Gotta catch 'em all: the microscale quest to understand cancer biology

Developing an improved understanding of the processes that drive cancer initiation and progression has been the focus of intense research in recent years. Here, we highlight recent advances in the innovative use of microscale engineered technologies to gain new insight into the integrative biophysical mechanisms that drive these processes.

Stem cells: to be born great, achieve greatness, or have greatness thrust upon them?

Induced pluripotent stem cells (iPSCs) have opened new doors in providing an ethical, patient-specific cell source towards tissue engineering. Developing these therapies involves the production of reprogrammed iPSCs, expanding them while maintaining pluripotency, then differentiating them into functional tissues. To bring these therapies to the clinic, efficient and GMP-compliant manufacturing methods are required. In this Research Highlight, we describe recent innovations to several aspects of the pluripotent cell therapy pipeline.

Next generation tools to accelerate the synthetic biology process

Synthetic biology follows the traditional engineering paradigm of designing, building, testing and learning to create new biological systems. While such approaches have enormous potential, major challenges still exist in this field including increasing the speed at which this workflow can be performed. Here, we present recently developed microfluidic tools that can be used to automate the synthetic biology workflow with the goal of advancing the likelihood of producing desired functionalities. With the potential for programmability, automation, and robustness, the integration of microfluidics and synthetic biology has the potential to accelerate advances in areas such as bioenergy, health, and biomaterials.

Getting there is half the battle: recent advances in delivering therapeutics

Delivery of therapeutic molecules at the right time, place and at the correct dosage is critical to improve the effectiveness of therapeutic regimens. Barriers in the body, normally needed to maintain function, often impede delivery of therapeutic payloads to their target areas. Designing innovative solutions to circumvent these environmental factors, and ensure the timely delivery of therapeutic doses, is an essential element in improving human health. Here we highlight recent studies that focus on bypassing different barriers crucial for improving therapeutic delivery, by temporarily modifying the in vivo microenvironment, re-designing therapeutic carrier vehicles to improve control characteristics and on-demand delivery, and developing convenience-based strategies to improve patient compliance and access to therapeutics.

Making it stick: the role of structural design in implantable technologies

Designing technologies that work within the human body requires innovation at the interface of biology, engineering, and material sciences. The human body presents a surprisingly hostile environment towards technologies designed to improve health, and recent approaches to these problems have leveraged the links between material form and function to improve implantable systems. The use of physical structure has emerged as a key design parameter in developing these systems, and has recently been applied to make significant progress in the field. Here, we highlight recent studies that demonstrate the innovative use of structure in the design of technologies meant to operate within the human body, with a specific focus on improving their biointegration, delivery, and functionality.

Patients are a virtue: advances in microengineered systems for clinical applications

Microscale technologies have been widely used in modern biology over the last decade, and have promised to revolutionize life sciences and biomedicine. However, the majority of microdevices developed to date have largely remained in the laboratory, with only a small fraction being applied in the field or clinic where their true impact on human health is best evaluated. Recently, microscale technologies have seen a rise in usage in applications with a clinical focus, indicating growing interest in this research direction. Here, we highlight the latest developments in microscale technologies designed specifically to handle, interrogate, and analyze human clinical samples for diagnostics and other applications.

Live long and prosper: the enterprise of understanding diseased epithelium

The epithelium is a particularly complicated and dynamic tissue, and dysregulation of epithelial structure and function is a hallmark of several lung diseases. Motivated by the life and recent passing of Leonard Nimoy, we highlight several recent studies that explore the nuanced relationship between the epithelium and disease progression. Specifically, we focus on recent innovative and integrative approaches that shed new light on epithelial wounding, healing, and development.

A follow-up study of the chronic kidney disease patients treated with Brazil nut: focus on inflammation and oxidative stress

Brazil nut is the richest known food source of selenium. The supplementation with Brazil nut during 3 months was effective in reducing oxidative stress and inflammation in hemodialysis (HD) patients. However, there are no available data on the antioxidant effect after that supplementation. The objective of this work was to determine if the beneficial effects of one Brazil nut supplementation per day during 3 months for the HD patients could be sustained after 12 months. Twenty-nine HD patients (58.6 % men, 51.0 ± 3.3 years) from RenalCor Clinic, Rio de Janeiro, Brazil, were followed up 12 months after the supplementation study had finished. The plasma levels of antioxidant substances as selenium, glutathione peroxidase (GPx), 8-isoprostane, 8-hydroxy-2-deoxyguanosine (8-OHdG) and cytokines (tumour necrosis factor alpha (TNF-α) and interleukin-6 (IL-6)) were determined before, after 3 months of supplementation and after 12 months. After 3-months supplementation, cytokines, 8-OHdG and 8-isoprostane plasma levels have decreased and the activity of GPx and selenium plasma levels have increased significantly. Additionally, after 12 months, the values of 8-isoprostane, 8-OHdG and cytokines increased and the activity of GPx and selenium plasma levels decreased significantly. The levels of oxidative stress and inflammation biomarkers after 12 months increased compared to the basal levels. Consequently, it is necessary to motivate patients to adopt different dietary intake patterns.

Surface-templated hydrogel patterns prompt matrix-dependent migration of breast cancer cells towards chemokine-secreting cells

This paper describes a novel technique for fabricating spatially defined cell-laden collagen hydrogels, using patterned, non-adhesive polyacrylamide-coated polydimethylsiloxane (PDMS) surfaces as a template. Precisely patterned embedded co-cultures of breast cancer cells and chemokine-producing cells generated with this technique revealed matrix-dependent and chemokine isoform-dependent migration of cancer cells. CXCL12 chemokine-secreting cells induce significantly more chemotaxis of cancer cells when the 3-D extracellular matrix (ECM) includes components that bind the secreted CXCL12 chemokines. Experimental observations using cells that secrete CXCL12 isoforms with different matrix affinities together with computational simulations show that stronger ligand-matrix interactions sharpen chemoattractant gradients, leading to increased chemotaxis of the CXCL12 gradient-sensing CXCR4 receptor-expressing (CXCR4+) cells patterned in the hydrogel. These results extend our recent report on CXCL12 isoform-dependent chemotaxis studies from 2-D to 3-D environments and additionally reveal the important role of ECM composition. The developed technology is simple, versatile and robust; and as chemoattractant-matrix interactions are common, the methods described here should be broadly applicable for study of physiological migration of many different cell types in response to a variety of chemoattractants.

Between a rock and a soft place: recent progress in understanding matrix mechanics

The mechanical properties of a cell's surrounding environment play a critical role in modulating cell function. We highlight recent advances in novel technologies, material design strategies, and bioanalytical approaches that have shed new light on the complex interplay between materials, mechanics and biological function.

The Discovery Channel: microfluidics and microengineered systems in drug screening

We highlight exciting findings and promising approaches in the recent literature in which researchers integrate advanced micro-engineering, design, and analytical strategies to improve the relevance and utility of high-throughput screening in the drug discovery pipeline.

Supersoft lithography: candy-based fabrication of soft silicone microstructures

We designed a fabrication technique able to replicate microstructures in soft silicone materials (E < 1 kPa). Sugar-based 'hard candy' recipes from the confectionery industry were modified to be compatible with silicone processing conditions, and used as templates for replica molding. Microstructures fabricated in soft silicones can then be easily released by dissolving the template in water. We anticipate that this technique will be of particular importance in replicating physiologically soft, microstructured environments for cell culture, and demonstrate a first application in which intrinsically soft microstructures are used to measure forces generated by fibroblast-laden contractile tissues.

Media additives to promote spheroid circularity and compactness in hanging drop platform

Three-dimensional spheroid cultures have become increasingly popular as drug screening platforms, especially with the advent of different high throughput spheroid forming technologies.

Micro, soft, windows: integrating super-resolution viewing capabilities into soft lithographic devices

Microengineered cell culture environments afford experimentalists with the critical ability to study cells in precisely-defined, yet physiologically-realistic environments. A significant, but often overlooked, feature of these technologies is the unique ability to optically probe cellular and sub-cellular processes during culture in these complex environments, thereby obtaining information that would not be possible via conventional techniques. Motivated by the recent presentation of the Nobel prizes for super-resolution imaging and more recent technological breakthroughs in lattice-based light sheet microscopy, in this research highlight we survey recent innovations in the design of microfluidic cell culture platforms, that will ultimately allow experimentalists to probe biological activity with high-spatial and temporal-resolution. These advances will provide new technology-driven windows into biological processes and mechanisms.

Microscale 3D collagen cell culture assays in conventional flat-bottom 384-well plates

Three-dimensional (3D) culture systems such as cell-laden hydrogels are superior to standard two-dimensional (2D) monolayer cultures for many drug-screening applications. However, their adoption into high-throughput screening (HTS) has been lagging, in part because of the difficulty of incorporating these culture formats into existing robotic liquid handling and imaging infrastructures. Dispensing cell-laden prepolymer solutions into 2D well plates is a potential solution but typically requires large volumes of reagents to avoid evaporation during polymerization, which (1) increases costs, (2) makes drug penetration variable and (3) complicates imaging. Here we describe a technique to efficiently produce 3D microgels using automated liquid-handling systems and standard, nonpatterned, flat-bottomed, 384-well plates. Sub-millimeter-diameter, cell-laden collagen gels are deposited on the bottom of a ~2.5 mm diameter microwell with no concerns about evaporation or meniscus effects at the edges of wells, using aqueous two-phase system patterning. The microscale cell-laden collagen-gel constructs are readily imaged and readily penetrated by drugs. The cytotoxicity of chemotherapeutics was monitored by bioluminescence and demonstrated that 3D cultures confer chemoresistance as compared with similar 2D cultures. Hence, these data demonstrate the importance of culturing cells in 3D to obtain realistic cellular responses. Overall, this system provides a simple and inexpensive method for integrating 3D culture capability into existing HTS infrastructure.

Fracture-based fabrication of normally closed, adjustable, and fully reversible microscale fluidic channels

Adjustable fluidic structures play an important role in microfluidic systems. Fracture of multilayered materials under applied tension has been previously demonstrated as a convenient, simple, and inexpensive approach to fabricate nanoscale adjustable structures; here, it is demonstrated how to extend this concept to the microscale. This is achieved by a novel pairing of materials that leverages fracture mechanics to limit crack formation to a specified region, allowing to create size-controllable and adjustable microfluidic structures. This technique can be used to fabricate "normally closed" microfluidic channels that are completely reversible, a feature that is challenging to achieve in conventional systems without careful engineering controls. The adjustable microfluidic channels are then applied to mechanically lyse single cells, and subsequently manipulate the released nuclear chromatin, creating new possibilities for epigenetic analysis of single cells. This simple, versatile, and robust technology provides an easily accessible pathway to construct adjustable microfluidic structures, which will be useful in developing complex assays and experiments even in resource-limited settings.

Defined topologically-complex protein matrices to manipulate cell shape via three-dimensional fiber-like patterns

Culturing cells in three-dimensional (3D) environments has been shown to significantly influence cell function, and may provide a more physiologically relevant environment within which to study the behavior of specific cell types. 3D tissues typically present a topologically complex fibrous adhesive environment, which is technically challenging to replicate in a controlled manner. Micropatterning technologies have provided significant insights into cell-biomaterial interactions, and can be used to create fiber-like adhesive structures, but are typically limited to flat culture systems; the methods are difficult to apply to topologically-complex surfaces. In this work, we utilize crack formation in multilayered microfabricated materials under applied strain to rapidly generate well-controlled and topologically complex 'fiber-like' adhesive protein patterns, capable of supporting cell culture and controlling cell shape on three-dimensional patterns. We first demonstrate that the features of the generated adhesive environments such as width, spacing and topology can be controlled, and that these factors influence cell morphology. The patterning technique is then applied to examine the influence of fiber structure on the nuclear morphology and actin cytoskeletal structure of cells cultured in a nanofibrous biomaterial matrix.

One-dimensional patterning of cells in silicone wells via compression-induced fracture

We have adapted our existing compression-induced fracture technology to cell culture studies by generating linear patterns on a complex cell culture well structure rather than on simple solid constructs. We present a simple method to create one-dimensional (1D), submicron, and linear patterns of extracellular matrix on a multilayer silicone material. We identified critical design parameters necessary to optimize compression-induced fracture patterning on the wells, and applied stresses using compression Hoffman clamps. Finite-element analyses show that the incorporation of the well improves stress homogeneity (stress variation = 25%), and, thus, crack uniformity over the patterned region. Notably, a shallow well with a thick base (vs. deeper wells with thinner bases) reduces out-of-plane deflections by greater than a sixth in the cell culture region, improving clarity for optical imaging. The comparison of cellular and nuclear shape indices of a neuroblast line cultured on patterned 1D lines and unpatterned 2D surfaces reveals significant differences in cellular morphology, which could impact many cellular functions. Because 1D cell cultures recapitulate many important phenotypical traits of 3D cell cultures, our culture system offers a simple means to further study the relationship between 1D and 3D cell culture environments, without demanding expensive engineering techniques and expertise.

On being the right size: scaling effects in designing a human-on-a-chip

Developing a human-on-a-chip by connecting multiple model organ systems would provide an intermediate screen for therapeutic efficacy and toxic side effects of drugs prior to conducting expensive clinical trials. However, correctly designing individual organs and scaling them relative to each other to make a functional microscale human analog is challenging, and a generalized approach has yet to be identified. In this work, we demonstrate the importance of rational design of both the individual organ and its relationship with other organs, using a simple two-compartment system simulating insulin-dependent glucose uptake in adipose tissues. We demonstrate that inter-organ scaling laws depend on both the number of cells and the spatial arrangement of those cells within the microfabricated construct. We then propose a simple and novel inter-organ 'metabolically supported functional scaling' approach predicated on maintaining in vivo cellular basal metabolic rates by limiting resources available to cells on the chip. This approach leverages findings from allometric scaling models in mammals that limited resources in vivo prompt cells to behave differently than in resource-rich in vitro cultures. Although applying scaling laws directly to tissues can result in systems that would be quite challenging to implement, engineering workarounds may be used to circumvent these scaling issues. Specific workarounds discussed include the limited oxygen carrying capacity of cell culture media when used as a blood substitute and the ability to engineer non-physiological structures to augment organ function, to create the transport-accessible, yet resource-limited environment necessary for cells to mimic in vivo functionality. Furthermore, designing the structure of individual tissues in each organ compartment may be a useful strategy to bypass scaling concerns at the inter-organ level.

Fracture-based micro- and nanofabrication for biological applications

While fracture is generally considered to be undesirable in various manufacturing processes, delicate control of fracture can be successfully implemented to generate structures at micro/nano length scales. Fracture-based fabrication techniques can serve as a template-free manufacturing method, and enables highly-ordered patterns or fluidic channels to be formed over large areas in a simple and cost-effective manner. Such technologies can be leveraged to address biologically-relevant problems, such as in the analysis of biomolecules or in the design of culture systems that imitate the cellular or molecular environment. This mini review provides an overview of current fracture-guided fabrication techniques and their biological applications. We first survey the mechanical principles of fracture-based approaches. Then we describe biological applications at the cellular and molecular levels. Finally, we discuss unique advantages of the different system for biological studies.

Resistance exercise training does not affect plasma irisin levels of hemodialysis patients

Irisin, a hormone secreted by myocytes induced in exercise, acts as a muscle-derived energy-expenditure signal that binds to undetermined receptors on the white adipose tissue surface, stimulating its browning and uncoupling protein 1 (UCP1) expression. The purpose of this study was to assess the effect of an intradialytic resistance exercise training program (RETP) on plasma irisin levels of hemodialysis (HD) patients and compare the baseline plasma irisin levels of HD patients to healthy subjects. This longitudinal study enrolled 26 patients undergoing HD (50% men, 44.8±14.1 years, body mass index (BMI) 23.5±3.9 kg/m²). The healthy subjects group consisted of 11 women and 7 men with mean age of 50.9±6.6 years and BMI, 24.2±2.7 kg/m². Anthropometric and biochemistry parameters (Irisin by Enzyme-Linked Immunosorbent Assay) were measured at the baseline and after 6 months of RETP (in both lower limbs). There was no difference regarding gender, age, and BMI between HD patients and healthy subjects. Plasma irisin levels in HD patients were lower than in healthy subjects (71.0±41.6 vs. 101.3±12.5 ng/ml, p<0.05). Although the muscle mass increased in consequence of exercise [evaluated by arm muscle area from 27.9 (24.1) to 33.1 (19.0) cm²], plasma irisin did not differ significantly after exercises (71.0±41.6 vs. 73.3±36.0 ng/ml). HD patients seem to have lower plasma irisin when compared to healthy subjects. Moreover, a resistance exercise training program was unable to augment plasma irisin despite increasing muscle mass.

Guided fracture of films on soft substrates to create micro/nano-feature arrays with controlled periodicity

While the formation of cracks is often stochastic and considered undesirable, controlled fracture would enable rapid and low cost manufacture of micro/nanostructures. Here, we report a propagation-controlled technique to guide fracture of thin films supported on soft substrates to create crack arrays with highly controlled periodicity. Precision crack patterns are obtained by the use of strategically positioned stress-focusing V-notch features under conditions of slow application of strain to a degree where the notch features and intrinsic crack spacing match. This simple but robust approach provides a variety of precisely spaced crack arrays on both flat and curved surfaces. The general principles are applicable to a wide variety of multi-layered materials systems because the method does not require the careful control of defects associated with initiation-controlled approaches. There are also no intrinsic limitations on the area over which such patterning can be performed opening the way for large area micro/nano-manufacturing.

Microdevice array-based identification of distinct mechanobiological response profiles in layer-specific valve interstitial cells

Aortic valve homeostasis is mediated by valvular interstitial cells (VICs) found in spatially distinct and mechanically dynamic layers of the valve leaflet. Disease progression is associated with the pathological differentiation of VICs to myofibroblasts, but the mechanobiological response profiles of cells specific to different layers in the leaflet remains undefined. Conventional mechanically dynamic macroscale culture technologies require a large number of cells per set of environmental conditions. However, large scale expansion of primary VICs in vitro does not maintain in vivo phenotypes, and hence conventional macroscale techniques are not well-suited to systematically probe response of these cell types to combinatorially manipulated mechanobiological cues. To address this issue, we developed a microfabricated composite material screening array to determine the combined effects of dynamic substrate stretch, soluble cues and matrix proteins on small populations of primary cells. We applied this system to study VICs isolated from distinct layers of the valve leaflet and determined that (1) mechanical stability and cellular adhesion to the engineered composite materials were significantly improved as compared to conventional stretching technologies; (2) VICs demonstrate layer-specific mechanobiological profiles; and (3) mechanical stimulation, matrix proteins and soluble cues produce integrated and distinct responses in layer-specific VIC populations. Strikingly, myofibroblast differentiation was most significantly influenced by cell origin, despite the presence of potent mechanobiological cues such as applied strain and TGF-β1. These results demonstrate that spatially-distinct VIC subpopulations respond differentially to microenvironmental cues, with implications for valve tissue engineering and pathobiology. The developed platform enables rapid identification of biological phenomena arising from systematically manipulating the cellular microenvironment, and may be of utility in screening mechanosensitive cell cultures with applications in drug screening, tissue engineering and fundamental cell biology.

Aqueous two-phase printing of cell-containing contractile collagen microgels

This work describes the use of aqueous two-phase systems to print cell-containing contractile collagen microdroplets. The fully aqueous conditions enable convenient formation of sub-microliter 'microgels' that are much smaller than otherwise possible to fabricate while maintaining high cell viability. The produced microgels contract over several days, mimicking the behavior of macroscale contraction assays, which have been valued as an important biological readout for over three decades. Use of microgels not only reduces reagent consumption and increases throughput of the assay, but also improves transport of molecules into and out of the collagen matrix, thereby enabling efficient and more precise studies of timed stimulation profiles. Utility of the technology is demonstrated by analyzing the effects of TGF-β1 on gel contraction, and we demonstrate that brief 'burst' stimulation profiles in microgels prompt contraction of the matrix, a feature not observed in the conventional macroscale assay. The fully aqueous process also enables the integration of contractile collagen microgels within existing cell culture systems, and we demonstrate proof-of-principle experiments in which a contractile collagen droplet is fabricated in situ on an existing epithelial monolayer. The simplicity, versatility and ability to robustly produce collagen microgels should allow effective translation of this microengineering technology into a variety of research environments.

Micro- and nanofluidic technologies for epigenetic profiling

This short review provides an overview of the impact micro- and nanotechnologies can make in studying epigenetic structures. The importance of mapping histone modifications on chromatin prompts us to highlight the complexities and challenges associated with histone mapping, as compared to DNA sequencing. First, the histone code comprised over 30 variations, compared to 4 nucleotides for DNA. Second, whereas DNA can be amplified using polymerase chain reaction, chromatin cannot be amplified, creating challenges in obtaining sufficient material for analysis. Third, while every person has only a single genome, there exist multiple epigenomes in cells of different types and origins. Finally, we summarize existing technologies for performing these types of analyses. Although there are still relatively few examples of micro- and nanofluidic technologies for chromatin analysis, the unique advantages of using such technologies to address inherent challenges in epigenetic studies, such as limited sample material, complex readouts, and the need for high-content screens, make this an area of significant growth and opportunity.

Organs-on-a-chip: a focus on compartmentalized microdevices

Advances in microengineering technologies have enabled a variety of insights into biomedical sciences that would not have been possible with conventional techniques. Engineering microenvironments that simulate in vivo organ systems may provide critical insight into the cellular basis for pathophysiologies, development, and homeostasis in various organs, while curtailing the high experimental costs and complexities associated with in vivo studies. In this article, we aim to survey recent attempts to extend tissue-engineered platforms toward simulating organ structure and function, and discuss the various approaches and technologies utilized in these systems. We specifically focus on microtechnologies that exploit phenomena associated with compartmentalization to create model culture systems that better represent the in vivo organ microenvironment.

(Micro)managing the mechanical microenvironment

Mechanical forces are critical components of the cellular microenvironment and play a pivotal role in driving cellular processes in vivo. Dissecting cellular responses to mechanical forces is challenging, as even "simple" mechanical stimulation in vitro can cause multiple interdependent changes in the cellular microenvironment. These stimuli include solid deformation, fluid flows, altered physical and chemical surface features, and a complex transfer of loads between the various interacting components of a biological culture system. The active mechanical and biochemical responses of cells to these stimuli in generating internal forces, reorganizing cellular structures, and initiating intracellular signals that specify cell fate and remodel the surrounding environment further complicates cellular response to mechanical forces. Moreover, cells present a non-linear response to combinations of mechanical forces, materials, chemicals, surface features, matrix properties and other effectors. Microtechnology-based approaches to these challenges can yield key insights into the mechanical nature of cellular behaviour, by decoupling stimulation parameters; enabling multimodal control over combinations of stimuli; and increasing experimental throughput to systematically probe cellular response. In this critical review, we briefly discuss the complexities inherent in the mechanical stimulation of cells; survey and critically assess the applications of present microtechnologies in the field of experimental mechanobiology; and explore opportunities and possibilities to use these tools to obtain a deeper understanding of mechanical interactions between cells and their environment.

Microfabricated platforms for mechanically dynamic cell culture

The ability to systematically probe in vitro cellular response to combinations of mechanobiological stimuli for tissue engineering, drug discovery or fundamental cell biology studies is limited by current bioreactor technologies, which cannot simultaneously apply a variety of mechanical stimuli to cultured cells. In order to address this issue, we have developed a series of microfabricated platforms designed to screen for the effects of mechanical stimuli in a high-throughput format. In this protocol, we demonstrate the fabrication of a microactuator array of vertically displaced posts on which the technology is based, and further demonstrate how this base technology can be modified to conduct high-throughput mechanically dynamic cell culture in both two-dimensional and three-dimensional culture paradigms.

Single cell deposition and patterning with a robotic system

Integrating single-cell manipulation techniques in traditional and emerging biological culture systems is challenging. Microfabricated devices for single cell studies in particular often require cells to be spatially positioned at specific culture sites on the device surface. This paper presents a robotic micromanipulation system for pick-and-place positioning of single cells. By integrating computer vision and motion control algorithms, the system visually tracks a cell in real time and controls multiple positioning devices simultaneously to accurately pick up a single cell, transfer it to a desired substrate, and deposit it at a specified location. A traditional glass micropipette is used, and whole- and partial-cell aspiration techniques are investigated to manipulate single cells. Partially aspirating cells resulted in an operation speed of 15 seconds per cell and a 95% success rate. In contrast, the whole-cell aspiration method required 30 seconds per cell and achieved a success rate of 80%. The broad applicability of this robotic manipulation technique is demonstrated using multiple cell types on traditional substrates and on open-top microfabricated devices, without requiring modifications to device designs. Furthermore, we used this serial deposition process in conjunction with an established parallel cell manipulation technique to improve the efficiency of single cell capture from ∼80% to 100%. Using a robotic micromanipulation system to position single cells on a substrate is demonstrated as an effective stand-alone or bolstering technology for single-cell studies, eliminating some of the drawbacks associated with standard single-cell handling and manipulation techniques.

Morfologia e histologia do oviduto de marrecas Ana boschas

Avaliaram-se o comprimento do infundíbulo, do magno, do istmo, do útero e da vagina e o número de pregas do magno e do istmo do oviduto de 20 marrecas Ana boschas na fase reprodutiva. O infundíbulo apresenta mucosa com pregas longitudinais e baixas, revestidas por epitélio pseudoestratificado cilíndrico ciliado, com células caliciformes. O magno, compartimento mais longo do oviduto, 25,38cm±3,20, encontra-se constituído por uma camada mucosa com pregas altas e espessas revestidas por células cilíndricas ciliadas e abundantes células caliciformes. O istmo é formado por uma mucosa com pregas estreitas e curtas e numerosas glândulas tubulares que se estendem para o interior da lâmina própria. O útero, região curta do oviduto, 5,25cm±1,26, apresenta parede com pregas e cristas baixas e numerosas glândulas tubulares enoveladas, dirigidas para o interior da lâmina própria. A vagina, um estreito tubo muscular, está constituído por oito anéis circulares, em média, e uma camada muscular altamente desenvolvida e espessa. A morfologia do oviduto da marreca apresenta características morfológicas e histológicas distintas dos galiniformes, observando-se que a vagina e a porção cranial do infundíbulo apresentam pregas e células caliciformes, respectivamente, sendo estas últimas estruturas ausentes nos galiniformes.

Microfabricated arrays for high-throughput screening of cellular response to cyclic substrate deformation

Mechanical forces play an important role in regulating cellular function and have been shown to modulate cellular response to other factors in the cellular microenvironment. Presently, no technique exists to rapidly screen for the effects of a range of uniform mechanical forces on cellular function. In this work, we developed and characterized a novel microfabricated array capable of simultaneously applying cyclic equibiaxial substrate strains ranging in magnitude from 2 to 15% to small populations of adherent cells. The array is versatile, and capable of simultaneously generating a range of substrate strain fields and magnitudes. The design can be extended to combinatorially manipulate other mechanobiological culture parameters in the cellular microenvironment. As a first demonstration of this technology, the array was used to determine the effects of equibiaxial mechanical strain on activation of the canonical Wnt/beta-catenin signaling pathway in cardiac valve mesenchymal progenitor cells. This high-throughput approach to mechanobiological screening enabled the identification of a novel co-dependence between strain magnitude and duration of stimulation in controlling beta-catenin nuclear accumulation. More generally, this versatile platform has broad applicability in the fields of mechanobiology, tissue engineering and pathobiology.

Integrating polyurethane culture substrates into poly(dimethylsiloxane) microdevices

Poly(dimethylsiloxane) (PDMS)-based microdevices have enabled rapid, high-throughput assessment of cellular response to precisely controlled microenvironmental stimuli, including chemical, matrix and mechanical factors. However, the use of PDMS as a culture substrate precludes long-term culture and may significantly impact cell response. Here we describe a method to integrate polyurethane (PU), a well-studied and clinically relevant biomaterial, into the PDMS multilayer microfabrication process, enabling the exploration of long-term cellular response on alternative substrates in microdevices. To demonstrate the utility of these hybrid microdevices for cell culture, we compared initial cell adhesion, cell spreading, and maintenance of protein patterns on PU and PDMS substrates. Initial cell adhesion and cell spreading after three days were comparable between collagen-coated PDMS and PU substrates (with or without collagen coating), but significantly lower on native PDMS substrates. However, for longer culture durations (> or = 6 days), cell spreading and protein adhesion on PU substrates was significantly better than that on PDMS substrates, and comparable to that on tissue culture-treated polystyrene. Thus, the use of a generic polyurethane substrate in microdevices enables longer-term cell culture than is possible with PDMS substrates. More generally, this technique can improve the impact and applicability of microdevice-based research by facilitating the use of alternate, relevant biomaterials while maintaining the advantages of using PDMS for microdevice fabrication.

Direct-test PCR for detection of meningococcal DNA and its serogroup characterization: standardization and adaptation for use in a public health laboratory

A direct PCR test (DT-PCR) was established to detect Neisseria meningitidis DNA in clinical samples from patients with suspected bacterial meningitis. Specific primers for the 16S rDNA of N. meningitidis were designed to amplify a 600 bp DNA fragment. One hundred and ninety-three clinical samples were analysed, corresponding to 114 samples from patients diagnosed as positive and 79 as negative for infection by N. meningitidis using conventional methods (culture, latex agglutination and counterimmunoelectrophoresis). These samples were submitted to PCR by two different clinical sample preparation approaches (with and without DNA extraction and purification) and submitted to different PCR protocols to improve the results. In agarose gel detection, the sensitivity value for DT-PCR was 88.5 % and, using dot-blot DNA detection, the sensitivity increased to 96.4 %. The detection limit for meningococcus in cerebrospinal fluid was 2x10(2) c.f.u. ml(-1). Serogroup prediction was done using a multiplex PCR protocol and the sensitivity was 83 % for agarose gel DNA detection and 96.4 % using dot-blot DNA detection.

Detection of protein S deficiency: a new functional assay compared to an antigenic technique

Congenital protein S (PS) deficiency is associated with increased risk of venous thrombosis. To investigate the possibility of automating PS testing with decreased turnaround time, a clotting-based functional protein S assay was evaluated and compared to an antigenic method. Samples were collected from 126 patients within 5 days of their first acute cerebral infarction, from 62 controls and from 47 consecutive samples for thrombophilia investigation. The normal range for the clotting-based kit, calculated from the results of 20 healthy controls, was 62-136% (mean +/- 2 SD). Intra- and inter-assay co-efficients of variation were < 3.0 and 10.0% respectively. There was no significant correlation between the two methods (r = 0.30, P > 0.05). Two patients had low PS antigen results with normal functional levels. Both techniques were used to compare a further group of 53 patients with defined abnormalities which included nine antigenic protein S deficiencies, five protein C deficient patients, 10 patients with a lupus anticoagulant (LA), 17 Factor V Leiden (FVL) heterozygotes, two FVL homozygotes and 10 patients on therapeutic levels of heparin. In this group we found that four of nine antigenic PS deficient patients had normal functional PS levels. The test was susceptible to the FVL mutation with four of 17 FVL heterozygotes and both of two FVL homozygotes giving low levels. One of five protein C-deficient patients also had a low functional PS result with a normal antigenic level. Normal results were obtained by both methods for all of the LA and patients on therapeutic heparin. We concluded that the automated protein S clotting assay was rapid and simple to perform but appeared to be influenced by factors other than PS deficiency. Results need to be interpreted with caution but may be useful as part of a full thrombophilia investigation.

Cloning and sequencing the Lactobacillus brevis gene encoding xylose isomerase

The gene (xylA) coding for the Lactobacillus brevis xylose isomerase (Xi) has been isolated and its complete nucleotide sequence determined. L. brevis Xi was purified and the N-terminal sequence determined. All attempts to directly clone the intact xylA using a degenerative primer deduced from amino acids (aa) 10-14 were not successful. A fragment coding for the first 462 bp from the 5' end of xylA was isolated by PCR with two primers, one coding for aa M36 to W43 and the second coding for an aa sequence (WGGREG) conserved in a number of Xi's isolated from other bacteria. From the sequence of this fragment, two additional PCR primers were synthesized, which were used in an 'outward' reaction to clone a 546-bp fragment including a region upstream from the N terminus. Finally, the complete xylA gene was cloned in a 0.43-kb NlaIII-SalI fragment and a 1.9-kb SalI-EcoRI fragment. The 449-aa sequence for the L. brevis Xi shows homology with Xis isolated from other bacteria, especially within the primary catalytic domains of the enzyme.

[Coronary transluminal angioplasty after the use of thrombolytic therapy in acute myocardial infarction]

PURPOSE

To present the Cardiology Institute of Rio Grande do Sul experience with percutaneous coronary angioplasty (PTCA), after thrombolytic therapy in acute myocardial infarction (AMI).

METHODS

Fifty-three patients with transmural AMI in whom early successful intravenous streptokinase recanalization was followed by PTCA. The mean age was 50 years, male patients were more frequent, the predominant area of infarct was anterior wall and more frequently the "culprit" coronary was the left anterior descendent. The main indication of PTCA was uniarterial lesion with less than 20 mm of length.

RESULTS

The success comes out in 44 patients (81.5%). Ten patients (18.5%) were considered unsuccessful and were referred to emergency bypass graft surgery. The in-hospital AMI rate after PTCA was 5.5%. In the follow-up the reestenoses rate was 11% and reocclusion was 3.7%. New PTCA was necessary in 3 patients (5.5%) and in one, by-pass graft (1.8%).

CONCLUSIONS

PTCA is an important and secure modality of complementary therapy after thrombolytic therapy with low morbidity and mortality.