GLANDULAR-LIKE MORPHOGENESIS AND SECRETORY ACTIVITY OF HUMAN TRACHEALGLAND-CELLS IN A 3-DIMENSIONAL COLLAGEN GEL MATRIX

The extracellular matrix has been demonstrated to affect the different iation of epithelial cells. We present evidence that in a three-dimens ional (3-D) type I collagen gel matrix, isolated human adult tracheal gland (HTC) cells are capable of reconstructing new functional gland-l ike tubules in vitro. During the first two weeks in culture, HTC cells developed globular epithelial cell aggregates in which lumina is abse nt. By the third week in culture, the tubulogenesis and the formation of branching structures became evident with a polarized morphology, wh ich in many aspects resembles the in vivo morphology. A central lumen was lined by polarized secretory epithelial cells exhibiting well-deve loped microvilli and apical secretory granules. Furthermore, we showed that the capacity of in vitro tracheal gland differentiation was asso ciated with the basal deposition of laminin and type IV collagen aroun d the gland-like tubules. A cell-associated 72 kDa type IV collagenase was expressed in developing tubule cells, as shown by immunocytochemi stry. The secretion of the antileucoprotease (ALP), a protein marker o f tracheal gland serous cells, was bidirectional in gland-like tubules , since up to 65% of released ALP was in the basolateral direction. Ta ken together, these observations indicate that isolated HTC cells in a 3-D collagen matrix form functional tracheal gland-like tubules and s uggest that similar new tracheobronchial gland formations may occur du ring the human normal gland development and remodeling. (C) 1994 Wiley -Liss, Inc.