Biomedical subjects

C M Giachelli

Publications and source records attributed to C M Giachelli.

At least 55 records · Page 3Linked to original sources

PubMed1996

Angiotensin II induction of osteopontin expression and DNA replication in rat arteries.

We recently identified the adhesive protein osteopontin as a novel smooth muscle cell product overexpressed in rat developing neointima and human atheroma. Although osteopontin is a candidate stimulant for intimal lesion progression because of its chemotactic and calcium binding functions, factors controlling osteopontin expression in arteries remain poorly defined. In vitro, smooth muscle cell expression of osteopontin is associated with cell cycle transit or alterations in cell phenotype, and it is increased by angiotensin II (Ang II) stimulation. In the present studies, we investigated both osteopontin expression and DNA replication in the arterial wall in response to chronic Ang II infusion in vivo. Rat carotid arteries with or without intimal thickening (induced by balloon catheterization) were examined. Ang II (250 ng/kg per minute) or vehicle was coinfused with bromodeoxyuridine (to label replicating DNA in vivo) for 2 weeks beginning 4 weeks after injury. With Ang II, smooth muscle cells overexpressed osteopontin as shown by protein immunohistochemistry, in situ hybridization, and Northern blot analyses. Osteopontin mRNA levels were increased markedly (approximately fivefold) in the normal artery media and injured artery neointima, but levels remained low in the injured artery media, in positive correlation (R2 = 0.88, P < .001) with DNA replication in the smooth muscle layers, further suggesting that osteopontin may be a growth-associated, phenotype-dependent gene for smooth muscle cells. However, osteopontin expression in neointima was not restricted to areas showing DNA replication, suggesting a nonobligatory association. Ang II induced severe hypertension. Arterial osteopontin expression was increased also by chronic catecholamine infusion, a model of vascular growth stimulation showing labile pressure elevations. Osteopontin induction in smooth muscle cells may contribute to Ang II-dependent intimal lesion progression and vascular remodeling events associated with renovascular diseases or hyperadrenergic disorders.

Angiotensin II↗

PubMed1996

Differential expression of alpha 1 type VIII collagen in injured platelet-derived growth factor-BB--stimulated rat carotid arteries.

Migration of smooth muscle cells from media to intima is critical for the development of neointimal thickening after balloon catheter injury of the rat carotid artery. The present experiments were designed to identify molecules expressed by smooth muscle cells migrating in vivo in the injured artery. Cell migration was maximized by infusing recombinant platelet-derived growth factor-BB (PDGF-BB) after a minimal filament denudation of the rat carotid artery, whereas cell proliferation was minimized by injecting an antibody against basic fibroblast growth factor (bFGF). This treatment caused an eightfold increase in smooth muscle cell migration into the intima but only a twofold increase in intimal smooth muscle cell replication rates. Differential display screening was used to isolate cDNAs that were overexpressed in the injured PDGF-BB-treated versus unmanipulated rat carotids. One of the clones isolated hybridized to a 4.2-kb mRNA species and shared 90% sequence homology to mouse alpha 1 type VIII collagen. Northern and Western blots confirmed overexpression of type VIII collagen in the injured PDGF-BB-treated vessels. In a separate series of experiments, we performed filament denudation injury and administered antibodies to inhibit the actions of endogenous bFGF and PDGF-BB, thereby decreasing smooth muscle cell migration, and found that type VIII collagen mRNA expression varied with migration. Using a different arterial injury model (balloon catheter injury), we showed that expression of type VIII collagen was maximal 2 to 4 days after injury, in coincidence with cell migration from the media to the intima. This molecule constitutes an important component of smooth muscle cell response to vessel injury and may play an important functional role in mediating migration.

Animals↗

PubMed1996

Autocrine secretion of osteopontin by vascular smooth muscle cells regulates their adhesion to collagen gels.

Osteopontin (OPN) is a secreted protein postulated to facilitate vascular smooth muscle cell (VSMC) adhesion and migration. Rat aortic VSMC lines were isolated after infection with recombinant retroviruses harboring OPN sense and antisense constructs. All lines grew normally in monolayer culture. On three-dimensional collagen gels, normal VSMCs and lines containing sense constructs (n=15) or empty vector (n=10) attached to gel and invaded the matrix. Four of five antisense clones did not adhere or invade. Antisense clones had lower OPN levels after stimulation with angiotensin II than sense clones or clones containing the empty vector (antisense, 257+/-102 ng/ml; sense, 473+/-104; vector, 434+/-66). Non-adhering antisense clones had lower mean OPN levels after angiotensin II stimulation (161+/-47 ng/ml) than sense or antisense lines with normal adhesion (486+/-63 ng/ml). The ability to adhere correlated with OPN levels >250 ng/ml. Adhesion and invasion were fully restored with addition of 100 to 200 ng/ml of exogenous OPN and were inhibited in normal VSMCs by incubation with 1 microgram/ml anti-OPN antibody. The autocrine secretion of OPN appears to play an important role in VSMC adhesion, spreading, and invasion.

Animals↗

PubMed1995

Expression of osteopontin in the head process late in gastrulation in the rat.

Osteopontin (OPN) is a secreted, glycosylated phosphoprotein. Previous studies have implicated OPN in calcification/decalcification and inflammation. We became interested in developmental expression of OPN because of our previous findings that suggest OPN may play a role in formation of new vascular layers after injury, and because of our observation of developmental regulation in vascular smooth muscle cells. While OPN was expressed at low levels in vessels, only late in development, examination of very early expression patterns revealed a surprising finding. OPN was expressed exclusively in the head process, on day 9.0 late in gastrulation in the rat. In vitro studies of vascular smooth muscle cells have previously demonstrated that OPN promotes cell adhesion and migration. It is suggested that OPN may promote migration of cells, during gastrulation, via integrins which may be present in the head process or overlying ectoderm.

Animals↗

PubMed1995

Osteopontin expression in cardiovascular diseases.

Adhesive interactions are recognized requirements for cellular proliferation, migration and differentiation during normal morphogenesis as well as disease. By differential cloning, osteopontin was identified as an adhesive protein upregulated during vascular remodeling and neointima formation in both rat models and human vascular diseases including atherosclerosis and restenosis. In functional studies, purified osteopontin promoted adhesion, focal contact formation, and migration of vascular smooth muscle and endothelial cells. Utilizing neutralizing antibodies, three integrin-type receptors, alpha v beta 3, alpha v beta 1, and alpha v beta 5 were found to support cellular adhesion to osteopontin. In contrast, only cells containing the alpha v beta 3 integrin could migrate towards an osteopontin gradient, demonstrating for the first time that different functions of osteopontin are mediated via distinct receptors. These results suggest a model whereby osteopontin, via its integrin-type receptors, contributes to vascular remodeling during development and disease by facilitating smooth muscle migration and simultaneously promoting endothelial coverage of the affected area.

Angiotensin II↗

PubMed1995

Renal expression of genes that promote interstitial inflammation and fibrosis in rats with protein-overload proteinuria.

Rats with significant proteinuria induced by daily injections of bovine serum albumin develop interstitial inflammation and fibrosis. The present study was designed to investigate the molecular basis of interstitial monocyte (Mø) recruitment and early interstitial fibrosis. Groups of rats were sacrificed after one, two and three weeks. Despite an increase in interstitial Mø at week 1, whole kidney mRNA levels were not elevated for monocyte chemoattractant protein-1 (MCP-1), osteopontin or vascular cell adhesion molecule-1 (VCAM-1). Only osteopontin mRNA levels were significantly elevated in the renal cortex at four days. At two and three weeks, MCP-1 and osteopontin mRNA levels were increased and the proteins showed distinct tubular patterns of distribution. By immunostaining increased expression of VCAM-1 and intercellular adhesion molecule-1 (ICAM-1) was restricted to their presence or the surface of the interstitial inflammatory cells. TGF-beta 1 mRNA levels were increased at weeks 1, 2 and 3 (2.1, 2.9, 3.6x); interstitial and occasional cortical tubular cells expressed TGF-beta 1 mRNA and protein. There was a progressive rise in the number of cortical interstitial fields with increased staining for collagen (col) 1 (18, 29, 44%), col III (39, 61, 63%), col IV (7, 13, 29%), laminin (4, 10, 30%), fibronectin (14, 28, 37%), tenascin (19, 22, 14%) and in total renal col measured biochemically (1.1, 1.4, 2.0x) at weeks 1, 2 and 3, respectively. Renal matrix protein mRNA levels were variable and not always predictive of fibrosis. Only col I and tenascin levels were increased at week 1; all matrix protein mRNA levels except col IV were increased at week 2; but only tenascin, laminin and col IV mRNA levels remained elevated at three weeks. Plasminogen activator inhibitor-1 (PAI-1) and tissue inhibitor of metallo-proteinases (TIMP)-1 mRNA levels were significantly increased at two weeks. During the three weeks there was no change in urokinase, stromelysin or TIMP-3 mRNA levels. These results suggest that both increased matrix protein synthesis and altered matrix remodeling/degradation contribute to the final interstitial fibrogenic process in rats with protein-overload proteinuria. Mø, one of the sources of TGF-beta 1, infiltrate the interstitium by complex recruitment mechanisms which may depend in part on osteopontin, ICAM-1 and VCAM-1 expression.

Animals↗

PubMed1995

Cellular proliferation and macrophage influx precede interstitial fibrosis in cyclosporine nephrotoxicity.

Chronic cyclosporine (CsA) nephrotoxicity is a major complication of solid organ transplantation, and is characterized histologically by striped tubulointerstitial fibrosis, tubular atrophy, and hyalinization of the afferent arteriole, a highly specific finding in cyclosporine injury. The salt-depleted rat model of chronic cyclosporine nephropathy mimics these lesions in humans. We conducted sequential studies of this model in groups of pair fed rats (N = 6) treated with CsA (15 mg/kg, s.q.) or an equivalent dose of olive oil. Proliferation of tubular and interstitial cells was documented early in the medulla by day 5 (3.2 +/- 2.1 vs. 0.81 +/- 0.4 cells/HPF in CsA vs. control, P < 0.02), and was maximal in areas of interstitial fibrosis by day 35 (7.9 +/- 3.7 vs. 0.52 +/- 0.2 cells/HPF in CsA vs. control, P < 0.005). The interstitial fibrosis was associated with a significant macrophage influx by day 35 (13.9 +/- 3.5 vs. 1.5 +/- 0.32 cells/HPF, CsA vs. control, P < 0.005), which correlated with increased cortical tubular staining for the macrophage adhesion protein, osteopontin. Elevated serum creatinine correlated with interstitial fibrosis at day 35 (0.85 +/- 0.11 vs. 0.40 +/- 0.03 mg/dl Cr, CsA vs. control, P < 0.005) by linear regression (r = 0.9, P < 0.05). Medullary proliferation and interstitial fibrosis correlated with decreased tubular concentrating ability, and higher urinary volume. Cortical interstitial fibrosis was maximal at day 35 and was associated with an increase in type I and type IV collagen deposition, while tubular injury was associated with increased vimentin expression. Tubular interstitial cells also expressed increased vimentin early in the medulla (day 10) and later in the cortex. Both groups remained normotensive despite significantly elevated juxtaglomerular (JG) apparatus renin expression in CsA treated animals, implicating the intrarenal-renal renin-angiotensin system in this disease. We conclude that cyclosporine nephrotoxicity is associated with early tubular and interstitial cell proliferation, and a significant macrophage influx that precedes the development of cortical interstitial fibrosis and afferent arteriolar hyalinosis. These early cellular changes correlate with functional abnormalities including decreased creatinine clearance (CCr) and decreased medullary concentrating ability, which stabilized despite progressive fibrosis. These cellular events may be important in the pathogenesis of chronic CsA nephrotoxicity.

Animals↗

PubMed1995

A subpopulation of smooth muscle cells in injured rat arteries expresses platelet-derived growth factor-B chain mRNA.

Proliferation of smooth muscle cells (SMCs) and formation of a neointima are characteristics of the response of rat carotid arteries to balloon injury. Rat platelet-derived growth factor (PDGF)-B was cloned, thus allowing us to use species-specific probes to carry out in situ hybridization on the surface of injured arteries. A distinct population of luminal SMCs (7% to 10%) in the developing neointima expressed PDGF-B mRNA, but very few luminal SMCs still expressed PDGF-B (0.5%) when the lesion had stopped growing. Primary SMC cultures revealed expression of PDGF-B mRNA in 1.6% of SMCs derived from normal tunica media and in 11% of SMCs derived from the neointima. These data demonstrate that SMCs in the injured vessel wall are heterogeneous with regard to PDGF-B expression and that subculturing of these cells may give rise to cultures that are either positive or negative for PDGF-B expression. Furthermore, with abundant expression of the PDGF receptor beta-subunit expressed by intimal SMCs, our findings provide evidence that PDGF-B synthesized by these cells may be involved in intimal lesion formation via a paracrine or autocrine mechanism.

Amino Acid Sequence↗

PubMed1995

Osteopontin and beta 3 integrin are coordinately expressed in regenerating endothelium in vivo and stimulate Arg-Gly-Asp-dependent endothelial migration in vitro.

Osteopontin is an Arg-Gly-Asp (RGD)-containing acidic glycoprotein postulated to mediate cellular adhesion and migration in a growing number of normal and pathological conditions through interaction with integrin molecules. In this report, we have investigated the potential contributions of osteopontin and one of its receptors, the alpha v beta 3 integrin, to endothelial regenerative processes by using both in vivo and in vitro models. In vivo, uninjured rat arterial endothelium had undetectable levels of osteopontin and beta 3-integrin mRNA by in situ hybridization. After balloon catheter denudation, osteopontin mRNA levels correlated temporally and spatially with active endothelial proliferation and migration, with the highest levels observed at the wound edge between 8 hours and 2 weeks after injury, declining to uninjured levels at 6 weeks, when regeneration was complete. Osteopontin protein levels, as determined by immunocytochemistry, paralleled the time course of mRNA expression. Likewise, beta 3-integrin mRNA and protein levels were substantially elevated in regenerating endothelial cells but were not detectable in uninjured or healed endothelium. In vitro, rat smooth muscle cell-derived and bacterial expressed mouse recombinant osteopontins both stimulated the adhesion and directed migration of bovine aortic endothelial cells through interactions with the alpha v beta 3 receptor. Structural mutants of osteopontin confirmed the importance of the RGD domain for both adhesion and migration of endothelial cells through alpha v beta 3. These data suggest important roles for osteopontin and beta 3 integrin in regenerating endothelium.

Animals↗

PubMed1995

Alpha-v beta-3 integrin expression in normal and atherosclerotic artery.

Recent evidence suggests that alpha v beta 3 integrin is a critical molecule in several processes involved in atherosclerosis progression and in restenosis, eg, smooth muscle cell (SMC) migration and angiogenesis. While several ligands for this integrin are known to be present in atherosclerotic plaque, little is known about the presence of alpha v beta 3 integrin at this site. In the present study, we have examined alpha v beta 3 expression in normal and atherosclerotic arteries. Thirty-six coronary artery segments from the recipient hearts of 24 patients undergoing heart transplantation were classified into two groups: nonatherosclerotic diffuse intimal thickening (DIT) and atherosclerotic plaques. Serial frozen sections were examined immunohistochemically with four different monoclonal antibodies directed against human alpha v beta 3 complex or the beta 3 subunit and with cell markers for SMCs, macrophages, and endothelial cells. The endothelium along the lumen of both DIT and plaque arteries showed high expression of alpha v beta 3. The media of both DIT and plaque arteries showed less intense but extensive expression of alpha v beta 3. Immunoprecipitation and reverse-transcribed polymerase chain reaction (RT-PCR) analyses performed on extracts from the aortic media confirmed the presence of alpha v beta 3 in the media. In the intima of both DIT and plaque arteries, alpha v beta 3 expression generally colocalized with SMCs but rarely with macrophages. The microvessels in the adventitia as well as in the plaque showed prominent expression of alpha v beta 3, in contrast to low expression in similar-sized microvessels of the skin.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

The adhesive and migratory effects of osteopontin are mediated via distinct cell surface integrins. Role of alpha v beta 3 in smooth muscle cell migration to osteopontin in vitro.

Osteopontin is an arginine-glycine-aspartate containing acidic glycoprotein postulated to mediate adhesion, migration, and biomineralization in diverse tissues. The mechanisms explaining this multifunctionality are not well understood, although it is known that one osteopontin receptor is the alpha v beta 3 integrin. In this work, we studied human smooth muscle cells varying in alpha v beta 3 levels to identify additional osteopontin receptors. We report that, in addition to alpha v beta 3, both alpha v beta 5 and alpha v beta 1 are osteopontin receptors. Moreover, the presence or absence of alpha v beta 3 on the cell surface altered the adhesive and migratory responses of smooth muscle cells to osteopontin. Adhesion of alpha v beta 3-deficient cell populations to osteopontin was only half that of cells containing alpha v beta 3, and migration toward an osteopontin gradient in the Boyden chamber was dependent on cell surface alpha v beta 3. Although alpha v beta 3-deficient smooth muscle cells were unable to migrate to osteopontin, they did migrate significantly in response to vitronectin and fibronectin. These findings represent the first description of alpha v beta 5 and alpha v beta 1 as osteopontin receptors and suggest that, while adhesion to osteopontin is supported by integrins containing beta 1, beta 3, and beta 5, migration in response to osteopontin appears to depend on alpha v beta 3. Thus, interaction with distinct receptors is one mechanism by which osteopontin may initiate multiple functions.

Adult↗

PubMed1995

Characterization of human aortic smooth muscle cells expressing HPV16 E6 and E7 open reading frames.

A comparative study of human papillomavirus type 16 E6E7-transfected and normal human aortic smooth muscle cells by morphological, electron microscopic, immunofluorescent, and biochemical analyses demonstrated that the E6E7-expressing cells retained much of the phenotype of normal aortic smooth muscle cells, including expression of smooth muscle markers and appropriate growth responses to PDGF and heparin. These cells differed from normal vascular smooth muscle cells in that they had slightly altered morphology and a higher growth rate that was not due to an autocrine response to secreted PDGF, and they contained more polyribosomes than normal smooth muscle cells.

Aorta↗

PubMed1995

Formation of the arterial media during vascular development.

We are still in the earliest stages of studying the molecular biology of vascular development. Key questions, even simple questions, such as the origin of endothelial precursors from the epiblast or the mesoderm, remain largely unanswered. For the smooth muscle cell, we do not even have a satisfactory molecular definition of cell type, because the known cell type-specific markers generally disappear when these cells are placed in vitro, and even in vivo smooth muscle cells identified by location can be very undifferentiated. A few bright spots illuminate this cloudy prospect. We do have endothelial lineage markers, and, given the powerful tools of promoting analysis, it seems likely that we will soon known a lot more about the identification of the endothelial lineage. It is hoped that this will help us understand how patterns of development of the vessel wall are controlled. Similarly, the failure of our early studies to identify molecules responsible for investment by smooth muscle can be seen as an exciting finding. If platelet-derived growth factor, fibroblast growth factor, and transforming growth factor beta are not expressed until after smooth muscle investment, still other as yet unidentified factors must be present to account for this stage of development of the vessel wall.

Animals↗

PubMed1994

Osteopontin expression in angiotensin II-induced tubulointerstitial nephritis.

Osteopontin is an arginine-glycine-aspartate (RGD) containing secreted phosphoprotein recently shown to stimulate a local macrophage influx when injected subcutaneously in mice. We examined the effect of angiotensin II infusion on renal injury and osteopontin expression in the rat kidney by in situ hybridization and immunohistochemistry. Preceding pathologic changes in tubular and interstitial cells, a dramatic increase in renal osteopontin protein and mRNA levels was observed primarily in epithelial cells of the distal tubules, collecting ducts and Bowman's capsule. Although both cortex and medulla showed increased osteopontin levels, the effect was most pronounced in the renal cortex which normally showed very little constitutive osteopontin expression. Interestingly, regions of the kidney expressing high osteopontin levels correlated with sites of monocyte/macrophage accumulation. These observations, coupled with recent findings that osteopontin may be a pro-inflammatory protein, suggests that osteopontin over-expression may facilitate monocyte/macrophage accumulation at the sites of renal tubulointerstitial injury.

Angiotensin II↗

PubMed1994

Osteopontin is synthesized by macrophage, smooth muscle, and endothelial cells in primary and restenotic human coronary atherosclerotic plaques.

How an atherosclerotic plaque evolves from minimal diffuse intimal hyperplasia to a critical lesion is not well understood. Cellular proliferation is a relatively infrequent and modest event in both primary and restenotic coronary atherectomy specimens, leading us to believe that other processes, such as the formation of extracellular matrix, cell migration, neovascularization, and calcification might be more important for lesion formation. The investigation of proteins that are overexpressed in plaque compared with the normal vessel wall may provide clues that will help determine which of these processes are key to lesion pathogenesis. One such molecule, osteopontin (OPN), is an arginine-glycine-aspartate-containing acidic phosphoprotein recently shown to be a novel component of human atherosclerotic plaques and selectively expressed in the rat neointima following balloon angioplasty. Using in situ hybridization and immunohistochemical methods, we demonstrate that in addition to macrophages, smooth muscle and endothelial cells synthesize OPN mRNA and protein in human coronary atherosclerotic plaque specimens obtained by directional atherectomy. In contrast, OPN mRNA and protein were not detected in nondiseased vessel walls. Furthermore, extracellular OPN protein collocalized with sites of early calcification in the plaque that were identified with a sensitive modification of the von Kossa staining technique. These findings, combined with studies showing that OPN has adhesive, chemotactic, and calcium-binding properties, suggest that OPN may contribute to cellular accumulations and dystrophic calcification in atherosclerotic plaques.

Aged↗

PubMed1994

Osteopontin promotes vascular cell adhesion and spreading and is chemotactic for smooth muscle cells in vitro.

Osteopontin is an Arg-Gly-Asp-containing acidic phosphoprotein recently shown to be upregulated in vascular smooth muscle during rat arterial neointima formation and in human atherosclerotic plaques. Functional studies showed that osteopontin promoted adhesion of both cultured aortic endothelial cells and aortic smooth muscle cells. Adhesion of vascular cells to osteopontin was dose dependent and half maximal when solutions containing 7 and 30 nmol/L osteopontin were used to coat wells for endothelial and smooth muscle cells, respectively. Smooth muscle cells adherent to osteopontin were spread after 60 minutes, whereas endothelial cells remained round, although flattened, at this time point but were spread at 90 minutes. Cell spreading on osteopontin was accompanied by the formation of focal adhesion plaques. A newly developed anti-osteopontin antibody completely inhibited adhesion of both cell types to osteopontin but not to fibronectin or vitronectin. In addition, the peptide GRGDSP blocked adhesion to osteopontin, suggesting that integrins mediate Arg-Gly-Asp-dependent adhesion. Indeed, an antibody against the alpha v beta 3 integrin neutralized adhesion of both endothelium and smooth muscle cells to osteopontin by approximately 50%, demonstrating that alpha v beta 3 is one osteopontin receptor on vascular cells. Osteopontin also promoted the migration of smooth muscle cells in a Boyden-type chamber, with half-maximal effects observed at 77 nmol/L osteopontin. Checkerboard analysis demonstrated that this stimulus was chemotactic in nature. Our findings suggest that osteopontin may be functionally important as an adhesive and chemotactic molecule for vascular cells, particularly when levels of osteopontin are dramatically increased, as is the case after arterial angioplasty and in atherosclerotic plaques.

Animals↗

PubMed1994

Macrophages express osteopontin during repair of myocardial necrosis.

Osteopontin is a secreted glycoprotein implicated in a variety of functions, including cell adhesion and migration. Because these functions may be of general importance in the response of tissue to injury, we examined osteopontin expression after experimental cardiac injury and human myocardial infarction. Rat hearts were injured by transdiaphragmatic freeze-thaw and examined from 1 to 28 days after injury. Osteopontin was absent from normal myocardium by immunocytochemistry, Western blotting, and in situ hybridization. On days 1 and 2 after injury, osteopontin mRNA and protein were expressed at high levels by macrophages infiltrating necrotic myocardium. Double labeling with the macrophage marker ED1, however, demonstrated that only a subset of macrophages expressed osteopontin. Western blot analysis showed a single 66-kd band in injured myocardium that was absent from control tissue. Although macrophages remained abundant in the ensuing granulation response and scar tissue formation, the expression of osteopontin was diminished on day 4 and markedly downregulated at 1 and 4 weeks after injury, with only rare cells expressing the message or protein. In a human heart with an 8-day-old myocardial infarct, there was abundant expression of osteopontin mRNA and protein in macrophages within the necrotic and granulation tissue. Transient expression of osteopontin was also observed in a subset of macrophages infiltrating lung, skin, and skeletal muscle injured during the experiment, indicating the response was not limited to the heart. Thus, synthesis of osteopontin by macrophages appears to be a generalized response in the reaction to tissue injury. Although macrophages persist in these lesions, osteopontin is dramatically downregulated as healing proceeds. These results provide the first evidence that osteopontin may be important in healing after tissue injury, possibly in cellular adhesion, chemotaxis, and/or phagocytosis.

Animals↗

PubMed1994

Characterization of cloned aortic smooth muscle cells from young rats.

Clones were derived by dilute plating from cultured aortic smooth muscle cells of 12-day-old rats. Clones Pup I to III resemble uncloned smooth muscle cultures from aortas of rat pups and from adult rat neointimas. They have a cobblestone morphology and proliferate in plasma-derived serum. By Northern analysis they contain platelet-derived growth factor B chain (PDGF-B) mRNA and high levels of CYPIA1, elastin, and osteopontin mRNAs, and they lack platelet-derived growth factor alpha-receptor (PDGF-alpha R) mRNA. In contrast, Pup V resembles smooth muscle cultures derived from uninjured adult rat arteries. It has an elongated morphology and proliferates poorly in plasma-derived serum. This clone expresses PDGF-alpha R mRNA, low levels of elastin and osteopontin mRNAs, and lacks CYPIA1 and PDGF-B mRNAs. Pup IV and VI have most of the properties of Pup I to III. We conclude that uncloned pup cultures are heterogeneous, but that the growth properties and gene expression pattern described for the uncloned culture is characteristic of individual clones within the population.

Actins↗