Multicompartment Microreactors Prevent Excitotoxic Dysfunctions In Rat Primary Cortical Neurons

Artificial Cells and HepG2 Cells in 3D-Bioprinted Arrangements

Artificial cells are engineered units with cell-like functions for different purposes including acting as supportive elements for mammalian cells. Artificial cells with minimal liver-like function are made of alginate and equipped with metalloporphyrins that mimic the enzyme activity of a member of the cytochrome P450 family namely CYP1A2. The artificial cells are employed to enhance the dealkylation activity within 3D bioprinted structures composed of HepG2 cells and these artificial cells. This enhancement is monitored through the conversion of resorufin ethyl ether to resorufin. HepG2 cell aggregates are 3D bioprinted using an alginate/gelatin methacryloyl ink, resulting in the successful proliferation of the HepG2 cells. The composite ink made of an alginate/gelatin liquid phase with an increasing amount of artificial cells is characterized. The CYP1A2-like activity of artificial cells is preserved over at least 35 days, where 6 nM resorufin is produced in 8 h. Composite inks made of artificial cells and HepG2 cell aggregates in a liquid phase are used for 3D bioprinting. The HepG2 cells proliferate over 35 days, and the structure has boosted CYP1A2 activity. The integration of artificial cells and their living counterparts into larger 3D semi-synthetic tissues is a step towards exploring bottom-up synthetic biology in tissue engineering.

Antioxidant Microgels Support Peroxide-Challenged Hepatic Cells

Access to therapeutic strategies that counter cellular stress induced by reactive oxygen species (ROS) is an important, long-standing challenge. Here, the assembly of antioxidant artificial cells is based on alginate hydrogels equipped with non-native catalysts, namely platinum nanoparticles and an EUK compound. These artificial cells are able to preserve the viability and lower the intracellular ROS levels of challenged hepatic cells by removing peroxides from the extracellular environment. Conceptually, this strategy illustrates the potential use of artificial cells with a synthetic catalyst toward long-term support of hepatic cells and potentially other mammalian cells.

Artificial cells eavesdropping on HepG2 cells

Cellular communication is a fundamental feature to ensure the survival of cellular assemblies, such as multicellular tissue, via coordinated adaption to changes in their surroundings. Consequently, the development of integrated semi-synthetic systems consisting of artificial cells (ACs) and mammalian cells requires feedback-based interactions. Here, we illustrate that ACs can eavesdrop on HepG2 cells focusing on the activity of cytochrome P450 1A2 (CYP1A2), an enzyme from the cytochrome P450 enzyme family. Specifically, d-cysteine is sent as a signal from the ACs via the triggered reduction of disulfide bonds. Simultaneously, HepG2 cells enzymatically convert 2-cyano-6-methoxybenzothiazole into 2-cyano-6-hydroxybenzothiazole that is released in the extracellular space. d-Cysteine and 2-cyano-6-hydroxybenzothiazole react to form d-luciferin. The ACs respond to this signal by converting d-luciferin into luminescence due to the presence of encapsulated luciferase in the ACs. As a result, the ACs can eavesdrop on the mammalian cells to evaluate the level of hepatic CYP1A2 function.

Platinum nanoparticle-based microreactors protect against the behavioral and neurobiological consequences of chronic stress exposure

Excitotoxicity is described as the exacerbated activation of glutamate AMPA and NMDA receptors that leads to neuronal damage, and ultimately to cell death. Astrocytes are responsible for the clearance of 80-90% of synaptically released glutamate, preventing excitotoxicity. Chronic stress renders neurons vulnerable to excitotoxicity and has been associated to neuropsychiatric disorders, i.e., anxiety. Microreactors containing platinum nanoparticles (Pt-NP) and glutamate dehydrogenase have shown in vitro activity against excitotoxicity. The purpose of the present study was to investigate the in vivo effects of these microreactors on the behavioral and neurobiological effects of chronic stress exposure. Rats were either unstressed or exposed for 2 weeks to an unpredictable chronic mild stress paradigm (UCMS), administered intra-ventral hippocampus with the microreactors (with or without the blockage of astrocyte functioning), and seven days later tested in the elevated T-maze (ETM; Experiment 1). The ETM allows the measurement of two defensive responses, avoidance and escape, in terms of psychopathology respectively related to generalized anxiety and panic disorder. Locomotor activity in an open field was also measured. Since previous evidence shows that stress inhibits adult neurogenesis, we evaluated the effects of the different treatments on the number of cells expressing the marker of migrating neuroblasts doublecortin (DCX) in the dorsal and ventral hippocampus (Experiment 2). Results showed that UCMS induces anxiogenic effects, increases locomotion, and decreases the number of DCX cells in the dorsal and ventral hippocampus, effects that were counteracted by microreactor administration. This is the first study to demonstrate the in vivo efficacy of Pt-NP against the behavioral and neurobiological effects of chronic stress exposure.