Revzin, Alexander

ABSTRACT Encapsulation of human pluripotent stem cells (hPSC) has high relevance for biomedical applications ranging from tissue engineering to drug screening and cellular therapies. Microcapsules serve a multitude of purposes—from promoting hPSC organization into spheroids to enabling scalable differentiation in vitro and providing immunoisolation in vivo. While multiple encapsulation strategies have been reported, there is typically a tradeoff between the structural complexity of capsules and throughput of their generation. Our paper describes a novel 3D printed microfluidic encapsulation device for fabricating structurally complex microcapsules with a hydrogel shell and aqueous core at rates of up to 1825 Hz. The use of 3D printing allowed to dramatically decrease device footprint when compared to standard soft lithography‐based microfluidic encapsulation devices. Leveraging decreased footprint and the ability to arrange fluidic networks in a 3D space, we fabricated a 10‐nozzle microencapsulation device that generated microcapsules at a rate 10‐times that of the single‐nozzle device. The novel microfluidic device was used to encapsulate hPSCs, human embryonic stem cells (hESCs), and induced pluripotent stem cells (iPSCs). Hydrogel microcapsules with aqueous core promoted hPSCs aggregation into spheroids or embryoid bodies, which maintained high levels of pluripotency. Our technology enables safe and effective encapsulation of hPSCs on a scale (billions of cells) required to treat patients.

Abstract Vaccine‐induced immune thrombotic thrombocytopenia (VITT) is a new disorder that emerged in the wake of coronavirus disease 2019 (COVID‐19) vaccination. It is a rare but life‐threatening condition that requires an aggressive course of treatment to improve patient outcomes. Currently, the diagnosis of VITT relies on a comprehensive panel of criteria, including a history of recent vaccination, platelet count, positive enzyme linked immunosorbent assays (ELISA) result for a closely related thrombotic disorder, heparin‐induced thrombocytopenia (HIT), and platelet factor 4 (PF4)‐dependent functional assays. The study describes a technically simple antigenic assay designed to detect autoimmune antibodies associated with VITT. It is first shown that cross‐linked platelet factor 4 (c‐PF4) represents an antigenic target specific for VITT/VITT‐like Abs. This antigenic target is then incorporated into a microfluidic electrochemical biosensor and specific and sensitive detection of VITT/VITT‐like antibodies is demonstrated in a fully automated manner while using microliter volumes of patient sera. Fifty‐five serum samples are tested using the microfluidic electrochemical biosensor and demonstrated high accuracy for the detection of VITT sera and VITT‐like monoclonal gammopathy of thrombotic ignificance (MGTS) antibodies compared to healthy controls and HIT patients. It is envisioned that the microfluidic electrochemical biosensor will be used in combination with other clinical criteria to enable timely, sensitive, and specific diagnosis of VITT.

This review describes approaches for encapsulation of pluripotent stem cells, the biomaterials used, strategies for differentiation into hepatocytes and β cells, and the impact of microencapsulation on cellular therapy.

AbstractPatient‐derived cancer organoids (PDOs) hold considerable promise for personalizing therapy selection and improving patient outcomes. However, it is challenging to generate PDOs in sufficient numbers to test therapies in standard culture platforms. This challenge is particularly acute for pancreatic ductal adenocarcinoma (PDAC) where most patients are diagnosed at an advanced stage with non‐resectable tumors and where patient tissue is in the form of needle biopsies. Here the development and characterization of microfluidic devices for testing therapies using a limited amount of tissue or PDOs available from PDAC biopsies is described. It is demonstrated that microfluidic PDOs are phenotypically and genotypically similar to the gold‐standard Matrigel organoids with the advantages of 1) spheroid uniformity, 2) minimal cell number requirement, and 3) not relying on Matrigel. The utility of microfluidic PDOs is proven by testing PDO responses to several chemotherapies, including an inhibitor of glycogen synthase kinase (GSKI). In addition, microfluidic organoid cultures are used to test effectiveness of immunotherapy comprised of NK cells in combination with a novel biologic. In summary, our microfluidic device offers considerable benefits for personalizing oncology based on cancer biopsies and may, in the future, be developed into a companion diagnostic for chemotherapy or immunotherapy treatments.