scholarly journals Conceptual Framework Development for a Double-Walled Aortic Stent-Graft to Manage Blood Pressure

2020 ◽  
Vol 14 (3) ◽  
Author(s):  
Shannen B. Kizilski ◽  
Omid Amili ◽  
Filippo Coletti ◽  
Rumi Faizer ◽  
Victor H. Barocas
Keyword(s):  
Stent Graft ◽  
Pulse Pressure ◽  
Fe Model ◽  
Flow Loop ◽  
Windkessel Model ◽  
Aortic Stent Graft ◽  
New Treatment ◽  
Gas Layer

Abstract A double-walled stent-graft (DWSG) design with a compressible gas layer was conceived with the goal of treating hypertension in patients receiving an aortic stent-graft. Early prototypes were developed to evaluate the design concept through static measurements from a finite element (FE) model and quasi-static inflation experiments, and through dynamic measurements from an in vitro flow loop and the three-element Windkessel model. The amount of gas in the gas layer and the properties of the flexible inner wall were the primary variables evaluated in this study. Properties of the inner wall had minimal effect on DWSG behavior, but increased gas charge led to increased fluid capacitance and larger reduction in peak and pulse pressures. In the flow loop, placement of the DWSG decreased pulse pressure by over 20% compared to a rigid stent-graft. Capacitance measurements were consistent across all methods, with the maximum capacitance estimated at 0.07 mL/mmHg for the largest gas charge in the 15 cm long prototype. Windkessel model predictions for in vivo performance of a DWSG placed in the aorta of a hypertensive patient showed pulse pressure reduction of 14% compared to a rigid stent-graft case, but pressures never returned to unstented values. These results indicate that the DWSG design has potential to be developed into a new treatment for hypertensive patients requiring an aortic intervention.

Evaluating the Effect of a Double-Walled Aortic Stent-Graft Prototype on Pulse Wave Velocity in an In Vitro Flow Loop

2020 ◽  
Author(s):  
Shannen B. Kizilski ◽  
Filippo Coletti ◽  
Rumi Faizer ◽  
Victor H. Barocas
Keyword(s):  
Pulse Wave Velocity ◽  
Wave Velocity ◽  
Stent Graft ◽  
Pulse Wave ◽  
Arterial Compliance ◽  
Pressure Sensors ◽  
Needle Valve ◽  
Flow Loop ◽  
Aortic Stent Graft

Abstract The effect of a double-walled stent-graft (DWSG) design on arterial compliance was evaluated using pulse wave velocity (PWV) measurements in an in vitro mock arterial flow loop. The DWSG prototype was compared to a rigid stent-graft and to an unstented aorta model. The time delay between two pressure sensors a fixed distance apart was used to calculate PWV. Latex tubing simulated the compliant aorta, and a needle valve provided downstream resistance. A series of pulse rates and stroke volumes was applied to enable measurements at different mean pressures for the same system. PWV for the rigid stent-graft was higher than in the other two cases across all mean pressures. The DWSG exhibited behavior similar to the unstented model, demonstrating the capability of the DWSG to maintain aortic compliance in patients requiring an aortic stent-graft.

Abstract 95: A Conformable and Compliant Nanocomposite Polymer Stent-Graft for Endovascular Repair of Aortic Arch

2012 ◽  
Vol 32 (suppl_1) ◽  
Author(s):  
Mital Desai ◽  
Maqsood Ahmed ◽  
Xiang Zhou ◽  
Zhong You ◽  
Alexander M Seifalian ◽  
...  
Keyword(s):  
Aortic Arch ◽  
Thoracic Aorta ◽  
Stent Graft ◽  
Endovascular Repair ◽  
Pulse Pressure ◽  
Vascular Tissue ◽  
Stiffness Index ◽  
Nanocomposite Polymer

Objectives: To develop new aortic stent-graft from polyhedral oligomeric silsesquioxane (POSS) and poly (carbonate-urea) urethane (PCU) nanocomposite polymer (NP) to achieve better conformability to arch anatomy and reduce aorta-prosthesis compliance mismatch. Methods: A constructed model of curved thoracic aorta from MRI was developed and anatomically accurate sutureless stent-graft was moulded using surface-modified Nitinol stents with composition of 55.8 wt.% Ni, diameter 0.62 mm and Af temperature less than 18 oC bonded to NP. An in vitro pulsatile flow phantom perfused NP stent-graft at physiological pulse pressure and flow. Diametrical compliance and stiffness index were calculated and comparison was made with ePTFE based in Gore TagTM thoracic stent-graft. Results: The NP stent-graft had uniform thickness of 150.7±6.6 μg and in its fully expanded shape, with diameter of 30 mm, matched curvature of aortic arch. Over temperature 37±1°C, mean pressure range 30-100 mm Hg, and pulse pressure 49±6 mm Hg, flow rate for NP stent-graft was 132±24 ml/min and ePTFE stent-graft was 140±25 ml/min (P=NS). Overall compliance of NP stent-graft was 3.3 ± 0.61%/mm Hg x 10-2 which was significantly better compared with ePTFE stent-graft (2.3±0.95 %/mm Hg x 10-2; P=0.0003). The ePTFE stent-graft was significantly stiffer with stiffness index β 92.7±46.1 compared to NP stent-graft (β 39.1±5.91; P<0.0001). The ePTFE stent-graft failed to exhibit anisotropic behaviour (i.e. visco-elasticity similar to natural vascular tissue) which was demonstrated by NP stent-graft. Conclusion: An innovative, curved, self-expanding and sutureless stent-graft is proposed for endovascular repair of thoracic aorta and aortic arch. The study confirmed the superior compliance, reduced elastic stiffness and visco-elasticity of POSS-PCU NP, which can help in improving device longevity by offering superior physiological and haemodynamic environment in vivo.

scholarly journals Inhibitory Effects of a Reengineered Anthrax Toxin on Canine Oral Mucosal Melanomas

Toxins ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 157 ◽  
Author(s):  
Adriana Tomoko Nishiya ◽  
Marcia Kazumi Nagamine ◽  
Ivone Izabel Mackowiak da Fonseca ◽  
Andrea Caringi Miraldo ◽  
Nayra Villar Scattone ◽  
...  
Keyword(s):  
Tumor Cells ◽  
Evaluation Criteria ◽  
Anthrax Toxin ◽  
Treatment Modalities ◽  
Inhibitory Effects ◽  
Upa Receptor ◽  
New Treatment ◽  
Oral Malignancy

Canine oral mucosal melanomas (OMM) are the most common oral malignancy in dogs and few treatments are available. Thus, new treatment modalities are needed for this disease. Bacillus anthracis (anthrax) toxin has been reengineered to target tumor cells that express urokinase plasminogen activator (uPA) and metalloproteinases (MMP-2), and has shown antineoplastic effects both, in vitro and in vivo. This study aimed to evaluate the effects of a reengineered anthrax toxin on canine OMM. Five dogs bearing OMM without lung metastasis were included in the clinical study. Tumor tissue was analyzed by immunohistochemistry for expression of uPA, uPA receptor, MMP-2, MT1-MMP and TIMP-2. Animals received either three or six intratumoral injections of the reengineered anthrax toxin prior to surgical tumor excision. OMM samples from the five dogs were positive for all antibodies. After intratumoral treatment, all dogs showed stable disease according to the canine Response Evaluation Criteria in Solid Tumors (cRECIST), and tumors had decreased bleeding. Histopathology has shown necrosis of tumor cells and blood vessel walls after treatment. No significant systemic side effects were noted. In conclusion, the reengineered anthrax toxin exerted inhibitory effects when administered intratumorally, and systemic administration of this toxin is a promising therapy for canine OMM.

scholarly journals YAP1 overexpression contributes to the development of enzalutamide resistance by induction of cancer stemness and lipid metabolism in prostate cancer

Oncogene ◽  
2021 ◽  
Author(s):  
Hsiu-Chi Lee ◽  
Chien-Hui Ou ◽  
Yun-Chen Huang ◽  
Pei-Chi Hou ◽  
Chad J. Creighton ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Lipid Metabolism ◽  
Critical Issue ◽  
Castration Resistant Prostate Cancer ◽  
Cancer Stemness ◽  
New Treatment ◽  
Underlying Mechanisms ◽  
Transcriptional Complex

AbstractMetastatic castration-resistant prostate cancer (mCRPC) is a malignant and lethal disease caused by relapse after androgen-deprivation (ADT) therapy. Since enzalutamide is innovated and approved by US FDA as a new treatment option for mCRPC patients, drug resistance for enzalutamide is a critical issue during clinical usage. Although several underlying mechanisms causing enzalutamide resistance were previously identified, most of them revealed that drug resistant cells are still highly addicted to androgen and AR functions. Due to the numerous physical functions of AR in men, innovated AR-independent therapy might alleviate enzalutamide resistance and prevent production of adverse side effects. Here, we have identified that yes-associated protein 1 (YAP1) is overexpressed in enzalutamide-resistant (EnzaR) cells. Furthermore, enzalutamide-induced YAP1 expression is mediated through the function of chicken ovalbumin upstream promoter transcription factor 2 (COUP-TFII) at the transcriptional and the post-transcriptional levels. Functional analyses reveal that YAP1 positively regulates numerous genes related to cancer stemness and lipid metabolism and interacts with COUP-TFII to form a transcriptional complex. More importantly, YAP1 inhibitor attenuates the growth and cancer stemness of EnzaR cells in vitro and in vivo. Finally, YAP1, COUP-TFII, and miR-21 are detected in the extracellular vesicles (EVs) isolated from EnzaR cells and sera of patients. In addition, treatment with EnzaR-EVs induces the abilities of cancer stemness, lipid metabolism and enzalutamide resistance in its parental cells. Taken together, these results suggest that YAP1 might be a crucial factor involved in the development of enzalutamide resistance and can be an alternative therapeutic target in prostate cancer.

scholarly journals “Empowering” Cardiac Cells via Stem Cell Derived Mitochondrial Transplantation- Does Age Matter?

2021 ◽  
Vol 22 (4) ◽  
pp. 1824
Author(s):  
Matthias Mietsch ◽  
Rabea Hinkel
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Treatment Strategies ◽  
Cardiac Cells ◽  
Aging Effects ◽  
Beneficial Effects ◽  
Micro Rnas ◽  
New Treatment

With cardiovascular diseases affecting millions of patients, new treatment strategies are urgently needed. The use of stem cell based approaches has been investigated during the last decades and promising effects have been achieved. However, the beneficial effect of stem cells has been found to being partly due to paracrine functions by alterations of their microenvironment and so an interesting field of research, the “stem- less” approaches has emerged over the last years using or altering the microenvironment, for example, via deletion of senescent cells, application of micro RNAs or by modifying the cellular energy metabolism via targeting mitochondria. Using autologous muscle-derived mitochondria for transplantations into the affected tissues has resulted in promising reports of improvements of cardiac functions in vitro and in vivo. However, since the targeted treatment group represents mainly elderly or otherwise sick patients, it is unclear whether and to what extent autologous mitochondria would exert their beneficial effects in these cases. Stem cells might represent better sources for mitochondria and could enhance the effect of mitochondrial transplantations. Therefore in this review we aim to provide an overview on aging effects of stem cells and mitochondria which might be important for mitochondrial transplantation and to give an overview on the current state in this field together with considerations worthwhile for further investigations.

scholarly journals Modelling human skull growth: a validated computational model

2017 ◽  
Vol 14 (130) ◽  
pp. 20170202 ◽  
Author(s):  
Joseph Libby ◽  
Arsalan Marghoub ◽  
David Johnson ◽  
Roman H. Khonsari ◽  
Michael J. Fagan ◽  
...  
Keyword(s):  
Computational Model ◽  
Three Dimensional ◽  
Basic Knowledge ◽  
Fe Model ◽  
Adult Size ◽  
Fe Method ◽  
Percentage Difference ◽  
Skull Growth

During the first year of life, the brain grows rapidly and the neurocranium increases to about 65% of its adult size. Our understanding of the relationship between the biomechanical forces, especially from the growing brain, the craniofacial soft tissue structures and the individual bone plates of the skull vault is still limited. This basic knowledge could help in the future planning of craniofacial surgical operations. The aim of this study was to develop a validated computational model of skull growth, based on the finite-element (FE) method, to help understand the biomechanics of skull growth. To do this, a two-step validation study was carried out. First, an in vitro physical three-dimensional printed model and an in silico FE model were created from the same micro-CT scan of an infant skull and loaded with forces from the growing brain from zero to two months of age. The results from the in vitro model validated the FE model before it was further developed to expand from 0 to 12 months of age. This second FE model was compared directly with in vivo clinical CT scans of infants without craniofacial conditions ( n = 56). The various models were compared in terms of predicted skull width, length and circumference, while the overall shape was quantified using three-dimensional distance plots. Statistical analysis yielded no significant differences between the male skull models. All size measurements from the FE model versus the in vitro physical model were within 5%, with one exception showing a 7.6% difference. The FE model and in vivo data also correlated well, with the largest percentage difference in size being 8.3%. Overall, the FE model results matched well with both the in vitro and in vivo data. With further development and model refinement, this modelling method could be used to assist in preoperative planning of craniofacial surgery procedures and could help to reduce reoperation rates.

Mesenchymal stem cell-derived extracellular vesicles in the failing heart: past, present, and future

2021 ◽  
Author(s):  
Catherine Karbasiafshar ◽  
Frank W. Sellke ◽  
M. Ruhul Abid
Keyword(s):  
Stem Cell ◽  
Extracellular Vesicles ◽  
Treatment Options ◽  
Current Treatment ◽  
Lifestyle Changes ◽  
Challenges And Opportunities ◽  
Artery Disease ◽  
New Treatment

Cardiovascular disease (CVD) is the leading cause of death globally. Current treatment options include lifestyle changes, medication, and surgical intervention. However, many patients are unsuitable candidates for surgeries due to comorbidities, diffuse coronary artery disease or advanced stages of heart failure. The search for new treatment options has recently transitioned from cell-based therapies to stem-cell derived extracellular vesicles (EVs). A number of challenges remain in the EV field, including the effect of comorbidities, characterization, and delivery, However, recent revolutionary developments and insight into the potential of 'personalizing' EV contents by bioengineering methods to alter specific signaling pathways in the ischemic myocardium hold promise. Here, we discuss the past limitations of cell-based therapies, and recent EV studies involving in vivo, in vitro, and omics, and future challenges and opportunities in EV-based treatments in CVD.

scholarly journals Metabolic Modeling of Clostridium difficile Associated Dysbiosis of the Gut Microbiota

Processes ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 97 ◽  
Author(s):  
Poonam Phalak ◽  
Michael Henson
Keyword(s):  
Clostridium Difficile ◽  
Treatment Strategies ◽  
E Coli ◽  
Biofilm Model ◽  
Commensal Species ◽  
Species Abundances ◽  
New Treatment ◽  
Biofilm Development

Recent in vitro experiments have demonstrated the ability of the pathogen Clostridium difficile and commensal gut bacteria to form biofilms on surfaces, and biofilm development in vivo is likely. Various studies have reported that 3%–15% of healthy adults are asymptomatically colonized with C. difficile, with commensal species providing resistance against C. difficile pathogenic colonization. C. difficile infection (CDI) is observed at a higher rate in immunocompromised patients previously treated with broad spectrum antibiotics that disrupt the commensal microbiota and reduce competition for available nutrients, resulting in imbalance among commensal species and dysbiosis conducive to C. difficile propagation. To investigate the metabolic interactions of C. difficile with commensal species from the three dominant phyla in the human gut, we developed a multispecies biofilm model by combining genome-scale metabolic reconstructions of C. difficile, Bacteroides thetaiotaomicron from the phylum Bacteroidetes, Faecalibacterium prausnitzii from the phylum Firmicutes, and Escherichia coli from the phylum Proteobacteria. The biofilm model was used to identify gut nutrient conditions that resulted in C. difficile-associated dysbiosis characterized by large increases in C. difficile and E. coli abundances and large decreases in F. prausnitzii abundance. We tuned the model to produce species abundances and short-chain fatty acid levels consistent with available data for healthy individuals. The model predicted that experimentally-observed host-microbiota perturbations resulting in decreased carbohydrate/increased amino acid levels and/or increased primary bile acid levels would induce large increases in C. difficile abundance and decreases in F. prausnitzii abundance. By adding the experimentally-observed perturbation of increased host nitrate secretion, the model also was able to predict increased E. coli abundance associated with C. difficile dysbiosis. In addition to rationalizing known connections between nutrient levels and disease progression, the model generated hypotheses for future testing and has the capability to support the development of new treatment strategies for C. difficile gut infections.

scholarly journals Multitarget Therapeutic Strategies for Alzheimer’s Disease: Review on Emerging Target Combinations

2020 ◽  
Vol 2020 ◽  
pp. 1-27 ◽  
Author(s):  
Samuele Maramai ◽  
Mohamed Benchekroun ◽  
Moustafa T. Gabr ◽  
Samir Yahiaoui
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Single Event ◽  
Neuroprotective Effects ◽  
New Agents ◽  
Major Health ◽  
New Treatment ◽  
Neuronal Functions

Neurodegenerative diseases represent nowadays one of the major health problems. Despite the efforts made to unveil the mechanism leading to neurodegeneration, it is still not entirely clear what triggers this phenomenon and what allows its progression. Nevertheless, it is accepted that neurodegeneration is a consequence of several detrimental processes, such as protein aggregation, oxidative stress, and neuroinflammation, finally resulting in the loss of neuronal functions. Starting from these evidences, there has been a wide search for novel agents able to address more than a single event at the same time, the so-called multitarget-directed ligands (MTDLs). These compounds originated from the combination of different pharmacophoric elements which endowed them with the ability to interfere with different enzymatic and/or receptor systems, or to exert neuroprotective effects by modulating proteins and metal homeostasis. MTDLs have been the focus of the latest strategies to discover a new treatment for Alzheimer’s disease (AD), which is considered the most common form of dementia characterized by neurodegeneration and cognitive dysfunctions. This review is aimed at collecting the latest and most interesting target combinations for the treatment of AD, with a detailed discussion on new agents with favorable in vitro properties and on optimized structures that have already been assessed in vivo in animal models of dementia.

Targeting the multiple myeloma hypoxic niche with TH-302, a hypoxia-activated prodrug

Blood ◽  
2010 ◽  
Vol 116 (9) ◽  
pp. 1524-1527 ◽  
Author(s):  
Jinsong Hu ◽  
Damian R. Handisides ◽  
Els Van Valckenborgh ◽  
Hendrik De Raeve ◽  
Eline Menu ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
Metastatic Potential ◽  
Treatment Target ◽  
Hypoxic Conditions ◽  
Cycle Arrest ◽  
G1 Cell Cycle Arrest ◽  
New Treatment

Hypoxia is associated with increased metastatic potential and poor prognosis in solid tumors. In this study, we demonstrated in the murine 5T33MM model that multiple myeloma (MM) cells localize in an extensively hypoxic niche compared with the naive bone marrow. Next, we investigated whether hypoxia could be used as a treatment target for MM by evaluating the effects of a new hypoxia-activated prodrug TH-302 in vitro and in vivo. In severely hypoxic conditions, TH-302 induces G0/G1 cell-cycle arrest by down-regulating cyclinD1/2/3, CDK4/6, p21cip-1, p27kip-1, and pRb expression, and triggers apoptosis in MM cells by up-regulating the cleaved proapoptotic caspase-3, -8, and -9 and poly ADP-ribose polymerase while having no significant effects under normoxic conditions. In vivo treatment of 5T33MM mice induces apoptosis of the MM cells within the bone marrow microenvironment and decreases paraprotein secretion. Our data support that hypoxia-activated treatment with TH-302 provides a potential new treatment option for MM.

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