Impact of transcatheter aortic valve implantation on circulating von Willebrand factor in patients with severe aortic stenosis.

INTRODUCTION: Severe aortic stenosis (AS) can lead to degradation of high molecular weight (HMW) von Willebrand factor (VWF) which can result in haemostatic abnormalities. While studies have explored changes in VWF profiles before and after surgical aortic valve replacement (SAVR), the longer-term changes in VWF profiles pre- and post-transcatheter aortic valve implantation (TAVI) are less understood. AIM: Our primary objective was to identify differences in VWF multimer profiles and VWF function pre-TAVI and 1-month post-TAVI. Our secondary objective was to correlate VWF markers with measures of AS severity. METHODS: Adult patients with severe AS referred for TAVI at our institution were prospectively enrolled in this cohort study. Blood samples were collected for plasma analysis at three time points for all patients: 1 day pre-TAVI, 3 days post-TAVI, and 1-month post-TAVI. VWF antigen, activity, propeptide, collagen binding, multimers, and factor VIII coagulant activity were determined at each time point. Correlations between VWF parameters and severity of AS were assessed. RESULTS: Twenty participants (15 males, five females) with severe AS were recruited for the study. There was a significant increase in HMW VWF between pre-procedure and 1-month post-TAVI (p < .05). There was a transient increase in VWF antigen levels and activity at 3-days post TAVI that decreased to pre-TAVI levels at 1-month. There were no statistically significant correlations between VWF markers and AS severity. CONCLUSIONS: This is the first study to elucidate longer-term (>1 week) improvements in HMW VWF after a TAVI procedure in severe AS patients.

Idiopathic pulmonary arterial hypertension - a unrecognized cause of high-shear high-flow haemostatic defects (otherwise referred to as acquired von Willebrand syndrome) in children.

Acquired von Willebrand syndrome (AVWS) is reported in high-flow high-shear congenital cardiac disorders. We hypothesized that the narrowed pulmonary vasculature in idiopathic pulmonary arterial hypertension (IPAH) may induce AVWS. We conducted a cross-sectional evaluation of children with IPAH. Patients with bleeding symptoms and/or laboratory abnormalities (thrombocytopenia, anomalies in coagulation screening tests) were tested in-depth for haemostatic defects. Fourteen children were followed with IPAH of which 8 were eligible. Four children exhibited abnormal bleeding scores (International Society on Thrombosis and Haemostasis Bleeding Assessment Tool: 3-5). All 8 patients showed very prolonged platelet function analyser (PFA)-100 closure times. Six children demonstrated either mild thrombocytopenia or low-normal von Willebrand factor (VWF) antigen (VWF:Ag) or VWF activity [mean (range), in iu/dl: VWF:Ag: 70 (61-91); VWF activity: 57 (34-70)]. Average VWF collagen binding capacity (VWF:CB) was 64 iu/dl (range: 53-123 iu/dl), with low-normal VWF activity/VWF:Ag or VWF:CB/VWF:Ag ratios occurring in five patients. All children had normal multimers distribution patterns. One patient underwent a lung transplantation, with normalization of haemostatic abnormalities post-surgery. Overall, 8 out of 14 children with IPAH had mild to moderate bleeding symptoms and/or laboratory abnormalities in keeping with AVWS. Normalization of the haemostatic defects following lung transplantation and lack of family history of bleeding attests to the acquired nature of their defects.

Characterization of aberrant splicing of von Willebrand factor in von Willebrand disease: an underrecognized mechanism.

Approximately 10% of von Willebrand factor (VWF) gene mutations are thought to alter messenger RNA (mRNA) splicing through disruption of consensus splice sites. This mechanism is likely underrecognized and affected by mutations outside consensus splice sites. During VWF synthesis, splicing abnormalities lead to qualitative defects or quantitative deficiencies in VWF. This study investigated the pathologic mechanism acting in 3 von Willebrand disease (VWD) families with putative splicing mutations using patient-derived blood outgrowth endothelial cells (BOECs) and a heterologous human embryonic kidney (HEK 293(T)) cell model. The exonic mutation c.3538G>A causes 3 in-frame splicing variants (23del, 26del, and 23/26del) which cannot bind platelets, blood coagulation factor VIII, or collagen, causing VWD through dominant-negative intracellular retention of coexpressed wild-type (WT) VWF, and increased trafficking to lysosomes. Individuals heterozygous for the c.5842+1G>C mutation produce exon 33 skipping, exons 33-34 skipping, and WT VWF transcripts. Pathogenic intracellular retention of VWF lacking exons 33-34 causes their VWD. The branch site mutation c.6599-20A>T causes type 1 VWD through mRNA degradation of exon 38 skipping transcripts. Splicing ratios of aberrant transcripts and coexpressed WT were altered in the BOECs with exposure to shear stress. This study provides evidence of mutations outside consensus splice sites disrupting splicing and introduces the concept that VWF splicing is affected by shear stress on endothelial cells.

Bleeding Scores for the Diagnosis of von Willebrand Disease.

Obtaining a personal history of bleeding is a critical component to the diagnosis of von Willebrand disease (VWD). The collection of this information can be challenging for physicians, however, as the reporting and interpretation of bleeding symptoms is subjective. The need for more precise quantification of bleeding symptoms was recognized and the Vicenza Bleeding Questionnaire was developed in 2005. This questionnaire collects data regarding the presence and severity of bleeding symptoms and generates a bleeding score by summing the severity of all symptoms reported by a patient. Several subsequent bleeding assessment tools (BATs) have been developed based from this original questionnaire and there has been a surge in the use of BATs in various clinical settings for the diagnosis and evaluation of VWD. This review will discuss the evolution of BATs over the past decade, as well as their use and validation in various settings for the diagnosis and evaluation of VWD. Additionally, we will discuss the clinical utility of BATs, the limitations of these tools, and future directions.

Von Willebrand factor regulates complement on endothelial cells.

Atypical hemolytic uremic syndrome and thrombotic thrombocytopenic purpura have traditionally been considered separate entities. Defects in the regulation of the complement alternative pathway occur in atypical hemolytic uremic syndrome, and defects in the cleavage of von Willebrand factor (VWF)-multimers arise in thrombotic thrombocytopenic purpura. However, recent studies suggest that both entities are related as defects in the disease-causing pathways overlap or show functional interactions. Here we investigate the possible functional link of VWF-multimers and the complement system on endothelial cells. Blood outgrowth endothelial cells (BOECs) were obtained from 3 healthy individuals and 2 patients with Type 3 von Willebrand disease lacking VWF. Cells were exposed to a standardized complement challenge via the combination of classical and alternative pathway activation and 50% normal human serum resulting in complement fixation to the endothelial surface. Under these conditions we found the expected release of VWF-multimers causing platelet adhesion onto BOECs from healthy individuals. Importantly, in BOECs derived from patients with von Willebrand disease complement C3c deposition and cytotoxicity were more pronounced than on BOECs derived from normal individuals. This is of particular importance as primary glomerular endothelial cells display a heterogeneous expression pattern of VWF with overall reduced VWF abundance. Thus, our results support a mechanistic link between VWF-multimers and the complement system. However, our findings also identify VWF as a new complement regulator on vascular endothelial cells and suggest that VWF has a protective effect on endothelial cells and complement-mediated injury.

Predicting operative bleeding in elective pediatric surgeries using the Pediatric Bleeding Questionnaire (PBQ).

To test the Pediatric Bleeding Questionnaire's (PBQ) utility for predicting excessive bleeding during elective surgery, we retrospectively evaluated 60 pediatric patients who had been preoperatively investigated for von Willebrand disease. Of 58 patients with bleeding scores (BS) ≤2 (within normal range), 1 hemorrhaged during surgery. Two had a BS of >2 (positive BS); however, neither bled excessively during surgery. The resulting sensitivity, specificity, positive predictive values, and negative predictive values of the PBQ are 0%, 97%, 0%, and 98%, respectively. On the basis of this small sample, we cannot recommend the PBQ for screening in this setting.

Gastrointestinal bleeding in von Willebrand patients: special diagnostic and management considerations.

INTRODUCTION: Severe and recurrent gastrointestinal (GI) bleeding caused by angiodysplasia is a significant problem in patients with von Willebrand disease (VWD) and in those with acquired von Willebrand syndrome (AVWS). At present, angiodysplasia-related GI bleeding is often refractory to standard treatment including replacement therapy with von Willebrand factor (VWF) concentrates and continues to remain a major challenge and cause of significant morbidity in patients despite advances in diagnostics and therapeutics. AREAS COVERED: This paper reviews the available literature on GI bleeding in VWD patients, examines the molecular mechanisms implicated in angiodysplasia-related GI bleeding, and summarizes existing strategies in the management of bleeding GI angiodysplasia in patients with VWF abnormalities. Suggestions are made for further research directions. EXPERT OPINION: Bleeding from angiodysplasia poses a significant challenge for individuals with abnormal VWF. Diagnosis remains a challenge and may require multiple radiologic and endoscopic investigations. Additionally, there is a need for enhanced understanding at a molecular level to identify effective therapies. Future studies of VWF replacement therapies using newer formulations as well as other adjunctive treatments to prevent and treat bleeding will hopefully improve care.

Von Willebrand disease (VWD) is the most common inherited bleeding disorder. It is caused by problems with von Willebrand factor (VWF), a protein in blood that helps stop bleeding. People with VWD either have low levels of VWF or VWF that does not work properly. The disease causes bleeding symptoms in 1 in 1000 individuals. Three main types of VWD exist. Depending on the type, people can have minimal symptoms or serious bleeding that needs hospital care.Patients with severe VWD may often experience repeated bleeding from the gastrointestinal tract. This is usually due to the formation of abnormal fragile vessels (malformations) called angiodysplasia, which have been linked to the absence or abnormal function of VWF. These fragile vessels are very difficult to find and diagnose. At present, available treatments for angiodysplasia, including long-term VWF replacement therapy, are not very effective. As a result, VWD patients with angiodysplasia have a poor quality of life.More research is needed to better evaluate current treatments and explore the contribution of abnormal VWF in the development of angiogenesis and angiodysplasia in VWD which may reveal new targets for treatment.

Patient-centered care in von Willebrand disease: are we there yet?

INTRODUCTION: Von Willebrand Disease is the most common inherited bleeding disorder. Paradoxically, affected individuals are often misdiagnosed and experience substantial diagnostic delay. There are sex-specific health disparities in VWD rooted in the stigmatization of vaginal bleeding, which leads to symptom dismissal, lack of timely access to care and lower health-related quality of life. AREAS COVERED: Following the core elements of patient-centered care - respect for patient preferences, values, and needs, we describe the current state of VWD care. Challenges of diagnostic delay, serial misrecognition of abnormal bleeding, and symptom dismissal are barriers that disproportionately affect women with VWD. These negative effects are further amplified in individuals living in low- and middle-income countries. We describe the importance of coordinated multidisciplinary care, as well as the need for patient education and empowered self-advocacy. EXPERT OPINION: While tremendous work has been done to improve the diagnosis and management of VWD, timely and high-quality research is urgently needed to address care gaps. Systemic changes such as resource investment, dedicated research funding for novel treatment modalities, and effective knowledge translation strategies to address structural barriers are needed to facilitate effective patient-centered care for VWD.

A transcriptome analysis of basal and stimulated VWF release from endothelial cells derived from patients with type 1 VWD.

Type 1 von Willebrand disease (VWD) is associated with a reduction in qualitatively normal von Willebrand factor (VWF). Current diagnostic guidelines only take into consideration the contribution of basal VWF levels, despite a lack of correlation with bleeding severity. Defects in stimulated VWF release, which occurs after hemostatic challenge, may contribute to bleeding in type 1 VWD, but the pathogenic mechanisms are poorly defined. In this study, a layered multiomic approach including messenger RNA (mRNA) and microRNA (miRNA) sequencing was used to evaluate transcriptome-wide differences between type 1 VWD- and control-derived endothelial colony forming cells (ECFCs) during basal and stimulated VWF release. ECFCs from 8 patients with type 1 VWD and 4 other patients were included in this study as controls. VWF protein analysis revealed heterogenous responses to stimulation among type 1 VWD and control ECFCs. During basal VWF release, 64 mRNAs and 7 miRNAs were differentially regulated between type 1 VWD and control ECFCs, and 65 putatively pathogenic miRNA-mRNA interactions were identified. During stimulated VWF release, 190 mRNAs and 5 mRNAs were differentially regulated between type 1 VWD and control ECFCs, and 110 putatively pathogenic miRNA-mRNA interactions were identified. Five gene ontology terms including coagulation, regulation of cell shape, and regulation of cell signaling were also differentially regulated in type 1 VWD ECFCs during stimulated release. To our knowledge, we have shown for the first time that transcriptome-wide differences exist between type 1 VWD and control ECFCs. These differences may contribute to bleeding in type 1 VWD, and further investigation may reveal novel biomarkers and therapeutic targets.

Human Adipose- and Amnion-Derived Mesenchymal Stromal Cells Similarly Mitigate Osteoarthritis Progression in the Dunkin Hartley Guinea Pig.

BACKGROUND: Clinical trials are currently underway to investigate the efficacy of intra-articular administration of mesenchymal stromal cells (MSCs) to mitigate osteoarthritis (OA) progression in the knee. Although multiple MSC sources exist, studies have yet to determine whether differences in therapeutic efficacy exist between them. PURPOSE: To compare the ability of intra-articularly injected adipose-derived MSCs (AD-MSCs) and amnion-derived MSCs (AM-MSCs) to mitigate the progression of knee OA in a small animal model of spontaneous OA, as well as to compare the therapeutic potential of MSCs in hyaluronic acid (HA) and in HA only with saline (OA) controls. STUDY DESIGN: Controlled laboratory study. METHODS: Injections of AD-MSCs or AM-MSCs suspended in HA or HA only were performed in the rear stifle joints of 3-month-old Dunkin Hartley guinea pigs (DHGPs). Repeat injections occurred at 2 and 4 months after the initial injection in each animal. Contralateral limbs received saline injections and served as untreated controls. Subsequently, joints were analyzed for osteoarthritic changes of the cartilage and subchondral bone via histologic and biochemical analyses. To evaluate MSC retention time in the joint space, DHGPs received a single intra-articular injection of fluorescently labeled AD-MSCs or AM-MSCs, and the fluorescence intensity was longitudinally tracked via an in vivo imaging system. RESULTS: No statistically significant differences in outcomes were found when comparing the ability of AD-MSCs and AM-MSCs to mitigate OA. However, the injection of AD-MSCs, AM-MSCs, and HA-only treatments more effectively mitigated cartilage damage compared with that of saline controls by demonstrating higher amounts of cartilage glycosaminoglycan content and improved histological proteoglycan scoring while reducing the percentage of osteophytes present. CONCLUSION: Intra-articular injection of AD-MSCs, AM-MSCs, or HA only was able to similarly mitigate the progression of cartilage damage and reduce the percentage of osteophytes compared with that of saline controls in the DHGP. However, this study was unable to establish the superiority of AD-MSCs versus AM-MSCs as a treatment to mitigate spontaneous OA. CLINICAL RELEVANCE: MSCs demonstrate the ability to mitigate the progression of knee OA and thus may be used in a prophylactic approach to delay the need for end-stage treatment strategies.

von Willebrand factor propeptide variants lead to impaired storage and ER retention in patient-derived endothelial colony-forming cells.

BACKGROUND: von Willebrand factor (VWF) is synthesized by vascular endothelial cells and megakaryocytes. The VWF propeptide is critical for multimerization and acts as an intra-molecular chaperone for mature VWF in sorting to its storage organelles, Weibel-Palade bodies (WPBs). In the Canadian Type 3 VWD study, almost half of the identified variants were in the VWF propeptide and these were associated with an increased bleeding phenotype. OBJECTIVE: To investigate VWF propeptide variants that cause quantitative von Willebrand disease (VWD) by utilizing patient-derived endothelial colony-forming cells (ECFCs). PATIENTS/METHODS: Endothelial colony-forming cells were isolated from five Type 3 VWD patients from four families with the following variants: (1) homozygous p.Asp75_Gly178del (deletion of exons 4 and 5 deletion; Ex4-5del), (2) homozygous p.Cys633Arg, (3) homozygous p.Arg273Trp, and (4) p.Pro293Glnfs*164 and p.Gln419* inherited in the compound heterozygous state. Additionally, ECFCs were isolated from six family members (two Type 1 VWD, four unaffected). RESULTS: Endothelial colony-forming cells from the Type 3 patient with the compound heterozygous genotype exhibited a true null VWF cellular phenotype, with negligible VWF detected. In contrast, the other three propeptide variants presented a similar expression pattern in homozygous ECFCs where VWF was synthesized but not packaged in WPBs, and variant VWF had an increased association with the endoplasmic reticulum (ER) marker, protein disulfide-isomerase (PDI), indicating an ER-retention phenotype. The biosynthetic phenotype was similar but to a lesser degree in heterozygous ECFCs expressing the non-null variants. CONCLUSION: This study further elucidates the importance of the VWF propeptide in the VWD phenotype using patient-derived cells.

A novel deletion mutation is recurrent in von Willebrand disease types 1 and 3.

Direct sequencing of VWF genomic DNA in 21 patients with type 3 von Willebrand disease (VWD) failed to reveal a causative homozygous or compound heterozygous VWF genotype in 5 cases. Subsequent analysis of VWF mRNA led to the discovery of a deletion (c.221-977_532 + 7059del [p.Asp75_Gly178del]) of VWF in 7 of 12 white type 3 VWD patients from 6 unrelated families. This deletion of VWF exons 4 and 5 was absent in 9 patients of Asian origin. We developed a genomic DNA-based assay for the deletion, which also revealed its presence in 2 of 34 type 1 VWD families, segregating with VWD in an autosomal dominant fashion. The deletion was associated with a specific VWF haplotype, indicating a possible founder origin. Expression studies indicated markedly decreased secretion and defective multimerization of the mutant VWF protein. Further studies have found the mutation in additional type 1 VWD patients and in a family expressing both type 3 and type 1 VWD. The c.221-977_532 + 7059del mutation represents a previously unreported cause of both types 1 and 3 VWD. Screening for this mutation in other type 1 and type 3 VWD patient populations is required to elucidate further its overall contribution to VWD arising from quantitative deficiencies of VWF.

Patients with aortic stenosis have von Willebrand factor abnormalities and increased proliferation of endothelial colony forming cells.

BACKGROUND: Patients with aortic stenosis (AS) can experience bleeding complications including gastrointestinal bleeding from angiodysplastic lesions due to acquired von Willebrand syndrome. Studies have pointed to a role for von Willebrand factor (VWF) in angiogenesis. OBJECTIVE: The objective of this study was to assess VWF defects in AS patients over time and the impact on angiogenesis using patient-derived endothelial colony-forming cells (ECFCs). PATIENTS/METHODS: Plasma sample collection and ECFC isolations were performed before valve replacement surgery, 3 to 5 days after, and 6 months after surgery. Plasma VWF antigen, activity, propeptide, collagen binding, multimers, factor VIII coagulant activity, and ADAMTS13 activity (a disintegrin-like and metalloprotease with thrombospondin type 1 motifs 13) were determined. ECFCs were assessed for VWF and angiopoietin-2 (Ang-2) storage and secretion, cell proliferation, and tubule formation in Matrigel. RESULTS AND CONCLUSIONS: Aortic stenosis patients exhibited quantitative and qualitative abnormalities of VWF including significantly increased VWF antigen, activity, and propeptide levels following surgery (P < .01). Increased high molecular weight VWF multimers were observed at all time points and in particular 3 to 5 days after surgery (mean = 14% ± 6%) relative to before (mean = 10% ± 4%), suggesting increased proteolysis by ADAMTS13 pre-operatively in a shear-dependent manner. ECFCs from patients with aortic stenosis were more proliferative than controls (P < .05) and had increased retention of Ang-2 (P < .05) suggesting epigenetic modification of the cells. Overall, there are hemostatic changes in AS patients that are present before valve replacement surgery and these persist long after surgery has occurred. These findings have implications for the current clinical management of AS patients.

Endothelial characteristics in healthy endothelial colony forming cells; generating a robust and valid ex vivo model for vascular disease.

BACKGROUND: Endothelial colony forming cells (ECFCs) derived from peripheral blood can be used to analyze the pathophysiology of vascular diseases ex vivo. However, heterogeneity is observed between ECFC clones and this variability needs to be understood and standardized for ECFCs to be used as a cell model for applications in vascular studies. OBJECTIVE: Determine reference characteristics of healthy control ECFCs to generate a valid ex vivo model for vascular disease. METHODS: Putative ECFCs (n = 47) derived from 21 individual healthy subjects were studied for cell morphology and specific cell characteristics. Clones were analyzed for the production and secretion of von Willebrand factor (VWF), cell proliferation, and the expression of endothelial cell markers. RESULTS: Based on morphology, clones were categorized into three groups. Group 1 consisted of clones with classic endothelial cell morphology, whereas groups 2 and 3 contained less condensed cells with increasing cell sizes. All clones had comparable endothelial cell surface expression profiles, with low levels of non-endothelial markers. However, a decrease in CD31 and a group-related increase in CD309 and CD45 expression, combined with a decrease in cell proliferation and VWF production and secretion, was observed in clones in group 3 and to a lesser extent in group 2. CONCLUSIONS: We observed group-related variations in endothelial cell characteristics when clones lacked the classic endothelial cell morphology. Despite this variation, clones in all groups expressed endothelial cell surface markers. Provided that clones with similar characteristics are compared, we believe ECFCs are a valid ex vivo model to study vascular disease.

Vascular endothelial cells evade complement-mediated membrane injury via Weibel-Palade body mobilization.

BACKGROUND: Defective complement inhibition can lead to the formation of membrane attack complexes (MAC; C5b-9) on the plasma membranes of vascular endothelial cells, resulting in injury that drives the progression of thrombotic microangiopathy (TMA), a key pathology in kidney disease. OBJECTIVE/METHODS: We examined the response of human endothelial cells to complement-mediated damage using blood outgrowth endothelial cells (BOECs) derived from healthy donors. BOECs were sensitized to complement factors present in normal human serum to induce the formation of C5b-9 on their plasma membranes. RESULTS: This triggered an expected abrupt rise in intracellular Ca2+ reflecting membrane leakage. Remarkably, while intracellular Ca2+ remained elevated, membrane leakage ceased within 30 minutes, and cells did not show significant death. Extensive mobilization of Weibel-Palade bodies (WPBs) was observed along with secretion of von Willebrand factor (VWF). The potential role of WPBs and VWF in mitigating complement-mediated damage was examined by comparing the effects of C5b-9 on BOECs derived from von Willebrand disease (VWD) patients expressing reduced amounts of VWF, lacking expression of functional VWF, or lacking both VWF and WPBs. BOECs lacking WPBs were not resistant to complement-mediated damage, but became resistant when transfected to express VWF (and thus WPBs). CONCLUSION: We conclude that BOECs exposed to C5b-9 attack respond by mobilizing WPBs, which mitigate and repair damage by fusing with the plasma membrane. We propose that a similar cell-specific response may protect the vascular endothelium from complement-mediated damage in vivo.

Differential Effector Response of Amnion- and Adipose-Derived Mesenchymal Stem Cells to Inflammation; Implications for Intradiscal Therapy.

Intervertebral disc degeneration (IVDD) is a progressive condition marked by tissue destruction and inflammation. The therapeutic effector functions of mesenchymal stem cells (MSCs) makes them an attractive therapy for patients with IVDD. While several sources of MSCs exist, the optimal choice for use in the inflamed IVD remains a significant question. Adipose (AD)- and amnion (AM)-derived MSCs have several advantages compared with other sources, however, no study has directly compared the impact of IVDD inflammation on their effector functions. Human MSCs were cultured in media with or without supplementation of interleukin-1ß (IL-1ß) and tumor necrosis factor-α at concentrations reportedly produced by IVDD cells. MSC proliferation and production of pro- and anti-inflammatory cytokines were quantified following 24 and 48 h of culture. Additionally, the osteogenic and chondrogenic potential of AD- and AM-MSCs was characterized via histology and biochemical analysis following 28 days of culture. In inflammatory culture, AM-MSCs produced significantly more anti-inflammatory IL-10 (14.47 ± 2.39 pg/ml; p = 0.004) and larger chondrogenic pellets (5.67 ± 0.26 mm2 ; p = 0.04) with greater percent area staining positively for glycosaminoglycan (82.03 ± 3.26%; p < 0.001) compared with AD-MSCs (0.00 ± 0.00 pg/ml; 2.76 ± 0.18 mm2 ; 34.75 ± 2.49%; respectively). Conversely, AD-MSCs proliferated more resulting in higher cell numbers (221,000 ± 8,021 cells; p = 0.048) and produced higher concentrations of pro-inflammatory cytokines prostaglandin E2 (1,118.30 ± 115.56 pg/ml; p = 0.030) and IL-1ß (185.40 ± 7.63 pg/ml; p = 0.010) compared with AM-MSCs (109,667 ± 5,696 cells; 1,291.40 ± 78.47 pg/ml; 144.10 ± 4.57 pg/ml; respectively). AD-MSCs produced more mineralized extracellular matrix (3.34 ± 0.05 relative absorbance units [RAU]; p < 0.001) compared with AM-MSCs (1.08 ± 0.06 RAU). Under identical inflammatory conditions, a different effector response was observed with AM-MSCs producing more anti-inflammatories and demonstrating enhanced chondrogenesis compared with AD-MSCs, which produced more pro-inflammatory cytokines and demonstrated enhanced osteogenesis. These findings may begin to help inform researchers which MSC source may be optimal for IVD regeneration. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2445-2456, 2019.

A decreased and less sustained desmopressin response in hemophilia A carriers contributes to bleeding.

The cause of hemophilia A carrier bleeding is not well established. Desmopressin (DDAVP), used clinically to treat or prevent bleeding, can also be used as a medical stress surrogate. This study's objective was to compare the response to DDAVP in hemophilia A carriers with that in normal control patients. Bleeding was assessed by the International Society on Thrombosis and Hemostasis Bleeding Assessment Tool (ISTH-BAT). DDAVP (0.3 µg/kg) was administered either IV or subcutaneously (SC), and blood was drawn at baseline and 1, 2, and 4 hours postadministration. Blood was assessed for factor VIII (FVIII) level, von Willebrand factor (VWF) antigen (VWF:Ag), VWF activity (VWF:RCo or VWF:GPIbM), thromboelastography (TEG), and thrombin generation assay (TGA) at all points, and for VWF propeptide (VWFpp):Ag ratio and ABO blood type at baseline. Carriers were older than control patients (median age, 34 and 21 years, respectively; P = .003) and had higher ISTH-BAT bleeding scores (median bleeding score, 8 and 0, respectively; P = .001). Carriers had a significantly reduced FVIII response to DDAVP compared with control patients (P ≤ .0001). When only carriers with normal baseline FVIII levels (n = 10) were included, carriers maintained a reduced FVIII response (P ≤ .0001). Furthermore, participants with abnormal bleeding scores had a significantly lower FVIII response to DDAVP compared with those with normal bleeding scores (P = .036). Hemophilia A carriers have a lower and less sustained FVIII response to DDAVP, suggesting an impaired ability to respond to hemostatic stress, which contributes to bleeding.

Abnormal angiogenesis in blood outgrowth endothelial cells derived from von Willebrand disease patients.

: Bleeding associated with angiodysplasia is a common, often intractable complication in patients with von Willebrand disease (VWD). von Willebrand factor (VWF), the protein deficient or defective in VWD, is a negative regulator of angiogenesis, which may explain the pathologic blood vessel growth in VWD. This study explores the normal range of angiogenesis in blood outgrowth endothelial cells (BOECs) derived from healthy donors and compares this to angiogenesis in BOECs from VWD patients of all types and subtypes. BOECs were assessed for VWF and angiopoietin-2 (Ang-2) gene expression, secretion, and storage. To explore angiogenic potential, we characterized cellular proliferation, matrix protein adhesion, migration, and tubule formation. We found great angiogenic variability in VWD BOECs with respect to each of the angiogenesis parameters. However, type 1 and 3 VWD BOECs had higher Ang-2 secretion associated with impaired endothelial cell migration velocity and enhanced directionality. Type 2A and 2B BOECs were the most proliferative and multiple VWD BOECs had impaired tubule formation in Matrigel. This study highlights the angiogenic variability in BOECs derived from VWD patients. Abnormal cell proliferation, migration, and increased Ang-2 secretion are common features of VWD BOECs. Despite the many abnormalities of VWD BOECs, significant heterogeneity among individual VWD phenotypes precludes a simple description of relationship between VWD type and in vitro surrogates for angiodysplasia.