Preparation and long-term cultivation of porcine tracheal and lung organ cultures by alternate exposure to gaseous and liquid medium phases

Abstract

Conventional methods of organ culture have proved unsatisfactory for mammalian lung because of the rapid collapse of the tissue and the loss of its normal structure. In an effort to circumvent this problem and to provide a means for visualizing the cellular relationships throughout the culture period, respiratory organs consisting of trachea and lungs of fetal or hysterectomy-derived 1- to 4-week-old pigs were embedded in warm 3% Noble agar in phosphate buffer silicone solution and cooled to firmness. By use of a described cutting device, the respective organs were sliced into thin, 0.5- to 1.0-mm tracheal ring or lung explants. These organ sections then were cultured by exposure to alternate gaseous and liquid-medium phases by rotation (12 rev per hr) in sealed Leighton tubes fitted in a described rotator. In short-,erm culture experiments, explants were best maintained in a culture-support medium containing Eagle's minimal essential medium, 20% fetal bovine serum, 0.5% lactalbumin hydrolysate, and other supplements in a pH range of 6.5 to 8.2, and a NaCl concentration of 0.1 M or less. By bright-field and scanning-electron microscopy, tracheal ring and lung explant cultures incubated for 2 months showed intact, uniform and active ciliated epithelial surfaces which compared favorably with those of fresh preparations. The lung cultures showed alveoli that remained expanded, and the cellular integrity of the tissues remained normal in appearance. This new method provides respiratory organs as continuous records with exceptional cellular clarity and readily available for histological processing. The organ cultures lend themselves well to pathogenesis studies in which subtle cellualr changes or a sequence of changes induced in pulmonary tissues are difficult to observe in the host.