బయోప్రాసెసింగ్ & బయోటెక్నిక్స్ జర్నల్

A mixture of green and blue-green algae was used as an adsorbant material for biosorption of lead, cadmium, copper, and arsenic ions in fluidized bed reactor. Batch experiments showed that the algal biomass was successfully used for the removal of these metal ions from wastewater. The maximum percentage removal for 1 g dose was 89, 82, 79, and 70 for Pb²⁺, Cu²⁺, Cd²⁺ and As³⁺, respectively. The experimental data fit well to an ion exchange equilibrium model. Affinity constants were calculated for each metal. A higher affinity of the biomass towards lead (Pb²⁺) was observed due to the high electronegativity of this metal. FTIR analyses showed that hydroxyl and carboxyl groups could be very effective for capturing these metals. An ideal plug flow model was adopted to characterize the fluidized bed reactor and solved numerically using MATLAB version (R2009b), which fit well to the experimental breakthrough data. The effects of different operating conditions such as: static bed height, superficial velocity and particle diameter on the removal process were investigated. Lead showed the largest operating time compared with others.

We have examined the method for the label-free optical microscopic image-based selection of cardiomyocytes from the mixture of collagenase-digested embryonic mouse heart cells using the on-chip imaging cell sorter system, in which 1/2000 s real-time high-speed camera-based phase-contrast cell image recognition was performed. To separate the cardiomyocytes from other cells including fibroblasts, we distinguished the roughness of the cell surface quantitatively as the index of sorting. The selected cells with smooth surface (roughness index not more than 1.1) for cardiomyocytes, and confirmed that the more than 80% of the collected and recultivated cells were self-beating and the 99.2% of them were identified as cardiomyocytes by immunostaining. The results indicates the potential of the label-free cell purification using imaging cell sorting system, especially for cardiomyocytes by the index of their cell surface roughness, which might be applicable for purification of cardiomyocytes for regenerative medicine.

Embryonic stem (ES) cells and induced pluripotent stem (iPS) cells are usually cultured on mouse embryonic fibroblasts (MEFs) isolated from fetuses. MEFs are primary cells and can only be cultured for several passages before senescence. Although the STO mouse stromal cell line has been used as a MEF substitute, performance of a STO feeder layer for ES/iPS cell culture is inferior to a MEF feeder layer. Thus, the development of effective feeder systems may be beneficial for advancing stem cell technology using ES/iPS cells. We established a STO feeder cell line expressing mouse leukemia inhibitory factor (LIF) and mouse E-cadherin (designated as STO/EL cells). ES/iPS cells were cultured on STO/EL feeder cells without LIF addition to the medium, while maintaining the expression of stem cell markers, Oct3/4, Nanog and Rex1. Quantitative evaluation of feeder performance by an alkaline phosphatase-positive colony-forming assay revealed that the colony forming efficiency was comparable to that of the conventional and most reliable culture method using MEFs with LIF addition. STO/EL cells can be used as an efficient feeder system for supporting ES/iPS cell culture in an undifferentiated state. The STO/EL feeder system may contribute toward medical and biological research of ES/iPS cells.

We investigated the effect of culture conditions on the micropatterned co-culture of rat hepatocytes with 3T3 cells. A micropatterned chip was prepared using polydimethylsiloxane (PDMS) microstencil such that the chip contained 724 hepatocyte islands, each 500 μm in diameter, in a triangular arrangement with 800-μm pitch, in which hepatocytes were co-cultured with 3T3 cells. The hepatocytes in micropatterned co-culture exhibited hepatocellular morphology, and the micropatterned configuration of hepatocyte islands was maintained for several weeks of culture by supporting the heterotypic interface between the hepatocytes and 3T3 cells. The albumin secretion activity of hepatocytes was highest in the micropatterned co-culture but decreased in the random co-culture, micropatterned mono-culture (hepatocytes only), and random mono-culture (hepatocytes only) in that order. Furthermore, earlier formation of co-culture promoted higher functional activity of hepatocytes as compared to later formation, and hepatocyte functions were induced with an increasing the density of inoculated 3T3 cells. These results suggest that the formation of a heterotypic interaction at an early stage is important for maintaining high levels of hepatocyte functions. The findings of this study will provide information useful for designing co-culture conditions for liver tissue engineering and pharmacological and toxicological studies.