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A new immobilization material for cell culture, ahydroxyapatite-pulp composite fiber (HAPC) sheet bed, was usedto grow CHO-K1 cells. The sheet bed for cell culture wasprepared from HAPC fiber by paper-making techniques. Scanning electron microscopic analysis revealed that the HAPCsheet bed had a structure consisting of piled fibers with spaces 10-200 mum in diameter and a pore surface area of 0.32 m(2) g(-1). Using a 25 x 25 mm(2) squareHAPC sheet bed 0.41 mm in thickness (85 g m(-2) basis weight) for cell culture, CHO-K1 cells grew to a cell densityof 3.7 x 10(7) cells cm(-3) in a 60 mm plastic dish over a 6-day culture period. High-density culture of CHO-K1 cells was successfully performed using the HAPC sheet bed in a 500 ml spinner flask over a 21-day culture period. The HAPC sheet bed, wound around the stirrer paddle, was rotated in the spinner flask in order to supply nutrientsand remove waste products efficiently. The HAPC sheet bedhas a large surface area to support cell growth and there islarge diffusion space inside of the bed. This newautoclavable substrate for anchorage-dependent cells can be easily scaled-up.

SynopsisThe staple fibers of Ca alginate or alginic acid were found to have interfiber self-bonding, which allowed us to make papers composed of fibers with homogeneous fiber diameter and fiber length without binders. The analysis of the effect of the molecular weight (MW) and fiber diameter on physical properties of the sheets showed that strength factors, except zero span breaking length and tear index, increased with increase of MW of alginic acid up to 6 X lo5 dalton. The folding endurance was the most sensitive to MW, requiring a MW of 5 x lo6 dalton or higher to reach the level of 10 folds. The breaking length of alginate fiber papers ranged from 2.0 to 3.5 km and was higher than that of the corresponding free acid fiber sheets. Investigation of the effect of fiber length indicated that the folding endurance increased almost linearly with increase in fiber length but that the breaking length and tear index were maximum at a fiber length of 3.0 mm, suggesting that these factors were mainly influenced by sheet formation. The paper formability of the metallic salts of alginate fiber was as follows:The admixture of acidic polysaccharides, such as pectin and K carrageenan with Na alginate, also made it possible to spin continuous yarn. Papers obtained from the admixed fibers had higher bulk density and Young's modulus by 1.5-1.8 times and were very transparent, just like glassine paper. X-ray microanalysis showed that the Ca alginate fiber had no skincore structure, homogeneously distributing Ca2+ in whole fiber.

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