Tissue Engineering of Ureteral Grafts: Preparation of Biocompatible Crosslinked Ureteral Scaffolds of Porcine Origin.

The surgical reconstruction of ureteric defects is often associated with post-operative complications and requires additional medical care. Decellularized ureters originating from porcine donors could represent an alternative therapy. Our aim was to investigate the possibility of manufacturing decellularized ureters, the characteristics of the extracellular matrix (ECM) and the biocompatibility of these grafts in vitro/in vivo after treatment with different crosslinking agents. To achieve these goals, native ureters were obtained from pigs and were decellularized. The success of decellularization and the ECM composition were characterized by (immuno)histological staining methods and a DNA-assay. In vitro: scaffolds were crosslinked either with carbodiimide (CDI), genipin (GP), glutaraldehyde, left chemically untreated or were lyophilized. Scaffolds in each group were reseeded with Caco2, LS48, 3T3 cells, or native rat smooth muscle cells (SMC). After 2 weeks, the number of ingrown cells was quantified. In vivo: crosslinked scaffolds were implanted subcutaneously into rats and the type of infiltrating cells were determined after 1, 9, and 30 days. After decellularization, scaffold morphology and composition of ECM were maintained, all cellular components were removed, DNA destroyed and strongly reduced. In vitro: GP and CDI scaffolds revealed a higher number of ingrown 3T3 and SMC cells as compared to untreated scaffolds. In vivo: at day 30, implants were predominantly infiltrated by fibroblasts and M2 anti-inflammatory macrophages. A maximum of MMP3 was observed in the CDI group at day 30. TIMP1 was below the detection limit. In this study, we demonstrated the potential of decellularization to create biocompatible porcine ureteric grafts, whereas a CDI-crosslink may facilitate the remodeling process. The use of decellularized ureteric grafts may represent a novel therapeutic method in reconstruction of ureteric defects.

Acoustic cavitation induced by ultrasonic cutting devices: a preliminary study.

Ultrasonic cutting is frequently used for the separation of foods, especially in case of commodities with multiple layers showing a different mechanical resistance. Both chemiluminescence measurements and the degradation of organochloric compounds served as an evidence for the occurrence of acoustic cavitation around excited cutting blades. Additionally, sensory experiments revealed that even a short ultrasonic treatment of edible oil is sufficient to generate a remarkable off-flavor.

Ultrasound promoted C-alkylation of benzyl cyanide--effect of reactor and ultrasound parameters.

Phase transfer catalysis is used widely in the synthesis of various organic chemicals in both liquid-liquid and solid-liquid systems. The C-alkylation of benzyl cyanide by 2-bromopropane in the presence of sodium hydroxide was investigated. The reaction rate of the phase transfer reaction can be increased by ultrasound, but frequency and power of ultrasound and the geometry of the ultrasonic field inside the reactor influence the reaction strongly. The results demonstrate clearly, that to achieve a high efficiency of ultrasonic systems in chemical processes the ultrasonic parameters and geometry of the sonotrode had to be adopted.