 Tg mice expressing human FOXM1 under the control of Rosa26 promoter (35). EBA flux was increased similarly at 24h post-LPS challenge in aged Foxm1 Tg mice compared to aged WT mice, demonstrating similar degree of lung vascular injury (Fig. 3A) . EBA flux was then reduced at 48h and returned to a level close to basal level at 72h post-LPS in aged Foxm1 Tg mice whereas it was persistently elevated in aged WT mice ( Fig. 3A) . MPO activity was also similarly increased during the injury phase in aged WT and Foxm1 Tg mice and returned to basal levels at 72h post-LPS in aged Foxm1 Tg mice but not in aged WT mice (Fig. 3B) . These data demonstrate normalized vascular repair and resolution of inflammation in aged Foxm1 Tg mice following LPS challenge.

Accordingly, transgenic expression of FoxM1 promoted survival. 70% of aged Foxm1 Tg mice survived in 7 days following LPS challenge whereas all the aged WT mice died (Fig. 3C) .

Next, we employed a gene therapy approach to determine if forced FoxM1 expression in lung vascular ECs of aged WT mice after sepsis can reactivate endothelial regeneration and thus restore the defective resolution of inflammatory lung injury. A mixture of liposome:plasmid DNA (36) expressing human FOXM1 under the control of human CDH5 promoter (EC-specific) or empty vector DNA was administered retro-orbitally to 19-20 mos. old WT mice at 12h post-LPS (established lung injury). At 72h post-LPS, liposome transduction of FOXM1 plasmid DNA resulted in a marked increase of FoxM1 expression in aged WT mice compared to vector DNA-transduced mice (Fig. 3D) . EBA flux was drastically decreased (Fig. 3E) and lung MPO activity returned to a level close to basal level (Fig. 3F) in FOXM1 plasmid DNA-transduced mice in contrast to vector DNA-transduced mice.

We also assessed whether the restored vascular repair and resolution of inflammation is attributable to reactivated endothelial proliferation (i.e. regeneration) in aged lungs. BrdU labeling study revealed a marked increase of EC proliferation in lungs of FOXM1 plasmid DNA-transduced mice in sharp contrast to vector DNAtransduced mice (Fig. 3, G and H) . Expression of FoxM1 target genes essential for cell cycle progression including Cdc25c, Ccna2, and Ccnb1 was also markedly induced in lungs of FOXM1 plasmid DNA-transduced mice (Fig. 3I) .

To further determine if forced expression of FoxM1 in mice at very old age (e.g., 25 mos. old, equivalent to human age of ≥80 years) could still reactivate the vascular repair program, we employed our newly developed poly(lactide-coglycolide)-b-poly(ethylene glycol) copolymer (PLGA-PEG)-based nanoparticles to deliver the FOXM1 plasmid DNA. The mixture of nanoparticle:plasmid DNA was administrated retro-orbitally to 25 mos. old mice at 24h post-LPS (established injury).

At 96h post-LPS, lungs were collected for EBA and MPO assays. As shown in Fig.   3J , lung vascular permeability measured in vector DNA-transduced mice at 96h post-LPS remained markedly elevated whereas it was greatly reduced in FOXM1 plasmid DNA-transduced mice comparable to the observation in 19-21 mos. old mice (Fig.   3E) . Similarly, lung MPO activity in FOXM1 plasmid DNA-transduced mice was also markedly reduced (Fig. 3K) , indicating normalized resolution of inflammation.

To validate the potential clinical relevance of our findings in aged mice, we collected lung autopsy samples from COVID-19 patients ( Table S1 ) and carried out RNAscope in situ hybridization assay to determine FOXM1 expression. FOXM1 expression in pulmonary vascular ECs was markedly induced in middle-aged COVID-19 patients but not in elderly patients (Fig. 4) . Anti-CD31 immunostaining shows extensive disruption of the endothelial monolayer of COVID-19 patients in both middle-aged and elderly patients (Fig. 4A) , manifesting the characteristic feature of endothelial injury of severe COVID-19 patients (16) (17) (18) (19) .

We next explored the possibility of pharmacological activation of FoxM1dependent endothelial regeneration in aged lungs which will have great translational potential for treatment of ARDS and severe COVID-19 in elderly patients. Given the important role of epigenetics in aging, we focused on DNA methyl transferase inhibitor (e.g., 5-Aza 2'-deoxycytidine) and histone deacetylase inhibitor (Trichostatin A). In a preliminary study, we observed that 5-Aza 2'-deoxycytidine BrdU immunostaining revealed that pulmonary vascular EC proliferation was drastically increased in Decitabine-treated aged mice, indicating reactivation of endothelial regeneration (Fig. 5, D and E) . Accordingly, expression of FoxM1 target genes essential for cell cycle progression were markedly induced in lungs of Decitabine-treated aged mice (Fig. 5F ). Decitabine treatment also markedly improved survival of aged WT mice. 80% of Decitabine-treated mice survived whereas only 20% of vehicle-treated WT mice survived at the same period (Fig. 5G) . To determine if the survival effect was mediated by Decitabine-activated FoxM1 expression in ECs, we employed the mice with EC-specific knockout of Foxm1 (Foxm1 EC ) (27). As shown in Fig. 5G . Decitabine treatment had no protective effects on the survival of aged Foxm1 EC mice following LPS challenge.

The present study demonstrates that in young adult mice, lung resident ECs mediate endothelial regeneration responsible for vascular repair and resulting inflammation resolution following polymicrobial sepsis-induced injury. However, aging impairs these processes leading to persistent inflammatory lung injury and high Studies have demonstrated that endothelial barrier dysfunction is the major contributor to lung injury and poor prognostic outcomes of sepsis, ARDS (4, 5, (37) (38) (39) (40) (41) , and severe COVID19 (16) (17) (18) (19) . Severe inflammation such as following sepsis induces pulmonary vascular EC loss and disrupts endothelial barrier. Employing genetic lineage tracing and FACS analysis, we demonstrate that resident EC is the origin of source for lung endothelial regeneration. Our bone marrow transplantation study further excluded the contribution of bone marrow-derived cells in this regenerative process. Together, these studies provide unequivocal evidence of the exclusive contribution of lung resident ECs to endothelial regeneration in a clinically relevant sepsis model, CLP-induced polymicrobial sepsis. Employing this genetic lineage tracing mouse model, our studies have demonstrated impaired endothelial regeneration in aged lungs in contrast to young adult mice. We observed defective endothelial proliferation and vascular repair in aged lungs following lung injury induced by both polymicrobial sepsis and endotoxemia, which resulted in persistent lung vascular leaking and inflammation and thus high mortality. The impaired recovery of aged lungs following sepsis challenge is not attributable to more severe injury in aged mice than young adult mice as we employed different doses of LPS to induce similar degree of lung injury during the injury phase. We also found that mice starting at age of 12 mos. exhibited defective vascular repair and inflammation resolution which had becoming more severe with aging. These data could explain the clinical observations that the incidence and mortality of ARDS resulting from sepsis, pneumonia, and COVID-19 in elderly patients was much higher than young adult patients (8) (9) (10) (11) (12) (13) (14) (15) .

ECs are normally quiescent with a very low turnover rate. In response to injury, expression of some transcriptional factors is induced to activate EC proliferation (42). We have shown previously that FoxM1 is markedly induced in lung ECs in the recovery phase but not in the injury phase in young adult mice following LPS challenge (27). Here we show that FoxM1 was not induced in aged lungs following sepsis challenge, which played a causal role in aging-impaired endothelial regeneration and resolution of inflammatory injury as transgenic expression of FoxM1 prevented the defective phenotype in aged FOXM1 Tg mice and promoted survival following LPS challenge. As FoxM1 was expressed ubiquitously in all cells in the FOXM1 Tg mice by the Rosa26 promoter, it is unknown if the beneficial effects were mediated by FoxM1-dependent endothelial regeneration in aged lungs. (49) .

(CLP) using a 23-gauge needle (50) . Briefly, mice were anesthetized with inhaled isofluorane (2.5% mixed with oxygen). When the mice failed to respond to paw pinch, buprenex (0.1 mg/kg) was administered subcutaneously prior to sterilization of the skin with povidone iodine, then a 3 midline abdominal incision was made. The cecum was exposed and ligated with a 4-0 silk tie placed 0.6 cm from the cecum tip, and the cecal wall was perforated with a 23-gauge needle.

Control mice (sham) underwent anesthesia, laparotomy, and wound closure, but no cecal ligation or puncture. Following the procedure, 500 µl of prewarmed normal saline was administered subcutaneously. Within 5 min following surgery, the mice woke from anesthesia. The recovered mice subcutaneously received a second dose of buprenex at 8h post-surgery. extravasation assay was performed as previously described (50) . Briefly, mice were retro-4 orbitally injected with EBA at a dose of 20 mg/kg BW at 30 minutes prior to tissue collection.

Lungs were perfused free of blood with PBS, blotted dry and weighed. Lung tissues were then homogenized in 1 ml PBS and incubated with 2 volumes of formamide at 60C for 18 hours. The homogenates were centrifuged at 10, 000  g for 30 minutes and the optical density of the supernatant was determined at 620 nm and 740 nm. The extravasated EBA in lung homogenate was presented as g of Evans blue dye per g lung tissue.

Myeloperoxidase assay. Following perfusion free of blood, lung tissues were collected and homogenized in 50 mmol/L phosphate buffer. Homogenates were then centrifuged at 15, 000  g for 20 minutes at 4C. The pellets were resuspended in phosphate buffer containing 0.5% hexadecyl trimethylammonium bromide and subjected to a cycle of freezing and thawing.

Subsequently, the pellets were homogenized and the homogenates were centrifuged again.

Absorbance was measured at 460 nm every 15secs for 3 minutes and data expressed as Bone marrow cells isolated from mTmG/EndoSCL-Cre ERT2 mice were transplanted to lethally irradiated C57BL/6 WT mice (2 mos. old) to generate chimeric mice. Upon tamoxifen treatment, bone marrow-derived EndoSCL-Cre + cells were labeled with GFP in these chimeric mice. FACS analysis shows that the percentages of CD45 -GFP + cells (e.g. ECs) and CD45 + GFP + cells in lungs of the chimeric mice at 144h post-CLP challenge were similar to that of Sham, demonstrating bone marrow-derived GFP+ cells didn't contribute to endothelial regeneration. Bars represent means. 

Incidence and outcomes of acute lung injury

The acute respiratory distress syndrome

Acute respiratory distress syndrome

The role of the endothelium in severe sepsis and multiple organ dysfunction syndrome

Broken barriers: a new take on sepsis pathogenesis

Sepsis and endothelial permeability

Regeneration of the endothelium as a novel therapeutic strategy for acute lung injury

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Physiology of aging related to outcome in the adult respiratory distress syndrome

Approach to adult respiratory distress syndrome and respiratory failure in elderly patients

A multicenter registry of patients with acute respiratory distress syndrome

Epidemiology, clinical course, and outcomes of critically ill adults with COVID-19 in New York City: a prospective cohort study

Features of 20 133 UK patients in hospital with covid-19 using the ISARIC WHO Clinical Characterisation Protocol: prospective observational cohort study

Presenting Characteristics, Comorbidities, and Outcomes Among 5700 Patients Hospitalized With COVID-19 in the New York City Area

Estimating the burden of SARS-CoV-2 in France

Pulmonary Vascular Endothelialitis, Thrombosis, and Angiogenesis in Covid-19

mGFP-or tdTomato-labelled cells were directly analyzed with 488nm or 561nm laser wavelengths, respectively

MO) was injected i.p. into mice at 100 mg/kg BW. Mouse lung cryosections were stained overnight with anti-BrdU (1:3, BD Biosciences, or 1:1000 Cell Signaling Technology, Danvers, MA) and incubated with Alexa Fluo 488-conjugated secondary antibody

BD Bioscience) antibodies at 4C. The sections were then incubated with Alexa Fluor 594-conjugated secondary antibodies (1:200, Thermal Fisher Scientific). The nuclei were counterstained with DAPI (Thermal Fisher Scientific). Three consecutive cryosections from each mouse lung were examined, the average number of BrdU + nuclei was used

Following reverse transcription, quantitative RT-PCR analysis was performed using a sequence detection system (ABI ViiA 7 system; Thermal Fisher Scientific). The following primers sets were used for analysis: mouse FoxM1 primers, 5ʹ-CACTTGGATTGAGGACCACTT-3ʹ and 5ʹ-GTCGTTTCTGCTGTGATTCC-3ʹ; mouse cyclophilin primers, 5ʹ-CTTGTCCATGGCAAATGCTG-3ʹ and 5ʹ-TGATCTTCTTGCTGGTCTTGC-3ʹ. Primers for mouse Cdc25c, Ccna2, Ccnb1, Tnf, Il6, and Nos2 were purchased from Qiagen. The mouse gene expression was normalized to cyclophilin

Western blot analysis was performed using an anti-FoxM1 antibody

CA) and the same blot was incubated with anti-β-actin antibody (1:3000, BD Biosciences) as a loading control

CA) combined with immunofluorescent staining for CD31 as a EC marker was carried out. Briefly, the tissue sections were baked for 1 h at 60°C, deparaffinized, and treated with H2O2 for 10 min at room temperature. Target retrieval was performed for 15 min at 100°C, followed by protease treatment for 15 min at 40°C. The sections were then hybridized with human FOXM1 probe (Cat # 446941, target region 308-1244 in NM_001243088.1, ACD, Bio-techne) for 2 h at 40°C followed by signal amplification for 30 minutes using RNAscope® Multiplex Fluorescent v2

Bio-techne) as per manufacturer's instructions. The signal was developed by incubating the slides with TSA plus Cyanine 5 system (PerkinElmer, Waltham, MA) for 30 minutes

1% normal donkey serum) for 1 h followed by with a primary antibody against CD31 (Cat # Ab28364, Abcam, Cambridge, MA) at 4°C overnight. The sections were washed and incubated with appropriate anti-rabbit secondary antibody labeled with Alexa Fluor 488 for 1 h. The slides were then counterstained with DAPI and mounted in Prolong Gold Antifade mounting medium

To quantify FOXM1 expression, a score system of 0-5 was used. 5 represented highest while 1 lowest expression in vascular ECs of each vessel. Fifteen 63X fields each section were randomly selected and examined

Genetically tagging endothelial cells in vivo: bone marrow-derived cells do not contribute to tumor endothelium

Endothelial beta-Catenin Signaling Is Required for Maintaining Adult Blood-Brain Barrier Integrity and Central Nervous System Homeostasis

Therapeutic Targeting of Vascular Remodeling and Right Heart Failure in Pulmonary Arterial Hypertension with a HIF-2alpha Inhibitor

Endothelial p110gammaPI3K Mediates Endothelial Regeneration and Vascular Repair After Inflammatory Vascular Injury

Aged Young Aged Young