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A Zalewski

Publications and source records attributed to A Zalewski.

At least 19 recordsLinked to original sources
PubMed1999

Role of matrix metalloproteinases and their tissue inhibitors in the regulation of coronary cell migration.

The migration of vascular cells is regulated by matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs). Because the activation of adventitial fibroblasts has been implicated in coronary repair, we have examined regional differences in cell outgrowth and the synthesis of MMPs/TIMPs in different layers of porcine coronary arteries. Coronary medial explants demonstrated significantly slower cell outgrowth than coronary adventitia in culture (P<0.001). These observations were paralleled by the predominant expression of TIMP-1 and -2 in the media (14-fold and 37-fold higher than in adventitia, respectively, P<0.001), whereas higher gelatinolytic activities (MMP-2 and -9) were released from adventitial explants. Smooth muscle cell outgrowth from the media was regulated by endogenous TIMPs, since TIMP inhibition (recombinant MMP-2 or neutralizing anti-TIMP antibodies) facilitated cell outgrowth (P<0.001). In contrast, the addition of recombinant TIMP-1 or -2 decreased adventitial cell outgrowth. In the coculture experiments, the presence of coronary media retarded adventitial cell outgrowth, whereas medial damage abrogated these effects, allowing for fibroblast migration (P<0.001). In conclusion, this study demonstrated differential migratory properties and distinct MMP/TIMP synthesis by coronary fibroblasts and smooth muscle cells. Endogenous TIMPs in the media may play an important role in maintaining coronary arterial wall homeostasis, whereas high levels of matrix-degrading activities confer the "invasive" characteristics of adventitial fibroblasts.

Animals↗
PubMed1998

Early injury to the media after saphenous vein grafting.

BACKGROUND: Injury to the smooth muscle cells of the media affects the remodeling process of vein grafts. The purpose of this study was to determine whether different techniques of surgical preparation influence the degree of medial smooth muscle injury. METHODS: Carotid-saphenous vein interposition grafting was performed in crossbred pigs (n = 32), using distended (n = 16) or nondistended (n = 16) conduits. After 3 to 90 days, the media was evaluated for the presence of smooth muscle cells (desmin stains), myofibroblast formation (transient alpha-SM actin expression), and apoptosis (TdT-mediated dUTP nick end-labeling [TUNEL]). RESULTS: Smooth muscle loss was uniformly severe; only 5% +/- 5% (p < 0.01) and 14% +/- 9% (p < 0.01) of the medial area of distended and nondistended veins were desmin positive in comparison with 80% +/- 9% of controls. Apoptosis appeared to contribute to medial smooth muscle loss (5.7% +/- 4.3% in vein grafts versus 0.0% +/- 0.0% of TUNEL-positive cells in controls; p = 0.05). There was a time dependent increase in medial myofibroblast formation (p < 0.05). CONCLUSIONS: Severe medial smooth muscle loss occurs in vein grafts, even when prepared without distension. Apoptosis contributes to the early disappearance of smooth muscle cells. Adjunctive measures, in addition to ideal surgical techniques, should be developed to prevent medial muscle loss.

Actins↗
PubMed1998

Sustained reduction of neointima with c-myc antisense oligonucleotides in saphenous vein grafts.

BACKGROUND: Treatment of saphenous veins with c-myc antisense oligomers during preparation for grafting reduces medial cellular proliferation and macrophage infiltration, and preserves medial smooth muscle content at 3 days. Accordingly, the purpose of this study was to examine whether c-myc antisense oligomers have an impact on late vein graft remodeling. METHODS: Sixty-two pigs underwent unilateral saphenous vein-carotid artery interposition grafting. Harvested veins were incubated either in saline (control group) or 20-micromol/L or 200-micromol/L concentrations of c-myc antisense oligomers (treated groups) for 30 minutes intraoperatively. Three months after surgery, vein graft histology was assessed. RESULTS: Forty-five of 62 randomized animals survived the experiment; no differences in animal survival or graft patency among the groups were observed (p = NS, chi2). C-myc antisense oligomers significantly decreased neointimal and wall thickness, as well as increased lumenal index, in treated groups (p<0.04, p<0.03, and p<0.001, respectively, analysis of variance). In contrast, there was no difference in medial thickness or perivascular wound healing. CONCLUSION: Intraoperative treatment of saphenous veins with c-myc antisense oligomers decreased neointimal formation at 3 months after grafting. In conjunction with our previous reports, these findings suggest that early inhibition of cellular proliferation and inflammatory infiltration results in a sustained reduction in neointimal formation and favorable graft remodeling.

Animals↗
PubMed1998

Saphenous vein graft protection: effects of c-myc antisense.

OBJECTIVE: Saphenous vein grafting is associated with extensive medial remodeling, characterized by cellular proliferation, loss of smooth muscle cells, and an inflammatory response. In this study, we examined whether unfavorable responses to vein grafting could be modified by the intraoperative application of c-myc antisense oligomers. METHODS: The intragraft cell proliferation, macrophage infiltration, and medial preservation were examined in a porcine model in the control and antisense-treated groups (n = 36). RESULTS: Saphenous veins showed transmural distribution of oligomers within 30 minutes of the ex vivo incubation. A concentration-dependent inhibition of cell proliferation in the media of saphenous grafts was noted 3 days later (0 to 200 mumol/L, p = 0.005). The growth inhibition was sequence-specific, because control oligomers produced only insignificant effects (20 mumol/L). Vascular effects of c-myc antisense were associated with a significant attenuation of macrophage infiltration in saphenous grafts. A concentration-dependent decrease in tissue edema (p = 0.0005) and the attenuated loss of smooth muscle cells (p = 0.002) were noted in the media of the arterialized venous conduits after c-myc antisense. CONCLUSIONS: Direct application of synthetic DNA to harvested saphenous veins resulted in a rapid transmural distribution. The inhibition of the intragraft cell proliferation in vivo after c-myc antisense was sequence dependent. Decrease in vein graft injury resulted in an attenuated inflammatory response and better medial preservation. These findings provide a rationale for assessment of the long-term effects of vein graft protection with c-myc antisense.

Animals↗
PubMed1997

Remodeling of autologous saphenous vein grafts. The role of perivascular myofibroblasts.

BACKGROUND: Aortocoronary saphenous vein grafts (SVGs) undergo structural changes that render them susceptible to atherosclerosis. Accordingly, the origin of neointimal hyperplasia-was examined in porcine arterialized SVGs to determine the mechanism of vein graft remodeling. METHODS AND RESULTS: At 2 to 4 days after surgery, the percentage of cells lacking differentiation markers characteristic for smooth muscle (SM) cells (ie, alpha-SM actin, desmin, and SM myosin) increased within the media of SVGs interposed in the carotid arteries (P < .001). At 7 to 14 days, these cells acquired a differentiated phenotype (ie, alpha-SM-actin positive/ variable desmin/SM-myosin negative) and accumulated in the neointima. At 3 months, the neointima was positive for alpha-SM actin but mostly negative for desmin, which contrasted with medial SMCs that were invariably positive for alpha-SM actin, desmin, and SM myosin. To determine the role of nonmuscle cells in the above process, perivascular wound fibroblasts were selectively labeled and found to translocate through the media of newly placed SVGs, contributing to neointimal formation. These migrating cells differentiated to myofibroblasts exhibiting sustained alpha-SM-actin expression. The intima of human SVGs, retrieved during repeat aortocoronary bypass surgery, exhibited the profile of cytoskeletal proteins that resembled myofibroblasts seen in porcine SVGs. CONCLUSIONS: Perivascular fibroblasts may infiltrate injured media of arterialized SVGs, differentiate to myofibroblasts (acquiring alpha-SM actin), and contribute to vein graft remodeling. The similarities between porcine and human SVGs regarding the repertoire of cytoskeletal proteins suggest the involvement of myofibroblasts in graft remodeling in the clinical setting.

Actins↗
PubMed1997

Origin of extracellular matrix synthesis during coronary repair.

BACKGROUND: Coronary injury triggers differentiation of activated adventitial fibroblasts to myofibroblasts, which may contribute to neointimal formation and vascular remodeling. Accordingly, the purpose of this study was to examine the cellular origin of the enhanced synthesis of extracellular matrix proteins during coronary repair. METHODS AND RESULTS: The time course and localization of collagen and elastin expression were examined by in situ hybridization and immunohistochemistry in porcine coronary arteries after balloon-induced injury. Procollagen-alpha 1(I) transcripts and intracellular type I procollagen protein increased in the adventitia within 2 days after injury. This was followed by a sustained synthesis of type I procollagen in neointima beginning at 7 days and the extracellular accumulation of type I collagen in both layers. The origin of synthetic cells was further examined by colocalization of type I procollagen and bromodeoxyuridine labeling to activated adventitial cells, which translocated to neointima. Neointimal cells exhibited sustained synthetic activity manifested by the presence of type I procollagen and elastin at 3 months after injury. In contrast, the media showed only minor changes in the synthesis of collagen or elastin throughout coronary repair. CONCLUSIONS: Activated adventitial fibroblasts are endowed with synthetic capabilities after coronary injury. They express type I procollagen, with some of them translocating to the intima, where they continue to synthesize procollagen. The accumulation of type I collagen is evident in the adventitia and neointima, whereas elastin accumulates mainly in neointima. These findings support the involvement of adventitial fibroblasts in coronary repair and remodeling after endoluminal injury.

Angioplasty, Balloon↗
PubMed1997

Wound healing around and within saphenous vein bypass grafts.

BACKGROUND: Myofibroblasts are a prominent cell type in wound healing. The goal of this study was to examine the extent to which myofibroblasts contribute to structural changes in saphenous vein bypass grafts. METHODS AND RESULTS: Control veins and reversed saphenous vein bypass conduits of porcine carotid arteries were examined 2 to 4, 7 to 14, and 30 to 90 days after surgery with immunohistochemical markers of cellular proliferation (proliferating cell nuclear antigen), cytoskeletal protein production (alpha-smooth muscle actin and desmin), and histochemistry (Verhoeff's stain). Control veins demonstrated an extremely low level of cellular proliferation and no evidence of myofibroblasts in the adventitia, media, or intima. After bypass grafting, cellular proliferation was followed by myofibroblast formation, which occurred in the perivascular area and within the media. This was evidenced by a dense, but transient, expression of alpha-smooth muscle actin and a variable expression of desmin at 1 to 2 weeks, and with a significant increase in collagenous tissue by 1 to 3 months. Major cytoskeletal protein changes also occurred in the intima, with the appearance of alpha-smooth muscle actin positive cells at 7 to 14 days. alpha-Smooth muscle actin was still present in the neointima at 1 to 3 months, which is compatible with a persistent myofibroblast formation. CONCLUSION: Myofibroblast formation occurs around and within saphenous veins after bypass grafting. This phenomenon is associated with significant remodeling of the vein grafts. The histologic changes are strikingly similar to events that occur during wound healing and may have implications for the development of neointimal hyperplasia and late vein graft disease.

Animals↗
PubMed1997

Vascular myofibroblasts. Lessons from coronary repair and remodeling.

Recent findings demonstrate that adventitial fibroblasts (i.e., nonmuscle cells) are endowed with several characteristics previously attributed to medial SM cells. The response of the coronary artery to balloon angioplasty is associated with the activation of adventitial cells in a porcine model. They appear to be the most reactive in the arterial wall, as reflected by the extent of proliferation and the synthesis of collagen. Differentiation of adventitial cells, which acquire alpha-SM actin, illustrates the formation of vascular myofibroblasts, a ubiquitous cellular mechanism of tissue repair. Myofibroblasts are involved in remodeling of the adventitia and may contribute to the formation of the neointima after balloon-induced coronary injury. These findings suggest that at least some synthetic SM-like cells present in intimal lesions may originate from medial or adventitial nonmuscle cells. Myofibroblasts also appear to play a role in other cardiovascular abnormalities (e.g., vein graft remodeling), which raises the possibility of targeted therapies.

Animals↗
PubMed1996

Adventitial myofibroblasts contribute to neointimal formation in injured porcine coronary arteries.

BACKGROUND: The adventitia undergoes remodeling changes after a deep medial coronary injury. Because this process is associated with the formation of adventitial myofibroblasts, which resemble medial smooth muscle (SM) cells, we have examined myofibroblast involvement in the development of neointima. METHODS AND RESULTS: In a porcine model, severe endoluminal coronary injury resulted in fibroblast proliferation and adventitial remodeling. Significant adventitial responses were associated with increased neointimal formation (P < .01). To examine the contribution of adventitial cells to the development of neointima, proliferating cells were labeled with bromodeoxyuridine (BrdU) at 12 and 24 hours after injury, and their subsequent localization was determined by immunohistochemistry (n = 24). At 2 to 3 days after severe injury, the adventitia contained numerous BrdU-labeled cells (37 +/- 4%), whereas the media demonstrated infrequent labeled cells (4 +/- 1%). Adventitial cells lacked alpha-SM actin and desmin, which distinguished them from medial SM cells. At 7 to 8 days, some labeled cells acquired characteristics of myofibroblasts expressing alpha-SM actin. They were found to translocate to the gap between dissected media and contributed to the formation of neointima (76 +/- 19%). At 18 to 35 days, labeled cells were abundant in the neointima (86 +/- 5%). They showed uniform immunostaining for alpha-SM actin but not for desmin, thereby differing from medial SM cells and blood-borne cells. CONCLUSIONS: This study demonstrates translocation of adventitial fibroblasts to neointima, their phenotypic modulation to myofibroblasts, and distinct characteristics of myofibroblasts within neointima after severe endoluminal coronary injury. These findings suggest the significance of vascular fibroblasts in the process of arterial repair.

Animals↗
PubMed1996

Adventitial remodeling after coronary arterial injury.

BACKGROUND: Intraluminal thrombus formation and medial smooth muscle (SM) cell proliferation are recognized responses of the arterial system to injury. In contrast to these well-characterized processes during vascular repair, changes involving the adventitia have been largely neglected in previous studies. Hence, the goal of this investigation was to assess the response of the adventitia to coronary arterial injury. METHODS AND RESULTS: Adventitial changes in porcine coronary arteries subjected to medial injury were characterized by immunohistochemistry, histochemistry, and microscopic morphometry. The rapid development of a hypercellular response in the adventitia was evident 3 days after balloon-induced medial injury. Cell proliferation, as assessed by proliferating cell nuclear antigen immunostaining, reached the maximum level in the adventitia at 3 days, whereas at 14 and 28 days, the number of replicating cells reverted toward the baseline. The proliferating activity in the adventitia exceeded that seen in the media at all times after injury. To further define the changes in the phenotype of adventitial cells, the expression of three cytoskeletal proteins (vimentin, alpha-SM actin, and desmin) was characterized. Fibroblasts in normal adventitia expressed vimentin but no alpha-SM actin or desmin. After injury, these cells acquired characteristics of myofibroblasts expressing alpha-SM actin, which peaked at 7 and 14 days. Desmin expression was patchy in the adventitia, as opposed to its homogeneous distribution in medial SM cells. The modulation of fibroblast phenotype was transient, inasmuch as alpha-SM actin immunostaining declined at 28 days after injury, when dense, collagen-rich scar was evident within the adventitia. The above-described changes involving hypercellularity of the adventitia, myofibroblast formation, and fibrosis were associated with a significant focal adventitial thickening at 3, 7, 14, and 28 days after injury (P < .01 versus uninjured coronary arteries). CONCLUSIONS: This study demonstrates the involvement of the adventitia in the vascular repair process after medial injury. The hypercellularity of the adventitial layer, proliferation of fibroblasts, and modulation of their phenotype to myofibroblasts are associated with the development of the thickened adventitia. It is postulated that these phenomena affect vascular remodeling and may provide an important insight into the mechanisms of vascular disorders.

Actins↗
PubMed1996

Peripheral vascular complications after intracoronary stent placement: prevention by use of a pneumatic vascular compression device.

Peripheral vascular complications are a significant source of morbidity after coronary artery stent implantation. The goal of this study was to assess the incidence, risk factors, and management of vascular complications after stent placement. The study population consisted of 101 consecutive patients who underwent stent placement for either elective or bailout indications. All patients received a standardized anticoagulation regimen of aspirin, dipyridamole, low molecular weight dextran, heparin, and warfarin. Peripheral vascular access sites were examined daily until hospital discharge. Vascular complications occurred in 16 of 101 (16%) patients, including femoral artery pseudoaneurysm (n = 11), hematoma requiring transfusion or surgery (n = 4), and arteriovenous fistula (n = 1). Intervention was required in 14 of 16 (88%) patients with complications. These included transfusion (n = 7), ultrasound-guided compression (n = 8), and/or vascular surgery (n = 7). Length of hospital stay was prolonged in patients with complications (14 +/- 9 vs. 8 +/- 5 d, P < 0.001). The development of peripheral vascular complications did not correlate with clinical or procedural variables such as age, cardiovascular risk factors, arterial sheath size, or elective vs. bailout indication. After the introduction of a pneumatic vascular compression device (FEMOSTOP, C.A. Bard, Billerica, MA), a significant reduction in vascular complications was observed. Complications occurred in only 1 of 41 (2.4%) patients in whom the compression device was used in contrast to 13 of 58 (22.4%) patients compressed manually (P < 0.01). Thus peripheral vascular complications are frequent after coronary artery stent placement and are associated with serious morbidity and prolongation of hospital stay. These complications are significantly reduced by the use of a pneumatic vascular compression device despite intensive systemic anticoagulation.

Hemostasis, Surgical↗
PubMed1996

Host nerve fibers that regenerate and reside long-term in a rejected nerve allograft are not protected by permability barriers.

We investigated whether permeability barriers develop and protect host nerve fibers that regenerate and reside long-term in a rejected nerve allograft. In order for the barriers to form, host cells have to enter the rejected allograft and differentiate into new endothelial and perineurial cells that respectively form the impermeable endoneurial blood-nerve and the perineurium-nerve barriers that are present in normal nerve. A 2-cm long graft of peroneal nerve was taken from American Cancer Institute (ACI) or Fischer (FR) rats and transplanted to bridge a 2-cm gap between the cut ends of the peroneal nerve of other FR rats. Six months postoperatively, histology revealed that regenerated host nerve fibers in ACI allografts were compartmentalized into numerous minifascicles by perineurial cells and that blood vessels were located outside rather than inside the perineurial compartments among the nerve fibers. Administration of the permeability indicator horseradish peroxidase to allograft recipients (intravenously or topically to the graft in situ) revealed that it entered the endoneurium of microcompartments and spread around the nerve fibers. In contrast, none of the indicator reached nerve fibers in FR syngrafts or normal ACI or FR nerves which were not microcompartmentalized. We concluded that host nerve fibers that regenerate and reside long-term in a rejected nerve allograft are not protected by permeability barriers.

Animals↗
PubMed1996

Transforming growth factor-beta 1 expression and myofibroblast formation during arterial repair.

Transforming growth factor-beta 1 (TGF-beta 1) plays a central role in tissue repair owing to its modulating effects on cell growth and the synthesis of extracellular matrix. We have previously shown that adventitial fibroblasts differentiate to myofibroblasts after endoluminal injury, thereby contributing to arterial remodeling. Since TGF-beta 1 exerts several biologic actions attributed to myofibroblasts, we examined its role in myofibroblast formation in a porcine model of balloon overstretch coronary artery injury. TGF-beta 1 transcripts were induced in numerous adventitial cells 2 days after injury (47 +/- 10%, P < .001 versus control). These cells displayed no smooth muscle (SM) markers, i.e., alpha-SM actin or desmin, which suggested their fibroblastic origin. This was further corroborated by the rare presence of macrophages in the injured adventitia (3 +/- 1%). At 7 to 8 days, most TGF-beta 1-expressing cells demonstrated alpha-SM actin immunoreactivity. Their myofibroblast phenotype was confirmed by electron microscopy, which revealed microfilaments (stress fibers) and a well-developed rough endoplasmic reticulum. The distribution of TGF-beta 1 transcripts by in situ hybridization was paralleled by the immunolocalization of intracellular and extracellular TGF-beta 1 epitopes. At later times (> 14 days after injury), the decrease in TGF-beta 1 coincided with the disappearance of adventitial myofibroblasts, whereas the neointima exhibited longer TGF-beta 1 expression. In conclusion temporal and spatial relationships between TGF-beta 1 and myofibroblast formation suggest an important role for autocrine TGF-beta 1 in the phenotypic modulation of vascular fibroblasts. Induction of TGF-beta 1 expression may provide a differentiation signal for adventitial fibroblasts to become myofibroblasts, which affect arterial remodeling via their mechanical and synthetic properties.

Animals↗
PubMed1994

Comparison of coronary angiographic findings during the first six hours of non-Q-wave and Q-wave myocardial infarction.

The angiographic features of non-Q-wave acute myocardial infarction (AMI) soon after symptom onset have not been previously reported. Accordingly, this study reviewed the coronary angiographic findings of 86 patients with AMI studied within 6 hours of symptom onset: 58 had Q-wave and 28 had non-Q-wave AMI. Patients with Q-wave and non-Q-wave AMI were comparable in terms of clinical characteristics, frequency of 1-vessel disease, and infarct-related artery location. Thrombus was observed in 49 patients (84%) with Q-wave AMI versus 12 (43%) with non-Q-wave AMI (p = 0.0002). Whereas complete occlusion of the infarct-related artery was present in 53 patients (91%) with Q-wave AMI, total coronary occlusion was present in only 11 (39%) with non-Q-wave AMI (p = 0.0001). Collaterals to occluded infarct arteries were seen in 10 patients (19%) with Q-wave AMI versus 5 (45%) with non-Q-wave AMI (p = 0.06). Residual perfusion of the infarct artery by either anterograde or collateral flow was typical of patients with non-Q-wave AMI (22 of 28, 79%) but was uncommon in those with Q-wave AMI (15 of 58, 26%) (p = 0.0001). Thus, coronary angiography performed within 6 hours of symptom onset demonstrates important differences between Q-wave and non-Q-wave AMI. Non-Q-wave AMI is characterized by partial perfusion of the infarct-related artery by either anterograde or collateral flow, and a lower incidence of thrombus than Q-wave AMI.(ABSTRACT TRUNCATED AT 250 WORDS)

Chi-Square Distribution↗
PubMed1994

Transcatheter delivery of c-myc antisense oligomers reduces neointimal formation in a porcine model of coronary artery balloon injury.

BACKGROUND: Smooth muscle cell proliferation and extracellular matrix accumulation are the principal mechanisms leading to vascular restenosis. We have previously demonstrated the growth-inhibitory effect of antisense oligomers targeting the c-myc proto-oncogene in human smooth muscle cells. The goal of this study was to investigate whether c-myc antisense oligomers reduce neointimal formation in balloon-denuded porcine coronary arteries. METHODS AND RESULTS: First, type I collagen synthesis, which reflects synthetic function, was markedly reduced following c-myc antisense oligomers in porcine vascular smooth muscle cells independent of the growth inhibition. These effects in vitro provided the rationale for assessing c-myc antisense oligomers in the prevention of neointima in vivo. Second, the efficiency of single transcatheter delivery of oligomers into denuded porcine coronary arteries was determined. Despite rapid plasma clearance following local delivery, oligomers persisted at the site of injection for at least 3 days, exceeding by severalfold their concentration in peripheral organs. Third, morphometric analyses were carried out in balloon-denuded coronary arteries at 1 month after transcatheter c-myc antisense oligomer administration. Maximal neointimal area was reduced from 0.80 +/- 0.17 mm2 in the control group (n = 12) to 0.24 +/- 0.06 mm2 in the antisense-treated group (n = 13, P < .01). Likewise, a significant reduction in maximal neointimal thickness was observed in the antisense-treated group (P < .01). These changes in vascular remodeling following denuding injury resulted in an increase in residual lumen from 64 +/- 6% in the control group to 81 +/- 5% in the antisense-treated group (P < .05). CONCLUSIONS: (1) Single transcatheter administration allowed for endoluminal delivery of oligomers to the site of coronary arterial injury. (2) C-myc antisense oligomers reduced the formation of neointima in denuded coronary arteries, implying a therapeutic potential of this approach for the prevention of coronary restenosis. (3) It is postulated that the c-myc proto-oncogene is involved in the process of vascular remodeling, regulating smooth muscle cell proliferation and extracellular matrix synthesis.

Angioplasty, Balloon, Coronary↗
PubMed1994

Transgene expression in the coronary circulation: transcatheter gene delivery.

Therapeutic and research applications of direct gene transfer in the coronary vasculature are limited by varying transgene activity found in the vessel wall. It remains to be determined whether this is due to difficulties in delivery of recombinant DNA into the coronary arteries or if it relates to the state of recipient cells in the arterial wall. Accordingly, using a clinically applicable protocol, we have examined the time course of transgene (luciferase) expression in porcine coronary vasculature following transcatheter gene transfer (1 day to 4 weeks). Liposome-mediated transfection by means of a transcatheter approach resulted in detectable luciferase activity in all transfected vessels at 1 day after gene delivery. However, the activity of a reporter gene rapidly declined at 7 days thereafter, with only 33% of coronary arteries demonstrating luciferase activity. Comparable levels of transgene sequences were present in transfected vessels, although no correlation with luciferase activity was found. To further determine possible mechanisms responsible for rapidly declining transgene expression in vivo, cell proliferation was induced in the vessel wall by means of either balloon denudation or by intramural injections of platelet derived growth factor BB (PDGF-BB) into the porcine coronary vasculature at the time of gene transfer. Luciferase activity was significantly augmented (23-fold) following mitogenic stimulation in vivo as compared with the control transfected coronary arteries. These data demonstrate that a practical transcatheter approach provides an effective route to deliver recombinant DNA sequences into the coronary arterial wall.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Downregulation of c-myc expression by antisense oligonucleotides inhibits proliferation of human smooth muscle cells.

BACKGROUND: Proliferation of smooth muscle cells (SMCs) plays an important role in vascular pathobiology, being involved in the development of coronary restenosis and atherosclerosis. The activation of nuclear proto-oncogenes appears to be a final common pathway onto which various mitogenic signals coverage. Accordingly, we attempted to determine whether the activation of the c-myc nuclear proto-oncogene is essential for human SMC proliferation and explored the possibility of inhibiting their growth using antisense oligonucleotides directed against c-myc messenger RNA (mRNA). METHODS AND RESULTS: Proliferation of human SMCs was associated with an increase in c-myc mRNA expression after growth stimulation. Using 15-mer phosphorothioate oligonucleotides (oligomers), we tested their growth-inhibitory effect in SMCs in vitro. Antisense oligomers directed against the translation initiation region of the human c-myc gene exhibited a significant antiproliferative effect, whereas sense and mismatched oligomers did not inhibit the growth. The growth-inhibitory effect of c-myc antisense oligomers was dose dependent and preventable by an excess of sense oligomers. Furthermore, growth inhibition of SMCs treated with c-myc antisense oligomers was associated with a marked decrease in the c-myc mRNA level. Phosphorothioate oligomers remained stable in medium containing 20% serum and were detectable in SMCs as early as 1 hour after cell exposure. Intact oligomers rapidly accumulated intracellularly and persisted within human SMCs for at least 16 hours. CONCLUSIONS: c-myc antisense oligomers reduced c-myc expression and produced a significant growth inhibition of human SMCs, indicating an important role of c-myc gene activation in the process of SMC proliferation. Furthermore, extracellular stability and rapid cellular uptake provide the basis for future studies assessing the therapeutic role of the c-myc antisense approach in reducing SMC proliferation in the process of vascular restenosis.

Cell Division↗