The MNM Biotech Lab uses engineering expertise to assist life scientists in the study, diagnosis, and treatment of human disease. By developing better models of the body, we help advance drug discovery, increase understanding of the mechanisms of disease, and develop clinical treatments. Areas of study include:
- Aqueous Two-Phase Systems
- Microfluidic Logic Circuits
- Interrogation and Control of Cell Signaling Mechanisms
- Assisted Reproductive Technology
- 3D Cell Culture
- Microenvironment Engineering and Materials Modifications
- Size-adjustable nanochannels and DNA linearization/stretching
- Cancer Metastasis and Migration
Aqueous Two-Phase Systems
Aqueous two-phase systems (ATPS) are formed when two incompatible polymer solutions are mixed above certain threshold concentrations. Historically such systems have been used in a range of biotechnology applications to purify or concentrate biomolecules based on properties of the two-phase system as well as the molecules of interest. Our lab has recently developed a number of unique applications for ATPS ranging from spatially controlled gene and protein delivery to patterned biomolecule arrays for high throughput analysis.
Microfluidic Logic Circuits
Microfluidics logic is a new field targeting the development of device-embedded, non-electrical, flow-controlled microsystems. Function-oriented microfluidic components such as normally-closed valves and microfluidic diodes can coordinate to provide flow switching and timing functions, much like that of a 555-timer in electronic circuits. This flow-powered fluidic gating scheme brings the autonomous signal processing ability of microelectronic circuits to microfluidics. Microfluidics, however, also has additional diversity in current information because it can also incorporate multiple distinct chemical or particulate species and can leverage chemical, electrical, and physical interactions to help control fluid flow. Our lab has the ability to fabricate self-regulating microfluidic devices and model fluid flow based on pressure, channel compliance, and contact surface area.
Interrogation and Control of Cell Signaling Mechanisms
Orchestration of cellular operations requires precise conversion of chemical signals from the environment into intracellular messages that cells must interpret with their internal protein machinery. Intracellular messages are conveyed by chemical messengers, such as calcium. Signals from the environment and chemical messengers are regularly frequency-encoded, the most common example being chemicals that regulate our circadian clocks. Despite the wealth of mathematical models available for predicting and interpreting the mechanisms mediating the conversion of extracellular signals into cell responses, there is a lack of experimental setups that enable manipulation and further elucidation of this process. Our lab has developed microfluidic technology capable of delivering periodic extracellular chemical stimuli that mimics the pulsatile nature of signaling systems in order to better characterize cell signaling dynamics real-time.
Assisted Reproductive Technology
Assisted reproductive technology (ART) is a means to achieve fertilization with partially or completely artificial means. Our lab has a long history of collaborations with the faculty of reproductive sciences at the University of Michigan. We have developed multiple ART microfluidic technologies: a sperm sorter, microfluidic insemination system, and embryo culture system. The sperm sorter uses passive flow to separate debris and dead sperm from viable sperm for later IVF. The microfluidic insemination system is a syringe driven device that increases insemination rates at lower sperm concentrations and therefore can be useful for those suffering from oligospermia. The embryo culture system uses a Braille platform developed in our lab to perfuse developing embryos in a way that mimics the fluid-mechanical and biochemical stimulation of ciliary currents and oviduct contractions to improve blastocyst development.
The human lung is one of the most physiologically complex systems in our body; the lung is exposed to cyclic stretch associated with breathing, but also fluid mechanical stresses of shear, pressure, and surface tension. It also must have a tight barrier to prevent infection, but be thin enough to permit sufficient gas exchange. Recently, our lab has developed microfluidic devices that better recapitulate the lung microenvironment. We have developed devices that create liquid plugs to study the effect of fluid stresses (shear, pressure, surface tension) on upper airway cells. To further advance our understanding of the lung – and specifically alveoli, we have created a microfluidic device that exposes alveolar cells to combined solid mechanics (stretch) and fluid mechanics (shear, pressure, surface tension) stresses. By recreating physiological and pathophysiological levels of these stresses, we can effectively study their individual and combined effects in the development of a variety of diseases including: acute respiratory distress syndrome (ARDS), ventilator-induced lung injury (VILI), neonatal respiratory distress syndrome (NRDS), and cystic fibrosis.
3D Cell Culture
Three-dimensional (3D) cell culture is motivated by the need to work with accurate models that closely mimic physiological tissues. Culture of cells as 3D aggregates is well-known to provide better accuracy in tests for basic biological research and therapeutics development. However, 3D culture models are often more complicated, cumbersome, and expensive than typical two-dimensional (2D) cultures. Our lab has utilized novel microscale technologies to develop devices that efficiently form and culture 3D spheroids from multiple cell types. Using microfluidic devices, we have created models for the detailed study of various cancer and stem cell biology. To scale up 3D culture and testing systems, our lab has also developed a versatile 384-well format cell culture plate that makes 3D spheroid formation, culture, and subsequent drug testing simple and adaptable to existing high-throughput screening (HTS) instruments. This hanging drop-based array platform allows for efficient formation of uniformly-sized spheroids, their long-term culture, and drug testing using liquid handling robots and plate readers. Our multiplexed 3D hanging drop culture and testing plate provides an efficient way to obtain biological insights that are often lost in 2D platforms.
Microenvironment Engineering and Materials Modifications
Inside living organisms, cells exist in microenvironments comprised of a complex mixture of extracellular matrix proteins, immobilized and soluble biochemicals, mineralized tissue, and various adjacent cell types. Cells dynamically interact with their surroundings – the microenvironment provides cues for cell signaling while the cell simultaneously manipulates its surroundings through chemical secretion and physical deformation. In order to understand biological processes that occur in healthy and diseased states, systems that faithfully replicate the physical, biochemical, electrical, and thermal characteristics of the microenvironment are required. Our lab uses a biocompatible polymer, polydimethylsiloxane (PDMS), to recapitulate cell microenvironments to better understand these processes. We have combined polymer modifications, biochemical diffusion, fluid flow, and thermal and electric fields to engineer representative microenvironments for muscle cells, bone marrow, metastasis, and embryo development, and are always interested in collaborations to engineer microenvironments for studying various cell systems.
Size-adjustable nanochannels and DNA linearization/stretching
Epigenetics is the study of inherited changes in gene expression caused by protein modifications of DNA. Traditional epigenetic studies use DNA microarrays to analyze epigenetic patterns; however, this process requires extensive sample preparation and can only analyze fragmented chains of DNA. We are interested in studying full-length DNA to detect epigenetic changes and have developed DNA nanochannels to this end. Nanochannels are defined as conduits with two dimensions below 100 nm. We can tightly control cross-sectional dimensions of these conduits by varying the applied external strain, thereby allowing us to linearize DNA to study physical properties of DNA and also probe epigenetic modifications.
Cancer Metastasis and Migration
The formation of secondary tumors is one of the critical aspects of cancer progression and metastasis in terms of treatment, diagnosis, and the likelihood of survival. Interesting but difficult to monitor, these tumors typically form in an organ-specific manner, many times due to secreted chemotactic molecules. For instance, metastases associated with breast cancer selectively form in the lung, liver, and bone marrow based on the existence of SDF-1, a common chemotactic molecule, yet do not form as frequently in other organ sites. In order to study the initiating step of these secondary tumors, we have developed a more physiological model allowing the observation of the interactions of circulating tumor cells and a vascular endothelium. This multi-layered membrane-based microfluidic device recapitulates vessels by combining chemical stimulation of the endothelium from the basal side and fluid flow and shear on the lumenal side. Using this system, we have elucidated molecular mechanisms underlying cancer cell adhesion and migration.