IB49140, IB49141, IB49142

An Optogenetic Platform to Dynamically Control the Stiffness of Collagen Hydrogels.

The extracellular matrix (ECM) comprises a meshwork of biomacromolecules whose composition, architecture, and macroscopic properties, such as mechanics, instruct cell fate decisions during development and disease progression. Current methods implemented in mechanotransduction studies either fail to capture real-time mechanical dynamics or utilize synthetic polymers that lack the fibrillar nature of their natural counterparts. Here we present an optogenetic-inspired tool to construct light-responsive ECM mimetic hydrogels comprised exclusively of natural ECM proteins. Optogenetic tools offer seconds temporal resolution and submicron spatial resolution, permitting researchers to probe cell signaling dynamics with unprecedented precision. Here we demonstrated our approach of using SNAP-tag and its thiol-targeted substrate, benzylguanine-maleimide, to covalently attach blue-light-responsive proteins to collagen hydrogels. The resulting material (OptoGel), in addition to encompassing the native biological activity of collagen, stiffens upon exposure to blue light and softens in the dark. Optogels have immediate use in dissecting the cellular response to acute mechanical inputs and may also have applications in next-generation biointerfacing prosthetics.

IB49140, IB49141, IB49142

A Novel Miniature CRISPR-Cas13 System for SARS-CoV-2 Diagnostics.

Rapid, point-of-care (POC) diagnostics are essential to mitigate the impacts of current (and future) epidemics; however, current methods for detecting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) require complicated laboratory tests that are generally conducted off-site and require substantial time. CRISPR-Cas systems have been harnessed to develop sensitive and specific platforms for nucleic acid detection. These detection platforms take advantage of CRISPR enzymes' RNA-guided specificity for RNA and DNA targets and collateral trans activities on single-stranded RNA and DNA reporters. Microbial genomes possess an extensive range of CRISPR enzymes with different specificities and levels of collateral activity; identifying new enzymes may improve CRISPR-based diagnostics. Here, we identified a new Cas13 variant, which we named as miniature Cas13 (mCas13), and characterized its catalytic activity. We then employed this system to design, build, and test a SARS-CoV-2 detection module coupling reverse transcription loop-mediated isothermal amplification (RT-LAMP) with the mCas13 system to detect SARS-CoV-2 in synthetic and clinical samples. Our system exhibits sensitivity and specificity comparable to other CRISPR systems. This work expands the repertoire and application of Cas13 enzymes in diagnostics and for potential in vivo applications, including RNA knockdown and editing. Importantly, our system can be potentially adapted and used in large-scale testing for diverse pathogens, including RNA and DNA viruses, and bacteria.

IB49140, IB49141, IB49142

Application of Bio-Active Elastin-like Polypeptide on Regulation of Human Mesenchymal Stem Cell Behavior.

Regenerative medicine using stem cells offers promising strategies for treating a variety of degenerative diseases. Regulation of stem cell behavior and rejuvenate senescence are required for stem cells to be clinically effective. The extracellular matrix (ECM) components have a significant impact on the stem cell's function and fate mimicking the local environment to maintain cells or generate a distinct phenotype. Here, human elastin-like polypeptide-based ECM-mimic biopolymer was designed by incorporating various cell-adhesion ligands, such as RGD and YIGSR. The significant effects of bioactive fusion ELPs named R-ELP, Y-ELP, and RY-ELP were analyzed for human bone-marrow-derived stem cell adhesion, proliferation, maintenance of stemness properties, and differentiation. Multivalent presentation of variable cell-adhesive ligands on RY-ELP polymers indeed promote efficient cell attachment and proliferation of human fibroblast cells dose-dependently. Similarly, surface modified with RY-ELP promoted strong mesenchymal stem cell (MSCs) attachment with greater focal adhesion (FA) complex formation at 6 h post-incubation. The rate of cell proliferation, migration, population doubling time, and collagen I deposition were significantly enhanced in the presence of RY-ELP compared with other fusion ELPs. Together, the expression of multipotent markers and differentiation capacity of MSCs remained unaffected, clearly demonstrating that stemness properties of MSCs were well preserved when cultured on a RY-ELP-modified surface. Hence, bioactive RY-ELP offers an anchorage support system and effectively induces stimulatory response to support stem cell proliferation.

IB49140, IB49141, IB49142

A thermophilic Cas13 enzyme for sensitive and specific one-pot detection of SARS-CoV-2

Robust, sensitive, and specific diagnostic platforms for early pathogen detection are essential for the identification of infected patients and management of current and future pandemics. CRISPR-Cas systems have been repurposed for SARS-CoV-2 detection in two-pot assays. Two-pot assays require extra steps and are prone to cross-contamination; however, the temperature range of current Cas enzymes limits the development of one-pot assays Here, we characterized TccCas13a, a thermophilic Cas13a enzyme with cis and trans activities from 37–70°C, and HheCas13a, which had a limited range and lower activity. We harnessed TccCas13a in a one-pot SARS-CoV-2 assay with two layers of amplification and TccCas13a-mediated collateral degradation of a single-stranded RNA reporter. This assay showed 95% sensitivity and 100% specificity compared with RT-qPCR on clinical samples. We also developed a mobile phone application to facilitate data reading, collection, and sharing. Our OPTIMA-dx detection module exhibits key features for point-of-care SARS-CoV-2 screening and pathogen detection in general.