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Abstract:
Pulmonary arteries from a case of plexogenic pulmonary arteriopathy were studied with the electron microscope. Many muscular pulmonary arteries showed intimal fibrosis of concentric or "onion-skin" type. The cells embedded within this fibrosis resembled smooth muscle but since they also possessed some features of fibroblasts we refer to them as myofibroblasts. Myofibroblasts also occurred in plexiform lesions together with fibroblasts and "fibrillary cells". These fibrillary cells contained numerous, prominent filaments with a random orientation. They lined the vascular channels of the plexiform lesions as well as being present within the stroma. They appeared to phagocytose fibrin and then to organise the plexiform lesion into a fibrous scar. Fibrillary cells closely resemble vasoformative reserve cells and the cells of the cardiac myxoma and so-called "papillary tumour" of heart valves. They may, therefore, be primitive multipotential cells found throughout the entire cardiovascular system.
Insights
Electron microscopy revealed myofibroblasts and novel "fibrillary cells" in plexogenic pulmonary arteriopathy. These fibrillary cells may represent primitive cardiovascular stem cells involved in lesion organization.
Area of Science:
- Cardiovascular Pathology
- Cell Biology
- Pulmonary Hypertension
Background:
- Plexogenic pulmonary arteriopathy is a severe vascular disease characterized by complex vascular remodeling.
- The cellular components and their origins within these lesions remain incompletely understood.
Observation:
- Electron microscopy was used to examine pulmonary arteries from a patient with plexogenic pulmonary arteriopathy.
- Intimal fibrosis, described as "onion-skin" type, was observed in muscular pulmonary arteries.
- Cells within the fibrosis, termed myofibroblasts, exhibited characteristics of both smooth muscle cells and fibroblasts.
Findings:
- Myofibroblasts and distinct "fibrillary cells" were identified within plexiform lesions.
- Fibrillary cells contained abundant, randomly oriented filaments and were found lining vascular channels and within the lesion stroma.
- These cells appeared to phagocytose fibrin and contribute to the organization of plexiform lesions into fibrous scars.
Implications:
- Fibrillary cells share similarities with vasoformative reserve cells and cells found in cardiac myxomas and valve tumors.
- This suggests fibrillary cells may be primitive, multipotential cardiovascular stem cells.
- Understanding these cells could offer new insights into the pathogenesis and potential therapeutic targets for pulmonary arteriopathy.