Long-Term Survival of Adult Human Lung Growing Subcutaneously in Congenitally Athymic Nude Mice

Abstract

Small airways and alveoli from normal adult human lung were implanted subcutaneously in nude mice. When the tissue was removed at 16 months the airway had formed into fluid-filled epithelium-lined cysts. The epithelial lining was typical of small and terminal airways, except where intracystic pressure had apparently flattened the epithelium. Ultrastructural examination of the columnar ciliated cells revealed supranuclear accumulations of granules, some irregular in outline and others lamellated. The nonciliated secretory cells closely resembled serous cells. The alveoli survived less well. Although partly expanded by secretion, probably from the type II pneumonocytes, the walls were frequently thickened by an increase in connective tissue, and there were few capillaries. The cells for which there was positive identification, or good presumptive evidence, for being of human type were columnar ciliated cells, serous cells, smooth muscle, cartilage, mast cells, type II pneumonocytes, and basal epithelial cells; the latter two cell types were apparently proliferating. The results show that human airway can be maintained long term as a xenograft.