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Alpha smooth muscle actin expression in developing and adult human lung
K O Leslie1, J J Mitchell, J L Woodcock-Mitchell
1Department of Pathology, University of Vermont, Burlington 05405.
Differentiation; Research in Biological Diversity
|August 1, 1990
Summary
Alpha smooth muscle actin (ASMA) cells are crucial for lung development. These cells, distinct from typical smooth muscle, appear during airway and vascular formation, suggesting a role in lung morphogenesis.
Area of Science:
- Pulmonary Biology
- Developmental Biology
- Cell Biology
Background:
- Myofibroblast-like cells expressing alpha smooth muscle actin (ASMA) are found in lung injury and repair.
- These cells differ from smooth muscle cells in structure, location, and myosin content.
- The origin and developmental role of these ASMA-expressing cells remain unclear.
Purpose of the Study:
- To investigate the developmental origins and distribution of alpha smooth muscle actin (ASMA)-expressing cells in the human lung.
- To determine if these cells have a developmental analog important for lung morphogenesis.
Main Methods:
- Human lung tissue from prenatal to adult stages was analyzed.
- A specific monoclonal antibody against alpha smooth muscle actin (ASMA) was used for immunohistochemistry.
- Cellular distribution and morphology were examined in relation to developing airway and vascular structures.
Main Results:
- ASMA-expressing cells were identified in prenatal lung, associated with developing vasculature and airways.
- No ASMA expression was observed in undifferentiated mesenchymal cells during prenatal development.
- Three distinct populations of ASMA cells were identified in the early postnatal lung: in large airways/vessels, within the acinus at septal tips, and associated with small blood vessels in alveolar sacs.
Conclusions:
- Alpha smooth muscle actin (ASMA) cells are present during the development of small and large airways and pulmonary vessels.
- These cells appear to emerge specifically during lung development, not from pre-existing smooth muscle.
- ASMA cells likely play a critical role in the branching morphogenesis of the developing lung.