RESUMO
The progress of research focused on cholangiocytes and the biliary tree during development and following injury is hindered by limited available quantitative methodologies. Current techniques include two-dimensional standard histological cell-counting approaches, which are rapidly performed, error prone, and lack architectural context or three-dimensional analysis of the biliary tree in opacified livers, which introduce technical issues along with minimal quantitation. The present study aims to fill these quantitative gaps with a supervised machine-learning model (BiliQML) able to quantify biliary forms in the liver of anti-keratin 19 antibody-stained whole slide images. Training utilized 5,019 researcher-labeled biliary forms, which following feature selection, and algorithm optimization, generated an F score of 0.87. Application of BiliQML on seven separate cholangiopathy models [genetic (Afp-CRE;Pkd1l1null/Fl, Alb-CRE;Rbp-jkfl/fl, and Albumin-CRE;ROSANICD), surgical (bile duct ligation), toxicological (3,5-diethoxycarbonyl-1,4-dihydrocollidine), and therapeutic (Cyp2c70-/- with ileal bile acid transporter inhibition)] allowed for a means to validate the capabilities and utility of this platform. The results from BiliQML quantification revealed biological and pathological differences across these seven diverse models, indicating a highly sensitive, robust, and scalable methodology for the quantification of distinct biliary forms. BiliQML is the first comprehensive machine-learning platform for biliary form analysis, adding much-needed morphologic context to standard immunofluorescence-based histology, and provides clinical and basic science researchers with a novel tool for the characterization of cholangiopathies.NEW & NOTEWORTHY BiliQML is the first comprehensive machine-learning platform for biliary form analysis in whole slide histopathological images. This platform provides clinical and basic science researchers with a novel tool for the improved quantification and characterization of biliary tract disorders.
Assuntos
Fígado , Aprendizado de Máquina Supervisionado , Fígado/patologia , Fígado/metabolismo , Animais , Camundongos , Sistema Biliar/patologia , Sistema Biliar/metabolismo , Processamento de Imagem Assistida por Computador/métodos , Ductos Biliares/patologia , Ductos Biliares/metabolismo , Doenças dos Ductos Biliares/patologia , Doenças dos Ductos Biliares/metabolismo , Modelos Animais de DoençasRESUMO
Mechanical forces are integral to many biological processes; however, current techniques cannot map the magnitude and direction of piconewton molecular forces. Here, we describe molecular force microscopy, leveraging molecular tension probes and fluorescence polarization microscopy to measure the magnitude and 3D orientation of cellular forces. We mapped the orientation of integrin-based traction forces in mouse fibroblasts and human platelets, revealing alignment between the organization of force-bearing structures and their force orientations.
Assuntos
Polarização de Fluorescência/métodos , Integrinas/metabolismo , Mecanotransdução Celular , Microscopia de Força Atômica/métodos , Microscopia de Fluorescência/métodos , Sondas Moleculares/metabolismo , Fenômenos Biomecânicos , Plaquetas/metabolismo , HumanosRESUMO
Abnormal sickle red blood cell (sRBC) biomechanics, including pathological deformability and adhesion, correlate with clinical severity in sickle cell disease (SCD). Clinical intravenous fluids (IVFs) of various tonicities are often used during treatment of vaso-occlusive pain episodes (VOE), the major cause of morbidity in SCD. However, evidence-based guidelines are lacking, and there is no consensus regarding which IVFs to use during VOE. Further, it is unknown how altering extracellular fluid tonicity with IVFs affects sRBC biomechanics in the microcirculation, where vaso-occlusion takes place. Here, we report how altering extracellular fluid tonicity with admixtures of clinical IVFs affects sRBC biomechanical properties by leveraging novel in vitro microfluidic models of the microcirculation, including 1 capable of deoxygenating the sRBC environment to monitor changes in microchannel occlusion risk and an "endothelialized" microvascular model that measures alterations in sRBC/endothelium adhesion under postcapillary venular conditions. Admixtures with higher tonicities (sodium = 141 mEq/L) affected sRBC biomechanics by decreasing sRBC deformability, increasing sRBC occlusion under normoxic and hypoxic conditions, and increasing sRBC adhesion in our microfluidic human microvasculature models. Admixtures with excessive hypotonicity (sodium = 103 mEq/L), in contrast, decreased sRBC adhesion, but overswelling prolonged sRBC transit times in capillary-sized microchannels. Admixtures with intermediate tonicities (sodium = 111-122 mEq/L) resulted in optimal changes in sRBC biomechanics, thereby reducing the risk for vaso-occlusion in our models. These results have significant translational implications for patients with SCD and warrant a large-scale prospective clinical study addressing optimal IVF management during VOE in SCD.
Assuntos
Anemia Falciforme/sangue , Anemia Falciforme/fisiopatologia , Deformação Eritrocítica/fisiologia , Líquido Extracelular/fisiologia , Fenômenos Biomecânicos , Adesão Celular/fisiologia , Células Cultivadas , Eritrócitos Anormais/fisiologia , Líquido Extracelular/química , Hemorreologia , Células Endoteliais da Veia Umbilical Humana/metabolismo , Células Endoteliais da Veia Umbilical Humana/fisiologia , Humanos , Concentração OsmolarRESUMO
Leukocytes normally marginate toward the vascular wall in large vessels and within the microvasculature. Reversal of this process, leukocyte demargination, leads to substantial increases in the clinical white blood cell and granulocyte count and is a well-documented effect of glucocorticoid and catecholamine hormones, although the underlying mechanisms remain unclear. Here we show that alterations in granulocyte mechanical properties are the driving force behind glucocorticoid- and catecholamine-induced demargination. First, we found that the proportions of granulocytes from healthy human subjects that traversed and demarginated from microfluidic models of capillary beds and veins, respectively, increased after the subjects ingested glucocorticoids. Also, we show that glucocorticoid and catecholamine exposure reorganizes cellular cortical actin, significantly reducing granulocyte stiffness, as measured with atomic force microscopy. Furthermore, using simple kinetic theory computational modeling, we found that this reduction in stiffness alone is sufficient to cause granulocyte demargination. Taken together, our findings reveal a biomechanical answer to an old hematologic question regarding how glucocorticoids and catecholamines cause leukocyte demargination. In addition, in a broader sense, we have discovered a temporally and energetically efficient mechanism in which the innate immune system can simply alter leukocyte stiffness to fine tune margination/demargination and therefore leukocyte trafficking in general. These observations have broad clinically relevant implications for the inflammatory process overall as well as hematopoietic stem cell mobilization and homing.
Assuntos
Movimento Celular , Granulócitos , Dispositivos Lab-On-A-Chip , Modelos Cardiovasculares , Catecolaminas/farmacologia , Movimento Celular/efeitos dos fármacos , Movimento Celular/fisiologia , Feminino , Glucocorticoides/farmacologia , Granulócitos/citologia , Granulócitos/metabolismo , Humanos , Contagem de Leucócitos/instrumentação , Contagem de Leucócitos/métodos , MasculinoRESUMO
Haemostasis occurs at sites of vascular injury, where flowing blood forms a clot, a dynamic and heterogeneous fibrin-based biomaterial. Paramount in the clot's capability to stem haemorrhage are its changing mechanical properties, the major drivers of which are the contractile forces exerted by platelets against the fibrin scaffold. However, how platelets transduce microenvironmental cues to mediate contraction and alter clot mechanics is unknown. This is clinically relevant, as overly softened and stiffened clots are associated with bleeding and thrombotic disorders. Here, we report a high-throughput hydrogel-based platelet-contraction cytometer that quantifies single-platelet contraction forces in different clot microenvironments. We also show that platelets, via the Rho/ROCK pathway, synergistically couple mechanical and biochemical inputs to mediate contraction. Moreover, highly contractile platelet subpopulations present in healthy controls are conspicuously absent in a subset of patients with undiagnosed bleeding disorders, and therefore may function as a clinical diagnostic biophysical biomarker.
Assuntos
Coagulação Sanguínea/fisiologia , Velocidade do Fluxo Sanguíneo/fisiologia , Plaquetas/fisiologia , Citometria de Fluxo/métodos , Mecanotransdução Celular/fisiologia , Ativação Plaquetária/fisiologia , Adesividade Plaquetária/fisiologia , Células Cultivadas , Módulo de Elasticidade/fisiologia , Dureza/fisiologia , Humanos , Nanopartículas/químicaRESUMO
The mechanism of action of the widely used in vivo ferric chloride (FeCl3) thrombosis model remains poorly understood; although endothelial cell denudation is historically cited, a recent study refutes this and implicates a role for erythrocytes. Given the complexity of the in vivo environment, an in vitro reductionist approach is required to systematically isolate and analyze the biochemical, mass transfer, and biological phenomena that govern the system. To this end, we designed an "endothelial-ized" microfluidic device to introduce controlled FeCl3 concentrations to the molecular and cellular components of blood and vasculature. FeCl3 induces aggregation of all plasma proteins and blood cells, independent of endothelial cells, by colloidal chemistry principles: initial aggregation is due to binding of negatively charged blood components to positively charged iron, independent of biological receptor/ligand interactions. Full occlusion of the microchannel proceeds by conventional pathways, and can be attenuated by antithrombotic agents and loss-of-function proteins (as in IL4-R/Iba mice). As elevated FeCl3 concentrations overcome protective effects, the overlap between charge-based aggregation and clotting is a function of mass transfer. Our physiologically relevant in vitro system allows us to discern the multifaceted mechanism of FeCl3-induced thrombosis, thereby reconciling literature findings and cautioning researchers in using the FeCl3 model.
Assuntos
Plaquetas/efeitos dos fármacos , Cloretos/farmacologia , Eritrócitos/efeitos dos fármacos , Compostos Férricos/farmacologia , Agregados Proteicos/efeitos dos fármacos , Aspirina/farmacologia , Fenômenos Biomecânicos , Plaquetas/química , Plaquetas/citologia , Agregação Celular/efeitos dos fármacos , Cloretos/antagonistas & inibidores , Cloretos/química , Eritrócitos/química , Eritrócitos/citologia , Compostos Férricos/antagonistas & inibidores , Compostos Férricos/química , Fibrinolíticos/farmacologia , Heparina/farmacologia , Humanos , Técnicas Analíticas Microfluídicas , Modelos Biológicos , Plasma Rico em Plaquetas/química , Cultura Primária de Células , Ligação Proteica , Eletricidade Estática , Trombose/metabolismo , Trombose/patologiaRESUMO
Although the biology of platelet adhesion on subendothelial matrix after vascular injury is well characterized, how the matrix biophysical properties affect platelet physiology is unknown. Here we demonstrate that geometric orientation of the matrix itself regulates platelet α-granule secretion, a key component of platelet activation. Using protein microcontact printing, we show that platelets spread beyond the geometric constraints of fibrinogen or collagen micropatterns with <5-µm features. Interestingly, α-granule exocytosis and deposition of the α-granule contents such as fibrinogen and fibronectin were primarily observed in those areas of platelet extension beyond the matrix protein micropatterns. This enables platelets to "self-deposit" additional matrix, provide more cellular membrane to extend spreading, and reinforce platelet-platelet connections. Mechanistically, this phenomenon is mediated by actin polymerization, Rac1 activation, and αIIbß3 integrin redistribution and activation, and is attenuated in gray platelet syndrome platelets, which lack α-granules, and Wiskott-Aldrich syndrome platelets, which have cytoskeletal defects. Overall, these studies demonstrate how platelets transduce geometric cues of the underlying matrix geometry into intracellular signals to extend spreading, which endows platelets spatial flexibility when spreading onto small sites of exposed subendothelium.
Assuntos
Plaquetas/citologia , Plaquetas/metabolismo , Exocitose/fisiologia , Síndrome da Plaqueta Cinza/patologia , Adesividade Plaquetária/fisiologia , Síndrome de Wiskott-Aldrich/patologia , Citoesqueleto de Actina/metabolismo , Estudos de Casos e Controles , Membrana Celular/metabolismo , Células Cultivadas , Fibrinogênio/metabolismo , Fibronectinas/metabolismo , Síndrome da Plaqueta Cinza/metabolismo , Humanos , Técnicas Imunoenzimáticas , Ativação Plaquetária , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/metabolismo , Pseudópodes , Síndrome de Wiskott-Aldrich/metabolismoRESUMO
Although the processes of haemostasis and thrombosis have been studied extensively in the past several decades, much of the effort has been spent characterizing the biological and biochemical aspects of clotting. More recently, researchers have discovered that the function and physiology of blood cells and plasma proteins relevant in haematologic processes are mechanically, as well as biologically, regulated. This is not entirely surprising considering the extremely dynamic fluidic environment that these blood components exist in. Other cells in the body such as fibroblasts and endothelial cells have been found to biologically respond to their physical and mechanical environments, affecting aspects of cellular physiology as diverse as cytoskeletal architecture to gene expression to alterations of vital signalling pathways. In the circulation, blood cells and plasma proteins are constantly exposed to forces while they, in turn, also exert forces to regulate clot formation. These mechanical factors lead to biochemical and biomechanical changes on the macro- to molecular scale. Likewise, biochemical and biomechanical alterations in the microenvironment can ultimately impact the mechanical regulation of clot formation. The ways in which these factors all balance each other can be the difference between haemostasis and thrombosis. Here, we review how the biomechanics of blood cells intimately interact with the cellular and molecular biology to regulate haemostasis and thrombosis in the context of health and disease from the macro- to molecular scale. We will also show how these biomechanical forces in the context of haemostasis and thrombosis have been replicated or measured in vitro.
Assuntos
Saúde , Hemostasia , Trombose/fisiopatologia , Animais , Fenômenos Biomecânicos , Eritrócitos/metabolismo , Humanos , Trombose/sangueRESUMO
While microscopy-based cellular assays, including microfluidics, have significantly advanced over the last several decades, there has not been concurrent development of widely-accessible techniques to analyze time-dependent microscopy data incorporating phenomena such as fluid flow and dynamic cell adhesion. As such, experimentalists typically rely on error-prone and time-consuming manual analysis, resulting in lost resolution and missed opportunities for innovative metrics. We present a user-adaptable toolkit packaged into the open-source, standalone Interactive Cellular assay Labeled Observation and Tracking Software (iCLOTS). We benchmark cell adhesion, single-cell tracking, velocity profile, and multiscale microfluidic-centric applications with blood samples, the prototypical biofluid specimen. Moreover, machine learning algorithms characterize previously imperceptible data groupings from numerical outputs. Free to download/use, iCLOTS addresses a need for a field stymied by a lack of analytical tools for innovative, physiologically-relevant assays of any design, democratizing use of well-validated algorithms for all end-user biomedical researchers who would benefit from advanced computational methods.
Assuntos
Inteligência Artificial , Microfluídica , Microscopia , Software , Células SanguíneasRESUMO
The correlation between cardiovascular disease and iron deficiency anemia (IDA) is well documented but poorly understood. Using a multi-disciplinary approach, we explore the hypothesis that the biophysical alterations of red blood cells (RBCs) in IDA, such as variable degrees of microcytosis and decreased deformability may directly induce endothelial dysfunction via mechanobiological mechanisms. Using a combination of atomic force microscopy and microfluidics, we observed that subpopulations of IDA RBCs (idRBCs) are significantly stiffer and smaller than both healthy RBCs and the remaining idRBC population. Furthermore, computational simulations demonstrated that the smaller and stiffer idRBC subpopulations marginate toward the vessel wall causing aberrant shear stresses. This leads to increased vascular inflammation as confirmed with perfusion of idRBCs into our "endothelialized" microfluidic systems. Overall, our multifaceted approach demonstrates that the altered biophysical properties of idRBCs directly lead to vasculopathy, suggesting that the IDA and cardiovascular disease association extends beyond correlation and into causation.
RESUMO
Neutrophil extracellular traps (NETs) is an antimicrobial cobweb-structured material produced by immune cells for clearance of pathogens in the body, but paradoxically associated with biofilm formation and exacerbated lung infections. To provide a better materials perspective on the pleiotropic roles played by NETs at diverse compositions/concentrations, a NETs-like material (called 'microwebs', abbreviated as µwebs) is synthesized for decoding the antimicrobial activity of NETs against Staphylococcus aureus in infection-relevant conditions. We show that µwebs composed of low-to-intermediate concentrations of DNA-histone complexes successfully trap and inhibit S. aureus growth and biofilm formation. However, with growing concentrations and histone proportions, the resulting microwebs appear gel-like structures accompanied by reduced antimicrobial activity that can even promote formation of S. aureus biofilms. Our simplified model of NETs provides a materials-based evidence on NETs-relevant pathology in the development of biofilms.
RESUMO
Hematopoietic stem cell (HSC) quiescence is a tightly regulated process crucial for hematopoietic regeneration, which requires a healthy and supportive microenvironmental niche within the bone marrow (BM). Here, we show that deletion of Ptpn21, a protein tyrosine phosphatase highly expressed in HSCs, induces stem cell egress from the niche due to impaired retention within the BM. Ptpn21-/- HSCs exhibit enhanced mobility, decreased quiescence, increased apoptosis, and defective reconstitution capacity. Ptpn21 deletion also decreased HSC stiffness and increased physical deformability, in part by dephosphorylating Spetin1 (Tyr246), a poorly described component of the cytoskeleton. Elevated phosphorylation of Spetin1 in Ptpn21-/- cells impaired cytoskeletal remodeling, contributed to cortical instability, and decreased cell rigidity. Collectively, these findings show that Ptpn21 maintains cellular mechanics, which is correlated with its important functions in HSC niche retention and preservation of hematopoietic regeneration capacity.
Assuntos
Células-Tronco Hematopoéticas/citologia , Células-Tronco Hematopoéticas/metabolismo , Homeostase , Proteínas Tirosina Fosfatases não Receptoras/metabolismo , Septinas/metabolismo , Animais , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fosforilação , Proteínas Tirosina Fosfatases não Receptoras/deficiência , Nicho de Células-TroncoRESUMO
Ultraviolet (UV) spectroscopy is a powerful tool for quantitative (bio)chemical analysis, but its application to molecular imaging and microscopy has been limited. Here we introduce ultraviolet hyperspectral interferometric (UHI) microscopy, which leverages coherent detection of optical fields to overcome significant challenges associated with UV spectroscopy when applied to molecular imaging. We demonstrate that this method enables quantitative spectral analysis of important endogenous biomolecules with subcellular spatial resolution and sensitivity to nanometer-scaled structures for label-free molecular imaging of live cells.
RESUMO
Hemostasis encompasses an ensemble of interactions among platelets, coagulation factors, blood cells, endothelium, and hemodynamic forces, but current assays assess only isolated aspects of this complex process. Accordingly, here we develop a comprehensive in vitro mechanical injury bleeding model comprising an "endothelialized" microfluidic system coupled with a microengineered pneumatic valve that induces a vascular "injury". With perfusion of whole blood, hemostatic plug formation is visualized and "in vitro bleeding time" is measured. We investigate the interaction of different components of hemostasis, gaining insight into several unresolved hematologic issues. Specifically, we visualize and quantitatively demonstrate: the effect of anti-platelet agent on clot contraction and hemostatic plug formation, that von Willebrand factor is essential for hemostasis at high shear, that hemophilia A blood confers unstable hemostatic plug formation and altered fibrin architecture, and the importance of endothelial phosphatidylserine in hemostasis. These results establish the versatility and clinical utility of our microfluidic bleeding model.