Sukezo Kawamura

Development of a culture carrier for anchorage-dependent animal cells using calcium phosphate ceramic sinters

Abstract Effects of the chemical and physical structure of bioactive ceramic sinters made by synthesized hydroxyapatite (HAP) and tricalcium phosphate (TCP) on cell growth were studied to develop new carrier materials for cultivation of anchorage-dependent animal cells. A sophisticated analytic method using animal cells was used to characterize the affinity between the cells and ceramic sinters. In this method, cells were treated with trypsin for three minutes before culturing on ceramic plates. The initial anchoring cell ratio and the specific growth rate on the sintered plate were measured to compare the bioaffinity of ceramic materials. Using sintered mixtures of HAP and TCP as culture carriers, the initial anchoring ratios on the plates were reduced compared to a polystyrene culture dish (LUX) and a glass dish which were used as control test samples. The growth rate of cells was slightly accelerated on some of ceramic plates, however. The highest value of the specific growth rate, 0.049 (1/h), which was about 11% higher than the rate on the LUX plate, was obtained on the sinter which consists of a 4:1 mixture of HAP and TCP.

The Adhesiveness and Growth of Anchorage-Dependent Animal Cells on Biocompatible Ceramic Culture Carriers

Abstract The growth of anchorage-dependent animal cells was significantly affected by the adhesiveness on carrier materials. The relationship between the cell division rate and adhesiveness was quantitatively studied by use of ceramic carriers whose chemical compositions were regulated stepwise. An apparatus using a spinner flask was designed to estimate numerically the adhesive strength of cells to ceramic carriers. Using this apparatus, the adhesive strength of cells to ceramic sinters made by mixtures of synthesized hydroxyapatite (HAP) and tricalcium phosphate (TCP), a polystyrene dish (LUX), a glass dish, and a ZrO 2 ceramic plate were measured. The adhesiveness was comparably analyzed by trypsination method. Both measurements showed that the adhesiveness of L929 cells to calcium-phosphate sinters was considerably weaker than to LUX. Kinetic analyses of cell division and the adhesiveness to various carriers showed that a certain degree of weak adhesiveness was apparently advantageous for accelerating cell division. Another noteworthy and compatible correlation was obtained by the numerical analysis of growth phase dependent changes of these physiological parameters. The relationship between the cell division rate and adhesiveness based on the quantitative analysis was applicable for all the ceramic carriers used in this study. Measurement of the contact angle of the ceramic carrier with water suggested that the hydrophobicity of the carrier material was the dominant factor in determining the adhesiveness at the cell-carrier interface. The calcium-phosphate ceramic sinters had contact angle values from 42° to 56°. On the other hand, LUX, glass and ZrO 2 carriers had more hydrophobic surfaces as the values were around 65°. The most favored carrier for cell division had weak hydrophobicity with an angle of 51°.

Bending strength of hydroxyapatite ceramics containing α-tricalcium phosphate

Hydroxyapatite powders containing coprecipitated tricalcium phosphate in an arbitrary ratio could be synthesized by mixing solutions of calcium nitrate and diammonium hydrogen phosphate at a definite reaction temperature and aging temperature. Effect of tricalcium phosphate addition on the bending strength of sintered hydroxyapatite was investigated using the synthesized hydroxyapatite powder. The bending strength of the sintered hydroxyapatite containing 17mol% tricalcium phosphate was 1910kgf/cm2, equivalent to the value of about 25% higher than that of the sintered bodies of pure hydroxyapatite. The crystal phase of the polycrystalline body consisted of hydroxyapatite and α-tricalcium phosphate.