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Development
of Pulmonary Neuroendocrine Cells of Fetal Hamster in Explant Culture |
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Takaaki Ito,
Hiroyuki Nogawa, Naoko Udaka, Hitoshi Kitamura, and Masayoshi Kanisawa
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Department
of Pathology (TI, NU, HK, MK), Yokohama City University School of Medicine,
Yokohama, and Department of Biology (HN), Faculty of Science Chiba University
School of Science, Ciba, Japan |
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Fetal hamster lung explant
was cultured in serum-free medium on gestational Day 11--2 days before the
appearance of pulmonary neuroendocrine cells (PNEC)--and the development
and differentiation of PNEC from immature fetal lung epithelium was examined
through immunostaining for neural cell adhesion molecule (NCAM) to establish
an in vitro system to study the mechanisms involved. PNEC were present in
the main bronchus after 2 days of culture. Thereafter, NCAM-positive clusters
of PNEC increased and were distributed from the large bronchus to the terminal
bronchiole with a proximal-to-distal wave. To elucidate the role of NCAM
in the fetal development of PNEC, whole fetal lung was cultured on gestational
Day 11 with an anti-NCAM antibody. This antibody slightly inhibited the
growth and branching morphogenesis of the lung and disturbed the formation
of PNEC clusters. NCAM may function to form clusters of PNEC known as neuroepithelial
bodies. We cultured fetal lung epithelial explant at gestational Day 11
after removing mesenchyme, including nerve tissue, with dispase digestion.
Immunohistochemical staining for NCAM revealed that PNEC were induced in
cultured fetal epithelium without mesenchymal tissue, but basement membrane
Matrigel was necessary to maintain cultured epithelium. In conclusion, PNEC
derive from immature airway epithelial cells. This organ culture system,
therefore, is a useful experimental model and should facilitate further
investigations of the development and differentiation of PNEC. Mesenchymal
and neural tissues are not always necessary for the development of PNEC,
but matrix substance and/or growth factors may be required to induce or
maintain PNEC. |
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