Enhanced liver progenitor cell survival and differentiation in vivo by spheroid implantation in a vascularized tissue engineering chamber.

Liver tissue engineering is hampered by poor implanted cell survival due to inadequate vascularization and cell-cell/cell-matrix interactions. Here, we use liver progenitor cell (LPC) spheroids to enhance cell-cell/cell-matrix interactions, with implantation into an angiogenic in vivo mouse chamber. Spheroids were generated in vitro in methylcellulose medium. Day 2 spheroids were optimal for implantation (22,407 +/-645 cells/spheroid), demonstrating maximal proliferation (Ki67 immunolabeling) and minimal apoptosis (caspase-3 immunolabelling). In vivo chambers established bilaterally on epigastric vessels of immunodeficient mice were implanted with equivalent numbers of LPCs as a cell suspension (200,000 cells), or spheroids (9 spheroids). At day 14, a trend of increased LPC survival was observed in spheroid-implanted chambers [pan-cytokeratin (panCK+) cells, p = 0.38, 2.4 fold increase)], with significantly increased differentiation [cytokeratin 18 (CK18+) cells, p < 0.002, 5.1 fold increase)] compared to cell suspension-implanted chambers. At day 45, both measures were significantly increased in spheroid-implanted chambers (panCK, p < 0.006, 16 fold increase) (CK18, p < 0.019, 6 fold increase). Hepatic acini/plates of CK18 + cells expressed hepatocyte nuclear factor 4-α and ß-catenin, indicating ongoing hepatic differentiation. Spheroid cell-delivery significantly increased LPC survival and differentiation compared to conventional cell suspensions. This LPC spheroid/vascularized chamber model has clinical potential to generate three-dimensional vascularized liver tissue for liver replacement.

Comparing sterile bag rubbing and paint on technique in skin preparation of the hands.

BACKGROUND: The aim of this study was to compare two techniques for surgical site skin preparation in hand surgery. METHODS: We compared the standard sponge paint technique versus a plastic bag immersion technique using a 10% povidone-iodine with alcohol solution (Betadine, ORION Laboratories Pty Ltd, Balcatta,WA,Australia) to prepare surgical site skin for hand surgery. This sterile bag rubbing technique involves using a sterile plastic bag filled with 60 mL of Betadine solution to immerse the subjects' hand. Samples were taken from 10 subjects for bacteria colony-forming unit (CFU) counts before and 3 min after surgical site preparation in each group. Outcome measures were preparation time and CFU reduction with a plate impression test using commercially available agar slides. RESULTS: The sterile bag rubbing technique significantly reduced (P < 0.0001) the time required for surgical site skin preparation (28 s) compared with the standard technique (86 s). Both techniques were found to have similar efficacy in the reduction of CFU. CONCLUSIONS: The sterile bag rubbing technique is a quicker alternative method for surgical site preparation in hand surgery and has comparable efficacy to the widely practised standard paint-on technique.