Highly conductive, stretchable, and cell‐adhesive hydrogel by nanoclay doping

Electrically conductive materials that mimic physical and biological properties of tissues are urgently required for seamless brain–machine interfaces. Here, a multinetwork hydrogel combining electrical conductivity of 26 S m−1, stretchability of 800%, and tissue‐like elastic modulus of 15 kPa with mimicry of the extracellular matrix is reported. Engineering this unique set of properties is enabled by a novel in‐scaffold polymerization approach. Colloidal hydrogels of the nanoclay Laponite are employed as supports for the assembly of secondary polymer networks. Laponite dramatically increases the conductivity of in‐scaffold polymerized poly(ethylene‐3,4‐diethoxy thiophene) in the absence of other dopants, while preserving excellent stretchability. The scaffold is coated with a layer containing adhesive peptide and polysaccharide dextran sulfate supporting the attachment, proliferation, and neuronal differentiation of human induced pluripotent stem cells directly on the surface of conductive hydrogels. Due to its compatibility with simple extrusion printing, this material promises to enable tissue‐mimetic neurostimulating electrodes

Functional skewing of the global CD8 T cell population in chronic hepatitis B virus infection

The inflamed liver in chronic hepatitis B virus (HBV) infection (CHB) is characterized by a large influx of non–virus-specific CD8 T cells. Little is known about the functional capacity of these lymphocytes, which could provide insights into mechanisms of failure of viral control and liver damage in this setting. We compared the effector function of total circulating and intrahepatic CD8 T cells in CHB patients and healthy donors. We demonstrated that CD8 T cells from CHB patients, regardless of their antigen specificity, were impaired in their ability to produce interleukin-2 and proliferate upon TCR-dependent stimulation. In contrast, these CD8 T cells had preserved production of the proinflammatory cytokines interferon-γ and tumor necrosis factor-α. This aberrant functional profile was partially attributable to down-regulation of the proximal T cell receptor signaling molecule CD3ζ, and could be corrected in vitro by transfection of CD3ζ or replenishment of the amino acid arginine required for its expression. We provide evidence for depletion of arginine in the inflamed hepatic microenvironment as a potential mechanism for these defects in global CD8 T cell signaling and function. These data imply that polarized CD8 T cells within the HBV-infected liver may impede proliferative antiviral effector function, while contributing to the proinflammatory cytokine environment

Hidden Voices of Black Men

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66982/2/10.1177_002193479402500102.pd

Electrically controlled click‐chemistry for assembly of bioactive hydrogels on diverse micro‐ and flexible electrodes

The seamless integration of electronics with living matter requires advanced materials with programmable biological and engineering properties. Here electrochemical methods to assemble semi-synthetic hydrogels directly on electronically conductive surfaces are explored. Hydrogels consisting of poly (ethylene glycol) (PEG) and heparin building blocks are polymerized by spatially controlling the click reaction between their thiol and maleimide moieties. The gels are grown as conformal coatings or 2D patterns on ITO, gold, and PtIr. This study demonstrates that such coatings significantly influence the electrochemical properties of the metal-electrolyte interface, likely due to space charge effects in the gels. Further a promising route toward engineering and electrically addressable extracellular matrices by printing arrays of gels with binary cell adhesiveness on flexible conductive surfaces is highlighted

Cytocompatible, injectable, and electroconductive soft adhesives with hybrid covalent/noncovalent dynamic network

Synthetic conductive biopolymers have gained increasing interest in tissue engineering, as they can provide a chemically defined electroconductive and biomimetic microenvironment for cells. In addition to low cytotoxicity and high biocompatibility, injectability and adhesiveness are important for many biomedical applications but have proven to be very challenging. Recent results show that fascinating material properties can be realized with a bioinspired hybrid network, especially through the synergy between irreversible covalent crosslinking and reversible noncovalent self‐assembly. Herein, a polysaccharide‐based conductive hydrogel crosslinked through noncovalent and reversible covalent reactions is reported. The hybrid material exhibits rheological properties associated with dynamic networks such as self‐healing and stress relaxation. Moreover, through fine‐tuning the network dynamics by varying covalent/noncovalent crosslinking content and incorporating electroconductive polymers, the resulting materials exhibit electroconductivity and reliable adhesive strength, at a similar range to that of clinically used fibrin glue. The conductive soft adhesives exhibit high cytocompatibility in 2D/3D cell cultures and can promote myogenic differentiation of myoblast cells. The heparin‐containing electroconductive adhesive shows high biocompatibility in immunocompetent mice, both for topical application and as injectable materials. The materials could have utilities in many biomedical applications, especially in the area of cardiovascular diseases and wound dressing

The distribution of CD45R, CD29 and CD45RO (UCHL1) antigens in mature CD4 positive T-cell leukaemias.

We have studied the expression of antigens characterizing functional T-cell subsets in 32 CD4+ mature T-cell leukaemias. In this analysis we used two monoclonal antibodies (McAb) of the CD45R group (2H4 and GRT22) which have been shown to identify the 'native/virgin' T-cell population that functions as 'suppressor-inducer' cells in vitro, and two McAb, CD29 (4B4) and CD45RO (UCHL1), which characterize non-identical 'memory' cells that proliferate in response to soluble recall antigens and provide help in antigen-specific IgG synthesis. Four groups of CD4+ cases were identified according to this reactivity: (a) 15 CD45R+, CD29+; (b) 13 CD45R-, CD29+; (c) three CD45R-, CD29-; and (d) one case only CD45+, CD29-. The high incidence of coexpression of CD45R and CD29 (47% of cases) is a new finding which contrasts with the mutual exclusion of these antigens on normal CD4+ T-lymphocytes. There was no correlation between subset phenotypes and pathological disease entities. None of the six cases of adult T-cell leukaemia/lymphoma (ATLL), which is known as a disorder of activated 'suppressor-inducer' cells, had the 'expected' CD45R+, CD29- phenotype. Reactivity with UCHL1 showed a good correlation with CD29 in the CD45R- CD29+ cases which included three with ATLL. These results may help in the further characterization of T-cell malignancies according to functional subgroups and may clarify further the role of T-differentiation antigens in health and disease