Henna Karvonen

Myofibroblasts in interstitial lung diseases show diverse electron microscopic and invasive features.

The characteristic features of myofibroblasts in various lung disorders are poorly understood. We have evaluated the ultrastructure and invasive capacities of myofibroblasts cultured from small volumes of diagnostic bronchoalveolar lavage (BAL) fluid samples from patients with different types of lung diseases. Cells were cultured from samples of BAL fluid collected from 51 patients that had undergone bronchoscopy and BAL for diagnostic purposes. The cells were visualized by transmission electron microscopy and immunoelectron microscopy to achieve ultrastructural localization of alpha-smooth muscle actin (α-SMA) and fibronectin. The levels of α-SMA protein and mRNA and fibronectin mRNA were measured by western blot and quantitative real-time reverse transcriptase polymerase chain reaction. The invasive capacities of the cells were evaluated. The cultured cells were either fibroblasts or myofibroblasts. The structure of the fibronexus, and the amounts of intracellular actin, extracellular fibronectin and cell junctions of myofibroblasts varied in different diseases. In electron and immunoelectron microscopy, cells cultured from interstitial lung diseases (ILDs) expressed more actin filaments and α-SMA than normal lung. The invasive capacity of the cells obtained from patients with idiopathic pulmonary fibrosis was higher than that from patients with other type of ILDs. Cells expressing more actin filaments had a higher invasion capacity. It is concluded that electron and immunoelectron microscopic studies of myofibroblasts can reveal differential features in various diseases. An analysis of myofibroblasts cultured from diagnostic BAL fluid samples may represent a new kind of tool for diagnostics and research into lung diseases.

Myofibroblast expression in airways and alveoli is affected by smoking and COPD

BackgroundChronic obstructive pulmonary disease (COPD) is characterized by structural changes in alveoli and airways. Our aim was to analyse the numbers of alpha-smooth muscle actin (α-SMA) positive cells, as a marker of myofibroblasts, in different lung compartments in non-smokers and smokers with normal lung function or COPD.Methodsα-SMA, tenascin-C (Tn-C) and EDA-fibronectin in alveolar level and airways were assayed by immunohistochemistry and quantified by image analysis. Immunohistochemical findings were correlated with clinical data. α-SMA protein was also analysed by Western blotting from fibroblastic cells cultured from peripheral lung of non-smokers, smokers without COPD and smokers with COPD.ResultsIn many cases, the endings of the detached alveolar walls were widened, the structures of which were named as widened alveolar tips. Widened alveolar tips contained α-SMA positive cells, which were obviously myofibroblasts. There were less alveolar tips containing positive cells for α-SMA in alveoli and α-SMA positive cells in bronchioles in smokers and in COPD compared to non-smokers. The quantity of α-SMA positive cells was increased in bronchi in COPD. Tn-C was elevated in bronchi in COPD and smokers’ lung. The α-SMA protein level was 1.43-fold higher in stromal cells cultured from non-smokers than in those of smokers.ConclusionsMyofibroblasts are localized variably in normal and diseased lung. This indicates that they have roles in both regeneration of lung and pathogenesis of COPD. The widened alveolar tips, these newly characterized histological structures, seemed to be the source of myofibroblasts at the alveolar level.

Lung Cancer–Associated Myofibroblasts Reveal Distinctive Ultrastructure and Function

Background: Cancer-associated stromal cells interact with carcinoma cells and thus participate in tumor growth. Our aim was to characterize the ultrastructure and contractile properties of stromal cells in collagen gel cultured from lung cancer of various histological types and from tumor-free lung. Methods: Cells cultured from lung cancer (13 adenocarcinomas, six squamous cell carcinomas, one adenosquamous carcinoma, and one pleomorphic carcinoma) and tumor-free lung were analyzed by transmission electron microscopy and three-dimensional collagen gel contraction assays. The expression of &agr;-smooth muscle actin (&agr;-SMA), a recognized myofibroblast marker, was examined by immunoelectron microscopy from individual cells and by Western blotting from the whole cultured cell population. Results: According to their ultrastructure, the cell lines were composed of fibroblastic and myofibroblastic cells. In electron microscopy, cells of lung cancer exhibited more myofibroblastic features displaying higher amounts of actin belts (p = 0.057) and &agr;-SMA labeling (p = 0.010) than cells from tumor-free lung. Myofibroblasts cultured from lung cancer of smokers expressed less &agr;-SMA labeling (p = 0.013) than counterparts from nonsmokers. Western blotting revealed that cancer-associated fibroblasts expressed more &agr;-SMA (p = 0.006) than cells from tumor-free lung, whereas cells from tumor-free central lung of smokers showed less &agr;-SMA (p = 0.039) than counterparts from nonsmokers. Cells cultured from cancer contracted more in collagen gel than those from tumor-free lung. The contractile capacity in collagen gel correlated with the frequency of extracellular component of fibronexus by transmission electron microscopy. Conclusions: Lung cancer–associated myofibroblasts are different both ultrastructurally and functionally when compared with cells cultured from tumor-free lung. Smoking altered myofibroblastic phenotype, regardless of their origin.

Stromal cells can be cultured and characterized from diagnostic bronchoalveolar fluid samples obtained from patients with various types of interstitial lung diseases

Increased proliferation of stromal cells is a typical feature encountered in several lung diseases. The objective of this study was to evaluate the success of standardized process for culturing stromal cells from small volumes of diagnostic bronchoalveolar lavage (BAL) fluid samples collected from various patients and to characterize the cultured cells. Small volumes (average 15 mL) of BAL fluid samples were collected from 98 patients who underwent bronchoscopy and BAL for diagnostic purposes. The cells were cultured in vitro and characterized by immunohistochemistry, electron microscopy, flow cytometry and differentiation tests. Cells could be cultured from 62% of samples with the success rate varying with the disease (p = 0.003). Cultures from samples of the patients with idiopathic pulmonary fibrosis, non‐specific interstitial pneumonia, connective tissue disorder associated interstitial lung disease and allergic alveolitis had a higher success rate than samples derived from control lung (p < 0.001, 0.03, 0.03 and 0.044, respectively). Smokers had a higher success rate compared with non‐smokers (p = 0.035). The cultured cells were fibroblasts or myofibroblasts, but shared also similarities with progenitor‐type cells. The study shows that mesenchymal cells can be cultured and studied from small volumes of diagnostic BAL fluid samples from patients with several different types of lung diseases.