AbstractWire myography to test vasomotor functions of blood vessels ex‐vivo are well‐established for the systemic circulation, however, there is no consensus on protocols for pulmonary arteries. We created a standardized wire myography protocol for healthy rat PAs and validated this in a pulmonary hypertension (PH) model. Vessels stretched to higher initial tensions (5.0, 7.5 and 10.0 mN) exhibited a uniform response to phenylephrine, a larger dynamic range, and lower EC50 values. The endothelium‐mediated relaxation showed that moderate tensions (7.5 and 10.0 mN) produced robust responses with higher maximum relaxation and lower EC50 values. For endothelium independent responses, the higher initial tension groups had lower and more consistent EC50 values than the lower initial tension groups. Pulmonary arteries from rats with PH were more responsive to vasoactive drugs when subjected to a higher initial tension. Notably, vessels in the PH group subjected to 15.0 mN exhibited high dynamic ranges in contractile and relaxation responses without tearing. Lastly, we observed attenuated cholinergic responses in these vessels—consistent with endothelial dysfunction in PH. Therefore, a moderate initial tension of 7.5–10.0 mN is optimal for healthy rat pulmonary arteries and a higher initial tension of 15.0 mN is optimal for pulmonary arteries from animals with PH.

Introduction DISC-0974 is a monoclonal antibody (mAB) targeting hemojuvelin and is currently in clinical trials evaluating effects on anemia in patients with myelofibrosis or chronic kidney disease. Inhibition of hemojuvelin (HJV) results in decreased hepcidin and reduction in ferroportin degradation, enabling more iron to be exported out of cells and into the bloodstream for transport to other cells and tissues. Methods A study was conducted in healthy, naïve cynomolgus monkeys to evaluate the safety, pharmacokinetics (PK), and pharmacodynamics (PD) of DISC-0974 following once-monthly dosing for 6 months. Male and female cynomolgus monkeys (n=6/sex/dose group) were intravenously administered DISC-0974 at doses of 0, 0.3, 1, or 6 mg/kg on Days 1, 29, 57, 85, 113, and 141. An additional IV dose was administered on Day 165 for males and Day 166 for females. Dose levels were selected where the high dose would maximally mobilize iron for sustained periods over the treatment regimen, with lower doses selected to provide a dose-response. Male and female monkeys (n=4/sex/group) were euthanized on Day 168 and 169, respectively, and subgroups were monitored for an additional 6 months (n=2/sex/group) to evaluate reversibility of any effects. PK was evaluated after the 1 st, 3 rd, and 6 th dose in all monkeys, as well as during the 6-month period after the final dose in the remaining monkeys. PD effects (i.e., serum iron and transferrin saturation [TSAT]) were monitored at the same timepoints as those collected for PK. Results DISC-0974 was well tolerated, and no DISC-0974-related adverse effects were observed. Systemic exposure, based on area under the curve (AUC) and maximum plasma concentrations (C max), increased with dose. Systemic exposures were achieved that reached and exceeded those observed in clinical trials. The high dose of 6 mg/kg achieved systemic exposures, based on AUC, that were >15-fold those observed in humans. Half-lives were consistent with an mAb, and repeated exposure did not result in accumulation with monthly dosing. Increases in serum iron (up to approximately 3-fold baseline) (Figure 1) and TSAT (>90%), representative of PD activity, correlated with systemic exposures of DISC-0974, with similar activity maintained after each of the 7 monthly doses. Conclusion Overall, these data demonstrate that DISC-0974 is well tolerated after repeated monthly exposure in cynomolgus monkeys, and an appropriate and durable PK/PD profile was observed, supporting clinical development of chronic once-monthly dosing.

Introduction: Accumulation of the photoreactive heme precursor protoporphyrin IX (PPIX) is a signature of the disease pathophysiology for both erythropoietic protoporphyria (EPP) and X-linked protoporphyria (XLP), and PPIX levels correlate with disease severity and light tolerance. Additionally, an elevated ratio of circulating metal-free PPIX vs. metal-bound PPIX is observed in patients with protoporphyrias, and the extent of metal-free elevation is distinguishable between EPP (85-100%) and XLP (50-85%). Therefore, the accurate determination of metal-free PPIX and metal-bound PPIX is of particular interest in patients with EPP or XLP. Methods: Novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) assays were developed and validated to quantify circulating metal-free and zinc (Zn)-complexed PPIX in whole blood and plasma. Each of the four assays were developed and validated according to applicable regulatory guidance for bioanalytical assay validation with regard to accuracy, precision, sensitivity, and selectivity. The minimum required sample volume for each assay was 200 µL, compared to >1 mL for most currently available protoporphyria-related assays. During bioanalytical method development, rapid degradation of metal-free PPIX (≥90%) and Zn-PPIX (up to 96%) was observed in plasma samples within 24 hours under ambient light conditions. In contrast, whole blood was less susceptible to photodegradation (i.e., ≤20% for both metal-free PPIX and Zn-PPIX) under the same conditions. The most effective method for maintaining sample integrity was reduction of light exposure during sample collection, handling, and processing. Implementation of light-reduction controls was used during method validation and facilitated improved stability of metal-free PPIX and Zn-PPIX in plasma and whole-blood samples. For the metal-free PPIX plasma assay validation, the effect of hemolysis was evaluated due to the apparent sequestration of metal-free PPIX in red blood cells. The bioanalytical work informed specific sample-collection procedures to mitigate instability and hemolysis, such as the use of opaque consumables for sample collection, controls for plasma aliquoting, and operating under low-light conditions for all sample handling and processing. BEACON is a Phase 2, randomized, open-label, parallel-arm trial (ACTRN12622000799752) of approximately 22 participants who will receive oral, once-daily administration of 20 or 60 mg of bitopertin for 6 months. Baseline light tolerance was assessed using 2 patient-reported outcomes measures during a 2- to 4-week screening period. Participants were asked to conduct weekly sun exposure challenges and time to first prodromal symptom (itching, burning, tingling, etc.) was averaged for the screening period. Results: More than 600 clinical samples from 17 participants in the BEACON study have been collected as of 06 June 2023 and analyzed using the validated porphyrin assays. Measured metal-free PPIX baseline values ranged from 1440 - 34,100 ng/mL (2.6 - 61 µM) in whole blood and 177 - 2560 ng/mL (0.31 - 4.5 µM) in plasma ( n=16). Baseline percentage of intra-patient plasma/whole-blood concentrations ranged from 2.5 - 16%. Each participant's baseline values were converted to erythrocyte metal-free PPIX concentrations using measured hematocrit levels and ranged from 3590 - 88400 ng/mL (6.4 - 157 µM). These values were comparable to data previously reported in the literature (6-139 µM 1). Additionally, higher baseline whole-blood metal-free PPIX concentrations were associated with decreased averages for time to prodrome (Table 1). Conclusion: Fully-validated LC-MS/MS assays to quantify metal-free PPIX and Zn-PPIX in plasma and whole blood were used to analyze clinical samples from the BEACON study evaluating bitopertin in EPP. PPIX values were consistent with previously reported values for patients with EPP. The methods also provided improved accuracy and specificity for metal-free vs. metal-complexed PPIX and reduced sample volume requirements. In addition, higher baseline whole-blood PPIX values were associated with decreased light tolerance within the trial population, supporting its use as a measure of disease severity in EPP.

Introduction: Erythropoietic protoporphyria (EPP) is associated with accumulation of photoreactive protoporphyrin IX (PPIX) in the skin and other organs, causing debilitating phototoxic skin reactions following exposure to sunlight, and potentially life-threatening protoporphyric hepatopathy in some patients. Reduction of PPIX is associated with amelioration of disease in the settings of hematopoietic stem cell transplant, pregnancy, and extracorporeal photoinactivation. Glycine transporter 1 (GlyT1) supplies extracellular glycine for the initial step of heme biosynthesis in erythroid cells. Bitopertin is an investigational, orally-administered inhibitor of GlyT1. It is hypothesized that GlyT1 inhibition leads to a decrease in heme pathway intermediates, including PPIX, and can improve light tolerance. Methods: BEACON is a Phase 2, randomized, open-label, parallel-arm trial (ACTRN12622000799752) of 22 participants who will receive oral, once-daily administration of 20 mg or 60 mg of bitopertin for 24 weeks. The trial is being conducted at 2 sites in Australia and includes participants ≥18 years of age with a confirmed diagnosis of EPP. The primary efficacy endpoint is percent change in whole-blood metal-free PPIX. Additional endpoints include daily patient-reported outcomes (PRO) of light tolerance and quality of life, as well as safety and tolerability. Results: As of data cutoff (05 July 2023), a total of 17 subjects had been enrolled. Treatment with bitopertin resulted in mean (SD) decreases in PPIX of -39% ± 17% by Day 43 (n=12), with more pronounced decreases observed with 60 mg compared to 20 mg (Figure 1). Bitopertin also improved multiple measures of light tolerance. A participant randomized to 20 mg bitopertin reported a >80-fold increase in sunlight tolerance on Day 88 of treatment, increasing from 4.5 minutes at baseline to over 6 hours; no prodromes were reported during any sunlight challenge after Day 20. A participant randomized to 60 mg bitopertin reported a >200-fold increase in sunlight tolerance on Day 74 of treatment, increasing from 1.3 minutes at baseline to over 4 hours, and did not report a prodrome during any sunlight challenge after Day 120. Aggregate measures of light tolerance also improved over time, including time to prodrome averaged over a 2-week period and weekly averages of total time in sunlight. The proportion of prodrome-free sunlight challenges increased from 2% during screening to 49% while receiving bitopertin (n=17), and the proportion of days without symptoms (with sun exposure) increased from 26% during screening to 74% while receiving bitopertin (n=17). Improvements in weekly averages of total time in sunlight were consistent and observed in 15/15 participants with post-baseline PPIX values. The greatest increases in weekly averages of total time in sunlight were observed in participants who experienced reductions in PPIX of at least 30% (Figure 2), for whichtotal time in sunlight increased from a weekly average of 339 minutes at baseline to a maximum of 999 minutes with bitopertin (n=11; mean duration of treatment: 133 days [range: 76 to ≥169 days]). Patient-reported phototoxic reactions decreased by 93% while on treatment compared to baseline (n=17). By Day 43, 15/16 participants reported in the Patient Global Impression of Change (PGIC) their EPP was much better or a little better, and 15/16 reported in the Patient Global Impression of Severity (PGIS) their EPP was mild or not at all severe. A majority (13/16) of participants responded in a novel PRO, the EPP Impact Questionnaire (EPIQ), that EPP had little or no impact on their quality of life while receiving bitopertin. No serious adverse events, discontinuations due to adverse events, or dose reductions have been reported. A total of 12 (71%) participants reported treatment-emergent adverse events; only dizziness and headache were reported in more than one subject. No meaningful changes in hemoglobin have been observed. Conclusion: By reducing whole-blood PPIX levels, bitopertin targets the underlying pathophysiology of EPP, resulting in consistent improvements in multiple measures of light tolerance and quality of life. Bitopertin has been well tolerated to date with no changes in hemoglobin, and its safety profile in EPP is consistent with prior studies that enrolled more than 4000 participants. Updated results will be presented at the meeting.

Hypoxia in the neonatal period is associated with early manifestations of adverse cardiovascular health in adulthood including higher risk of hypertension and atherosclerosis. We hypothesize that this occurs due to activation of lysyl oxidases (LOXs) and the remodeling of the large conduit vessels, leading to early arterial stiffening. Newborn C57Bl/6 mice were exposed to hypoxia (FiO(2) = 11.5%) from postnatal day 1 (P1) to postnatal day 11 (P11), followed by resumption of normoxia. Controls were maintained in normoxia. Using in vivo (pulse wave velocity; PWV) and ex vivo (tensile testing) arterial stiffness indexes, we determined that mice exposed to neonatal hypoxia had significantly higher arterial stiffness compared with normoxia controls by young adulthood (P60), and it increased further by P120. Echocardiography performed at P60 showed that mice exposed to hypoxia displayed a compensated dilated cardiomyopathy. Western blotting revelated that neonatal hypoxia accelerated age-related increase in LOXL2 protein expression in the aorta and elevated LOXL2 expression in the PA at P11 with a delayed decay toward normoxic controls. In the heart and lung, gene and protein expression of LOX/LOXL2 were upregulated at P11, with a delayed decay when compared to normoxic controls. Neonatal hypoxia results in a significant increase in arterial stiffness in early adulthood due to aberrant LOX/LOXL2 expression. This suggests an acceleration in the mechanical decline of the cardiovascular system, that contributes to increased risk of hypertension in young adults exposed to neonatal hypoxia that may increase susceptibility to further insults.

Rurioctocog alfa pegol prophylaxis targeting factor VIII (FVIII) troughs ≥1% has shown to be efficacious with an acceptable safety profile in people with hemophilia A (PwHA). The PROPEL trial compared safety and efficacy of 2 target FVIII troughs in PwHA aged 12 to 65 years, with severe disease, annualized bleeding rate ≥2, and previous FVIII treatment. PwHA were randomized to 12 months' pharmacokinetic (PK)-guided rurioctocog alfa pegol prophylaxis targeting FVIII troughs of 1% to 3% (reference arm) or 8% to 12% (elevated arm); first 6 months was treatment-adjustment period. The primary endpoint was absence of bleeds during the second 6 months, analyzed using multiple imputations (full analysis set [FAS]). In the 1% to 3% and 8% to 12% arms, respectively, point estimates (95% confidence interval) of proportions of PwHA with zero total bleeds were 42% (29% to 55%) and 62% (49% to 75%) in FAS (N = 115; P = .055) and 40% (27% to 55%) and 67% (52% to 81%) in per-protocol analysis set (N = 95; P = .015). Dosing frequency and consumption varied in each arm. Adverse events (AEs) occurred in 70/115 (60.9%) PwHA; serious AEs in 7/115 (6%) PwHA, including 1 treatment-related in 8% to 12% arm (transient anti–FVIII inhibitor). There were no deaths, serious thrombotic events, or AE-related discontinuations. PK-guided prophylaxis was achievable and efficacious in both arms. No new safety signals were observed in the 8% to 12% arm. These results demonstrate elevated FVIII troughs can increase the proportion of PwHA with zero bleeds and emphasize the importance of personalized treatment. This trial was registered at www.clinicaltrials.gov as #NCT02585960.

Tissue transglutaminase (TG2), a multifunctional protein of the transglutaminase family, has putative transamidation-independent functions in aging-associated vascular stiffening and dysfunction. Developing preclinical models will be critical to fully understand the physiologic relevance of TG2’s transamidation-independent activity and to identify the specific function of TG2 for therapeutic targeting. Therefore, in this study, we harnessed CRISPR-Cas9 gene editing technology to introduce a mutation at cysteine 277 in the active site of the mouse Tgm2 gene. Heterozygous and homozygous Tgm2 -C277S mice were phenotypically normal and were born at the expected Mendelian frequency. TG2 protein was ubiquitously expressed in the Tgm2 -C277S mice at levels similar to those of wild-type (WT) mice. In the Tgm2 -C277S mice, TG2 transglutaminase function was successfully obliterated, but the transamidation-independent functions ascribed to GTP, fibronectin, and integrin binding were preserved. In vitro, a remodeling stimulus led to the significant loss of vascular compliance in WT mice, but not in the Tgm2 -C277S or TG2 −/− mice. Vascular stiffness increased with age in WT mice, as measured by pulse-wave velocity and tensile testing. Tgm2 -C277S mice were protected from age-associated vascular stiffening, and TG2 knockout yielded further protection. Together, these studies show that TG2 contributes significantly to overall vascular modulus and vasoreactivity independent of its transamidation function, but that transamidation activity is a significant cause of vascular matrix stiffening during aging. Finally, the Tgm2 -C277S mice can be used for in vivo studies to explore the transamidation-independent roles of TG2 in physiology and pathophysiology.

Evidence links osteoporosis and cardiovascular disease but the cellular and molecular mechanisms are unclear. Here we identify skeleton-secreted platelet-derived growth factor-BB (PDGF-BB) as a key mediator of arterial stiffening in response to aging and metabolic stress. Aged mice and those fed high-fat diet (HFD), relative to young mice and those fed normal chow food diet, respectively, had higher serum PDGF-BB and developed bone loss and arterial stiffening. Bone/bone marrow preosteoclasts in aged mice and HFD mice secrete an excessive amount of PDGF-BB, contributing to the elevated PDGF-BB in blood circulation. Conditioned medium prepared from preosteoclasts stimulated proliferation and migration of the vascular smooth muscle cells. Conditional transgenic mice, in which PDGF-BB is overexpressed in preosteoclasts, had 3-fold higher serum PDGF-BB concentration and developed simultaneous bone loss and arterial stiffening spontaneously at a young age. Conversely, in conditional knockout mice, in which PDGF-BB is deleted selectively in preosteoclasts, HFD did not affect serum PDGF-BB concentration; as a result, HFD-induced bone loss and arterial stiffening were attenuated. These studies confirm that preosteoclasts are a main source of excessive PDGF-BB in blood circulation during aging and metabolic stress and establish the role of skeleton-derived PDGF-BB as an important mediator of vascular stiffening.

Background: Autologous haematopoietic stem cell (HSC) transplantation is a recommended therapeutic option for selected patients with autoimmune diseases. G-CSF mobilisation of HSCs requires 4-7 days of injections that are associated with significant side effects and potential for severe complications including disease flares (e.g., scleroderma and multiple sclerosis). MGTA-145 is a biologic that activates CXCR2 on neutrophils, and with plerixafor rapidly mobilises HSCs in mice and non-human primates. The combination promises to be a same-day, G-CSF-free mobilisation regimen. Objectives: To evaluate the safety, tolerability, and mobilisation efficacy of MGTA-145 monotherapy and combination therapy with plerixafor in healthy volunteers. Methods: This healthy volunteer phase 1 study consisted of 4 parts- Part A: single-agent MGTA-145 or placebo; Part B: MGTA-145 or placebo given immediately or 2 hours after plerixafor; Part C: MGTA-145 or placebo given 2 hours after plerixafor on 2 consecutive days; Part D: MGTA-145 given 2 hours after plerixafor, just prior to apheresis cell collection. Results: Monotherapy of MGTA-145 mobilised CD34+ cells within minutes and peaked within 1 hour post MGTA-145 (median 11 CD34+ cells/µL, a 7-fold increase vs baseline). White blood cells and neutrophils followed a similar pattern. Importantly, markers of neutrophil activation were relatively unchanged (≤2-fold vs baseline). MGTA-145 combined with plerixafor increased CD34+ cell mobilisation, whether given simultaneously or 2h after plerixafor (Fig. 1A). Mobilisation was highly enriched for CD34+CD90+CD45RA- HSCs, which tracked closely with the total CD34 count. At the 0.03 mg/kg dose with 2h stagger, median peak CD34+ peripheral blood mobilisation was ≥40 cells/µL in Part B. On a second consecutive day of dosing, MGTA-145 + plerixafor mobilises HSCs to levels comparable to day 1. Initial data from the ongoing Part D show that sufficient numbers of cells (median 4.3 x 10^6 CD34+ cells/kg) for transplant were collected in a single day.. Preliminary data from NSG mouse transplant studies of those mobilised HSCs in part D show higher engraftment rates of MGTA-145 + plerixafor mobilised HSCs, compared to G-CSF-mobilised HSCs. Figure. Peripheral blood mobilisation after plerixafor + 0.03 mg/kg MGTA-145 in healthy subjects with simultaneous and 2h stagger dosing after plerixafor. Dotted line: previously reported CD34+ counts with plerixafor alone mobilisation (Chen et al , Blood Advances . 2018). MGTA-145 monotherapy was well tolerated with no significant adverse events (AEs). Grade 1, transient lower back pain that dissipated within minutes was reported. The combination of MGTA-145 with plerixafor was well tolerated, with some subjects experiencing grade 1/2 gastrointestinal AEs commonly observed with plerixafor and one grade 2 back pain with MGTA-145 at 0.075 mg/kg that resolved within minutes. Conclusion: MGTA-145 monotherapy was well-tolerated and induced rapid mobilisation of significant numbers of HSCs. CD34+ cell mobilisation with MGTA-145 + plerixafor was immediate and superior to plerixafor alone. These data suggest that the combination can enable the collection of sufficient HSCs for transplant in one day without the need for G-CSF. Further development as a first line mobilisation product is warranted in autoimmune diseases, gene therapy and haematologic malignancies. Table. Single-day Mobilisation and Apheresis Cell Yields in Part D Subject Total CD34+ Yield (x106 cells) CD34+/kg (x106 cells) CD90+ (%) 801 319 4.1 39% 807 322 4.4 41% 817 500 5.3 26% 821 (*completed only 13L of planned 20L collection) 239 2.7 19% Median 321 4.3 33% Disclosure of Interests: John Dipersio Shareholder of: Magenta, Consultant of: Cellworks, Tioma, Rivervest, Bioline, Asterias, Amphivena and Bluebird, Celgene, Incyte, NeoImuneTech, Macrogenics, Steven Devine: None declared, Jonathan Hoggatt Shareholder of: Magenta, Grant/research support from: Magenta, Consultant of: Magenta, David Scadden Shareholder of: Magenta, Consultant of: Magenta, Haley Howell Shareholder of: Magenta, Employee of: Magenta, Veit Schmelmer Shareholder of: Magenta, Employee of: Magenta, Jason Neale Shareholder of: Magenta, Employee of: Magenta, Tony Boitano Shareholder of: Magenta, Employee of: Magenta, Michael Cooke Shareholder of: Magenta, Employee of: Magenta, Dwight Morrow Shareholder of: Magenta, Employee of: Magenta, Glen Raffel Shareholder of: Magenta, Employee of: Magenta, Will Savage Shareholder of: Magenta, Employee of: Magenta, Kevin Goncalves Shareholder of: Magenta, Employee of: Magenta, Pat Falahee Shareholder of: Magenta, Employee of: Magenta, John Davis Shareholder of: Magenta, Employee of: Magenta

Mice are the most common animal model to investigate human disease and explore physiology. Mice are practical, cost efficient, and easily used for genetic manipulations. Although variability in cardiac structure and function among mouse strains is well noted, the effect of mouse strain on vascular stiffness indices is not known. Here, we compared mouse strain-dependent differences in key vascular stiffness indices among frequently used inbred mouse strains-C57Bl/6J, 129S, and Bl6/129S. In young healthy animals, baseline blood pressure and heart rate were identical in all strains, and independent of gender. However, both active in vivo and passive ex vivo vascular stiffness indices exhibited distinct differences. Specifically, both male and female 129S animals demonstrated the highest tensile stiffness, were least responsive to acetylcholine-induced vasorelaxation, and showed the lowest pulse wave velocity (PWV), an index of in vivo stiffness. C57Bl/6J mice demonstrated the highest PWV, lowest tensile stiffness, and the highest response to acetylcholine-induced vasorelaxation. Interestingly, within each strain, female mice had more compliant aortas. C57Bl/6J mice had thinner vessel walls with fewer layers, whereas 129S mice had the thickest walls with the most layers. Values in the Bl6/129S mixed background mice fell between C57Bl/6J and 129S mice. In conclusion, we show that underlying vascular properties of different inbred wild-type mouse strains are distinct, despite superficial similarities in blood pressure. For each genetic modification, care should be taken to identify proper controls, and conclusions might need to be verified in more than one strain to minimize the risk of false positive studies.

BACKGROUND:Hypertension is a well-established driver of vascular remodeling and stiffening. The goal of this study was to evaluate whether restoring normal blood pressure (BP) fully restores vascular stiffness toward that of normotensive controls.METHODS:C57Bl6/J male mice received angiotensin II (angII; 1 μg/kg/min) via infusion pump for 8 weeks (hypertension group: HH), angII for 4 weeks (hypertension group: H4), angII for 4 weeks followed by 4 weeks of recovery (reversal group: HN), or sham treatment (normotensive group: NN). BP, heart rate, and pulse wave velocity (PWV) were measured longitudinally. At the end of the study period, aortas were harvested for testing of vasoreactivity, passive mechanical properties, and vessel structure.RESULTS:The HH group exhibited a sustained increase in BP and PWV over the 8-week period (p < 0.01). In the HN group, BP and PWV increased during the 4-week angII infusion, and, though BP was restored during the 4-week recovery, PWV exhibited only partial restoration (p < 0.05). Heart rate was similar in all cohorts. Compared to NN controls, both HH and HN groups had significantly increased wall thickness (p < 0.05 HH vs. NN, p < 0.01 HN vs. NN), mucosal extracellular matrix accumulation (p < 0.0001 HH vs. NN, p < 0.05 HN vs. NN), and intralamellar distance (p < 0.001 HH vs. NN, p < 0.01 HN vs. NN). Both intact and decellularized vessels were noted to have significantly higher passive stiffness in the HH and H4 cohorts than in NN controls (p < 0.0001). However, in the HN cohort, intact vessels were only modestly stiffer than those of NN controls, and decellularized HN vessels were identical to those from the NN controls. Compared to NN controls, the HH and HN cohorts exhibited significantly diminished phenylephrine-induced contraction (p < 0.0001) and endothelium-dependent vasodilation (p < 0.05).CONCLUSION:Hypertension causes a significant increase in in vivo aortic stiffness that is only partially reversible after BP normalization. Although hypertension does lead to matrix stiffening, restoration of BP restores matrix mechanics to levels similar to those of normotensive controls. Nevertheless, endothelial and vascular smooth muscle cell dysfunction persist after restoration of normotension. This dysfunction is, in part, responsible for augmented PWV after restoration of BP.

Chronic graft-versus-host disease (cGVHD) affects >50% of hematopoietic stem cell transplant patients. Extracorporeal photopheresis (ECP), an immunomodulatory therapy, provides clinical benefit in steroid-refractory (SR) cGVHD, possibly via regulatory T (Treg) and natural killer (NK) cell expansion. We demonstrated that low-dose interleukin-2 (IL2) led to clinical improvement in SR-cGVHD and stimulated preferential Treg and NK-cell expansion with minimal effect on conventional T (Tcon) cells. We evaluated the effect of ECP (weeks 1-16) plus IL2 (1 × 106 IU/m2, weeks 9-16) in 25 adult patients with SR-cGVHD in a prospective phase 2 trial. Objective responses occurred in 29% and 62% of evaluable patients at weeks 8 (ECP alone) and 16 (ECP plus IL2), respectively. Eight weeks of ECP alone was associated with a marked decline in CD4+ Tcon (P = .03) and CD8+ T cells (P = .0002), with minimal change in Treg cells, Treg:Tcon cell ratio, or NK cells. Adding IL2 induced an increase in Treg cells (P < .05 at weeks 9-16 vs week 8), Treg:Tcon cell ratio (P < .0001 at weeks 9-16 vs week 8), and NK cells (P < .05 at weeks 9-16 vs week 8). Patients responding to ECP alone had significantly fewer CD4+ Tcon and CD8+ T cells at baseline compared with patients who responded after IL2 addition and patients who did not respond; neither Treg nor NK cells were associated with response to ECP alone. Altogether, ECP plus IL2 is safe and effective in patients with SR-cGVHD. ECP and IL2 have distinct immunologic effects, suggesting different therapeutic mechanisms of action. This trial was registered at www.clinicaltrials.gov as #NCT02340676.

Scientific Research Question: Prophylaxis with extended half-life recombinant FVIII rurioctocog alfa pegol (SHP660, BAX 855; Baxalta [part of Shire, Lexington, MA]) targeting FVIII trough levels ≥1% is effective and well-tolerated in people with severe hemophilia A. As patients may benefit from higher trough levels, this study (NCT02585960) evaluated the safety and efficacy of rurioctocog alfa pegol in PK-guided prophylaxis targeting 2 different FVIII trough levels in previously treated patients.

Allergic transfusion reactions (ATRs) are the most common adverse reaction to blood products, particularly platelets and plasma. Evidence indicates that an IgE-mediated, immediate hypersensitivity is a common ATR mechanism. Selective protein deficiencies, e.g., IgA deficiency, are the cause in a small minority of ATRs, but in most cases the cause is unknown. Plasma reduction of cellular blood products, such as platelet additive solution, and solvent/detergent plasma decreases the incidence of ATRs. Diphenhydramine, a commonly used premedication, does not prevent ATRs from occurring but does alleviate symptoms once they occur.

BACKGROUNDRed blood cell (RBC) transfusions remain essential in the treatment of patients with sickle cell disease (SCD) and -thalassemia. Alloimmunization, a well-documented complication of transfusion, increases the risk of delayed hemolytic transfusion reactions, complicates crossmatching and identifying compatible units, and delays provision of transfusions. Guidance is required to optimize the RBC product administered to these patients. STUDY DESIGN AND METHODSAn international, multidisciplinary team conducted a systematic review and developed, following the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology, recommendations to assist treating physicians and transfusion specialists in their decision to select RBCs for these patients. RESULTSEighteen studies (17 clinical studies and one cost-effectiveness study) were included in the systematic review. The overall quality of the studies was very low. In total, 3696 patients were included: 1680 with -thalassemia and 2016 with SCD. CONCLUSIONThe panel recommends that ABO D CcEe K-matched RBCs are selected for individuals with SCD and -thalassemia, even in the absence of alloantibodies, to reduce the risk of alloimmunization. In patients with SCD and -thalassemia who have developed clinically significant alloantibodies, selection of RBCs antigen negative to the alloantibody is recommended, if feasible. In these patients, selection of more extended phenotype-matched RBCs will likely reduce the risk of further alloimmunization. However, given the limited availability of extended phenotype-matched units, attention should be given to ensure that a delay in transfusion does not adversely affect patient care.