Abraham Phillip Lee

University of California, Irvine | UCI · Department of Biomedical Engineering

Chimeric antigen receptor (CAR) T-cell therapy shows unprecedented efficacy for cancer treatment, particularly in treating patients with various blood cancers, most notably B-cell acute lymphoblastic leukemia. In recent years, CAR T-cell therapies have been investigated for treating other hematologic malignancies and solid tumors. Despite the remar...

Fast, nondestructive three-dimensional (3D) imaging of live suspension cells remains challenging without substrate treatment or fixation, precluding scalable single-cell morphometry with minimal alterations. While optical sectioning techniques achieve 3D live cell imaging, lateral versus depth resolution differences further complicate analysis. We...

Hereditary Hemorrhagic Telangiectasia (HHT) is a rare congenital disease in which fragile vascular malformations (VM) – including small telangiectasias and large arteriovenous malformations (AVMs) – focally develop in multiple organs. There are few treatment options and no cure for HHT. Most HHT patients are heterozygous for loss-of-function mutati...

Hereditary Hemorrhagic Telangiectasia (HHT) is a rare congenital disease in which fragile vascular malformations focally develop in multiple organs. These can be small (telangiectasias) or large (arteriovenous malformations, AVMs) and may rupture leading to frequent, uncontrolled bleeding. There are few treatment options and no cure for HHT. Most H...

Three-dimensional (3D) imaging of non-adherent cells in suspension media is challenging due to their propensity to drift when not fixed to a substrate, as required by optical sectioning technologies. Resolution differences in the lateral versus depth directions typically present in those systems further complicates single-cell morphometry of cellul...

Autologous cell therapy depends on T lymphocyte expansion efficiency and is hindered by suboptimal interactions between T cell receptors (TCR) and peptide‐MHC molecules. Various artificial antigen presenting cell systems that enhance these interactions are often labor‐intensive, fabrication costly, highly variable, and potentially unscalable toward...

Dielectrophoresis (DEP) is a powerful tool for label-free sorting of cells, even those with subtle differences in morphological and dielectric properties. Nevertheless, a major limitation is that most existing DEP techniques can efficiently sort cells only at low throughputs (<1 mL h−1). Here, we demonstrate that the integration of a three-dimensio...

Thin film shape memory alloys (SMAs) have the potential to become a primary actuating mechanism for mechanical devices with dimensions in the micron to millimeter range requiring large forces over long displacements. In this paper, the thermo-mechanical behavior of shape memory films is presented, techniques for characterizing Ni-Ti-based shape mem...

Measurement of fluid viscosity represents a huge need for many biomedical and materials processing applications. Sample fluids containing DNA, antibodies, protein-based drugs, and even cells have become important therapeutic options. The physical properties, including viscosity, of these biologics are critical factors in the optimization of the bio...

Phospholipid-stabilized microbubbles are utilized as contrast agents in medical ultrasound imaging, and researchers are currently investigating their potential as theranostic agents. Due to the inadequate water solubility and poor stability of numerous new therapeutics, the development of stable microbubbles with the capacity to encapsulate hydroph...

Chimeric antigen receptor (CAR) T-cell therapy shows unprecedented efficacy for cancer treatment, particularly in treating patients with various blood cancers, most notably B-cell acute lymphoblastic leukemia (B-ALL). In recent years, CAR T-cell therapies are being investigated for treating other hematologic malignancies and solid tumors. Despite t...

The success of autologous cell therapy, which depends highly on T lymphocyte expansion efficiency, is often hindered by suboptimal interactions between T-cell receptors and peptide-MHC molecules. Here, we demonstrate 3D confinement-enabled priming of T cell–MHC immune synapse junctions based on cytoskeletal forces within minutes, which is 200-fold...

In this study, efficient T cell activation is demonstrated using cell‐sized artificial antigen‐presenting cells (aAPCs) with protein‐conjugated bilayer lipid membranes that mimic biological cell membranes. The highly uniform aAPCs are generated by a facile method based on standard droplet microfluidic devices. These aAPCs are able to activate the T...

In this study, efficient T cell activation is demonstrated using cell-sized artificial antigen-presenting cells (aAPCs) with protein-conjugated bilayer lipid membranes that mimic biological cell membranes. The highly uniform aAPCs are generated by a facile method based on standard droplet microfluidic devices. These aAPCs are able to activate the T...

Droplet microfluidics has become an indispensable technology to encapsulate cells of interest in a monodispersed aqueous compartment for single-cell analysis. In addition, the confinement of cells in picoliter droplets offers high-throughput, single-cell resolution, and high signal-to-noise ratio for various cellular assays that unmasks cellular he...

Purpose: Microbubble-enhanced ultrasound has been proposed as a method to achieve targeted ocular drug delivery. We designed an in vitro experiment to identify the optimal concentration of a stable phospholipid mixture that biochemically recapitulates a monodisperse microbubble suspension and is nontoxic to human retinal epithelium cells (ARPE-19)....

Many cellular analytical technologies measure only the average response from a cell population with an assumption that a clonal population is homogenous. The ensemble measurement often masks the difference among individual cells that can lead to misinterpretation. The advent of microfluidic technology has revolutionized single-cell analysis through...

The vascular network of the circulatory system plays a vital role in maintaining homeostasis in the human body. In this paper, a novel modular microfluidic system with a vertical two-layered configuration is developed to generate large-scale perfused microvascular networks in vitro. The two-layer polydimethylsiloxane (PDMS) configuration allows the...

A high‐throughput non‐viral intracellular delivery platform is introduced for the transfection of large cargos with dosage‐control. This platform, termed Acoustic‐Electric Shear Orbiting Poration (AESOP), optimizes the delivery of intended cargo sizes with poration of the cell membranes via mechanical shear followed by the modulated expansion of th...

Correction for ‘The vascular niche in next generation microphysiological systems’ by Makena L. Ewald et al. , Lab Chip , 2021, DOI: 10.1039/d1lc00530h.

In recent years, microphysiological system (MPS, also known as, organ-on-a-chip or tissue chip) platforms have emerged with great promise to improve the predictive capacity of preclinical modeling thereby reducing the high attrition rates when drugs move into trials. While their designs can vary quite significantly, in general MPS are bioengineered...

This study analyzes the swelling behavior of native, unmodified, spherically uniform, monodisperse poly(lactic-co-glycolic acid) (PLGA) microparticles in a robust high-throughput manner. This work contributes to the complex narrative of PLGA microparticle behavior and release mechanisms by complementing and extending previously reported studies on...

We check in with past, present, and future Editors-in-Chief, including Andreas Manz (2001–2008), Abe Lee (2017–2020), and Aaron Wheeler (2021–), about the state of the field.

We demonstrate a label free and high-throughput microbubble-based acoustic microstreaming technique to isolate rare circulating cells such as circulating cancer associated fibroblasts (cCAFs) in addition to circulating tumor cells (CTCs) and immune cells (i.e. leukocytes) from clinically diagnosed patients with a capture efficiency of 94% while pre...

In this work, we describe the mechanism of particle trapping and release at the flow-focusing microfluidic droplet generation junction, utilizing the hydrodynamic microvortices generated in the dispersed phase. This technique is based solely on our unique flow-focusing geometry and the flow control of the two immiscible phases and, thus, does not r...

Around 95% of anti-cancer drugs that show promise during preclinical study fail to gain FDA-approval for clinical use. This failure of the preclinical pipeline highlights the need for improved, physiologically-relevant in vitro models that can better serve as reliable drug-screening and disease modeling tools. The vascularized micro-tumor (VMT) is...

Intracellular delivery of cargos for cell engineering plays a pivotal role in transforming medicine and biomedical discoveries. Recent advances in microfluidics and nanotechnology have opened up new avenues for efficient, safe, and controllable intracellular delivery, as they improve precision down to the single-cell level. Based on this capability...

Human blood plasma contains numerous soluble, diffusible, and secreted biomarkers that are used for clinical diagnosis and prognosis of various diseases. However, the blood of some patients is hemolyzed rapidly due to the rupture of cell membranes and releases chemicals and biological molecules that yield false-positive fluorescence detection resul...

This editorial celebrates the 20th year of Lab on a Chip .

Around 95% of anti-cancer drugs that show promise during preclinical study fail to gain FDA-approval for clinical use. This failure of the preclinical pipeline highlights the need for improved, physiologically-relevant in vitro models that can better serve as reliable drug-screening tools. The vascularized micro-tumor (VMT) is a novel three-dimensi...

This paper provides a synopsis of discussions related to biomedical engineering core curricula that occurred at the Fourth BME Education Summit held at Case Western Reserve University in Cleveland, Ohio in May 2019. This summit was organized by the Council of Chairs of Bioengineering and Biomedical Engineering, and participants included over 300 fa...

We created an integrated microfluidic cell separation system that incorporates hydrophoresis and dielectrophoresis modules to facilitate high-throughput continuous cell separation. The hydrophoresis module consists of a serpentine channel with ridges and trenches to generate a diverging fluid flow that focuses cells into two streams along the chann...

The purpose of this review is to assess the state-of-the-art fabrication methods, advances in genome editing, and the use of machine learning to shape the prospective growth in cardiac tissue engineering. Those interdisciplinary emerging innovations would move forward basic research in this field and their clinical applications. The long-entrenched...

The rapid progress of droplet microfluidics and its wide range of applications have created a high demand for the mass fabrication of low-cost, high throughput droplet generator chips aiding both biomedical research and commercial usage. Existing polymer or glass based droplet generators have failed to successfully meet this demand which generates...

There is a growing need to screen multiple infections simultaneously rather than diagnosis of one pathogen at a time in order to improve the quality of healthcare while saving initial screening time and reduce costs. This is the first demonstration of a five-step protein array assay for the multiplexed detection of HIV, HPV and HSV antibodies on an...

Characterization of single cell metabolism is imperative for understanding subcellular functional and biochemical changes associated with healthy tissue development and the progression of numerous diseases. However, single‐cell analysis often requires the use of fluorescent tags and cell lysis followed by genomic profiling to identify the cellular...

While lipoplex (cationic lipid‐nucleic acid complex)‐mediated intracellular delivery is widely adopted in mammalian cell transfection, its transfection efficiency for suspension cells, e.g., lymphatic and hematopoietic cells, is reported at only ≈5% or even lower. Here, efficient and consistent lipoplex‐mediated transfection is demonstrated for har...

Understanding the cellular properties controlling neural stem and progenitor cell (NSPC) fate choice will improve their therapeutic potential. The electrophysiological measure whole-cell membrane capacitance reflects fate bias in the neural lineage but the cellular properties underlying membrane capacitance are poorly understood. We tested the hypo...

Reliable separation and isolation of target single cells from bodily fluids with high purity is of great significance for an accurate and quantitative understanding of the cellular heterogeneity. Here, we describe a fully integrated single-blood-cell analysis platform capable of size-selective cell separation from a population containing a wide dis...

Autonomous and self-powered micropumps are in critical demand for versatile cell- and tissue-based applications as well as for low-cost point-of-care testing (POCT) in microfluidics fields. The hydrostatic pressure-driven passive micropumps are simple and widely used, but they cannot maintain steady and continuous flow for long periods of time. Her...

Purpose of Review Advanced technologies can aid discoveries in stem cell science in surprising ways. The application of electrokinetic techniques, which use electric fields to interrogate or separate cells, to the study of stem cells has yielded important insights into stem cell function. These techniques probe inherent cell properties, obviating t...

The rapid screening and isolation of single leukemia cells from blood has become critical for early leukemia detection and tumor heterogeneity interrogation. However, due to the size overlap between leukemia...

Analyzing undiluted whole human blood is a challenge due to its complex composition of hematopoietic cellular populations, nucleic acids, metabolites, and proteins. We present a novel multi-functional microfluidic acoustic streaming platform that enables sorting, enrichment and in situ identification of cellular subsets from whole blood. This singl...

Cell-sized lipid vesicles (CLVs) have shown great promise for therapeutic and artificial cell applications, but their fragility and short shelf life has hindered widespread adoption and commercial viability. We present a method to circumvent the storage limitations of CLVs such as giant unilamellar vesicles (GUVs) and single-compartment multisomes...

Single cell analysis has emerged as a paradigm shift in cell biology to understand the heterogeneity of individual cells in a clone for pathological interrogation. Microfluidic droplet technology is a compelling platform to perform single cell analysis by encapsulating single cells inside picoliter-nanoliter (pL-nL) volume droplets. However, one of...

Numerous applications in biology and medicine require the efficient and reliable separation of cells for disease diagnosis, genetic analysis, drug screening, and therapeutics. In this work, we demonstrate a novel technology that integrates a passive and an active device to separate, enrich and release cells on-demand from a complex blood sample, or...

This protocol describes detailed practical procedures for generating 3D intact and perfusable microvascular network that connects to microfluidic channels without appreciable leakage. This advanced 3D microvascular network model incorporates different stages of vascular development including vasculogenesis, endothelial cell (EC) lining, sprouting a...

We present an in situ mRNA extraction platform to quantify marker-genes’ expression levels of single target cells within high-density microfluidic trapping arrays. This platform enables single-cell transcriptomic analysis to reveal in-depth information of cellular mechanisms and population heterogeneity. Although microfluidic technology enables the...

In recent years, lipid vesicles have become popular vehicles for the creation of biosensors. Vesicles can hold reaction components within a selective permeable membrane that provides an ideal environment for membrane protein biosensing elements. The lipid bilayer allows a protein to retain its native structure and function, and the membrane fluidit...

Ideally, a modular microfluidics platform should be simple to assemble and support 3D configurations for increased versatility. The modular building blocks should also be mass producible like electrical components. These are fundamental features of world-renowned Legos® and why Legos® inspire many existing modular microfluidics platforms. In this p...

There is a growing awareness that complex 3-dimensional (3D) organs are not well represented by monolayers of a single cell type - the standard format for many drug screens. To address this deficiency, and with the goal of improving screens so that drugs with good efficacy and low toxicity can be identified, microphysiological systems (MPS) are bei...

Infectious diseases remain a major health concern in many parts of the developing world, where access to adequate health care and modern diagnostic tools are absent. Current diagnostic technologies like ELISA and PCR require large sample volumes, bulky, expensive instrumentation, highly trained personnel, long experimental time, and a modern infras...

There is a growing interest in developing microphysiological systems that can be used to model both normal and pathological human organs in vitro. This “organs-on-chips” approach aims to capture key structural and physiological characteristics of the target tissue. Here we describe in vitro vascularized microtumors (VMTs). This “tumor-on-a-chip” pl...

We present a microfluidic lab-on-printed circuit board (PCB) device containing alloy vertical electrodes for sorting microparticles using dielectrophoresis. The device consists of a hydrodynamic prefocuser and an electronic sorting region. Lining the two sidewalls of the electronic sorting region are regularly spaced rectangular metal electrodes re...

Organic fluorescent dyes are widely used for the visualization of bound antibody in a variety of immunofluorescence assays. However, the detection equipment is often expensive, fragile and hard to deploy widely. Quantum dots (Qdot®) are nanocrystals made of semiconductor materials that emit light at different wavelengths according to the size of th...

Coculturing multiple cell types together in 3-dimensional (3D) cultures better mimics the in vivo microphysiological environment, and has become widely adopted in recent years with the development of organ-on-chip systems. However, a bottleneck in set-up of these devices arises as a result of the delivery of the gel into the microfluidic chip being...

Medical ultrasound imaging often employs ultrasound contrast agents (UCAs), injectable microbubbles stabilized by shells or membranes. In tissue, the compressible gas cores can strongly scatter acoustic signals, resonate, and emit harmonics. However, bubbles generated by conventional methods have nonuniform sizes, reducing the fraction that resonat...

This paper reports a method for generating an intact and perfusable microvascular network that connects to microfluidic channels without appreciable leakage. This platform incorporates different stages of vascular development including vasculogenesis, endothelial cell (EC) lining, sprouting angiogenesis, and anastomosis in sequential order. After f...

We demonstrate an on-chip integrated droplet generator enabled by lateral cavity acoustic transducer (LCAT) oil and water microfluidic pumps. Both oil-in-water (O/W) and water-in-oil (W/O) droplet generation are demonstrated. The LCAT pumps are energized by piezoelectric acoustic energy to induce rectified microstreaming for pumping liquid. In this...

Dielectrophoresis (DEP) has proven an invaluable tool for the enrichment of populations of stem and progenitor cells owing to its ability to sort cells in a label-free manner and its biological safety. However, DEP separation devices have suffered from a low throughput preventing researchers from undertaking studies requiring large numbers of cells...

Canine cancers develop in immunocompetent environments and share many similar features observed in human cancers, such as long periods of latency for initiation, progression and development, metastasis, acquired drug resistance and recurrence. Osteosarcoma is a primary bone tumor that occurs in dogs. It is highly aggressive and metastatic in nature...

The continued growth of microfluidics into industry settings in areas such as point-of-care diagnostics and targeted therapeutics necessitates a workforce trained in microfluidic technologies and experimental methods. Laboratory courses for students at the university and high school levels will require cost-effective in-class demonstrations that in...

We present a microfluidic platform for simultaneous on-chip pumping and size-based separation of cells and particles without external fluidic control systems required for most existing platforms. The device utilizes an array of acoustically actuated air/liquid interfaces generated using dead-end side channels termed Lateral Cavity Acoustic Transduc...

This research demonstrates an integrated microfluidic titration assay to characterize the cation concentrations in working buffer to rapidly optimize the signal-to-noise ratio (SNR) of molecular beacons (MBs). The "Microfluidic Droplet Array Titration Assay" (MiDATA) integrated the functions of sample dilution, sample loading, sample mixing, fluore...

Neural stem and progenitor cells (NSPCs) are heterogeneous populations of self-renewing stem cells and more committed progenitors that differentiate into neurons, astrocytes and oligodendrocytes. Accurately identifying and characterizing the different progenitor cells in this lineage has continued to be a challenge for the field. We found previousl...

As the primary structural protein of our bodies, fibrillar collagen and its organizational patterns determine the biomechanics and shape of tissues. While the molecular assembly of individual fibrils is well understood, the mechanisms determining the arrangement of fibers and thus the shape and form of tissues remain largely unknown. We have develo...

This paper reports, for the first time, a microfluidic system that can reproduce the vascular anastomosis between a perfused vessel network in a 3D tissue chamber and an endothelial cell (EC)-lined microfluidic channel. By using a decoupling design of the microfluidic device, the physiological microenvironment including both the interstitial flow f...

Microfabricated systems are increasingly being used to recapitulate physiological environments for tissue engineering, however the accuracy of the approach requires simultaneous delivery of multiple types of stimuli to the tissue. Here, we use a microfabricated system that allows for precise fluid delivery of nutrients, coupled with an integrated e...

Ultrasound imaging often calls for the injection of contrast agents, micron-sized bubbles which echo strongly in blood and help distinguish vascularized tissue. Such microbubbles are also being augmented for targeted drug delivery and gene therapy, by the addition of surface receptors and therapeutic payloads. Unfortunately, conventional production...

We present a novel method to fragment DNA by using lateral cavity acoustic transducers (LCATs). DNA solution is placed within a microfluidic device containing LCATs. The LCATs cause microstreaming, which fragments DNA within the solution without any need for purification or downstream processing. The LCAT-based DNA fragmentation method offers an ea...