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The P2X7 receptor (P2X7R) is a cation membrane channel activated by extracellular adenosine 5′-triphosphate. Activation of this receptor results in numerous downstream events including the modulation of neurotransmission, release of pro-inflammatory mediators, cell proliferation or cell death. While the expression of P2X7Rs is well documented on microglia and oligodendrocytes, the presence of functional P2X7Rs on neurons and astrocytes remains debated. Furthermore, to date, functional studies on the P2X7R are mostly limited to studies in cells from rodents and immortalised cell lines expressing human P2X7Rs. To assess the functional expression of P2X7Rs in human neurons and astrocytes, we differentiated human-induced pluripotent stem cells (hiPSCs) into forebrain cortical neurons that co-express FOXG1 and βIII-tubulin as well as S100 β-expressing astrocytes. Immunostaining revealed prominent punctate P2X7R staining on the soma and processes of hiPSC-derived neurons and astrocytes. In addition, our data show that stimulation with the potent nonselective P2X7R agonist BzATP induces robust calcium rises in hiPSC-derived neurons and astrocytes, which were blocked by the selective P2X7R antagonist AFC-5128. Together, our findings provide evidence for the functional expression of P2X7Rs in hiPSC-derived forebrain cortical neurons and astrocytes demonstrating that these cells offer the potential for investigating P2X7R-mediated pathophysiology and drug screening in vitro.

GaInAsP/InP passive microring resonator devices were successfully fabricated using a vertical integration concept with GaInAsP/InP-on-GaAs wafer bonding. BCB adhesive bonding has been identified as the preferred wafer bonding process. This paper reports results on the development of the wafer bonding and on the microring fabrication.