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Microcirculation (New York, N.Y. : 1994) Nov 2019Historically, major advances in microvascular research have been made by integrating physiology and bioengineering approaches. This Special Topics Issue focuses on...
Historically, major advances in microvascular research have been made by integrating physiology and bioengineering approaches. This Special Topics Issue focuses on providing a spotlight on emerging areas of microvascular research, showcasing how interdisciplinary collaborations and application of novel techniques can impact our understanding of tissue-specific microvascular remodeling by integrating cell behaviors across scales. The authors in this issue investigate pericyte physiology, perturbations to uteroplacental blood flow, bone microvascular alterations in aging, molecular markers of revascularization, and microfluidic devices to mimic the lymphatic system. The articles highlight the continued importance of expanding our understanding of the microvascular system in health, and disease extends microvascular boundaries in the face of current paradigms, and illustrates how emerging leaders in the field are creating new scientific niches.
Topics: Animals; Biomedical Research; Humans; Microcirculation; Microvessels
PubMed: 31090984
DOI: 10.1111/micc.12558 -
Circulation Research Jan 2016The microcirculation is responsible for orchestrating adjustments in vascular tone to match local tissue perfusion with oxygen demand. Beyond this metabolic dilation,... (Review)
Review
The microcirculation is responsible for orchestrating adjustments in vascular tone to match local tissue perfusion with oxygen demand. Beyond this metabolic dilation, the microvasculature plays a critical role in modulating vascular tone by endothelial release of an unusually diverse family of compounds including nitric oxide, other reactive oxygen species, and arachidonic acid metabolites. Animal models have provided excellent insight into mechanisms of vasoregulation in health and disease. However, there are unique aspects of the human microcirculation that serve as the focus of this review. The concept is put forth that vasculoparenchymal communication is multimodal, with vascular release of nitric oxide eliciting dilation and preserving normal parenchymal function by inhibiting inflammation and proliferation. Likewise, in disease or stress, endothelial release of reactive oxygen species mediates both dilation and parenchymal inflammation leading to cellular dysfunction, thrombosis, and fibrosis. Some pathways responsible for this stress-induced shift in mediator of vasodilation are proposed. This paradigm may help explain why microvascular dysfunction is such a powerful predictor of cardiovascular events and help identify new approaches to treatment and prevention.
Topics: Animals; Blood Circulation; Cardiovascular Diseases; Endothelium, Vascular; Humans; Microcirculation; Vasodilation
PubMed: 26837746
DOI: 10.1161/CIRCRESAHA.115.305364 -
Sensors (Basel, Switzerland) Nov 2022: Microcirculation is a vital sign that supplies oxygen and nutrients to maintain normal life activities. Sepsis typically influences the operation of microcirculation,...
: Microcirculation is a vital sign that supplies oxygen and nutrients to maintain normal life activities. Sepsis typically influences the operation of microcirculation, which is recovered by the administration of medicine injection. : Sepsis-induced variation and recovery of microcirculation are quantitatively detected using microcirculation images acquired by a non-contact imaging setup, which might assist the clinical diagnosis and therapy of sepsis. : In this study, a non-contact imaging setup was first used to record images of microcirculation on the back of model rats. Specifically, the model rats were divided into three groups: (i) the sham group as a control group; (ii) the cecum ligation and puncture (CLP) group with sepsis; and (iii) the CLP+thrombomodulin (TM) group with sepsis and the application of TM alfa therapy. Furthermore, considering the sparsity of red blood cells (RBCs), the blood velocity is estimated by robust principal component analysis (RPCA) and U-net, and the blood vessel diameter is estimated by the contrast difference between the blood vessel and tissue. : In the experiments, the continuous degradation of the estimated blood velocity and blood vessel diameter in the CLP group and the recovery after degradation of those in the CLP+TM group were quantitatively observed. The variation tendencies of the estimated blood velocity and blood vessel diameter in each group suggested the effects of sepsis and its corresponding therapy.
Topics: Rats; Animals; Microcirculation; Sepsis; Punctures
PubMed: 36366167
DOI: 10.3390/s22218471 -
Current Cardiology Reviews 2022Invasive assessment of coronary physiology has radically changed the paradigm of myocardial revascularization in patients with coronary artery disease. Despite the... (Review)
Review
Invasive assessment of coronary physiology has radically changed the paradigm of myocardial revascularization in patients with coronary artery disease. Despite the prognostic improvement associated with ischemia-driven revascularization strategy, functional assessment of angiographic intermediate epicardial stenosis remains largely underused in clinical practice. Multiple tools have been developed or are under development in order to reduce the invasiveness, cost, and extra procedural time associated with the invasive assessment of coronary physiology. Besides epicardial stenosis, a growing body of evidence highlights the role of coronary microcirculation in regulating coronary flow with consequent pathophysiological and clinical and prognostic implications. Adequate assessment of coronary microcirculation function and integrity has then become another component of the decision-making algorithm for optimal diagnosis and treatment of coronary syndromes. This review aims at providing a comprehensive description of tools and techniques currently available in the catheterization laboratory to obtain a thorough and complete functional assessment of the entire coronary tree (both for the epicardial and microvascular compartments).
Topics: Coronary Angiography; Coronary Artery Disease; Coronary Stenosis; Fractional Flow Reserve, Myocardial; Humans; Microcirculation; Percutaneous Coronary Intervention
PubMed: 34521331
DOI: 10.2174/1573403X17666210908114154 -
Frontiers in Endocrinology 2021The pancreas is regarded as consisting of two separate organ systems, the endocrine and exocrine pancreas. While treatment of a disease with either an endocrine or... (Review)
Review
The pancreas is regarded as consisting of two separate organ systems, the endocrine and exocrine pancreas. While treatment of a disease with either an endocrine or exocrine pathogenesis may affect the function of the entire pancreas, the pancreatic diseases have been treated by clinicians in different medical disciplines, including endocrinologists and gastroenterologists. Islet microcirculation has long been considered to be regulated independently from that of the exocrine pancreas. A new model proposes that pancreatic islet blood flow is integrated with the surrounding exocrine capillary network. This recent model may provide revived or contrasting hypotheses to test, since the pancreatic microcirculation has critical implications for the regulation of islet hormones as well as acinar pancreas functions. In this mini-review, practical applications of and studies of islet microcirculation are described with a specific emphasis on large-scale data analysis to ensure sufficient sample size accounting for known islet heterogeneity. For small animal studies, intravital microscopy based on two-photon excitation microscopes is a powerful tool that enables capturing the flow direction and speed of individual fluorescent-labeled red blood cells. Complementarily, for structural analysis of blood vessels, the recent technical advancements of confocal microscopy and tissue clearing have enabled us to image the three-dimensional network structure in thick tissue slices.
Topics: Animals; Cytological Techniques; Hemodynamics; Humans; In Vitro Techniques; Islets of Langerhans; Microcirculation; Models, Biological
PubMed: 34040578
DOI: 10.3389/fendo.2021.602620 -
Biotechnology Advances Nov 2016In the past decade, significant advances have been made in the design and optimization of novel biomaterials and microfabrication techniques to generate vascularized... (Review)
Review
In the past decade, significant advances have been made in the design and optimization of novel biomaterials and microfabrication techniques to generate vascularized tissues. Novel microfluidic systems have facilitated the development and optimization of in vitro models for exploring the complex pathophysiological phenomena that occur inside a microvascular environment. To date, most of these models have focused on engineering of increasingly complex systems, rather than analyzing the molecular and cellular mechanisms that drive microvascular network morphogenesis and remodeling. In fact, mutual interactions among endothelial cells (ECs), supporting mural cells and organ-specific cells, as well as between ECs and the extracellular matrix, are key driving forces for vascularization. This review focuses on the integration of materials science, microengineering and vascular biology for the development of in vitro microvascular systems. Various approaches currently being applied to study cell-cell/cell-matrix interactions, as well as biochemical/biophysical cues promoting vascularization and their impact on microvascular network formation, will be identified and discussed. Finally, this review will explore in vitro applications of microvascular systems, in vivo integration of transplanted vascularized tissues, and the important challenges for vascularization and controlling the microcirculatory system within the engineered tissues, especially for microfabrication approaches. It is likely that existing models and more complex models will further our understanding of the key elements of vascular network growth, stabilization and remodeling to translate basic research principles into functional, vascularized tissue constructs for regenerative medicine applications, drug screening and disease models.
Topics: Animals; Cell Line; Cellular Microenvironment; Extracellular Matrix; Humans; Mice; Microcirculation; Microvessels; Neovascularization, Physiologic; Tissue Engineering
PubMed: 27417066
DOI: 10.1016/j.biotechadv.2016.07.002 -
Microcirculation (New York, N.Y. : 1994) Apr 2017Endothelial cells express a diverse array of ion channels including members of the strong inward rectifier family composed of K 2 subunits. These two-membrane spanning... (Review)
Review
Endothelial cells express a diverse array of ion channels including members of the strong inward rectifier family composed of K 2 subunits. These two-membrane spanning domain channels are modulated by their lipid environment, and exist in macromolecular signaling complexes with receptors, protein kinases and other ion channels. Inward rectifier K channel (K ) currents display a region of negative slope conductance at membrane potentials positive to the K equilibrium potential that allows outward current through the channels to be activated by membrane hyperpolarization, permitting K to amplify hyperpolarization induced by other K channels and ion transporters. Increases in extracellular K concentration activate K allowing them to sense extracellular K concentration and transduce this change into membrane hyperpolarization. These properties position K to participate in the mechanism of action of hyperpolarizing vasodilators and contribute to cell-cell conduction of hyperpolarization along the wall of microvessels. The expression of K in capillaries in electrically active tissues may allow K to sense extracellular K , contributing to functional hyperemia. Understanding the regulation of expression and function of microvascular endothelial K will improve our understanding of the control of blood flow in the microcirculation in health and disease and may provide new targets for the development of therapeutics in the future.
Topics: Animals; Endothelium, Vascular; Humans; Membrane Microdomains; Membrane Potentials; Microcirculation; Microvessels; Potassium Channels, Inwardly Rectifying; Protein Subunits; Regional Blood Flow; Signal Transduction
PubMed: 27652592
DOI: 10.1111/micc.12319 -
Current Hypertension Reports Jan 2019In this review, we summarized the current knowledge of connecting tubule-glomerular feedback (CTGF), a novel mechanism of renal microcirculation regulation that... (Review)
Review
PURPOSE OF REVIEW
In this review, we summarized the current knowledge of connecting tubule-glomerular feedback (CTGF), a novel mechanism of renal microcirculation regulation that integrates sodium handling in the connecting tubule (CNT) with kidney hemodynamics.
RECENT FINDINGS
Connecting tubule-glomerular feedback is a crosstalk communication between the CNT and the afferent arteriole (Af-Art), initiated by sodium chloride through the epithelial sodium channel (ENaC). High sodium in the CNT induces Af-Art vasodilation, increasing glomerular pressure and the glomerular filtration rate and favoring sodium excretion. CTGF antagonized and reset tubuloglomerular feedback and thus increased sodium excretion. CTGF is absent in spontaneous hypertensive rats and is overactivated in Dahl salt-sensitive rats. CTGF is also modulated by angiotensin II and aldosterone. CTGF is a feedback mechanism that integrates sodium handling in the CNT with glomerular hemodynamics. Lack of CTGF could promote hypertension, and CTGF overactivation may favor glomerular damage and proteinuria. More studies are needed to explore the alterations in renal microcirculation and the role of these alterations in the genesis of hypertension and glomerular damage in animals and humans.
KEY POINTS
• CTGF is a vasodilator mechanism that regulates afferent arteriole resistance. • CTGF is absent in spontaneous hypertensive rats and overactivated in Dahl salt-sensitive rats. • CTGF in excess may promote glomerular damage and proteinuria, while the absence may participate in sodium retention and hypertension.
Topics: Animals; Feedback; Humans; Hypertension; Kidney Glomerulus; Kidney Tubules; Microcirculation; Proteinuria; Rats; Renal Circulation; Sodium
PubMed: 30659366
DOI: 10.1007/s11906-019-0911-5 -
JACC. Cardiovascular Imaging Jul 2022
Topics: Coronary Circulation; Heart; Humans; Microcirculation; Predictive Value of Tests
PubMed: 35798396
DOI: 10.1016/j.jcmg.2022.03.020 -
Journal of the Chinese Medical... Aug 2015From a hemodynamic point of view, hepatic vascular resistance and portal inflow determine the level of portal pressure. Factors that determine hepatic vascular... (Review)
Review
From a hemodynamic point of view, hepatic vascular resistance and portal inflow determine the level of portal pressure. Factors that determine hepatic vascular resistance include both structural and dynamic components. Among the structural components are histological characteristics such as steatosis, fibrosis, regeneration nodules, and neo-angiogenesis. Dynamic structures include cells with contractile properties such as hepatocytes, hepatic stellate cells, sinusoidal endothelial cells, and Kupffer cells. The contributions of the interactions between four cells in cirrhotic livers resulted in hepatic endothelial dysfunction, hepatic microcirculatory dysfunction, hepatic venous dysregulation, hepatic fibrogenesis, and subsequently increased intrahepatic resistance and portal hypertension in cirrhosis. The pathogenic mechanisms that trigger the associated abnormalities in hepatic microcirculations include persistent endotoxemia, increased hepatic oxidative stress, activated endocannabinoids substances, pathogenic sinusoidal remodeling, and hypoperfusion in cirrhotic livers. Cumulative data suggested that various therapeutic strategies targeting hepatic microcirculation provided effective improvement of the systemic abnormalities of cirrhosis. Accordingly, the mechanistic and therapeutic approaches focusing on the disarrangement of hepatic microcirculation will be introduced in this article.
Topics: Bacterial Translocation; Endocannabinoids; Fibroblast Growth Factor 2; Humans; Liver Circulation; Liver Cirrhosis; Microcirculation; Nitric Oxide; Vascular Endothelial Growth Factor A
PubMed: 26074366
DOI: 10.1016/j.jcma.2015.05.005