Alveolar type II epithelial (ATII) cells repopulate the alveolus after acute lung injury. We hypothesized that injury would initiate signals in nearby survivors. When rat ATII monolayers were wounded, elevations in intracellular free Ca2+ concentration ([Ca2+]i) began at the edge of the wound and propagated outward as a wave for at least 300 μm. The [Ca2+]iwave was due to both influx of extracellular Ca2+ and release of intracellular Ca2+ stores. Reducing Ca2+ influx with brief treatments of ethylene glycol-bis(β-aminoethyl ether)- N, N, N′, N′-tetraacetic acid or Gd3+ reduced both the amplitude and the apparent speed. Draining intracellular Ca2+ stores by pretreatment with cyclopiazonic acid eliminated the [Ca2+]iwave. Therefore, the [Ca2+]iwave depended critically on intracellular Ca2+ stores. [Ca2+]ielevations propagated over a break in the monolayer, suggesting that extracellular pathways were involved. Furthermore, extracellular factors from injured cells elevated [Ca2+]iin uninjured cultures. We conclude that wounding produces a [Ca2+]iwave in surviving cells and part of this response is mediated by soluble factors released into the extracellular space during injury.
A three-compartment bioartificial liver (BAL) has been developed for potential treatment of fulminant hepatic failure. It has been shown previously that viability and liver-specific functions were maintained in laboratory-scale bioreactors of such design. In this study, the performance of hepatocytes in a clinical-scale bioartificial liver was verified by sustained specific production rates of albumin and urea, along with oxygen consumption rates for up to 56 h and liver-specific gene expression for up to 72 h. In addition, transmission of porcine endogenous retrovirus and other type C retroviral particles across the hollow fibers was not detected under both normal and extreme operating fluxes. These results demonstrate that the clinical-scale BAL performs at a level similar to the laboratory scale and that it offers a viral barrier against porcine retroviruses.
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