Biopolymer processing and handling is greatly facilitated by the use of ionic liquids, given the increased solubility, and in some cases, structural stability imparted to these molecules. Focussing ...on proteins, we highlight here not just the key drivers behind protein-ionic liquid interactions that facilitate these functionalities, but address relevant current and potential applications of protein-ionic liquid interactions, including areas of future interest.
Endothelialization of small diameter synthetic vascular grafts is a potential solution to the thrombosis and intimal hyperplasia that plague current devices. Endothelial colony forming cells, which ...are blood-derived and similar to mature endothelial cells, are a potential cell source. Anisotropic spatial growth restriction micropatterning has been previously shown to affect the morphology and function of mature endothelial cells in a manner similar to unidirectional fluid shear stress. To date, endothelial colony forming cells have not been successfully micropatterned. This study addresses the hypothesis that micropatterning of endothelial colony forming cells will induce morphological elongation, cytoskeletal alignment, and changes in immunogenic and thrombogenic-related gene expression.
Spatially growth restrictive test surfaces with 25 μm-wide lanes alternating between collagen-I and a blocking polymer were created using microfluidics. Case-matched endothelial colony forming cells and control mature carotid endothelial cells were statically cultured on either micropatterned or non-patterned surfaces. Cell elongation was quantified using shape index. Using confocal microscopy, cytoskeletal alignment was visualized and density and apoptotic rate were determined. Gene expression was measured using quantitative PCR to measure KLF-2, eNOS, VCAM-1, and vWF.
Endothelial colony forming cells were successfully micropatterned for up to 50 hours. Micropatterned cells displayed elongation and actin alignment. Micropatterning increased the packing densities of both cell types, but did not affect apoptotic rate, which was lower in endothelial colony forming cells. KLF-2 gene expression was increased in micropatterned relative to non-patterned endothelial colony forming cells after 50 hours. No significant differences were seen in the other genes tested.
Endothelial colony forming cells can be durably micropatterned using spatial growth restriction. Micropatterning has a significant effect on the gross and subcellular morphologies of both cell types. Further study is required to fully understand the effect of micropatterning on endothelial colony forming cell gene expression.
OBJECTIVE—Factor XI (FXI) contributes to thrombotic disease while playing a limited role in normal hemostasis. We generated a unique, humanized anti-FXI antibody, AB023, which blocks factor ...XIIa-mediated FXI activation without inhibiting FXI activation by thrombin or the procoagulant function of FXIa. We sought to confirm the antithrombotic activity of AB023 in a baboon thrombosis model and to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics in healthy adult subjects.
APPROACH AND RESULTS—In a primate model of acute vascular graft thrombosis, AB023 reduced platelet and fibrin accumulation within the grafts by >75%. To evaluate the safety of AB023, we performed a first-in-human study in healthy adult volunteers without any serious adverse events. Overall, 10 of 21 (48%) subjects experienced 20 treatment-emergent adverse events, with 7 of 16 (44%) subjects following active treatment and 3 of 5 (60%) subjects following placebo. AB023 did not increase bleeding or prothrombin times. Anticoagulation was verified by a saturable ≈2-fold prolongation of the partial thromboplastin time for over 1 month after the highest dose.
CONCLUSIONS—AB023, which inhibits contact activation-initiated blood coagulation in vitro and experimental thrombus formation in primates, produced a dose-dependent duration of limited anticoagulation without drug-related adverse effects in a phase 1 trial. When put in context with earlier observations suggesting that FXI contributes to venous thromboembolism and cardiovascular disease, although contributing minimally to hemostasis, our data further justify clinical evaluation of AB023 in conditions where contact-initiated FXI activation is suspected to have a pathogenic role.
CLINICAL TRIAL REGISTRATION—URLhttp://www.clinicaltrials.gov. Unique identifierNCT03097341.
Considerable changes are expected in the regulation of myocardial and limb skeletal muscle perfusion from the pre‐ to post‐natal condition based on changes in gravitational force, work load, and ...arterial O2 content. Yet the impact of birth on the growth and function of microvasculature in striated muscle is poorly understood. Our objective was to assess resting and maximal microvascular flow in the cardiac left ventricle (LV; with high workload before and after birth), and biceps femoris (BF; hindlimb muscle with little workload before birth). We hypothesized that resting flow in the fetus exceeds that in the neonate because of low fetal arterial O2 content, but that flow reserve is greater in the neonate in order to support ambulation. We expected this increase in reserve to be greater in skeletal than myocardial muscle.
Fetuses (N=8) were instrumented at 130 d gestational age (dGA, birth is at 146 d) and studied exteriorized from the uterus at 135 dGA. Lambs (N=8) were instrumented 2 d after birth and studied at 5 d. Instrumentation included arterial, venous, and left atrial catheters for systemic pressure monitoring, arterial blood sampling, and drug delivery; and an inflatable occluder around the descending thoracic aorta. Myocardial perfusion (Q) in mL/min/g of tissue was assessed by transthoracic contrast echocardiography at rest, during adenosine‐induced hyperemia, and during combined hyperemia and increased perfusion pressure produced by transient constriction of the postductal aorta. Work was determined by the product of heart rate and perfusion pressure. Hindlimb BF muscle Q was assessed at rest, and during contractile work produced by electrostimulation (2 Hz, 10 mA). Differences were assessed by the Mann‐Whitney U‐test. One fetus and one lamb were excluded from analysis because of abnormal blood gasses at the time of study.
At rest, LV myocardial Q was 2‐fold higher in fetuses than neonates (Fig 1A), as was Q normalized to work; whereas, O2 delivery was similar between groups (Fig 1B). Maximal flow during hyperemia followed a similar pattern, with fetal Q, as well as Q per work, exceeding that in the neonate by a factor of 7, whereas maximal O2 delivery per work was similar between age groups. Skeletal muscle (BF) flow in the fetus was highly variable both at rest and during exercise. Median resting Q, resting O2 delivery, and exercised flow were all at least 5‐fold higher in the fetus than neonate, however the difference only reached statistical significance for resting flow (Fig 1A,B). Exercise O2 delivery was similar between ages. Flow reserve was similar between the fetus and neonate in both myocardium and skeletal muscle (Fig 1C).
At rest, elevated flow in the fetal LV supported similar levels of O2 delivery per work as found in the newborn. Surprisingly, there was a tendency for increased O2 delivery in the fetal skeletal muscle compared to the newborn; we speculate that this reflects differences in regulation of non‐nutritive flow between the ages studied. Overall, the results of this study suggest that despite the dramatically different physiological circumstances between the fetus and newborn, microvascular growth is regulated to preserve similar levels of flow reserve in both.
Syndecans in hematopoietic cells and their niches Hagen, Matthew W.; Setiawan, Nicollette J.; Woodruff, Kelsey A. ...
American Journal of Physiology: Cell Physiology,
08/2024, Volume:
327, Issue:
2
Journal Article
Peer reviewed
Heparan sulfate proteoglycans are a family of glycoproteins that modulate cell signaling by binding growth factors and changing their bioavailability. Syndecans are a specific family of transmembrane ...heparan sulfate proteoglycans that regulate cell adhesion, migration, and signaling. In this review, we will summarize emerging evidence for the functions of syndecans in the normal and malignant blood systems and their microenvironments. More specifically, we detail the known functions of syndecans within normal hematopoietic stem cells. Furthermore, we discuss the functions of syndecans in hematological malignancies, including myeloid malignancies, lymphomas, and bleeding disorders. As normal and malignant hematopoietic cells require cues from their microenvironments to function, we also summarize the roles of syndecans in cells of the stromal, endothelial, and osteolineage compartments. Syndecan biology is a rapidly evolving field; a comprehensive understanding of these molecules and their place in the hematopoietic system promises to improve our grasp on disease processes and better predict the efficacies of growth factor-targeting therapies.
BackgroundFlow diverters offer a promising treatment for cerebral aneurysms. However, they have associated thromboembolic risks, mandating chronic dual antiplatelet therapy (DAPT). Shield Technology ...is a phosphorylcholine surface modification of the Pipeline Embolization Device (PED) flow diverter, which has shown significant reductions in material thrombogenicity in vitro.ObjectiveTo compare the thrombogenicity of PED, PED with Shield Technology (PED+Shield), and the Flow-Redirection Endoluminal Device (FRED)—with and without single antiplatelet therapy and DAPT—under physiological flow.MethodsAn established non-human primate ex vivo arteriovenous shunt model of stent thrombosis was used. PED, PED+Shield, and FRED were tested without antiplatelet therapy, with acetylsalicylic acid (ASA) monotherapy, and with DAPT. Radiolabeled platelet deposition was quantified over 1 hour for each device and total fibrin deposition was also quantified.ResultsCumulative statistical analysis showed significantly lower platelet deposition on PED compared with FRED. The same statistical model showed significant decreases in platelet deposition when ASA, clopidogrel, or Shield Technology was used. Direct comparisons of device performances within antiplatelet conditions showed consistent significant decreases in platelet accumulation on PED+Shield relative to FRED. PED+Shield showed significant reductions in platelet deposition compared with unmodified PED without antiplatelet therapy and with DAPT. PED accumulated minimal fibrin with and without Shield Technology.ConclusionsIn this preclinical model, we have shown that the Shield Technology phosphorylcholine modification reduces the platelet-specific thrombogenicity of a flow diverter under physiologically relevant flow with and without DAPT. We have further identified increased fibrin-driven thrombogenicity associated with FRED relative to PED.
Pleomorphic hyalinizing angiectatic tumor (PHAT) is a rare, benign soft tissue tumor with uncertain pathogenesis and lineage most commonly found in the lower and upper extremities. No reports exist ...of this tumor metastasizing, though local recurrence is common. To date, only approximately 100 cases have been reported. We present the case of a patient presenting with hoarseness and dyspnea found to have PHAT of the larynx, a location previously unreported in the literature and requiring unique management considerations.
Artificial small-diameter vascular grafts remain an unmet need in modern medicine, due to the thrombosis and neointimal hyperplasia that plague currently available synthetic devices. Tissue ...engineering techniques, including
endothelialization, could offer a solution to this problem. A potential minimally invasive source of patient autologous endothelium is endothelial colony-forming cells (ECFCs), endothelial-like outgrowth products of circulating progenitors. While ECFCs respond to shear stress similar to mature endothelial cells (ECs), their response to luminal topographic micropatterning (TMP), a biomaterial modification with the potential to flow-independently, enhance the attachment, migration, gene expression, and function of mature ECs, remains unstudied. In this study, case-matched carotid endothelial cells (CaECs) and blood-derived ECFCs are statically cultured on polyurethane substrates with micropatterned pitches (pitch = peak to peak distance) ranging from 3-to 14 μm. On all pattern pitches tested, both CaECs and ECFCs showed significant and robust alignment to the angle of the micropatterns. Using a novel cell-by-cell image analysis technique, it was found that actin fibers similarly and significantly aligned to the angle of micropatterned features on all pitches tested. Microtubules analyzed through the same novel approach showed significant alignment on most pitches examined, with a greater variation in fiber angle overall. Interestingly, only CaECs showed significant cellular elongation, and notably to a lower degree than previously seen either
due to flow or
due to spatial growth restriction micropatterning, but consistent with earlier studies of TMP. Neither cell type displayed any significant micropattern-driven changes in the expression of KLF-2 or the downstream adhesion molecules it regulates. These results demonstrate that TMP flow-independently affects ECFC morphology, but that alignment alone is insufficient to drive protective changes in EC and ECFC function.
New Findings
What is the central question of this study?
How does the microvascular perfusion of striated muscle change during the dynamic developmental period between the late gestation fetus and ...early neonate?
What is the main finding and its importance?
In both myocardium and skeletal muscle, perfusion of striated muscle is significantly reduced in the neonate compared to the late term fetus, but flow reserve is unchanged. The results suggest striated muscle capillary networks grow more slowly relative to the myofibres they nourish during the perinatal period.
Microvascular perfusion of striated muscle is an important determinant of health throughout life. Birth is a transition with profound effects on the growth and function of striated muscle, but the regulation of microvascular perfusion around this transition is poorly understood. We used contrast‐enhanced ultrasound perfusion imaging (CEUS) to study the perfusion of left ventricular myocardium and hindlimb biceps femoris, which are populations of muscle with different degrees of change in pre‐ to postnatal workloads and different capacities for postnatal proliferative growth. We studied separate groups of lambs in late gestation (135 days’ gestational age; 92% of term) and shortly after birth (5 days’ postnatal age). We used CEUS to quantify baseline perfusion, perfusion during hyperaemia induced by adenosine infusion (myocardium) or electrically stimulated unloaded exercise (skeletal muscle), flow reserve and oxygen delivery. We found heart‐to‐body weight ratio was greater in neonates than fetuses. Microvascular volume and overall perfusion were lower in neonates than fetuses in both muscle groups at baseline and with hyperaemia. Flux rate differed with muscle group, with myocardial flux being faster in neonates than fetuses, but skeletal muscle flux being slower. Oxygen delivery to skeletal muscle at baseline was lower in neonates than fetuses, but was not significantly different in myocardium. Flow reserve was not different between ages. Given the significant somatic growth, and the transition from hyperplastic to hypertrophic myocyte growth occurring in the perinatal period, we postulate that the primary driver of lower neonatal striated muscle perfusion is faster growth of myofibres than their associated capillary networks.
PDF
