Application of lung microphysiological systems to COVID-19 modeling and drug discovery: a review

There is a pressing need for effective therapeutics for coronavirus disease 2019 (COVID-19), the respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. The process of drug development is a costly and meticulously paced process, where progress is often hindered by the failure of initially promising leads. To aid this challenge, in vitro human microphysiological systems need to be refined and adapted for mechanistic studies and drug screening, thereby saving valuable time and resources during a pandemic crisis. The SARS-CoV-2 virus attacks the lung, an organ where the unique three-dimensional (3D) structure of its functional units is critical for proper respiratory function. The in vitro lung models essentially recapitulate the distinct tissue structure and the dynamic mechanical and biological interactions between different cell types. Current model systems include Transwell, organoid and organ-on-a-chip or microphysiological systems (MPSs). We review models that have direct relevance toward modeling the pathology of COVID-19, including the processes of inflammation, edema, coagulation, as well as lung immune function. We also consider the practical issues that may influence the design and fabrication of MPS. The role of lung MPS is addressed in the context of multi-organ models, and it is discussed how high-throughput screening and artificial intelligence can be integrated with lung MPS to accelerate drug development for COVID-19 and other infectious diseases.

Solution structure of two molecular motor domains: nonclaret disjunctional and kinesin

The effects of selected ligands on the structure of the truncated heavy-chain chemomechanical motor domains of Drosophila ncd and human kinesin were compared using the technique of transient electric birefringence. The 366-amino acid C-terminal motor domain of Drosophila nonclaret disjunctional, ncd(335-700), and the 349-amino acid N-terminal motor domain of human kinesin, kinesin(349), were studied at 4 degrees C in neutral buffers with ionic strength of 100 mM to form complexes with either MgADP or MgADP.Vi. The rotational diffusion time adjusted to 20 degrees C and water, tau 20,W, for ncd(335-700).MgADP is 32.8 ns, and for ncd(335-700).MgADP.Vi is 34.8 ns, suggesting prolate ellipsoids with dimensions 9.40 x 3.77 nm and 9.73 x 3.70 nm, respectively. The specific Kerr constant, Ksp, of ncd is -1.65 x 10(-12) cm2V-2 for the MgADP complex and -1.15 x 10(-12) cm2V-2 for the MgADP.Vi complex. The large negative Ksp for a prolate protein suggests an unusual charge distribution with two long surfaces with opposite charge. The tau 20,W for kinesin(349).MgADP is longer than the corresponding ncd motor and shows a decrease with increased electric field. The kinesin(349).MgADP.Vi complex has a longer tau 20,W. The Ksp for kinesin(349) is 0.36 x 10(-12) cm2V-2 for each complex.