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Cell Retention (cell + retention)
Selected AbstractsHydrogels as a Platform for Stem Cell Delivery to the HeartCONGESTIVE HEART FAILURE, Issue 3 2010Mazen Kurdi PhD Stem cell therapy offers great promise to repair the injured or failing heart. The outcomes of clinical trials to date, however, have shown that the actual benefit realized falls far short of the promise. A number of factors may explain why that is the case, but poor stem cell retention and engraftment in the hostile environment of the injured heart would seem to be a major factor. Improving stem cell retention and longevity once delivered would seem a logical means to enhance their reparative function. One way to accomplish this goal may be injectable hydrogels, which would serve to fix stem cells in place while providing a sheltering environment. Hydrogels also provide a means to allow for the paracrine factors produced by encapsulated stem cells to diffuse into the injured myocardium. Alternatively, hydrogels themselves can be used for the sustained delivery of reparative factors. Here the authors discuss chitosan-based hydrogels. Congest Heart Fail. 2010;16:132,135. © 2010 Wiley Periodicals, Inc. [source] Real-time monitoring of intracellular calcium dynamic mobilization of a single cardiomyocyte in a microfluidic chip pertaining to drug discoveryELECTROPHORESIS, Issue 24 2007Xiujun Li Abstract A microfluidic method for real-time quantitative measurement of cellular response pertaining to drug discovery is reported. This method is capable of multiple-step liquid delivery for measuring the drug response of a single cardiomyocyte, due to the improved cell retention by a newly designed chip. The chip, which consists of a cell-retention chamber with a weir structure, was fabricated just by a one-photomask microfabrication procedure followed by on-chip etching. This method differs from the conventional method, which uses two-mask photolithography to fabricate the microchannel (deep etch) and the weir structure (shallow etch). The dimensions of the weir structure have been predicted by a mathematical model, and confirmed by confocal microscopy. Using this microfluidic method, the dynamic [Ca2+]i mobilization in a single cardiomyocyte during its spontaneous contraction was quantified. Furthermore, we measured the cellular response of a cardiomyocyte on (i) a known cardiotonic agent (caffeine), (ii) a cardiotoxic chemotherapeutic drug (daunorubicin), and (iii) an herbal anticancer drug candidate , isoliquiritigenin (IQ) based on the fluorescent calcium measurement. It was found that IQ had produced a less pronounced effect on calcium mobilization of the cardiomyocytes whereas caffeine and daunorubicin had much stronger effects on the cells. These three experiments on cardiomyocytes pertaining to drug discovery were only possible after the improved cell retention provided by the new chip design (MV2) required for multiple-step real-time cellular analysis on a microchip, as compared with our old chip design (MV1). [source] A noninvasive technique for the measurement of the energetic state of free-suspension mammalian cellsBIOTECHNOLOGY PROGRESS, Issue 2 2010M. Ben-Tchavtchavadze Abstract A perfusion small-scale bioreactor allowing on-line monitoring of the cell energetic state was developed for free-suspension mammalian cells. The bioreactor was designed to perform in vivo nuclear magnetic resonance (NMR) spectroscopy, which is a noninvasive and nondestructive method that permits the monitoring of intracellular nutrient concentrations, metabolic precursors and intermediates, as well as metabolites and energy shuttles, such as ATP, ADP, and NADPH. The bioreactor was made of a 10-mm NMR tube following a fluidized bed design. Perfusion flow rate allowing for adequate oxygen supply was found to be above 0.79 mL min,1 for high-density cell suspensions (108 cells). Chinese hamster ovary (CHO) cells were studied here as model system. Hydrodynamic studies using coloration/decoloration and residence time distribution measurements were realized to perfect bioreactor design as well as to determine operating conditions bestowing adequate homogeneous mixing and cell retention in the NMR reading zone. In vivo 31P NMR was performed and demonstrated the small-scale bioreactor platform ability to monitor the cell physiological behavior for 30-min experiments. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source] Perfusion Culture of Hybridoma Cells for Hyperproduction of IgG2a Monoclonal Antibody in a Wave Bioreactor-Perfusion Culture SystemBIOTECHNOLOGY PROGRESS, Issue 1 2007Ya-Jie Tang A novel wave bioreactor-perfusion culture system was developed for highly efficient production of monoclonal antibody IgG2a (mAb) by hybridoma cells. The system consists of a wave bioreactor, a floating membrane cell-retention filter, and a weight-based perfusion controller. A polyethylene membrane filter with a pore size of 7 ,m was floating on the surface of the culture broth for cell retention, eliminating the need for traditional pump around flow loops and external cell separators. A weight-based perfusion controller was designed to balance the medium renewal rate and the harvest rate during perfusion culture. BD Cell mAb Medium (BD Biosciences, CA) was identified to be the optimal basal medium for mAb production during batch culture. A control strategy for perfusion rate (volume of fresh medium/working volume of reactor/day, vvd) was identified as a key factor affecting cell growth and mAb accumulation during perfusion culture, and the optimal control strategy was increasing perfusion rate by 0.15 vvd per day. Average specific mAb production rate was linearly corrected with increasing perfusion rate within the range of investigation. The maximum viable cell density reached 22.3 × 105 and 200.5 × 105 cells/mL in the batch and perfusion culture, respectively, while the corresponding maximum mAb concentration reached 182.4 and 463.6 mg/L and the corresponding maximum total mAb amount was 182.4 and 1406.5 mg, respectively. Not only the yield of viable cell per liter of medium (32.9 × 105 cells/mL per liter medium) and the mAb yield per liter of medium (230.6 mg/L medium) but also the mAb volumetric productivity (33.1 mg/L·day) in perfusion culture were much higher than those (i.e., 22.3 × 105 cells/mL per liter medium, 182.4 mg/L medium, and 20.3 mg/L·day) in batch culture. Relatively fast cell growth and the perfusion culture approach warrant that high biomass and mAb productivity may be obtained in such a novel perfusion culture system (1 L working volume), which offers an alternative approach for producing gram quantity of proteins from industrial cell lines in a liter-size cell culture. The fundamental information obtained in this study may be useful for perfusion culture of hybridoma cells on a large scale. [source] 3136: Donor and recipient endothelial cell populations in transplanted corneas: new insights from endothelial imagingACTA OPHTHALMOLOGICA, Issue 2010N LAGALI Purpose To elucidate the pattern of donor and recipient endothelial cell population in transplanted human corneas and investigate factors impacting this mosaic. Methods 36 corneal grafts were collected from recipients of opposite sex to the donor, at the time of re-transplantation. An endothelial sheet was harvested from each graft, and labeled by fluorescent in situ hybridization of the sex chromosomes, to identify cells as donor or recipient-derived. Images of the graft endothelium were assembled to depict the pattern of cell population of the graft, and the proportion of donor cells present was estimated. Results Endothelial cells of donor origin were found in 26 of 36 grafts, persisting up to 26 years after transplantation. The proportion of donor endothelial cells in the graft was not significantly correlated with postoperative time (P = 0.19). Endothelial images indicated a highly variable pattern of recipient cell repopulation of the graft. A tendency towards donor cell retention in transparent, successful grafts was noted; however, this feature alone was not a reliable indicator of long-term graft transparency. Recent in-vivo optical coherence tomography studies of transplanted corneas indicate a possible mechanism impacting the donor and recipient cell patterns observed on the endothelial surface. Conclusion Two-dimensional imaging of the corneal graft endothelium revealed a variable pattern and extent of donor and recipient cell population, indicating the highly dynamic nature of the corneal endothelium after transplantation. [source] | |||||||||||||