Strain-induced bands of Büngner formation promotes axon growth in 3D tissue-engineered constructs.

Treatment of peripheral nerve lesions remains a major challenge due to poor functional recovery; hence, ongoing research efforts strive to enhance peripheral nerve repair. In this study, we aimed to establish three-dimensional tissue-engineered bands of Büngner constructs by subjecting Schwann cells (SCs) embedded in fibrin hydrogels to mechanical stimulation. We show for the first time that the application of strain induces (i) longitudinal alignment of SCs resembling bands of Büngner, and (ii) the expression of a pronounced repair SC phenotype as evidenced by upregulation of BDNF, NGF, and p75.

On-column virus inactivation by solvent/detergent treatment for a recombinant biological product.

Each process step in the manufacture of biological products requires expensive resources and reduces total process productivity. Since downstream processing of biologicals is the main cost driver, process intensification is a persistent topic during the entire product life cycle. We present here one approach for the intensification of bioprocesses by applying on-column virus inactivation using solvent/detergent (S/D) treatment during ion-exchange chromatography.

A microfluidic impedance-based extended infectivity assay: combining retroviral amplification and cytopathic effect monitoring on a single lab-on-a-chip platform.

Detection, quantification and monitoring of virus - host cell interactions are of great importance when evaluating the safety of pharmaceutical products. With the wide usage of viral based vector systems in combination with mammalian cell lines for the production of biopharmaceuticals, the presence of replication competent viral particles needs to be avoided and potential hazards carefully assessed. Consequently, regulatory agencies recommend viral clearance studies using plaque assays or TCID assays to evaluate the efficiency of the production process in removing viruses.

Engineering of three-dimensional pre-vascular networks within fibrin hydrogel constructs by microfluidic control over reciprocal cell signaling.

Reengineering functional vascular networks remains an integral part in tissue engineering, since the incorporation of non-perfused tissues results in restricted nutrient supply and limited waste removal. Microfluidic devices are routinely used to mimic both physiological and pathological vascular microenvironments. Current procedures either involve the investigation of growth factor gradients and interstitial flow on endothelial cell sprouting alone or on the heterotypic cell-cell interactions between endothelial and mural cells.

Monitoring cellular stress responses using integrated high-frequency impedance spectroscopy and time-resolved ELISA.

We have developed a lab-on-a-chip system for continuous and non-invasive monitoring of microfluidic cell cultures using integrated high-frequency contactless impedance spectroscopy. Electrically insulated microfabricated interdigitated electrode structures were embedded into four individually addressable microchambers to reliably and reproducibly detect cell-substrate interactions, cell viability and metabolic activity. While silicon nitride passivated sensor substrates provided a homogeneous cell culture surface that minimized cell orientation along interdigitated electrode structures, the application of high-frequency AC fields reduced the impact of the 300 nm thick passivation layer on sensor sensitivity.