BE Seminars & Events

July 12, 2013 we celebrated bicentennial of Claude Bernard, who has established a dominant tradition of experimental medicine/physiology, which is based on rigorous experimental investigation of animal models of pathological and normal physiological mechanisms at different scales. This approach served us well and resulted in more and more deepening understanding of physiology at the system, organ, cellular, and molecular levels. However, clinical translation of molecular and cellular findings is increasingly frustrated by significant physiological and pharmacological differences between human, on the one hand, and handful of popular animal models, on the other hand. Cardiovascular physiology is a particularly striking example of rather limited success of translation from bench to bedside. To bridge the gap between the basic physiology and clinical cardiology we have established the Human Heart Physiology Program at Washington University in Saint Louis, which has procured and studied in vitro using state of the art imaging and electrophysiology methodology 250 live human hearts from donors and patients with heart failure. Our studies have revealed the human-specific mechanisms responsible for lethal arrhythmias and impaired excitation-contraction coupling associated with heart failure, including: (1) slow conduction, (2) delayed repolarization, (3) altered calcium handling; (4) retarded metabolism; (5) altered feed-back loops of beta-adrenergic system. Our studies have confirmed the clinical validity of a number of mechanistic findings in animal models, but also uncovered several significant discrepancies between animal models and humans. Conclusions: Rigorous physiological bench investigation of the human cardiovascular system in health and disease is required to improve clinical translation of discoveries in animal models.

The brain is a complex, densely wired circuit made out of heterogeneous cells, which vary in their shapes, molecular composition, and patterns of connectivity. In order to help discover how neural circuits implement brain functions, and how these computations go awry in brain disorders, we invent technologies to enable the scalable, systematic observation and control of biological structures and processes in the living brain. We have developed genetically-encoded reagents that, when expressed in specific neuron types in the nervous system, enable their electrical activities to be precisely driven or silenced in response to millisecond timescale pulses of light. I will give an overview of these “optogenetic” tools, adapted from natural photosensory and photosynthetic proteins, and discuss new tools we are developing, including molecules with novel color sensitivities and other unique capabilities. Often working in interdisciplinary collaborations, we have developed microfabricated hardware to enable complex and distributed neural circuits to be controlled and observed in a fully 3-D fashion, as well as robots that can automatically record neurons intracellularly and integratively in live brain. These tools are in widespread use to enable systematic analysis of neural circuit functions, are also opening up new frontiers on the understanding and treatment of brain disorders, and may serve as components of new platforms for diagnosing and treating brain disease.

Nanoparticles with unique physical and chemical properties can be rendered water-soluble and biocompatible for use in cancer diagnosis, imaging and therapy. This talk will highlight some of the recent advances in the following four areas: 1) application of materials in improving the sensitivity of biomarker detection; 2) use of different nanomaterials (both rigid inorganic materials and biodegradable polymeric materials) for multimodality imaging (PET, optical, MRI, photoacoustic, etc); 3) drug and gene loaded nanomaterials for cancer therapy; and 4) theranostic nanoplatforms with both imaging and therapeutic components combined. The challenges and future perspectives of nanomedicine in cancer research will also be discussed.

Whole-cell patch clamp electrophysiology of neurons in vivo enables the recording of electrical events in cells with great precision, and supports a wide diversity of cellular morphological and molecular analysis experiments. However, high levels of skill are required in order to perform in vivo patching, and the process is time-consuming and painstaking. An automated in vivo patching robot would not only empower a great number of neuroscientists to perform such experiments, but would also open up fundamentally new kinds of experiment enabled by the resultant high throughput. We discovered that in vivo blind whole cell patch clamp electrophysiology could be implemented as a straightforward algorithm, and developed an automated robotic system capable of performing this algorithm. We validated the performance of our robot in both the cortex and hippocampus of anesthetized and awake mice. Our robot achieves yields, cell recording qualities, and operational speeds that are comparable to, or exceed, those of experienced human investigators, and is simple and inexpensive to implement. Recent developments include coupling "autopatching" to optogenetics, recording multiple neurons simultaneously, and patching deep structures including mouse brain stem.

Cell deformability (i.e., the ability to change shape under an applied force) is a promising physical marker indicative of underlying structural changes associated with various disease processes and changes in cell state. We are combining precision microfluidic control of cells with automated high-speed image analysis for high-throughput cell classification based on intrinsic biomechanical properties. I will first discuss general strategies we are developing to passively manipulate particles and fluids using simple geometric modifications within microchannels. Our approaches make use of fluid inertia, generally neglected in microfluidic systems, to create well-defined directional forces and fluid deformations that can be combined in a sequential and hierarchical manner to program complex particle and fluid motions. Low complexity modular components to manipulate cells, particles, and fluid streams in which inertial fluid physics is abstracted from the designer has the capability transform biological, chemical, and materials automation in a similar fashion to how modular control of electrons and abstraction of semiconductor physics transformed computation. We apply these fundamental techniques to position cells for high-speed fluid-based deformation and optical analysis. The “deformability cytometer” instrument shows promise in identifying cancer cells, activated white blood cells, and stem cells in mixed populations – without labels - for a variety of clinical and regenerative medicine applications.

Sessile marine organisms are very effective at adhering to substrates under wet conditions and in harsh environments. The proteins employed by mussels, for example, have very specialized amino acid compositions undoubtedly related to the particular challenges of achieving permanent adhesion in the wet marine environment. Mussel adhesive proteins (MAPs) are known to contain high levels of 3,4-dihydroxy-L-alanine (DOPA), a catecholic amino acid that is believed to confer cohesive and adhesive properties to these proteins. I will summarize the adhesive and cohesive roles of DOPA, and describe our efforts to develop biomimetic polymer hydrogels and coatings from synthetic catechol-containing polymers. Synthetic mimics of MAPs take the form of linear or branched polymers with catecholic endgroups or side chains, where the catechols serve the role of a cross-linking component, or surface anchor for attachment to surfaces. These biologically inspired polymers have a variety of functional uses, including tissue repair, drug delivery and antifouling coatings.

Abstract forthcoming.