2017-2018

Engineering the cellular microenvironment

In vivo, the cellular microenvironment is a combination of specific, localized stimuli of mechanical, chemical, and sometimes electrical cues that guide cellular responses and dictate their physiology. In vitro cell culture rarely captures any of this localized microenvironmental influence and as a result is often lacking in providing detailed insight into native (in vivo-like) cellular responses. With recent advances in nontraditional material micro- and nanofabrication, we are now able to control local mechanical stimuli by precise placement of structures with different mechanical and chemical properties to study their effects on cellular attachment, proliferation, differentiation, and metabolism. In this presentation, tools for controlling the cellular mechanical and chemical microenvironment will be presented, along with microfluidic tools for more precise interactions and control of cells and cellular products. Specific examples including our new technology for localized control of chemical delivery based on localized electroosmotic flow through nanofluidic membranes to individual cells (Single Cell Culture Wells, SiCCWells), tools for studying tumor cell migration based on microtopography, and enhancing implant-tissue bonding through defined microtopography will be discussed. With the combination of these techniques, we now have a wide array of parameters available to test single cell or cell cluster cultures for providing more detailed analyses of the effects of individual parameters on cell physiology, and more precise tools for analyzing patient samples.

The Revolution Will Be Compartmentalized

The NIH Molecular Libraries Program (MLP) was founded to translate the discoveries of the Human Genome Project into therapeutics through a network of high-throughput screening (HTS) centers. A decade of discovery produced hundreds of probes — highly selective small molecules that modulate cellular function — but centralized compound screening bears the same cost and infrastructure burdens of millennial DNA sequencing centers, which has limited access to the technology and, more significantly, the rate of small molecule discovery. We are building a distributable drug discovery platform consisting of DNA-encoded combinatorial compound bead libraries and microfluidic integrated circuits that load individual compound library beads into picoliter-scale droplets of assay reagent, photochemically cleave the compound from the bead and into the droplet, incubate the dosed droplets, and sort hit-containing droplets based on biological activity for DNA amplification and sequencing. We have now synthesized various DNA-encoded compound libraries, developed droplet-scale assays for diverse targets (HIV-1 protease, ZIKV NS2B-NS3 protease, autotaxin, bacterial ribosome), and discovered new inhibitor hit structure families during library screening. The scalability of this platform will democratize drug discovery and replenish the pipeline of therapeutics, especially those targeting rapidly-evolving bacterial and viral pathogens, and neglected diseases.