Mesenchymal stromal cells with chimaeric antigen receptors for enhanced immunosuppression.

Allogeneic mesenchymal stromal cells (MSCs) are a safe treatment option for many disorders of the immune system. However, clinical trials using MSCs have shown inconsistent therapeutic efficacy, mostly owing to MSCs providing insufficient immunosuppression in target tissues. Here we show that antigen-specific immunosuppression can be enhanced by genetically modifying MSCs with chimaeric antigen receptors (CARs), as we show for E-cadherin-targeted CAR-MSCs for the treatment of graft-versus-host disease in mice. CAR-MSCs led to superior T-cell suppression and localization to E-cadherin+ colonic cells, ameliorating the animals' symptoms and survival rates. On antigen-specific stimulation, CAR-MSCs upregulated the expression of immunosuppressive genes and receptors for T-cell inhibition as well as the production of immunosuppressive cytokines while maintaining their stem cell phenotype and safety profile in the animal models. CAR-MSCs may represent a widely applicable therapeutic technology for enhancing immunosuppression.

Comparison of replicating and nonreplicating vaccines against SARS-CoV-2.

Most gene-based severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines are nonreplicating vectors. They deliver the gene or messenger RNA to the cell to express the spike protein but do not replicate to amplify antigen production. This study tested the utility of replication in a vaccine by comparing replication-defective adenovirus (RD-Ad) and replicating single-cycle adenovirus (SC-Ad) vaccines that express the SARS-CoV-2 spike protein. SC-Ad produced 100 times more spike protein than RD-Ad and generated significantly higher antibodies against the spike protein than RD-Ad after single immunization of Ad-permissive hamsters. SC-Ad-generated antibodies climbed over 14 weeks after single immunization and persisted for more than 10 months. When the hamsters were challenged 10.5 months after single immunization, a single intranasal or intramuscular immunization with SC-Ad-Spike reduced SARS-CoV-2 viral loads and damage in the lungs and preserved body weight better than vaccination with RD-Ad-Spike. This demonstrates the utility of harnessing replication in vaccines to amplify protection against infectious diseases.

Oncolytic virus-mediated expansion of dual-specific CAR T cells improves efficacy against solid tumors in mice.

Oncolytic viruses (OVs) encoding a variety of transgenes have been evaluated as therapeutic tools to increase the efficacy of chimeric antigen receptor (CAR)-modified T cells in the solid tumor microenvironment (TME). Here, using systemically delivered OVs and CAR T cells in immunocompetent mouse models, we have defined a mechanism by which OVs can potentiate CAR T cell efficacy against solid tumor models of melanoma and glioma. We show that stimulation of the native T cell receptor (TCR) with viral or virally encoded epitopes gives rise to enhanced proliferation, CAR-directed antitumor function, and distinct memory phenotypes. In vivo expansion of dual-specific (DS) CAR T cells was leveraged by in vitro preloading with oncolytic vesicular stomatitis virus (VSV) or reovirus, allowing for a further in vivo expansion and reactivation of T cells by homologous boosting. This treatment led to prolonged survival of mice with subcutaneous melanoma and intracranial glioma tumors. Human CD19 CAR T cells could also be expanded in vitro with TCR reactivity against viral or virally encoded antigens and was associated with greater CAR-directed cytokine production. Our data highlight the utility of combining OV and CAR T cell therapy and show that stimulation of the native TCR can be exploited to enhance CAR T cell activity and efficacy in mice.

Structure-determining step in the hierarchical assembly of peptoid nanosheets.

Organic two-dimensional nanomaterials are of growing importance, yet few general synthetic methods exist to produce them in high yields and to precisely functionalize them. We previously developed an efficient hierarchical supramolecular assembly route to peptoid bilayer nanosheets, where the organization of biomimetic polymer sequences is catalyzed by an air-water interface. Here we determine at which stages of assembly the nanoscale and atomic-scale order appear. We used X-ray scattering, grazing incidence X-ray scattering at the air-water interface, electron diffraction, and a recently developed computational coarse-grained peptoid model to probe the molecular ordering at various stages of assembly. We found that lateral packing and organization of the chains occurs during the formation of a peptoid monolayer, prior to its collapse into a bilayer. Identifying the structure-determining step enables strategies to influence nanosheet order, to predict and optimize production yields, and to further engineer this class of material. More generally, our results provide a guide for using fluid interfaces to catalytically assemble 2D nanomaterials.

Antibody-mimetic peptoid nanosheets for molecular recognition.

The ability of antibodies to bind a wide variety of analytes with high specificity and high affinity make them ideal candidates as molecular recognition elements for chemical and biological sensors. However, their widespread use in sensing devices has been hampered by their poor stability and high production cost. Here we report the design and synthesis of a new class of antibody-mimetic materials based on functionalized peptoid nanosheets. A high density of conformationally constrained peptide and peptoid loops are displayed on the surface of free-floating nanosheets to generate an extended, multivalent two-dimensional material that is chemically and biologically stable. The nanosheet serves as a robust, high-surface area scaffold upon which to display a wide variety of functional loop sequences. The functionalized nanosheets were characterized by atomic force microscopy, X-ray diffraction, and X-ray reflectivity measurements, and were shown to serve as substrates for enzymes (protease and casein kinase II), as well as templates for the growth of defined inorganic materials (gold metal).

Shaken, not stirred: collapsing a peptoid monolayer to produce free-floating, stable nanosheets.

Two-dimensional nanomaterials play a critical role in biology (e.g., lipid bilayers) and electronics (e.g., graphene) but are difficult to directly synthesize with a high level of precision. Peptoid nanosheet bilayers are a versatile synthetic platform for constructing multifunctional, precisely ordered two-dimensional nanostructures. Here we show that nanosheet formation occurs through an unusual monolayer intermediate at the air-water interface. Lateral compression of a self-assembled peptoid monolayer beyond a critical collapse pressure results in the irreversible production of nanosheets. An unusual thermodynamic cycle is employed on a preparative scale, where mechanical energy is used to buckle an intermediate monolayer into a more stable nanosheet. Detailed physical studies of the monolayer-compression mechanism revealed a simple preparative technique to produce nanosheets in 95% overall yield by cyclical monolayer compressions in a rotating closed vial. Compression of monolayers into stable, free-floating products may be a general and preparative approach to access 2D nanomaterials.

Invariance of the solid-liquid interfacial energy in electrowetting probed via capillary condensation.

Capillary condensation is employed to probe the solid-liquid interfacial energy in electrowetting on dielectric. The height of an annular water meniscus formed via capillary condensation inside the surface force apparatus is measured as a function of the potential applied across the meniscus and the dielectric stack where the meniscus is formed. According to the Kelvin equation, a decrease in the solid-liquid interfacial energy at constant temperature and relative humidity should lead to an increase in the meniscus height. Our experimental results on nanometer-sized meniscus are in agreement with the work of Mugele [J. Phys.: Condens. Matter 2007, 19, 375112] and unequivocally demonstrate that the real contact angle (or the solid-liquid interfacial energy) remains unaltered in electrowetting on dielectric.

Supramolecular ion-pair interactions to control monolayer assembly.

We demonstrate that noncovalent ion-pair interactions in solution can be employed to control the molecular spacing of thiols in a self-assembled monolayer (SAM) on gold. Ion-pairs formed between the carboxylate tail-group of 16-mercaptohexadecanoic acid (MHA) and tetraalkylammonium (TAA+) hydroxide salts of various alkyl side-chain lengths remain intact during chemisorption of the thiol on gold. The resulting ion-pair SAMs exhibit a 1:1 molar ratio of MHA:TAA+ on the surface and are covalently bound to the gold surface through the thiol headgroup of MHA. We hypothesize that the incorporation of the bulky TAA+ group competes with the strong tendency of the thiols to organize into an ordered monolayer, which highlights the strength of the ion-pair complexes. The ion-pair films can be converted into a loosely packed MHA monolayer by rinsing the SAM with a solution of potassium perchlorate, which releases the TAA+ from the surface. Contact angle measurements and X-ray spectroscopy (XPS) confirm the stoichiometry and covalent attachment of the monolayers. XPS analysis and contact angle measurements indicate that the surface density of bound MHA decreases with increasing size of the TAA+ cation. These results suggest that steric hindrance created by the bulky side-chains of the TAA+ cation dictates the lateral spacing of MHA chains on the surface.

Oral delivery of insulin loaded poly(fumaric-co-sebacic) anhydride microspheres.

The bioadhesive polymer, poly(fumaric-co-sebacic) anhydride, p(FASA), was used to fabricate small diameter insulin microspheres and evaluate their in vivo performance in a type 1 diabetic rat as well as a type 1 diabetic dog model. The process of phase inversion nanoencapsulation was used to fabricate p(FASA) microspheres containing insulin. Using laser diffraction spectrometry, 90% of the microspheres used in the fed double dose rat experiments were found to have a volumetric diameter of 5.9 microm or smaller. In comparison, 90% of the microspheres used in fed single dose rat experiments were found to have a volumetric diameter of 2.6 microm or smaller while the microspheres used in the diabetic dog experiments were found to have a volumetric diameter of 1.2 microm or smaller. Insulin microspheres administered to diabetic rats in the fed double dose experiment produced a relative bioavailability (RB) of 23.3% while insulin microspheres administered to diabetic rats in the fed single dose experiment produced a RB of 5.5+/-1.7%. Insulin microspheres administered to fasted diabetic dogs produced a RB of 5.5+/-3.4%.