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1.
Proc Natl Acad Sci U S A ; 118(15)2021 04 13.
Artículo en Inglés | MEDLINE | ID: mdl-33876768

RESUMEN

Bundles of stiff filaments are ubiquitous in the living world, found both in the cytoskeleton and in the extracellular medium. These bundles are typically held together by smaller cross-linking molecules. We demonstrate, analytically, numerically, and experimentally, that such bundles can be kinked, that is, have localized regions of high curvature that are long-lived metastable states. We propose three possible mechanisms of kink stabilization: a difference in trapped length of the filament segments between two cross-links, a dislocation where the endpoint of a filament occurs within the bundle, and the braiding of the filaments in the bundle. At a high concentration of cross-links, the last two effects lead to the topologically protected kinked states. Finally, we explore, numerically and analytically, the transition of the metastable kinked state to the stable straight bundle.


Asunto(s)
Citoesqueleto de Actina/química , Colágeno/química , Simulación de Dinámica Molecular
2.
Proc Natl Acad Sci U S A ; 118(29)2021 07 20.
Artículo en Inglés | MEDLINE | ID: mdl-34266950

RESUMEN

Despite the ubiquitous importance of cell contact guidance, the signal-inducing contact guidance of mammalian cells in an aligned fibril network has defied elucidation. This is due to multiple interdependent signals that an aligned fibril network presents to cells, including, at least, anisotropy of adhesion, porosity, and mechanical resistance. By forming aligned fibrin gels with the same alignment strength, but cross-linked to different extents, the anisotropic mechanical resistance hypothesis of contact guidance was tested for human dermal fibroblasts. The cross-linking was shown to increase the mechanical resistance anisotropy, without detectable change in network microstructure and without change in cell adhesion to the cross-linked fibrin gel. This methodology thus isolated anisotropic mechanical resistance as a variable for fixed anisotropy of adhesion and porosity. The mechanical resistance anisotropy |Y*| -1 - |X*| -1 increased over fourfold in terms of the Fourier magnitudes of microbead displacement |X*| and |Y*| at the drive frequency with respect to alignment direction Y obtained by optical forces in active microrheology. Cells were found to exhibit stronger contact guidance in the cross-linked gels possessing greater mechanical resistance anisotropy: the cell anisotropy index based on the tensor of cell orientation, which has a range 0 to 1, increased by 18% with the fourfold increase in mechanical resistance anisotropy. We also show that modulation of adhesion via function-blocking antibodies can modulate the guidance response, suggesting a concomitant role of cell adhesion. These results indicate that fibroblasts can exhibit contact guidance in aligned fibril networks by sensing anisotropy of network mechanical resistance.


Asunto(s)
Adhesión Celular , Fibroblastos/química , Anisotropía , Fenómenos Biomecánicos , Fibrina/química , Fibrina/metabolismo , Fibroblastos/citología , Fibroblastos/metabolismo , Humanos , Porosidad , Estrés Mecánico
3.
Opt Lett ; 46(6): 1409-1412, 2021 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-33720199

RESUMEN

We demonstrate an interferometric method to provide direct, single-shot measurements of cavitation bubble dynamics with nanoscale spatial and temporal resolution with results that closely match theoretical predictions. Implementation of this method reduces the need for expensive and complex ultra-high speed camera systems for the measurement of single cavitation events. This method can capture dynamics over large time intervals with sub-nanosecond temporal resolution and spatial precision surpassing the optical diffraction limit. We expect this method to have broad utility for examination of cavitation bubble dynamics, as well as for metrology applications such as optorheological materials characterization. This method provides an accurate approach for precise measurement of cavitation bubble dynamics suitable for metrology applications such as optorheological materials characterization.

4.
Anal Chem ; 92(11): 7683-7689, 2020 06 02.
Artículo en Inglés | MEDLINE | ID: mdl-32352281

RESUMEN

Molecular sensors from protein engineering offer new methods to sensitively bind to and detect target analytes for a wide range of applications. For example, these sensors can be integrated into probes for implantation, and then yield new and valuable physiological information. Here, a new Förster resonance energy transfer (FRET)-based sensor is integrated with an optical fiber to yield a device measuring free Ca2+. This membrane encapsulated optical fiber (MEOF) device is composed of a sensor matrix that fills poly(tetrafluoroethylene) (PTFE) with an engineered troponin C (TnC) protein fused to a pair of FRET fluorophores. The FRET efficiency is modulated upon Ca2+ ion binding. The probe further comprises a second, size-excluding filter membrane that is synthesized by filling the pores of a PTFE matrix with a poly(ethylene glycol) dimethacrylate (PEGDMA) hydrogel; this design ensures protection from circulating proteases and the foreign body response. The two membranes are stacked and placed on a thin, silica optical fiber for optical excitation and detection. Results show the biosensor responds to changes in Ca2+ concentration within minutes with a sensitivity ranging from 0.01 to 10 mM Ca2+, allowing discrimination of hyper- and hypocalcemia. Furthermore, the system reversibly binds Ca2+ to allow continuous monitoring. This work paves the way for the use of engineered structure-switching proteins for continuous optical monitoring in a large number of applications.


Asunto(s)
Calcio/análisis , Transferencia Resonante de Energía de Fluorescencia , Troponina C/metabolismo , Animales , Batrachoidiformes/metabolismo , Calcio/metabolismo , Procesos Fotoquímicos , Proteolisis , Troponina C/química
5.
Langmuir ; 32(49): 13124-13136, 2016 12 13.
Artículo en Inglés | MEDLINE | ID: mdl-27797529

RESUMEN

The targeted delivery of nanoparticle carriers holds tremendous potential to transform the detection and treatment of diseases. A major attribute of nanoparticles is the ability to form multiple bonds with target cells, which greatly improves the adhesion strength. However, the multivalent binding of nanoparticles is still poorly understood, particularly from a dynamic perspective. In previous experimental work, we studied the kinetics of nanoparticle adhesion and found that the rate of detachment decreased over time. Here, we have applied the adhesive dynamics simulation framework to investigate binding dynamics between an antibody-conjugated, 200-nm-diameter sphere and an ICAM-1-coated surface on the scale of individual bonds. We found that nano adhesive dynamics (NAD) simulations could replicate the time-varying nanoparticle detachment behavior that we observed in experiments. As expected, this behavior correlated with a steady increase in mean bond number with time, but this was attributed to bond accumulation only during the first second that nanoparticles were bound. Longer-term increases in bond number instead were manifested from nanoparticle detachment serving as a selection mechanism to eliminate nanoparticles that had randomly been confined to lower bond valencies. Thus, time-dependent nanoparticle detachment reflects an evolution of the remaining nanoparticle population toward higher overall bond valency. We also found that NAD simulations precisely matched experiments whenever mechanical force loads on bonds were high enough to directly induce rupture. These mechanical forces were in excess of 300 pN and primarily arose from the Brownian motion of the nanoparticle, but we also identified a valency-dependent contribution from bonds pulling on each other. In summary, we have achieved excellent kinetic consistency between NAD simulations and experiments, which has revealed new insights into the dynamics and biophysics of multivalent nanoparticle adhesion. In future work, we will leverage the simulation as a design tool for optimizing targeted nanoparticle agents.


Asunto(s)
Anticuerpos/química , Molécula 1 de Adhesión Intercelular/química , Nanopartículas/química , Biofisica , Cinética
6.
ACS Biomater Sci Eng ; 9(10): 5666-5678, 2023 Oct 09.
Artículo en Inglés | MEDLINE | ID: mdl-37713253

RESUMEN

Controlling cell-substrate interactions via the microstructural characteristics of biomaterials offers an advantageous path for modulating cell dynamics, mechanosensing, and migration, as well as for designing immune-modulating implants, all without the drawbacks of chemical-based triggers. Specifically, recent in vivo studies have suggested that a porous implant's microscale curvature landscape can significantly impact cell behavior and ultimately the immune response. To investigate such cell-substrate interactions, we utilized a 3D computational model incorporating the minimum necessary physics of cell migration and cell-substrate interactions needed to replicate known in vitro behaviors. This model specifically incorporates the effect of membrane tension, which was found to be necessary to replicate in vitro cell behavior on curved surfaces. Our simulated substrates represent two classes of porous materials recently used in implant studies, which have markedly different microscale curvature distributions and pore geometries. We found distinct differences between the overall migration behaviors, shapes, and actin polymerization dynamics of cells interacting with the two substrates. These differences were correlated to the shape energy of the cells as they interacted with the porous substrates, in effect interpreting substrate topography as an energetic landscape interrogated by cells. Our results demonstrate that microscale curvature directly influences cell shape and migration and, therefore, is likely to influence cell behavior. This supports further investigation of the relationship between the surface topography of implanted materials and the characteristic immune response, a complete understanding of which would broadly advance principles of biomaterial design.

7.
ACS Sens ; 7(2): 441-452, 2022 02 25.
Artículo en Inglés | MEDLINE | ID: mdl-35175733

RESUMEN

Clinical research shows that frequent measurements of both pH and lactate can help guide therapy and improve patient outcome. However, current methods of sampling blood pH and lactate make it impractical to take readings frequently (due to the heightened risk of blood infection and anemia). As a solution, we have engineered a subcutaneous pH and lactate sensor (PALS) that can provide continuous, physiologically relevant measurements. To measure pH, a sheet containing a pH-sensitive fluorescent dye is placed over 400 and 465 nm light-emitting diodes (LEDs) and a filter-coated photodetector. The filter-coated photodetector collects an emitted signal from the dye for each LED excitation, and the ratio of the emitted signals is used to monitor pH. To measure lactate, two sensing sheets comprising an oxygen-sensitive phosphorescent dye are each mounted to a 625 nm LED. One sheet additionally comprises the enzyme lactate oxidase. The LEDs are sequentially modulated to excite the sensing sheets, and their phase shift at the LED drive frequency is used to monitor lactate. In vitro results indicate that PALS successfully records pH changes from 6.92 to 7.70, allowing for discrimination between acidosis and alkalosis, and can track lactate levels up to 9 mM. Both sensing strategies exhibit fast rise times (< 5 min) and stable measurements. Multianalyte in vitro models of physiological disorders show that the sensor measurements consistently quantify the expected pathophysiological trends without cross talk; in vivo rabbit testing further indicates usefulness in the clinical setting.


Asunto(s)
Ácido Láctico , Oxígeno , Animales , Colorantes Fluorescentes , Concentración de Iones de Hidrógeno , Monitoreo Fisiológico , Conejos
8.
Nature ; 434(7036): 1040-5, 2005 Apr 21.
Artículo en Inglés | MEDLINE | ID: mdl-15846350

RESUMEN

The mechanical environment crucially influences many cell functions. However, it remains largely mysterious how mechanical stimuli are transmitted into biochemical signals. Src is known to regulate the integrin-cytoskeleton interaction, which is essential for the transduction of mechanical stimuli. Using fluorescent resonance energy transfer (FRET), here we develop a genetically encoded Src reporter that enables the imaging and quantification of spatio-temporal activation of Src in live cells. We introduced a local mechanical stimulation to human umbilical vein endothelial cells (HUVECs) by applying laser-tweezer traction on fibronectin-coated beads adhering to the cells. Using the Src reporter, we observed a rapid distal Src activation and a slower directional wave propagation of Src activation along the plasma membrane. This wave propagated away from the stimulation site with a speed (mean +/- s.e.m.) of 18.1 +/- 1.7 nm s(-1). This force-induced directional and long-range activation of Src was abolished by the disruption of actin filaments or microtubules. Our reporter has thus made it possible to monitor mechanotransduction in live cells with spatio-temporal characterization. We find that the transmission of mechanically induced Src activation is a dynamic process that directs signals via the cytoskeleton to spatial destinations.


Asunto(s)
Mecanotransducción Celular/fisiología , Proteínas Proto-Oncogénicas pp60(c-src)/metabolismo , Citoesqueleto de Actina/metabolismo , Secuencia de Aminoácidos , Animales , Fenómenos Biomecánicos , Adhesión Celular , Membrana Celular/enzimología , Membrana Celular/metabolismo , Células Endoteliales/citología , Células Endoteliales/metabolismo , Activación Enzimática , Fibroblastos , Fibronectinas/metabolismo , Transferencia Resonante de Energía de Fluorescencia , Células HeLa , Humanos , Ratones , Microesferas , Microtúbulos/metabolismo , Modelos Moleculares , Sondas Moleculares/análisis , Datos de Secuencia Molecular , Proteínas Proto-Oncogénicas pp60(c-src)/genética , Venas Umbilicales/citología
9.
Sci Rep ; 10(1): 13144, 2020 08 04.
Artículo en Inglés | MEDLINE | ID: mdl-32753667

RESUMEN

We introduce laser cavitation rheology (LCR) as a minimally-invasive optical method to characterize mechanical properties within the interior of biological and synthetic aqueous soft materials at high strain-rates. We utilized time-resolved photography to measure cavitation bubble dynamics generated by the delivery of focused 500 ps duration laser radiation at λ = 532 nm within fibrin hydrogels at pulse energies of Ep = 12, 18 µJ and within polyethylene glycol (600) diacrylate (PEG (600) DA) hydrogels at Ep = 2, 5, 12 µJ. Elastic moduli and failure strains of fibrin and PEG (600) DA hydrogels were calculated from these measurements by determining parameter values which provide the best fit of the measured data to a theoretical model of cavitation bubble dynamics in a Neo-Hookean viscoelastic medium subject to material failure. We demonstrate the use of this method to retrieve the local, interior elastic modulus of these hydrogels and both the radial and circumferential failure strains.


Asunto(s)
Módulo de Elasticidad , Hidrogeles/química , Rayos Láser , Ensayo de Materiales , Modelos Teóricos
10.
Acta Biomater ; 94: 173-182, 2019 08.
Artículo en Inglés | MEDLINE | ID: mdl-31233892

RESUMEN

Mitigation of the foreign body response (FBR) and successful tissue integration are essential to ensuring the longevity of implanted devices and biomaterials. The use of porous materials and coatings has been shown to have an impact, as the textured surfaces can mediate macrophage interactions with the implant and influence the FBR, and the pores can provide space for vascularization and tissue integration. In this study, we use a new class of implantable porous biomaterials templated from bicontinuous interfacially jammed emulsion gels (bijels), which offer a fully percolating, non-constricting porous network with a uniform pore diameter on the order of tens of micrometers, and surfaces with consistent curvature. We demonstrate that these unique morphological features, inherent to bijel-templated materials (BTMs), can enhance tissue integration and vascularization, and reduce the FBR. Cylindrical polyethylene glycol diacrylate (PEGDA) BTMs, along with PEGDA particle-templated materials (PTMs), and non-templated materials (NTMs), were implanted into the subcutaneous space of athymic nude mice. After 28 days, implants were retrieved and analyzed via histological techniques. Within BTMs, blood vessels of increased size and depth, changes in collagen deposition, and increased presence of pro-healing macrophages were observed compared to that of PTM and NTM implants. Bijel templating offers a new route to biomaterials that can improve the function and longevity of implantable devices. STATEMENT OF SIGNIFICANCE: All implanted biomaterials are subject to the foreign body response (FBR) which can have a detrimental effect on their efficacy. Altering the surface chemistry can decrease the FBR by limiting the amount of proteins adsorbed to the implant. This effect can be enhanced by including pores in the biomaterial to allow new tissue growth as the implant becomes integrated in the body. Here, we introduce a new class of self-assembled biomaterials comprising a fully penetrating, non-constricting pore phase with hyperbolic (saddle) surfaces for enhanced tissue integration. These unique morphological characteristics result in dense blood vessel formation and favorable tissue response properties demonstrated in a four-week implantation study.


Asunto(s)
Materiales Biocompatibles/química , Ingeniería de Tejidos/métodos , Animales , Prótesis Vascular , Reacción a Cuerpo Extraño , Inmunohistoquímica , Implantes Experimentales , Macrófagos/citología , Ensayo de Materiales , Ratones , Ratones Desnudos , Microscopía Fluorescente , Nanopartículas/química , Neovascularización Patológica/patología , Distribución Normal , Tamaño de la Partícula , Polietilenglicoles/química , Porosidad , Prótesis e Implantes , Diseño de Prótesis , Dióxido de Silicio/química , Tejido Subcutáneo/patología , Cicatrización de Heridas
11.
APL Bioeng ; 3(1): 016103, 2019 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31069336

RESUMEN

Macrophages are versatile cells of the innate immune system that can adopt a variety of functional phenotypes depending on signals in their environment. In previous work, we found that culture of macrophages on fibrin, the provisional extracellular matrix protein, inhibits their inflammatory activation when compared to cells cultured on polystyrene surfaces. Here, we sought to investigate the role of matrix stiffness in the regulation of macrophage activity by manipulating the mechanical properties of fibrin. We utilize a photo-initiated crosslinking method to introduce dityrosine crosslinks to a fibrin gel and confirm an increase in gel stiffness through active microrheology. We observe that matrix crosslinking elicits distinct changes in macrophage morphology, integrin expression, migration, and inflammatory activation. Macrophages cultured on a stiffer substrate exhibit greater cell spreading and expression of αM integrin. Furthermore, macrophages cultured on crosslinked fibrin exhibit increased motility. Finally, culture of macrophages on photo-crosslinked fibrin enhances their inflammatory activation compared to unmodified fibrin, suggesting that matrix crosslinking regulates the functional activation of macrophages. These findings provide insight into how the physical properties of the extracellular matrix might control macrophage behavior during inflammation and wound healing.

12.
J Cell Physiol ; 217(3): 745-51, 2008 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-18683212

RESUMEN

The combination of laser tweezers, fluorescent imaging, and real-time automated tracking and trapping (RATTS) can measure sperm swimming speed and swimming force simultaneously with mitochondrial membrane potential (MMP). This approach is used to study the roles of two sources of ATP in sperm motility: oxidative phosphorylation, which occurs in the mitochondria located in the sperm midpiece and glycolysis, which occurs along the length of the sperm tail (flagellum). The relationships between (a) swimming speed and MMP and (b) swimming force and MMP are studied in dog and human sperm. The effects of glucose, oxidative phosphorylation inhibitors and glycolytic inhibitors on human sperm motility are examined. The results indicate that oxidative phosphorylation does contribute some ATP for human sperm motility, but not enough to sustain high motility. The glycolytic pathway is shown to be a primary source of energy for human sperm motility.


Asunto(s)
Glucólisis , Pinzas Ópticas , Fosforilación Oxidativa , Motilidad Espermática/fisiología , Adenosina Trifosfato/metabolismo , Animales , Antimicina A/farmacología , Medios de Cultivo , Perros , Glucosa/farmacología , Glucólisis/efectos de los fármacos , Humanos , Masculino , Potencial de la Membrana Mitocondrial/efectos de los fármacos , Microscopía Fluorescente , Fosforilación Oxidativa/efectos de los fármacos , Rotenona/farmacología , Motilidad Espermática/efectos de los fármacos
13.
J Biomed Opt ; 13(1): 014002, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-18315360

RESUMEN

We combine laser tweezers with custom computer tracking software and robotics to analyze the motility [swimming speed, VCL (curvilinear velocity), and swimming force in terms of escape laser power (Pesc)] and energetics [mitochondrial membrane potential (MP)] of individual sperm. Domestic dog sperm are labeled with a cationic fluorescent probe, DiOC2(3), that reports the MP across the inner membrane of the mitochondria located in the sperm's midpiece. Individual sperm are tracked to calculate VCL. Pesc is measured by reducing the laser power after the sperm is trapped using laser tweezers until the sperm is capable of escaping the trap. The MP is measured every second over a 5-s interval during the tracking phase (sperm is swimming freely) and continuously during the trapping phase. The effect of the fluorescent probe on sperm motility is addressed. The sensitivity of the probe is measured by assessing the effects of a mitochondrial uncoupling agent (CCCP) on MP of free swimming sperm. The effects of prolonged exposed to the laser tweezers on VCL and MP are analyzed. The system's capabilities are demonstrated by measuring VCL, Pesc, and MP simultaneously for individual sperm. This combination of imaging tools is useful to quantitatively assess sperm quality and viability.


Asunto(s)
Separación Celular/instrumentación , Potencial de la Membrana Mitocondrial/fisiología , Pinzas Ópticas , Robótica/instrumentación , Motilidad Espermática/fisiología , Espermatozoides/fisiología , Animales , Separación Celular/métodos , Células Cultivadas , Perros , Diseño de Equipo , Análisis de Falla de Equipo , Masculino , Robótica/métodos
14.
J R Soc Interface ; 5(20): 297-302, 2008 Mar 06.
Artículo en Inglés | MEDLINE | ID: mdl-17650470

RESUMEN

Optical trapping is a non-invasive biophysical tool which has been widely applied to study physiological and biomechanical properties of cells. Using laser 'tweezers' in combination with custom-designed computer tracking algorithms, the swimming speeds and the relative swimming forces of individual sperm can be measured in real time. This combination of physical and engineering tools has been used to examine the evolutionary effect of sperm competition in primates. The results demonstrate a correlation between mating type and sperm motility: sperm from polygamous (multi-partner) primate species swim faster and with greater force than sperm from polygynous (single partner) primate species. In addition, sperm swimming force linearly increases with swimming speed for each species, yet the regression relating the two parameters is species specific. These results demonstrate the feasibility of using these tools to study rapidly moving (microm s(-1)) biological cells.


Asunto(s)
Algoritmos , Movimiento Celular/fisiología , Pinzas Ópticas , Primates/fisiología , Conducta Sexual Animal/fisiología , Espermatozoides/fisiología , Animales , Masculino , Análisis de Regresión , Espermatozoides/citología
15.
ACS Biomater Sci Eng ; 4(2): 587-594, 2018 Feb 12.
Artículo en Inglés | MEDLINE | ID: mdl-30555892

RESUMEN

Numerous processing techniques aim to impart interconnected, porous structures within regenerative medicine materials to support cell delivery and direct tissue growth. Many of these techniques lack predictable control of scaffold architecture, and rapid prototyping methods are often limited by time-consuming, layer-by-layer fabrication of micro-features. Bicontinuous interfacially jammed emulsion gels (bijels) offer a robust, self-assembly-based platform for synthesizing a new class of morphologically unique cell delivery biomaterials. Bijels form via kinetic arrest of temperature-driven spinodal decomposition in partially miscible binary liquid systems. These non-equilibrium soft materials are comprised of co-continuous, fully percolating, non-constricting liquid domains separated by a nanoparticle monolayer. Through the selective introduction of biocompatible precursors, hydrogel scaffolds displaying the morphological characteristics of the parent bijel can be formed. We report using bijel templating to generate structurally unique, fibrin-loaded polyethylene glycol hydrogel composites. Demonstration of composite bijel-templated hydrogels (CBiTHs) as a new cell delivery system was carried out in vitro using fluorescence-based tracking of cells delivered to previously acellular fibrin gels. Imaging analysis confirmed repeatable delivery of normal human dermal fibroblasts to acellular fibrin gels.

16.
Cancer Res ; 78(10): 2503-2512, 2018 05 15.
Artículo en Inglés | MEDLINE | ID: mdl-29535219

RESUMEN

Label-free nonlinear optical microscopy (NLOM) based on two-photon excited fluorescence (TPEF) from cofactors nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD+) is widely used for high-resolution cellular redox imaging. In this work, we combined three label-free NLOM imaging methods to quantitatively characterize breast cancer cells and their relative invasive potential: (i) TPEF optical redox ratio (ORR = FAD+/NADH + FAD+), (ii) coherent Raman scattering of cellular lipids, and (iii) second harmonic generation of extracellular matrix (ECM) collagen. 3D spheroid models of primary mammary epithelial (PME) cells and breast cancer cell lines (T47D and MDA-MB-231) were characterized based on their unique ORR and lipid volume fraction signatures. Treatment with 17ß-estradiol (E2) increased glycolysis in both PME and T47D ER+ breast cancer acini. However, PME cells displayed increased lipid content with no effect on ECM, while T47D cells had decreased lipid storage (P < 0.001) and significant reorganization of collagen. By measuring deuterated lipids synthesized from exogenously administered deuterium-labeled glucose, treatment of T47D cells with E2 increased both lipid synthesis and consumption rates. These results confirm that glucose is a significant source for the cellular synthesis of lipid in glycolytic breast cancer cells, and that the combination of cellular redox and lipid fraction imaging endpoints is a powerful approach with new and complementary information content.Significance: These findings provide unique insight into metabolic processes, revealing correlations between cancer metastasis and cellular redox state, lipid metabolism, and extracellular matrix. Cancer Res; 78(10); 2503-12. ©2018 AACR.


Asunto(s)
Neoplasias de la Mama/patología , Células Epiteliales/metabolismo , Matriz Extracelular/metabolismo , Glucosa/metabolismo , Glucólisis/fisiología , Metabolismo de los Lípidos/fisiología , Lípidos/fisiología , Microscopía Óptica no Lineal/métodos , Colágeno/metabolismo , Estradiol/farmacología , Femenino , Flavina-Adenina Dinucleótido/química , Glucólisis/efectos de los fármacos , Humanos , Lípidos/biosíntesis , NAD/química , Oxidación-Reducción , Esferoides Celulares , Células Tumorales Cultivadas
17.
Biomaterials ; 162: 99-108, 2018 04.
Artículo en Inglés | MEDLINE | ID: mdl-29438884

RESUMEN

Matrix stiffness is a well-established instructive cue in two-dimensional cell cultures. Its roles in morphogenesis in 3-dimensional (3D) cultures, and the converse effects of cells on the mechanics of their surrounding microenvironment, have been more elusive given the absence of suitable methods to quantify stiffness on a length-scale relevant for individual cell-extracellular matrix (ECM) interactions. In this study, we applied traditional bulk rheology and laser tweezers-based active microrheology to probe mechanics across length scales during the complex multicellular process of capillary morphogenesis in 3D, and further characterized the relative contributions of neovessels and supportive stromal cells to dynamic changes in stiffness over time. Our data show local ECM stiffness was highly heterogeneous around sprouting capillaries, and the variation progressively increased with time. Both endothelial cells and stromal support cells progressively stiffened the ECM, with the changes in bulk properties dominated by the latter. Interestingly, regions with high micro-stiffness did not necessarily correlate with remodeled regions of high ECM density as shown by confocal reflectance microscopy. Collectively, these findings, especially the large spatiotemporal variations in local stiffness around cells during morphogenesis in soft 3D fibrin gels, underscore that characterizing ECM mechanics across length scales. provides an opportunity to attain a deeper mechanobiological understanding of the microenvironment's roles in cell fate and tissue patterning.


Asunto(s)
Matriz Extracelular/química , Hidrogeles/química , Técnicas de Cultivo de Célula , Fibrina/química , Fibroblastos/citología , Humanos , Microscopía Confocal , Pinzas Ópticas
18.
Acta Biomater ; 47: 14-24, 2017 01 01.
Artículo en Inglés | MEDLINE | ID: mdl-27662809

RESUMEN

Fibrin is a major component of the provisional extracellular matrix formed during tissue repair following injury, and enables cell infiltration and anchoring at the wound site. Macrophages are dynamic regulators of this process, advancing and resolving inflammation in response to cues in their microenvironment. Although much is known about how soluble factors such as cytokines and chemokines regulate macrophage polarization, less is understood about how insoluble and adhesive cues, specifically the blood coagulation matrix fibrin, influence macrophage behavior. In this study, we observed that fibrin and its precursor fibrinogen elicit distinct macrophage functions. Culturing macrophages on fibrin gels fabricated by combining fibrinogen with thrombin stimulated secretion of the anti-inflammatory cytokine, interleukin-10 (IL-10). In contrast, exposure of macrophages to soluble fibrinogen stimulated high levels of inflammatory cytokine tumor necrosis factor alpha (TNF-α). Macrophages maintained their anti-inflammatory behavior when cultured on fibrin gels in the presence of soluble fibrinogen. In addition, adhesion to fibrin matrices inhibited TNF-α production in response to stimulation with LPS and IFN-γ, cytokines known to promote inflammatory macrophage polarization. Our data demonstrate that fibrin exerts a protective effect on macrophages, preventing inflammatory activation by stimuli including fibrinogen, LPS, and IFN-γ. Together, our study suggests that the presentation of fibrin(ogen) may be a key switch in regulating macrophage phenotype behavior, and this feature may provide a valuable immunomodulatory strategy for tissue healing and regeneration. STATEMENT OF SIGNIFICANCE: Fibrin is a fibrous protein resulting from blood clotting and provides a provisional matrix into which cells migrate and to which they adhere during wound healing. Macrophages play an important role in this process, and are needed for both advancing and resolving inflammation. We demonstrate that culture of macrophages on fibrin matrices exerts an anti-inflammatory effect, whereas the soluble precursor fibrinogen stimulates inflammatory activation. Moreover, culture on fibrin completely abrogates inflammatory signaling caused by fibrinogen or known inflammatory stimuli including LPS and IFN-γ. Together, these studies show that the presentation of fibrin(ogen) is important for regulating a switch between macrophage pro- and anti-inflammatory behavior.


Asunto(s)
Fibrina/farmacología , Fibrinógeno/farmacología , Inflamación/patología , Macrófagos/patología , Animales , Antiinflamatorios/metabolismo , Biomarcadores/metabolismo , Adhesión Celular/efectos de los fármacos , Polaridad Celular/efectos de los fármacos , Forma de la Célula/efectos de los fármacos , Colágeno/farmacología , Citocinas/metabolismo , Citoprotección/efectos de los fármacos , Citoesqueleto/efectos de los fármacos , Citoesqueleto/metabolismo , Femenino , Geles , Interferón gamma , Lipopolisacáridos , Activación de Macrófagos/efectos de los fármacos , Macrófagos/efectos de los fármacos , Ratones Endogámicos C57BL , Ratas
19.
J Tissue Eng ; 8: 2041731417691645, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-28228933

RESUMEN

Success of cell therapy in avascular sites will depend on providing sufficient blood supply to transplanted tissues. A popular strategy of providing blood supply is to embed cells within a functionalized hydrogel implanted within the host to stimulate neovascularization. However, hydrogel systems are not always amenable for removal post-transplantation; thus, it may be advantageous to implant a device that contains cells while also providing access to the circulation so retrieval is possible. Here we investigate one instance of providing access to a vessel network, a thin sheet with through-cut slits, and determine if it can be vascularized from autologous materials. We compared the effect of slit width on vascularization of a thin sheet following subcutaneous implantation into an animal model. Polydimethylsiloxane sheets with varying slit widths (approximately 150, 300, 500, or 1500 µm) were fabricated from three-dimensional printed molds. Subcutaneous implantation of sheets in immunodeficient mice revealed that smaller slit widths have evidence of angiogenesis and new tissue growth, while larger slit widths contain native mature tissue squeezing into the space. Our results show that engineered slit sheets may provide a simple approach to cell transplantation by providing a prevascularized and innervated environment.

20.
Biomaterials ; 116: 118-129, 2017 02.
Artículo en Inglés | MEDLINE | ID: mdl-27914984

RESUMEN

Extracellular matrix (ECM) is an essential and dynamic component of all tissues and directly affects cellular behavior by providing both mechanical and biochemical signaling cues. Changes in ECM can alter tissue homeostasis, potentially leading to promotion of cellular transformation and the generation of tumors. Therefore, understanding ECM compositional changes during cancer progression is vital to the development of targeted treatments. Previous efforts to reproduce the native 3D cellular microenvironment have utilized protein gels and scaffolds that incompletely recapitulate the complexity of native tissues. Here, we address this problem by extracting and comparing ECM from normal human colon and colon tumor that had metastasized to liver. We found differences in protein composition and stiffness, and observed significant differences in vascular network formation and tumor growth in each of the reconstituted matrices, both in vitro and in vivo. We studied free/bound ratios of NADH in the tumor and endothelial cells using Fluorescence Lifetime Imaging Microscopy as a surrogate for the metabolic state of the cells. We observed that cells seeded in tumor ECM had higher relative levels of free NADH, consistent with a higher glycolytic rate, than those seeded in normal ECM. These results demonstrate that the ECM plays an important role in the growth of cancer cells and their associated vasculature.


Asunto(s)
Neoplasias del Colon/patología , Neoplasias del Colon/fisiopatología , Matriz Extracelular/metabolismo , Matriz Extracelular/patología , Neovascularización Patológica/patología , Neovascularización Patológica/fisiopatología , Microambiente Tumoral , Proliferación Celular , Neoplasias del Colon/irrigación sanguínea , Humanos , Células Tumorales Cultivadas
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