Expression of calponin in rabbit and human aortic smooth muscle cells

Summary Polyclonal antibodies to chicken gizzard calponin were used to localize calponin and determine calponin expression in rabbit and human aortic smooth muscle cells in culture. Calponin was localized on the microfilament bundles of cultured smooth muscle cells. Early in primary culture,ccalponin staining was accumulated preferentially in the central part of the cell body. With time in culture, the number of calponin-negative smooth muscle cells increased while the distribution of calponin in calponin-positive cells became more even along the stress fibers. Calponin content and the calponin/actin ratio decreased about 5-fold in rabbit aortic smooth muscle cells during the first week in primary culture and remained low in proliferating cells. The same tendency in calponin expression was observed when human vascular smooth muscle was studied. On cryostat sections of human umbilical cord, calponin antibodies mainly stained vessel walls of both the arteries and veins, although less intensive labelling was also observed in non-vascular tissue. When primary isolates of human aortic intimal and medial smooth muscle cells were compared with corresponding passaged cultures, it was found that calponin content was reduced about 9-fold in these cells in culture and was similar to the amount of calponin in endothelial cells and fibroblasts. Thus, high calponin expression may be used as an additional marker of vascular smooth muscle cell contractile phenotype.     

Culture of human neoplastic gastrointestinal smooth muscle cells

Summary Due to limited growth potential of primary cultures and the absence of continuous lines of healthy enteric smooth muscle, we have studied the culture behavior of neoplastic gastrointestinal smooth muscle cells. Forty-six human enteric smooth muscle neoplasms (leiomyomas and leiomyosarcomas) were studied while fresh and/or after culture in vitro and growth in vivo in athymic nude mice, with assessments made of morphology, growth characteristics, and biochemical markers of differentiation. The state of differentiation of the tumors varied, with well-differentiated tumors tending to express binding sites for the gastrointestinal hormone cholecystokinin, whereas less well-differentiated tumors did not. Poorly differentiated tumors were the easiest to establish in culture in vitro and to grow in vivo in nude mice. When the cells placed directly into culture proliferated to confluent density, they underwent morphologic differentiation from a spread, fibroblastlike shape to a slender spindle morphology, with these cells possessing fewer biosynthetic organelles and arranging themselves in characteristic “hill and valley” arrays. However, the highly differentiated characteristics of expression of desmin or cholecystokinin-binding sites were not observed in cultured cells. In contrast, cells that had been passaged in nude mice before culture displayed a proliferative phenotype and failed to undergo morphologic differentiation on reaching confluent density. Four human enteric smooth muscle cell lines (documented by chromosomal analysis) originating in stomach, jejunum, ileum, and rectum were established using this strategy. This work was supported by grants DK32878 and DK34988 from the National Institutes of Health, Bethesda, MD.     

组织贴块法建立人气道平滑肌细胞体外培养模型的研究

背景：人气道平滑肌已被证实参与气道重塑,气道平滑肌的重塑已成为慢性呼吸道疾病的主要病理改变之一。人气道平滑肌细胞的培养对慢性呼吸道疾病的研究有重要意义。组织贴块法培养人气道平滑肌细胞是原代培养人气道平滑肌细胞的基本方法之一。目的：采用组织贴块法建立人气道平滑肌体外培养模型。方法：采集人气道组织,用组织贴块法进行人气道平滑肌细胞的原代培养,获得的细胞经形态学和免疫细胞化学染色鉴定。结果：培养的细胞呈典型的”谷峰”状生长,胞浆内特异性的平滑肌肌动蛋白阳性表达,符合平滑肌细胞的形态学特征和生物学特性。结论：组织贴块法易操作,结果可信,并可培养出高纯度活性好的人气道平滑肌细胞,成功建立了体外人气道平滑肌细胞增殖模型,提供了研究慢性呼吸道疾病的细胞培养模型。     

Reorganization of structural proteins in vascular smooth muscle cells grown in collagen gel and basement membrane matrices (Matrigel): a comparison with their in situ counterparts

When smooth muscle cells are enzyme-dispersed from tissues they lose their original filament architecture and extracellular matrix surrounds. They then reorganize their structural proteins to accommodate a 2-D growth environment when seeded onto culture dishes. The aim of the present study was to determine the expression and reorganization of the structural proteins in rabbit aortic smooth muscle cells seeded into 3-D collagen gel and Matrigel (a basement membrane matrix). It was shown that smooth muscle cells seeded in both gels gradually reorganize their structural proteins into an architecture similar to that of their in vivo counterparts. At the same time, a gradual decrease in levels of smooth muscle-specific contractile proteins (mainly smooth muscle myosin heavy chain-2) and an increase in beta-nonmuscle actin occur, independent of both cell growth and extracellular matrix components. Thus, smooth muscle cells in 3-D extracellular matrix culture and in vivo have a similar filament architecture in which the contractile proteins such as actin, myosin, and alpha-actinin are organized into longitudinally arranged "myofibrils" and the vimentin-containing intermediate filaments form a meshed cytoskeletal network. However, the myofibrils reorganized in vitro contain less smooth muscle-specific and more nonmuscle contractile proteins.     

An ultrastructural study of regeneration of minced smooth muscle in the vas deferens of the guinea-pig

Summary Electron microscopic studies were made of the regeneration of minced smooth muscle of the vas deferens of the guinea-pig 3 days to 15 weeks after operation. At 3–5 days the mince contained degenerating smooth muscle cells and dedifferentiating cells showing characteristics of embryonic smooth muscle cells: numerous free ribosomes, well developed rough endoplasmic reticulum and Golgi apparatus with few peripherally placed myofilaments associated with dense bodies. During the first two weeks of regeneration, scattered cells surrounded by debris and collagen were separated by a large extra-cellular space. After three weeks, extracellular space was reduced to near normal values. Regenerating cells had a shorter length than normal cells, but during later stages of regeneration they showed an increase in diameter. Muscle effector bundles began to form after 2 to 3 weeks. Initially there were large gaps between the muscle cells, but at later stages of bundle formation, the extracellular space between the muscle cells was much reduced. From 3 weeks, arterioles appeared between the smooth muscle bundles in the regenerating areas. Regeneration of individual smooth muscle cells was complete by 15 weeks after the operation.This work was supported by grants from the Wellcome Trust and the Medical Research Council     

Biochemical markers of contraction in human myometrial smooth muscle cells in culture

Summary Phosphorylation of a light chain subunit of myosin by Ca²⁺ and calmodulin-dependent myosin light chain kinase is believed to be essential for smooth muscle contraction. The biochemical properties of the myosin phosphorylation system in human myometrial smooth muscle cells in monolayer culture were compared with those of human myometrial tissue and nonmuscle cells in culture. Native myosin was isolated from other cellular proteins of crude homogenates by polyacrylamide gel electrophoresis (in the presence of pyrophosphate) and quantified by densitometry. The myosin content of myometrial smooth muscle cells in culture and that of myometrial tissue were similar and four- to five-fold greater than that of human endometrial stromal cells or skin fibroblasts in culture. The specific activities of myosin light chain kinase in homogenates of myometrial smooth muscle cells that were maintained in culture and in myometrial tissue were similar (2.05±0.18 and 1.60±0.37 nmol phosphate incorporated per min per mg protein, respectively). On the other hand, enzyme activity in skin fibroblasts was only 5% of that in myometrial smooth muscle cells. Myosin light chain kinase activity in myometrial smooth muscle cells was dependent upon Ca²⁺ and was inhibited reversibly by the calmodulin antagonist, calmidazolium. The intracellular Ca²⁺ concentration measured by quin2 fluorescence was 0.12 μM in resting cells and increased in a concentration-dependent manner with KC1 to a maximal value of 0.47 μM. These results indicate that biochemical processes important for smooth muscle contraction are retained in human myometrial smooth muscle cells in culture. This research was supported by grants HL26043, HD11149, and GM07062 from the National Institutes of Health, Bethesda, MD.     

Inhibition of hepatic stellate cell contraction during activation in vitro by vascular endothelial growth factor in association with upregulation of FLT tyrosine kinase receptor family, FLT-1.

Activated hepatic stellate cells produce vascular endothelial growth factor (VEGF). VEGF has been shown to act on mesenchymal cells as well. If hepatic stellate cells can express FLT tyrosine receptor family, flt-1 and KDR/flk-1, their function might be regulated by VEGF in an autocrine manner. This hypothesis was tested using hepatic stellate cells isolated from normal rats. Northern blot analysis and immunocytochemical study revealed that hepatic stellate cells cultured for 3 days on plastic dishes expressed both flt-1 and KDR/flk-1. When the culture was prolonged to 10 days, the flt-1 mRNA expression was increased, whereas both KDR/flk-1 mRNA and protein expressions diminished. DNA and collagen syntheses were minimal in the cells cultured for 3 days, but marked in those cultured for 10 days. Addition of recombinant human VEGF to the culture medium did not change both syntheses but attenuated an increase of smooth muscle alpha-actin expression in the cells during culture on plastic dishes and also contraction of collagen gels on which the cells were cultured. We conclude that VEGF may inhibit contraction of hepatic stellate cells appearing during activation by culture, probably through attenuation of smooth muscle alpha-actin expression via upregulated VEGF receptor, flt-1.     

Characterization of myosin heavy chains in cultured aorta smooth muscle cells. A comparative study

Myosin heavy chains (MHCs) from rat aorta smooth muscle cells were analyzed prior to and after these cells were placed into cell culture using sodium dodecyl sulfate-5% polyacrylamide gels, immunoblots, and two-dimensional peptide maps of tryptic digests. Rat aorta smooth muscle cells prior to culture were found to contain two MHCs (mass = 204 and 200 kDa) which cross-reacted with antibodies raised to smooth muscle myosin, but not with antibodies raised to platelet myosin. Tryptic peptide maps of these two MHCs showed no major differences when compared to each other and to maps of vas deferens and uterus smooth muscle MHCs. When rat aorta smooth muscle cells were placed into culture, the MHCs isolated from the cell extracts differed, depending on whether the cells were rapidly growing or postconfluent. Extracts from log-phase cultures contained predominantly MHCs that migrated more rapidly than smooth muscle myosin in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (mass = 196 kDa) and cross-reacted with antibodies raised to platelet myosin, but not to smooth muscle myosin. Tryptic peptide maps of this MHC were very similar to those obtained with MHCs from non-muscle sources such as platelets and fibroblasts. In contrast, extracts from postconfluent rat aorta cell cultures contained three MHCs (mass = 204, 200, and 196 kDa). Using immunoblots and peptide maps, the fastest migrating MHC was found to be identical to the 196-kDa non-muscle MHC, while the two slower migrating MHCs had the same properties as aorta smooth muscle MHCs prior to culture. These results suggest that smooth muscle cells grown in primary culture contain predominantly (greater than 80%) non-muscle myosin while actively growing, but at a postconfluent stage, contain more equivalent amounts of smooth muscle and non-muscle myosins.     

Sulfated glycoproteins and extracellular matrix of cultured human pulmonary endothelial cells

Endothelial cells derived from human pulmonary arteries incorporate (³H)-glucosamine and ³⁵SO₄ into glycosaminoglycans and into the carbohydrate side chains of glycoproteins. These ³H/³⁵S-carbohydrate chains were isolated from cells and culture medium after Pronase digestion. The ³H/³⁵S-glycosaminoglycans were separated from the ³H/³⁵S glycopeptides by chromatography on Sephadex G-50. The distribution of cellular glycosaminoglycans and glycopeptides indicated that 30–60% of the cellular ³⁵S-glycopeptides may be associated with the matrix components that are synthesized by the cell and attached to a plastic substratum. Human pulmonary arterial endothelial cells were grown on collagen or on a matrix derived from vascular smooth muscle cells in order to investigate how smooth muscle cell extracellular matrix components may regulate the synthesis of endothelial cell glycoconjugates. Endothelial cells grown on plastic release various proportions of the glycoconjugates they synthesize into the culture medium. However, these same cells, when grown on substratum composed of extracellular matrix materials, synthesized altered proportions of cell-associated glycosaminoglycans and reduced the levels of total glycosaminoglycans they released into the culture medium. Thus the growth of endothelial cells on a matrix of smooth muscle cell components indicates that the glycosaminoglycan materials released into the culture medium by cells grown on a plastic substratum may not be an accurate reflection of the levels or composition of extracellular matrix materials made by endothelial cells in vivo.     

Release of nitric oxide from human vascular smooth muscle cells

It has recently been shown that nitric oxide (NO) or a labile NO-releasing compound is produced in endothelial cells. In the present study we measured the NO-release from human vascular smooth muscle cells in culture. The cells released an average 2.2 x 10(-9) moles nitric oxide per 10(8) cells in ten minutes with a large variation between different cell lines and passages without stimulators. The NO-release was markedly reduced by the inhibitor of NO-formation NG-momomethyl-L-arginine (L-NMMA, 10(-5) M) to 3% of the control levels (p less than 0.02, n = 4), but unaffected by acetylcholine, bradykinin or endothelin -1, -2 or -3. In a microperfusion system the compound released from human vascular smooth muscle cells caused profound relaxation of isolated rat mesenteric resistance arteries. Thus, human vascular smooth muscle cells in culture produce and release biologically active NO from L-arginine.     

Platelet factors stimulate fibroblasts and smooth muscle cells quiescent in plasma serum to proliferate

Whole blood serum is widely recognized as essential for the growth of diploid cells in culture. Dermal fibroblasts and arterial smooth muscle cells fail to proliferate in culture in the presence of serum derived from platelet-poor plasma. Platelet-poor plasma serum is capable of maintaining monkey arterial smooth muscle cells quiescent in culture at either low (1.5 x 10(3)) or high (2.0 x 10(4)) population densities. The proportion of cell traversing the cell cycle under these conditions was approximately 3%. Equal numbers of quiescent smooth muscle cells initiated DNA synthesis and cell division when treated with whole blood serum or with an equivalent quantity of platelet-poor plasma serum supplemented with a factor(s) derived from a supernate obtained after exposure of human platelets to purified thrombin in vitro.     

Characterization of cyclic nucleotide and inositol 1,4,5-trisphosphate-sensitive calcium-exchange activity of smooth muscle cells cultured from the human corpora cavernosa

Smooth muscle-mediated expansion and contraction of the vascular sinusoids of the corpora cavernosa may modulate male erectile function. To elucidate the biochemical events that control erection by promoting or inhibiting contraction of cavernosal smooth muscle, tissue from a potent man was grown in cell culture. The cells grew as noncontractile cultures, but had the following smooth muscle cell properties: These cells expressed desmin, the muscle cell-specific intermediate filament protein. They accumulated 45Ca2+ from the medium, which was released by exposure to the ionophore A23187, to cyclic nucleotides (cyclic guanosine 5'-monophosphate [GMP] much greater than cyclic adenosine 3',5'-monophosphate [AMP]), and to the phosphodiesterase inhibitor, papaverine; and; they accumulated Ca2+ in an ATP-dependent manner when the cultured cells were permeabilized by digitonin extraction. ATP-dependent Ca2+ uptake was inhibited approximately 80% by ruthenium red and simulated by cyclic GMP much greater than cyclic AMP. Inositol 1,4,5-trisphosphate (IP3), which is thought to mediate the release of Ca2+ by the smooth muscle cell sarcoplasmic reticulum in vivo, released approximately 0.85 pmol Ca2+/million cells from the digitonin-extracted cells. IP3-dependent release occurred in the presence of ruthenium red and was not affected by cyclic GMP or cyclic AMP. These results indicate that smooth muscle from this human source can be grown successfully in cell culture and that the biochemical pathways that regulate tension in vivo may be perpetuated in vitro. Moreover, some of the clinical responses to drugs administered in situ for erectile dysfunction (e.g. papaverine) may be the result of altered cavernosal smooth muscle cell Ca2+ exchange and may be mediated by cyclic GMP.     

Adult human arterial smooth muscle cells in primary culture Modulation from contractile to synthetic phenotype

Summary Smooth muscle cells were isolated enzymatically from adult human arteries, grown in primary culture in medium containing 10% whole blood serum, and studied by transmission electron microscopy and [³H]thymidine autoradiography. In the intact arterial wall and directly after isolation, each smooth muscle cell had a nucleus with a wide peripheral zone of condensed chromatin and a cytoplasm dominated by myofilament bundles with associated dense bodies. After 1–2 days of culture, the cells had attached to the substrate and started to spread out. At the same time, a characteristic fine-structural modification took place. It included nuclear enlargement, dispersion of the chromatin and formation of large nucleoli. Moreover, myofilament bundles disappeared and an extensive rough endoplasmic reticulum and a large Golgi complex were organized in the cytoplasm. This morphological transformation of the cells was completed in 3–4 days. It was accompanied by initiation of DNA replication and mitosis.The observations demonstrate that adult human arterial smooth muscle cells, when cultivated in vitro, pass through a phenotypic modulation of the same type as arterial smooth muscle cells from experimental animals. This modulation gives the cells morphological and functional properties resembling those of the modified smooth muscle cells found in fibroproliferative lesions of atherosclerosis. Further studies of the regulation of smooth muscle phenotype and growth may provide important clues for a better understanding of the pathogenesis of atherosclerosis.     

Adult stem cell homing and differentiation in vitro on composite fibrin matrix

Strategies to generate differentiated cells from haematopoetic progenitor cells will enhance potential use of adult stem cells for therapeutic transplantation or tissue engineering. Transplantation of undifferentiated stem cells into recipient tissue hinges on the hypothesis of a milieu dependent differentiation and it has been suggested that a clot-equivalent scaffold is crucial for these circulating cells to anchor and multiply. Here a natural scaffold, fibrin along with fibronectin, gelatin and growth factors has been used to induce endothelial progenitor cells and smooth muscle progenitor cells to differentiate into endothelial cells and smooth muscle cells, respectively, from peripheral blood mononuclear cells. Characteristics of endothelial cells have been verified by the detection of mRNA for and immunostaining the cells for von Willebrand factor, uptake of acetylated low-density lipoproteins and measurement of released nitric oxide in the culture medium, as nitrite. The specific molecules that characterized smooth muscle cells were alpha smooth muscle actin and calponin, besides deposition of collagen type I and elastin, onto the culture matrix. The adhesive proteins used for the fabrication of endothelial progenitor cells matrix and smooth muscle progenitor cells matrix were the same, but specific differentiation was brought about by modulating the growth factor composition in the matrix and in the culture medium. Both endothelial and smooth muscle cells were consistently developed from 20 ml of human blood.     

IL-1beta inhibits intestinal smooth muscle proliferation in an organ culture system: involvement of COX-2 and iNOS induction in muscularis resident macrophages

Intestinal inflammation causes hyperplasia of smooth muscle that leads to thickening of the smooth muscle layer, resulting in dysmotility. IL-1beta is a proinflammatory cytokine that plays a central role in intestinal inflammation. In this study, to evaluate the effect of IL-1beta on proliferation of ileal smooth muscle cells in vivo, we utilized an organ culture system. When rat ileal smooth muscle tissue was cultured under serum-free conditions for 3 days, most smooth muscle cells maintained their arrangement and kept their contractile phenotype. When 10% FBS was added, an increased number of smooth muscle cells per unit area was observed. Moreover, immunohistochemical staining for PCNA demonstrated that FBS induced proliferation of smooth muscle cells. IL-1beta inhibited the proliferative effect of FBS. Furthermore, IL-1beta upregulated inducible nitric oxide (NO) synthase and cyclooxygenase-2 mRNA and protein and thus stimulated NO and PGE(2) productions. Moreover, exogenously applied NO and PGE(2) inhibited the increase of bromodeoxyuridine-positive cells stimulated with FBS. Immunostaining revealed that the majority of cyclooxygenase-2 and inducible NO synthase was located in the dense network of macrophages resident in the muscularis, which were immunoreactive to ED2. Based on these findings, IL-1beta acts as an anti-proliferative mediator, which acts indirectly through the production of PGE(2) and NO from resident macrophage within ileal smooth muscle tissue.     

Isolation and culture of smooth muscle cells from human umbilical cord arteries

Summary A short method is described for obtaining a large number of pure vascular smooth muscle cells in culture. The smooth muscle cells were isolated from human umbilical cord arteries digested twice by an enzyme mixture of collagenase, trypsin, elastase, and DNAase with addition of α-tosyl-lysyl chloromethane. Primary cell culture and first subculture were not contaminated by endothelial cells, no Factor VIII being produced. The cultures consisted of smooth muscle cells as appeared from phase contrast and electron microscopy. Part of this study was supported by a scholarship from the Dutch Ministry of Education and Science and by the Leyden University Foundation.     

An elastinolytic enzyme detected in the culture medium of human arterial smooth muscle cells

The culture medium of human arterial smooth muscle cells exhibits an elastinolytic activity with 68 and 64 kDa on elastin substrate gels. The enzymatic activities are inhibited by ethylenediamine tetraacetic acid, a metalloproteinase inhibitor, but not by other inhibitors of serine, cysteine and aspartic proteinases. The proteinase in the culture medium is activatable by 4-aminophenylmercuric acetate and degrades insoluble elastin. Compared to other matrix metalloproteinases (MMP), the activity shows the similar elastinolytic pattern to that by MMP-2 purified from human rheumatoid synovium, while MMP-3 and MMP-9 have different lytic patterns and MMP-1 possesses no elastinolytic activity. An immunoblot analysis demonstrated that the 68-kDa enzyme is MMP-2. An immunofluorescence study illustrates that MMP-2 is localized within the cytoplasm of the smooth muscle cells. These findings suggest that the elastinolytic enzyme secreted by human arterial smooth muscle cells is MMP-2.     

Meta-vinculin distribution in adult human tissues and cultured cells

Meta-vinculin distribution in adult human tissue was studied by immunoblotting technique. Meta-vinculin was found in smooth (aorta wall and myometrium) and cardiac muscle, rather than in skeletal muscle, liver, kidney and cultured cells - macrophages, foreskin fibroblasts, peripheral blood lymphocytes and vascular endothelial cells. In the primary culture of smooth muscle cells from human aorta the meta-vinculin/vinculin ratio was reduced, and on the onset of cell division meta-vinculin could hardly be detected. Subcultured smooth muscle cells from human aorta did not contain meta-vinculin. The data show that the presence of meta-vinculin is characteristic of 'contractile' smooth muscle cells rather than of proliferating in vitro.     

Role of lipoproteins in growth of human adult arterial endothelial and smooth muscle cells in low lipoprotein-deficient serum

Recently improved culture conditions for human adult arterial endothelial and smooth muscle cells from a wide variety of donors have been used to study the effects of lipoproteins on proliferation of both cell types in low serum culture medium. Optimal growth of endothelial and smooth muscle cells in an optimal nutrient medium (MCDB 107) containing epidermal growth factor, a partially purified fraction from bovine brain, and 1% (v/v) lipoprotein-deficient serum was dependent on either high- or low-density lipoprotein. High- and low-density lipoprotein stimulated cell growth by three- and five-fold, respectively, over a 6-day period. Optimal stimulation of both endothelial and smooth muscle cell growth occurred between 20 and 60 micrograms/ml of high- and low-density lipoproteins, respectively. No correlation between the activation of 3-hydroxyl-3-methylglutaryl coenzyme. A reductase activity and lipoprotein-stimulated cell proliferation was observed. Lipid-free total apolipoproteins or apolipoprotein C peptides from high-density lipoprotein were partially effective and together with oleic acid effectively replaced native high-density lipoprotein for the support of endothelial cell growth. In contrast, apolipoproteins or apolipoprotein C peptides from high-density lipoprotein alone or with oleic acid had no effect on smooth muscle cell proliferation. The results suggest a functional role of high- and low-density lipoproteins and apolipoproteins in the proliferation of human adult endothelial and smooth muscle cells.