In the present study, a novel system for the hypoxic culture of individual tissues was established for the subculturing of cell lines for research as well as for clinical culture of primary cells. To provide a hypoxic environment throughout the process of tissue handling and culture, we designed a clean bench with CO
2 gas circulation and a hypoxic culture incubator containing disposable capsules. The bench top was covered with an acrylic chamber, and an atmosphere of 5.0% CO
2-air was maintained using a sensor control. The cleanliness class of the chamber could easily be improved to 1 within 5 min of circulative filtration, even though it was found to be 10
5 before the unit was operated. Gas buffer solution (220 ml of 20 mM HEPES, 25 mM NaHCO
3, pH 7.4) placed in a 500-ml plastic capsule in the unit stabilized the culture environment by functioning as a heat storage and gas pool. The inflow of air that occurred by the cap of the capsule was opened was excluded by the infusion of purging gas (5.0% CO
2 and 95% N
2); the O
2 level returned to 2.0% within 4 min, after which the gas supply automatically switched to the culture gas (2.0% O
2, 5.0% CO
2, and 93% N
2). If this purging process was omitted, restoration of the O
2 level required 120 min, even though the inner volume was only 280 ml.
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