In this issue: Biotechnolgy Journal 5/2011

Abstract

AbstractLaser injection of nanoparticlesUmanzor‐Alvarez et al., Biotechnol. J. 2011, 6, 519–524Targeted delivery of materials to individual cells remains a challenge in nanoscience and nanomedicine. While manual microinjection is used for large cells, it is impractical in smaller dimensions, such as mammalian or bacterial cells. Near infrared (NIR) laser injection may be a promising alternative. In this issue, authors from Virginia Polytechnic Institute and State University and Norfolk State University, (Blacksburg and Norfolk, VA, USA) report on the efficacy and toxicity of delivering quantum dots (QDs) into cells of Xenopus laevis embryos by NIR laser injection. This model system allows monitoring in living cells and a developing organism at the same time. Parameters for NIR pulses were identified that did not affect embryonic viability or morphology and delivered QDs as effectively as manual injection.Medium flow stimulates gene expressionVinci et al., Biotechnol. J. 2011, 6, 544–564Primary cultures of adult human liver cells are currently regarded as gold standard for investigating drug metabolism, toxicity and side effects. However, down‐regulation of detoxification genes, notably cytochrome P450 (CYPs), in primary hepatocyte cultures is a long‐standing and major concern. In this issue, researchers from Pisa, Italy, and Montpellier, France, evaluate the influence of medium flow in a multichamber modular bioreactor (MCmB) on gene expression and enzyme activities involved in drug metabolism and transport. A number of CYPs as well as multidrug resistance proteins 1 and 2, were specifically up‐regulated by medium flow as compared with static controls. Down‐regulation of detoxification genes in conventional (static) cultures is therefore partly a consequence of the absence of medium circulation.Stem cell stimulationViitanen et al., Biotechnol. J. 2011, 6, 600–603Typical multielectrode arrays (MEAs) using TiN, Pt, Au, or indium tin oxide (ITO) electrode materials are suitable for measurement applications. However, when they are used for long term stimulation of cells, these conductive materials may produce compounds that are toxic. In addition, for larger cell clusters, MEAs with small area electrode tips do not provide sufficient long range and evenly distributed potential gradients. In this issue, Authors from Tampere, Finland, describe the construction of electrode structures using plain titanium on glass as the electrode material. These structures were placed on the bottom of microtiter plate wells where the cells were incubated. This technique could successfully be used for long‐term stimulation of human embryonic stem cell (hESC)‐derived cardiomyocyte clusters on thinfilm microelectrode structures.