1,721,047 research outputs found
Liver–Heart on chip models for drug safety
Full text linkCurrent pre-clinical models to evaluate drug safety during the drug development process (DDP) mainly rely on traditional two-dimensional cell cultures, considered too simplistic and often ineffective, or animal experimentations, which are costly, time-consuming, and not truly representative of human responses. Their clinical translation thus remains limited, eventually causing attrition and leading to high rates of failure during clinical trials. These drawbacks can be overcome by the recently developed Organs-on-Chip (OoC) technology. OoC are sophisticated in vitro systems capable of recapitulating pivotal architecture and functionalities of human organs. OoC are receiving increasing attention from the stakeholders of the DDP, particularly concerning drug screening and safety applications. When a drug is administered in the human body, it is metabolized by the liver and the resulting compound may cause unpredicted toxicity on off-target organs such as the heart. In this sense, several liver and heart models have been widely adopted to assess the toxicity of new or recalled drugs. Recent advances in OoC technology are making available platforms encompassing multiple organs fluidically connected to efficiently assess and predict the systemic effects of compounds. Such Multi-Organs-on-Chip (MOoC) platforms represent a disruptive solution to study drug-related effects, which results particularly useful to predict liver metabolism on off-target organs to ultimately improve drug safety testing in the pre-clinical phases of the DDP. In this review, we focus on recently developed liver and heart on chip systems for drug toxicity testing. In addition, MOoC platforms encompassing connected liver and heart tissues have been further reviewed and discussed
Electromechanical Stimulation of 3D Cardiac Microtissues in a Heart-on-Chip Model
No full textModeling human cardiac tissues in vitro is essential to elucidate the biological mechanisms related to the heart physiopathology, possibly paving the way for new treatments. Organs-on-chips have emerged as innovative tools able to recreate tissue-specific microenvironments, guiding the development of miniaturized models and offering the opportunity to directly analyze functional readouts. Here we describe the fabrication and operational procedures for the development of a heart-on-chip model, reproducing cardiac biomimetic microenvironment. The device provides 3D cardiac microtissue with a synchronized electromechanical stimulation to support the tissue development. We additionally describe procedures for characterizing tissue evolution and functionality through immunofluorescence, real time qPCR, calcium imaging and microtissue contractility investigations
Mechanical Induction of Osteoarthritis Traits in a Cartilage-on-a-Chip Model
Full text linkThe present lack of effective therapies for osteoarthritis, the most diffused musculoskeletal disease, correlates with the absence of representative in vitro disease models. Microfabrication techniques and soft lithography allow the development of organs and tissues on chip with increased mimicry of human pathophysiology. Exploitation of polydimethylsiloxane elasticity, furthermore, permits to incorporate finely controlled mechanical actuators which are of the utmost importance in a faithful representation of the intrinsically active environment of musculoskeletal districts, to increase our comprehension of the disease onset and to successfully predict the response to pharmacological therapies. Here, we portray the fabrication and operational processes for the development of a cartilage-on-a-chip model. Additionally, we describe the methodologies to induce a phenotype reminiscent of osteoarthritis solely through hyperphysiological cyclic compression. The techniques to assess achievement of such features through immunofluorescence and gene expression are also detailed
Enhancing all-in-one bioreactors by combining interstitial perfusion, electrical stimulation, on-line monitoring and testing within a single chamber for cardiac constructs
Full text linkTissue engineering strategies have been extensively exploited to generate functional cardiac patches. To maintain cardiac functionality in vitro, bioreactors have been designed to provide perfusion and electrical stimulation, alone or combined. However, due to several design limitations the integration of optical systems to assess cardiac maturation level is still missing within these platforms. Here we present a bioreactor culture chamber that provides 3D cardiac constructs with a bidirectional interstitial perfusion and biomimetic electrical stimulation, allowing direct cellular optical monitoring and contractility test. The chamber design was optimized through finite element models to house an innovative scaffold anchoring system to hold and to release it for the evaluation of tissue maturation and functionality by contractility tests. Neonatal rat cardiac fibroblasts subjected to a combined perfusion and electrical stimulation showed positive cell viability over time. Neonatal rat cardiomyocytes were successfully monitored for the entire culture period to assess their functionality. The combination of perfusion and electrical stimulation enhanced patch maturation, as evidenced by the higher contractility, the enhanced beating properties and the increased level of cardiac protein expression. This new multifunctional bioreactor provides a relevant biomimetic environment allowing for independently culturing, real-time monitoring and testing up to 18 separated patches
Photo and Soft Lithography for Organ-on-Chip Applications
No full textOrgans-on-Chip devices are generally fabricated by means of photo- and soft lithographic techniques. Photolithography is a process that involves the transfer of a pattern onto a substrate by a selective exposure to light. In particular, in this chapter two different photolithography methods will be described: liquid and dry photolithography. In liquid photolithography, a silicon wafer is spin-coated with liquid photoresist and exposed to UV light in order to be patterned. In dry photolithography, the silicon wafer is laminated with resist dry film before being patterned through UV light. In both cases, the UV light can be collimated on top of the wafer either through photomasks or by direct laser exposure. The obtained patterned wafer is then used as a mold for the soft lithographic process (i.e., replica molding) to produce polymer-based microdevices
Integrating Biosensors in Organs-on-Chip Devices: A Perspective on Current Strategies to Monitor Microphysiological Systems
Full text linkOrgans-on-chip (OoC), often referred to as microphysiological systems (MPS), are advanced in vitro tools able to replicate essential functions of human organs. Owing to their unprecedented ability to recapitulate key features of the native cellular environments, they represent promising tools for tissue engineering and drug screening applications. The achievement of proper functionalities within OoC is crucial; to this purpose, several parameters (e.g., chemical, physical) need to be assessed. Currently, most approaches rely on off-chip analysis and imaging techniques. However, the urgent demand for continuous, noninvasive, and real-time monitoring of tissue constructs requires the direct integration of biosensors. In this review, we focus on recent strategies to miniaturize and embed biosensing systems into organs-on-chip platforms. Biosensors for monitoring biological models with metabolic activities, models with tissue barrier functions, as well as models with electromechanical properties will be described and critically evaluated. In addition, multisensor integration within multiorgan platforms will be further reviewed and discussed
Towards the knee on a chip: development of a microfluidic platform for the mechanical stimulation of three dimensional cartilaginous constructs.
No full textPlatelet Membrane-Related Morphologic Alterations: An Early Marker of Supra-Physiologic Shear-Mediated Platelet Activation Associated with VADs
No full textPurpose: Shear-mediated platelet activation (SMPA) results in frequent, serious thrombotic events in patients supported on ventricular assist device (VADs). Despite recognition of supra-physiologic shear stress as an initiator of SMPA details of its mechanism and associated events is only partially understood. Further, current assays of platelet activation typically measure biochemical markers, aggregation, or thrombin generation - which are not necessarily reflective of early processes of SMPA. We hypothesized that SMPA, driven by VADassociated supra-physiologic shear stress, can result in membrane-associated morphologic changes prior to assayed biochemical events. Methods: Fresh human gel filtered-platelets (GFP) were subjected to dynamic shear stress in novel microfluidic platforms fabricated to emulate VADs. Shear exposure included repetitive peaks of 7 Pa x 5 ms followed by shear stress of 1 Pa x 10 ms between consecutive peaks, at a constant flow rate of 15 ul/min, for 100, 200 and 300 peaks of stress exposure - emulating VADs . Platelet activation was assessed for morphologic change via scanning electron microscopy (SEM); and for biochemical activation via thrombin generation via platelet activity state (PAS) assay. Results: Platelets exposed to VAD-associated supra-physiologic shear stresses demonstrated early and progressive membrane-associated morphologic alteration, with increasing pseudopod formation and length (Fig 1B,C). In contrast, despite early morphologic changes platelet activation remained undetectable as measured by the PAS assay (thrombin generation, Fig 1A). Conclusion: SMPA advances via a progression of initial morphological, followed by biochemical signaling and processes. As such a negative PAS assay does not necessarily indicate the absence of mechanical PA or the presence of “resting” platelets. SEM appears to be a sensitive assay revealing the earliest changes in the natural history of SMPA
Development of a Microfluidic Vascularized Osteochondral Model as a Drug Testing Platform for Osteoarthritis
Full text linkOsteoarthritis (OA) is a degenerative joint disease characterized by changes in cartilage and subchondral bone. To date, there are no available drugs that can counteract the progression of OA, partly due to the inadequacy of current models to recapitulate the relevant cellular complexity. In this study, an osteochondral microfluidic model is developed using human primary cells to mimic an OA-like microenvironment and this study validates it as a drug testing platform. In the model, the cartilage compartment is created by embedding articular chondrocytes in fibrin hydrogel while the bone compartment is obtained by embedding osteoblasts, osteoclasts, endothelial cells, and mesenchymal stem cells in a fibrin hydrogel enriched with calcium phosphate nanoparticles. After developing and characterizing the model, Interleukin-1β is applied to induce OA-like conditions. Subsequently, the model potential is evaluated as a drug testing platform by assessing the effect of two anti-inflammatory drugs (Interleukin-1 Receptor antagonist and Celecoxib) on the regulation of inflammation- and matrix degradation-related markers. The model responded to inflammation and demonstrated differences in drug efficacy. Finally, it compares the behavior of the “Cartilage” and “Cartilage+Bone” models, emphasizing the necessity of incorporating both cartilage and bone compartments to capture the complex pathophysiology of OA
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