Sacrificial capillary pumps to engineer multiscalar biological forms.

Natural tissues are composed of diverse cells and extracellular materials whose arrangements across several length scales-from subcellular lengths (micrometre) to the organ scale (centimetre)-regulate biological functions. Tissue-fabrication methods have progressed to large constructs, for example, through stereolithography and nozzle-based bioprinting, and subcellular resolution through subtractive photoablation. However, additive bioprinting struggles with sub-nozzle/voxel features and photoablation is restricted to small volumes by prohibitive heat generation and time.

Notch1 and Notch3 coordinate for pericyte-induced stabilization of vasculature.

The Notch pathway regulates complex patterning events in many species and is critical for the proper formation and function of the vasculature. Despite this importance, how the various components of the Notch pathway work in concert is still not well understood. For example, NOTCH1 stabilizes homotypic endothelial junctions, but the role of NOTCH1 in heterotypic interactions is not entirely clear.

Harnessing Mechanobiology for Tissue Engineering.

A primary challenge in tissue engineering is to recapitulate both the structural and functional features of whole tissues and organs. In vivo, patterning of the body plan and constituent tissues emerges from the carefully orchestrated interactions between the transcriptional programs that give rise to cell types and the mechanical forces that drive the bending, twisting, and extensions critical to morphogenesis. Substantial recent progress in mechanobiology-understanding how mechanics regulate cell behaviors and what cellular machineries are responsible-raises the possibility that one can begin to use these insights to help guide the strategy and design of functional engineered tissues.

Uncovering mutation-specific morphogenic phenotypes and paracrine-mediated vessel dysfunction in a biomimetic vascularized mammary duct platform.

The mammary gland is a highly vascularized tissue capable of expansion and regression during development and disease. To enable mechanistic insight into the coordinated morphogenic crosstalk between the epithelium and vasculature, we introduce a 3D microfluidic platform that juxtaposes a human mammary duct in proximity to a perfused endothelial vessel. Both compartments recapitulate stable architectural features of native tissue and the ability to undergo distinct forms of branching morphogenesis.

Multiple roles of lymphatic vessels in peripheral lymph node development.

The mammalian lymphatic system consists of strategically located lymph nodes (LNs) embedded into a lymphatic vascular network. Mechanisms underlying development of this highly organized system are not fully understood. Using high-resolution imaging, we show that lymphoid tissue inducer (LTi) cells initially transmigrate from veins at LN development sites using gaps in venous mural coverage.

Biomimetic Model of Tumor Microenvironment on Microfluidic Platform.

The "Tumor microenvironment" (TME) is a complex, interacting system of the tumor and its surrounding environment. The TME has drawn more attention recently in attempts to overcome current drug resistance and the recurrence of cancer by understanding the cancer and its microenvironment systematically, beyond past reductionist approaches. However, a lack of experimental tools to dissect the intricate interactions has hampered in-depth research into the TME.

Microvessels-on-a-Chip to Assess Targeted Ultrasound-Assisted Drug Delivery.

Microbubbles have been used in ultrasound-assisted drug delivery to help target solid tumors via blood vessels in vivo; however, studies to understand the phenomena at the cellular level and to optimize parameters for ultrasound or microbubbles in vivo are challenging and expensive to perform. Here, we utilize microfluidic microvessels-on-a-chip that enable visualization of microbubble/ultrasound-dependent drug delivery to microvasculature. When exposed to pulsed ultrasound, microbubbles perfused through microvessels-on-a-chip were observed to stably oscillate.

Interstitial flow regulates the angiogenic response and phenotype of endothelial cells in a 3D culture model.

A crucial yet ill-defined phenomenon involved in the remodeling of vascular networks, including angiogenic sprouting, is flow-mediated endothelial dynamics and phenotype changes. Despite interstitial flow (IF) being ubiquitously present in living tissues surrounding blood capillaries, it is rarely investigated and poorly understood how endothelial cells respond to this flow during morphogenesis. Here we develop a microfluidic 3D in vitro model to investigate the role of IF during vasculogenic formation and angiogenic remodeling of microvascular networks.

Establishment and antitumor effects of dasatinib and PKI-587 in BD-138T, a patient-derived muscle invasive bladder cancer preclinical platform with concomitant EGFR amplification and PTEN deletion.

Muscle-invasive bladder cancer (MIBC) consists of a heterogeneous group of tumors with a high rate of metastasis and mortality. To facilitate the in-depth investigation and validation of tailored strategies for MIBC treatment, we have developed an integrated approach using advanced high-throughput drug screening and a clinically relevant patient-derived preclinical platform. We isolated patient-derived tumor cells (PDCs) from a rare MIBC case (BD-138T) that harbors concomitant epidermal growth factor receptor (EGFR) amplification and phosphatase and tensin homolog (PTEN) deletion.

Three-dimensional biomimetic model to reconstitute sprouting lymphangiogenesis in vitro.

Formation of new lymphatic vessels, termed lymphangiogenesis, is central for diverse biological processes during development, inflammation and tumor metastasis. However, reliable in vitro model is still under demand for detailed elucidation of how sprouting lymphangiogenesis is initiated and coordinated. Here, we describe a microfluidic platform optimized for close reconstitution of lymphangiogenesis, achieved by on-chip integration of salient constituents of lymphatic microenvironment found in vivo.

Microfluidic vascularized bone tissue model with hydroxyapatite-incorporated extracellular matrix.

Current in vitro systems mimicking bone tissues fail to fully integrate the three-dimensional (3D) microvasculature and bone tissue microenvironments, decreasing their similarity to in vivo conditions. Here, we propose 3D microvascular networks in a hydroxyapatite (HA)-incorporated extracellular matrix (ECM) for designing and manipulating a vascularized bone tissue model in a microfluidic device. Incorporation of HA of various concentrations resulted in ECM with varying mechanical properties.

Engineering of a Biomimetic Pericyte-Covered 3D Microvascular Network.

Pericytes enveloping the endothelium play an important role in the physiology and pathology of microvessels, especially in vessel maturation and stabilization. However, our understanding of fundamental pericyte biology is limited by the lack of a robust in vitro model system that allows researchers to evaluate the interactions among multiple cell types in perfusable blood vessels. The present work describes a microfluidic platform that can be used to investigate interactions between pericytes and endothelial cells (ECs) during the sprouting, growth, and maturation steps of neovessel formation.

Snail1 induced in breast cancer cells in 3D collagen I gel environment suppresses cortactin and impairs effective invadopodia formation.

Although an in vitro 3D environment cannot completely mimic the in vivo tumor site, embedding tumor cells in a 3D extracellular matrix (ECM) allows for the study of cancer cell behaviors and the screening of anti-metastatic reagents with a more in vivo-like context. Here we explored the behaviors of MDA-MB-231 breast cancer cells embedded in 3D collagen I. Diverse tumor environmental conditions (including cell density, extracellular acidity, or hypoxia as mimics for a continuous tumor growth) reduced JNKs, enhanced TGFβ1/Smad signaling activity, induced Snail1, and reduced cortactin expression.

A bioengineered array of 3D microvessels for vascular permeability assay.

Blood vessels exhibit highly regulated barrier function allowing selective passage of macromolecules. Abnormal vascular permeability caused by disorder in barrier function is often associated with various pathological states such as tumor progression or pulmonary fibrosis. There are no realistic in vitro models for measuring vascular permeability as most models are limited to mimicking anatomical structural properties of in vivo vessel barriers.

β-Amyloid is transmitted via neuronal connections along axonal membranes.

Objective: β-amyloid plaque is a critical pathological feature of Alzheimer disease. Pathologic studies suggest that neurodegeneration may occur in a retrograde fashion from axon terminals near β-amyloid plaques, and that plaque may spread through brain regions. However, there is no direct experimental evidence to show transmission of β-amyloid.

Engineering of functional, perfusable 3D microvascular networks on a chip.

Generating perfusable 3D microvessels in vitro is an important goal for tissue engineering, as well as for reliable modelling of blood vessel function. To date, in vitro blood vessel models have not been able to accurately reproduce the dynamics and responses of endothelial cells to grow perfusable and functional 3D vascular networks. Here we describe a microfluidic-based platform whereby we model natural cellular programs found during normal development and angiogenesis to form perfusable networks of intact 3D microvessels as well as tumor vasculatures based on the spatially controlled co-culture of endothelial cells with stromal fibroblasts, pericytes or cancer cells.

Application of a new wall-less plate technology to complex multistep cell-based investigations using suspension cells.

Despite significant progresses, cell-based assays still have major limitations part to because of their plate format. Here, we present a wall-less plate technology based on unique liquid dynamics named DropArray that takes advantage of hydrophobic and hydrophilic surface properties. Liquid velocities within the DropArray plate were quantified through fluid dynamics simulation and complete retention of suspension cells experimentally demonstrated within the range of simulated shear stresses.

Biological applications of microfluidic gradient devices.

Molecular gradients play an important role in diverse physiological and pathological phenomena such as immune response, wound healing, development and cancer metastasis. In the past 10 years, engineering tools have been increasingly used to develop experimental platforms that capture important aspects of cellular microenvironments to allow quantitative and reproducible characterization of cellular response to gradients. This review discusses the emergence of microfluidics-based gradient generators and their applications in enhancing our understanding of fundamental biological processes such as chemotaxis and morphogenesis.

Structural requirements for the neuroprotective effects of aspirin analogues against N-methyl-D-aspartate and zinc ion neurotoxicity.

In order to elucidate the structural requirements for the dual neuroprotective activity of aspirin against N-methyl-D-aspartate (NMDA) and zinc ion neurotoxicity, various aspirin analogues and derivatives, modified at the carboxylic group, the acetyl group, and the chain length between the carboxylic acid moiety and phenyl ring, were synthesized. Replacement of the carboxylic acid group with alkyl groups (compounds 2c and 2d) resulted in a dramatic increase in neuroprotective activity against NMDA neurotoxicity, while reduction of the carboxylic acid group to the alcohol (compound 2g) completely abolished this activity. In contrast to NMDA neurotoxicity, compounds that are devoid of the carboxylic acid group did not show any activity against zinc ion neurotoxicity.