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L Weir

Publications and source records attributed to L Weir.

At least 19 recordsLinked to original sources
PubMed1996

Therapeutic angiogenesis following arterial gene transfer of vascular endothelial growth factor in a rabbit model of hindlimb ischemia.

The plasmid phVEGF165, expressing the 165-amino-acid isoform of vascular endothelial growth factor (VEGF), an endothelial cell specific mitogen, was applied to the polymer coating of an angioplasty balloon and delivered percutaneously to the iliac artery of rabbits in which the femoral artery had been excised to cause hindlimb ischemia. Site-specific transfection of phVEGF165 resulted in augmented development of collateral vessels documented by serial angiograms, and increased capillary density as well as increased capillary/myocyte ratio documented histochemically at necropsy. Consequent amelioration of the hemodynamic deficit in the ischemic limb was documented by improvement in the calf blood pressure ratio (ischemic/normal limb) to 0.70 +/- 0.08 in the VEGF-transfected group vs 0.50 +/- 0.18 in controls (p < 0.05). These findings suggest that site-specific arterial gene transfer of VEGF165 may achieve physiologically meaningful therapeutic modulation of vascular insufficiency.

Animals↗
PubMed1996

Arterial gene transfer for therapeutic angiogenesis in patients with peripheral artery disease.

The age-adjusted prevalence of peripheral arterial disease (PAD) in the U.S. population has been estimated to approach 12%. The clinical consequences of occlusive peripheral arterial disease (PAD) include pain on walking (claudication), pain at rest, and loss of tissue integrity in the distal limbs; the latter may ultimately lead to amputation of a portion of the lower extremity. Surgical bypass techniques and percutaneous catheter-based interventions may be used to successfully revascularize the limbs of certain patients with PAD. In many patients, however, the anatomic extent and distribution of arterial occlusion is too severe to permit relief of pain and/or healing of ischemic ulcers. No effective medical therapy is available for the treatment of such patients. The purpose of this clinical protocol is to document the safety of therapeutic angiogenesis achieved in this case by percutaneous catheter-based delivery of the gene encoding vascular endothelial growth factor (VEGF) in patients with PAD; and, as secondary objectives, investigate the bioactivity of this strategy to relieve rest pain and heal ischemic ulcers of the lower extremities. The rationale for this human protocol is based upon preclinical studies performed in a rabbit model of hindlimb ischemia. These studies are described in detail below and in the manuscripts enclosed in the Appendix to this proposal. In brief, a single intra-arterial bolus of VEGF recombinant human protein, delivered percutaneously to the ischemic limb via an intravascular catheter, resulted in angiographic, hemodynamic, physiologic, and histologic evidence of augmented collateral artery development. Subsequently, similar results were achieved using an angioplasty catheter with a hydrogel-coated balloon to deliver 400 micrograms of a plasmid containing the cDNA for VEGF to the internal iliac artery in the same animal model. Accordingly, we propose to administer arterial gene (VEGF) therapy to patients with rest pain and/or ischemic leg ulcers considered not to be candidates for conventional revascularization techniques. The dose of plasmid to be administered will be progressively escalated beginning with 500 micrograms for the first four patients, 1000 micrograms for the following six patients, 2000 micrograms for the third group of six patients, and 400 micrograms for the fourth group of six patients.

Arteries↗
PubMed1996

Processing of chimeric antisense oligonucleotides by human vascular smooth muscle cells and human atherosclerotic plaque. Implications for antisense therapy of restenosis after angioplasty.

BACKGROUND: Antisense oligonucleotides have been used in animals to inhibit the accumulation of vascular smooth muscle cells (VSMCs) after arterial injury. This has raised prospects for an oligonucleotide-mediated approach to prevent restenosis in patients undergoing angioplasty. However, little is known about the processing of oligonucleotides by human VSMCs or their bioavailability in human atherosclerotic tissue. METHODS AND RESULTS: Oligonucleotides were synthesized with a mixture of unmodified and sulfur-modified linkages (S-chimeric oligonucleotides). These were more stable than unmodified oligonucleotides and could be recovered from within human VSMCs after 36 hours. Oligonucleotide antisense to human proliferating cell nuclear antigen mRNA specifically reduced DNA synthesis (P < .01) and proliferating cell nuclear antigen protein content (P < .05) in human VSMCs. Confocal microscopy of both live and fixed cells showed modest oligonucleotide uptake that was primarily nuclear. Surprisingly, cationic liposomes did not enhance nuclear uptake but led to extensive, punctated cytoplasmic loading without an enhanced antisense effect. Oligonucleotides incubated with human coronary atherosclerosis fragments associated with cells within 1 hour, despite the presence of abundant extracellular matrix. CONCLUSIONS: S-chimeric oligonucleotides are stable and can specifically inhibit gene expression in human VSMCs. Nuclear transport is a feature of oligonucleotide processing by human VSMCs, indicating a potential influence at the nuclear level rather than with cytoplasmic mRNA. Cationic liposomes increased oligonucleotide uptake but not intracellular bioavailability, and S-chimeric oligonucleotides can be incorporated into cells within human atherosclerotic plaque, despite the presence of a dense extracellular matrix.

Angioplasty↗
PubMed1996

Apocrine carcinoma of the lip: a case report including immunohistochemical and ultrastructural study, discussion of differential diagnosis, and review of the literature.

The light microscopic, immunohistochemical, and ultrastructural features of a case of apocrine carcinoma of the upper lip of a 54-year-old white man are described. The neoplasm had a cribriform intraductal component resembling apocrine carcinoma of the breast. The tumor had irregular borders and infiltrated skeletal muscle. The neoplastic cells had abundant eosinophilic granular cytoplasm and showed apical decapitation secretion characteristic of apocrine differentiation. The differential diagnosis is discussed with particular reference to distinction of the tumor from oncocytic carcinoma and ductal carcinoma of minor salivary gland.

Adenocarcinoma↗
PubMed1996

Characterization of the nonmuscle myosin heavy chain IIB promoter: regulation by E2F.

To identify DNA sequences important for the transcriptional regulation of the nonmuscle myosin heavy chain IIB (NMMHC-IIB) gene we isolated and sequenced genomic clones that contain the promoter of the gene for both human and mouse. In addition to considerable homology in the first (untranslated) exon (91%) we found 80% sequence identity in the 700 base pairs immediately upstream of the major start of transcription (+1) as well as significant homologies as far as 1500 base pairs upstream. The promoter region was characterized using luciferase reporter constructs transiently transfected into NIH3T3 cells. Consensus binding sites for several known transcription factors are present that are completely conserved between the mouse and human genes, including CRE/ATF, Sp1, CAAT, and the cell-cycle transcription factor E2F. Gel shift assays indicated that E2F can bind to its putative binding site in vitro. To test whether this site is functional we cotransfected NMMHC-IIB promoter constructs driving luciferase with a vector expressing E2F-1. The E2F-1 vector stimulated luciferase activity from an intact promoter whereas mutation of the site eliminates binding and diminishes transactivation. These data provide strong evidence that E2F or an E2F-related transcription factor is involved in the regulation of nonmuscle myosin expression.

3T3 Cells↗
PubMed1995

Expression of gax, a growth arrest homeobox gene, is rapidly down-regulated in the rat carotid artery during the proliferative response to balloon injury.

gax is a recently described homeobox gene whose expression in the adult is largely confined to cardiovascular tissues, gax has been shown to be rapidly down-regulated in cultured vascular smooth muscle cells (VSMC) upon stimulation by serum or platelet-derived growth factor. The temporal profile of gax expression in vitro matches that of two families of growth arrest genes: the gas genes and the gadd genes. All of these genes are expressed at their highest levels in quiescent cells and are down-regulated following mitogen activation. Here we report that gax is also down-regulated in vivo in the vascular wall in response to endothelial denudation by balloon angioplasty. The reduction in steady state levels of gax mRNA is transient and occurs with a similar time course to that seen in vitro. The down-regulation of gax in response to balloon injury mirrors the up-regulation seen in a number of early response genes such as c-myc and c-fos. This report is the first to document the in vivo expression of a growth arrest gene which regulates proliferation of vascular smooth muscle cells. In addition, in contrast with previous reports which have demonstrated up-regulation of several genes following balloon injury and/or angioplasty, the present report demonstrates the down-regulation of a regulatory gene within hours of balloon injury. The characteristics of gax suggest it may be required to maintain the gene expression of proteins in VSMC that are associated with the nonproliferative or contractile phenotype in smooth muscle cells.

Angioplasty, Balloon↗
PubMed1995

Radiation treatment of cervical lymph node metastases from an unknown primary: an analysis of outcome by treatment volume and other prognostic factors.

One hundred and forty-four patients with diagnosis of carcinoma involving cervical lymph nodes from an unknown primary site were seen at the Princess Margaret Hospital, Toronto between 1970 and 1986. This paper addresses the outcome of two treatment approaches using radiation treatment as potentially curative therapy. The treatment approaches compared in a retrospective analysis are radiation to the involved node regions alone (85 cases), and radiation to both the nodes and to potential primary sites in the head and neck (59 cases). The overall 5-year survival rate of the entire group of 144 cases was 41%. There was a trend to increased survival in favour of the group receiving radiation to the nodes and potential primary sites (p = 0.07), however, when differences in extent of nodal involvement were considered and adjusted for using the Cox Proportional Hazard Model, no difference in survival, or cause-specific survival was found between the two treatment groups (p = 0.18 and 0.22, respectively). A total of seven head and neck primary cancers were subsequently discovered, six in the group receiving radiation only to the nodes and one in the group receiving radiation to the nodes and primary sites. The results of this retrospective analysis need to be interpreted with caution but suggest that, for some patients with this diagnosis, radiation to the involved node region alone is adequate. A discussion of the literature is presented with attention to the effect of extent of treatment on outcome.

Carcinoma, Squamous Cell↗
PubMed1994

Liposome-mediated gene transfer into human vascular smooth muscle cells.

BACKGROUND: Complexing recombinant DNA with cationic liposomes is a convenient means of introducing foreign genes into cells (lipofection) and could potentially form the basis for genetically modifying diseased blood vessels in patients. The mechanism of lipofection is incompletely understood, but it is recognized that the degree of successful gene transfer is highly dependent on cell type. To date, there has been no reported experience with lipofection of human vascular smooth muscle cells. METHODS AND RESULTS: Primary cultures of human vascular smooth muscle cells were transfected under optimized conditions with a plasmid expressing either firefly luciferase (Luc) or nuclear-localized beta-galactosidase (NL-beta-gal). Cells were derived from either normal human internal mammary arteries (n = 6), fragments of primary atherosclerotic plaque (n = 4), or fragments of restenotic lesions (n = 5). Concurrent lipofection of rabbit vascular smooth muscle cells and NIH 3T3 cells was performed as well. Cultures derived from 15 patients all demonstrated positive expression of the reporter gene. Compared with NIH 3T3 cells, however, expression in human vascular smooth muscle cells was markedly reduced: in cells derived from internal mammary artery, Luc expression, normalized for protein content, was 123-fold lower than in NIH 3T3 cells, whereas the proportion of cells expressing NL-beta-gal was 30-fold lower. Luc expression in cells derived from restenotic tissue was significantly greater than from cells derived from primary plaque (P < .03). Within a given population of cells, the mitotic index of cells expressing the recombinant gene was significantly higher than the mitotic index for the total population of cells (P < .05). Finally, cotransfection experiments, in which lipofection of smooth muscle cells was performed using genes for NL-beta-gal and for human growth hormone, showed that among positive transfects, a high proportion of cells (23% to 36%) coexpressed both genes. CONCLUSIONS: The efficiency of successful lipofection in human vascular smooth muscle cells in vitro is low. Transfection appears to be preferentially facilitated in cells derived from restenotic tissue, and specific properties of smooth muscle cells, including growth rates, appear to be critical for successful transfection. Further elucidation of cell properties that promote transfection is required to augment the efficiency of liposome-mediated gene transfer in human vascular cells.

3T3 Cells↗
PubMed1994

Use of the rabbit ear artery to serially assess foreign protein secretion after site-specific arterial gene transfer in vivo. Evidence that anatomic identification of successful gene transfer may underestimate the potential magnitude of transgene expression.

BACKGROUND: The development of molecular strategies for the treatment of restenosis has been hindered by low efficiencies of in vivo arterial transfection. Expression of intracellular marker proteins is generally evident in < 1% of vascular smooth muscle cells after in vivo arterial transfection. Efforts to improve the efficiency of in vivo gene transfer have been further impeded by the use of transgenes encoding for intracellular marker proteins, necessitating tissue removal and limiting survey for expression to one point in time. METHODS AND RESULTS: To study gene expression on a serial basis in vivo and determine the relation between a secreted gene product and transfection efficiency after in vivo arterial gene transfer, a method for performing and serially monitoring gene expression in vivo was developed using the central artery of the rabbit ear. Liposome-mediated transfection of plasmid DNA containing the gene for human growth hormone (hGH) was successfully performed in 18 of 23 arteries. Serum hGH levels measured 5 days after transfection ranged from 0.1 to 3.8 ng/mL (mean, 0.97 ng/mL); in contrast, serum drawn from the control arteries demonstrated no evidence of hGH production. Serial measurement of hGH from transfected arteries demonstrated maximum hGH secretion 5 days after transfection and no detectable hormone after 20 days. Despite these levels of secreted gene product documented in vivo, immunohistochemical staining of sections taken from the rabbit ear artery at necropsy disclosed only rare cells in which there was evidence of successful transfection. CONCLUSIONS: These experiments demonstrate a useful method of performing serial in vivo analyses of gene expression after vascular transfection and that anatomic analyses of transfection efficiency may underestimate the potential magnitude of expression in the case of a secreted gene product. These findings have implications for the clinical application of somatic gene therapy because low-efficiency transfection with a gene encoding for a secreted protein may achieve therapeutic effects not realized by transfection with genes encoding for proteins that remain intracellular.

Animals↗
PubMed1994

Increased gene expression after liposome-mediated arterial gene transfer associated with intimal smooth muscle cell proliferation. In vitro and in vivo findings in a rabbit model of vascular injury.

Arterial gene transfer represents a novel strategy that is potentially applicable to a variety of cardiovascular disorders. Attempts to perform arterial gene transfer using nonviral vectors have been compromised by a low transfection efficiency. We investigated the hypothesis that cellular proliferation induced by arterial injury could augment gene expression after liposome-mediated gene transfer. Nondenuded and denuded rabbit arterial strips were maintained in culture for up to 21 d, after which transfection was performed with a mixture of the plasmid encoding firefly luciferase and cationic liposomes. In non-denuded arteries, the culture interval before transfection did not affect the gene expression. In contrast, denuded arteries cultured for 3-14 d before transfection yielded 7-13-fold higher expression (vs. day 0; P < 0.005). Transfection was then performed percutaneously to the iliac arteries of live rabbits with or without antecedent angioplasty. Gene expression increased when transfection was performed 3-7 d postangioplasty (P < 0.05). Proliferative activity of neointimal cells assessed in vitro by [3H]thymidine incorporation, and in vivo by immunostaining for proliferating cell nuclear antigen, increased and declined in parallel with gene expression. These findings thus indicate that the expression of liposome-mediated arterial gene transfer may be augmented in presence of ongoing cellular proliferation.

Animals↗
PubMed1993

Relation between activated smooth-muscle cells in coronary-artery lesions and restenosis after atherectomy.

BACKGROUND: Neointimal proliferation leading to restenosis frequently develops after coronary angioplasty. This process is associated with a change in vascular smooth-muscle cells from a contractile (quiescent) phenotype to a synthetic or proliferating (activated) one. We investigated whether the presence of activated smooth-muscle cells in coronary lesions at the time of coronary atherectomy predisposes patients to subsequent restenosis. METHODS: We used in situ hybridization to study the expression of messenger RNA in coronary-atherectomy specimens from 20 patients. Plaque material was hybridized with a probe for the B isoform of human nonmuscle myosin heavy chain, a major nonmuscle myosin isoform in activated, but not quiescent, smooth-muscle cells. Angiographic follow-up data were obtained a mean (+/- SD) of 174 +/- 54 days after atherectomy in 16 of the 20 patients, and the extent of recurrent luminal narrowing was analyzed quantitatively. The presence of restenosis was assessed by exercise thallium scintigraphy in the other four patients. RESULTS: Atherectomy specimens from 10 of the 20 patients showed hybridization with the probe, defined as the clustering of more than 20 silver grains per cell nucleus in more than 10 nuclei in five high-power fields (x250); specimens from the other 10 patients showed no such hybridization. At follow-up, restenosis had developed in 8 of the 10 patients with positive hybridization results, but was absent in 9 of the 10 patients with negative results (P = 0.007). The degree of late loss in luminal diameter was significantly higher in patients with positive hybridization results than in those with negative results (ratio of late loss to immediate gain after atherectomy, 0.76 +/- 0.3 vs. 0.36 +/- 0.3; P < 0.001). CONCLUSIONS: We conclude that the expression of the B isoform of nonmuscle myosin heavy chain is increased in some coronary atherosclerotic plaques and that this increase in expression identifies a group of lesions at high risk for restenosis after atherectomy.

Adult↗
PubMed1993

Prevention of smooth muscle cell outgrowth from human atherosclerotic plaque by a recombinant cytotoxin specific for the epidermal growth factor receptor.

Smooth muscle cell proliferation in the intima of arteries is a principal event associated with vascular narrowing after balloon angioplasty and bypass surgery. Techniques for limiting smooth muscle cell proliferation, however, have not as yet yielded any therapeutic benefit for these conditions. This may reflect the present lack of sufficiently potent and specific inhibitors of smooth muscle cell proliferation. DAB389 EGF is a genetically engineered fusion protein in which the receptor-binding domain of diphtheria toxin has been replaced by human epidermal growth factor. We evaluated the effect of this fusion toxin on human vascular smooth muscle cells in culture. Incubation of proliferating cells with DAB389 EGF yielded a dose-dependent inhibition of protein synthesis, as assessed by uptake of [3H]leucine, with an IC50 of 40 pM. The cytotoxic effect was inhibited in the presence of excess EGF or with monoclonal antibody to the EGF receptor. We further studied the effect of the fusion toxin on smooth muscle cell outgrowth from human atherosclerotic plaque. Outgrowth was markedly inhibited after as little as 1 h of exposure to the fusion protein. Furthermore, complete inhibition of proliferation of cells within the plaque could be attained. These results demonstrate that DAB389 EGF is highly cytotoxic to human smooth muscle cells proliferating in culture and can prevent smooth muscle cell outgrowth from "growth-stimulated" human atherosclerotic plaque. DAB389 EGF may therefore be of therapeutic value in vascular diseases characterized by smooth muscle cell accumulation.

Arteriosclerosis↗
PubMed1993

Proliferative activity in peripheral and coronary atherosclerotic plaque among patients undergoing percutaneous revascularization.

We evaluated the proliferative activity of human atherosclerotic lesions associated with active symptoms of ischemia, by assessing the expression of the proliferating cell nuclear antigen (PCNA). We confirmed in vitro that PCNA, an essential component of the DNA synthesis machinery, is selectively expressed in proliferating human vascular smooth muscle cells. 37 atherosclerotic lesions (18 primary and 19 restenotic) retrieved by directional atherectomy from either coronary or peripheral arteries were then studied for the expression of PCNA, using in situ hybridization or immunohistochemistry. Among plaques studied by in situ hybridization, 7 out of 11 primary and 11 out of 11 restenotic lesions contained PCNA-positive cells. The mean rate of proliferation (percent of PCNA-positive cells) was 7.2 +/- 10.8% in primary lesions and 20.6 +/- 18.2% in restenotic lesions (P < 0.05). Among specimens studied by immunohistochemistry, five out of seven primary and eight out of eight restenotic lesions contained proliferating cells. The mean rate of proliferation was again higher in the restenotic (15.2 +/- 13.6%) than primary (3.6 +/- 3.5%) lesions (P < 0.05). Proliferating cells were detected as late as 1 yr after angioplasty. We conclude that cellular proliferation is a feature of atherosclerotic lesions which are associated with symptoms of ischemia, but that it is more prominent in restenosis compared to primary lesions. These findings have implications for therapies aimed at limiting lesion growth, particularly after percutaneous revascularization.

Adult↗
PubMed1993

Using Orem's Model.

My actual knowledge of care plans and nursing models was non-existent until my conversion course to RGN in 1989. I found it difficult to grasp and at times a paper exercise. A care plan should be used as a link between the outpatient's nurse and ward nurses involved with the patient's primary care and the personnel in theatre responsible for the patient. The purpose of nursing documentation is to show that care has been planned for each individual patient; to inform nursing staff and others involved in delivering care; to record changes in the patient's condition or care; to maintain continuity of care.

Female↗
PubMed1993

Direct myocardial transfection in two animal models. Evaluation of parameters affecting gene expression and percutaneous gene delivery.

BACKGROUND: Gene therapy represents a novel approach to the treatment of a variety of disease states. Direct injection of pure untreated DNA into skeletal and cardiac muscle is sufficient to perform gene transfer in vivo. Little information is available, however, regarding the extent to which individual parameters of direct gene delivery affect the efficiency of myocardial transfection. Moreover, the fact that all previously reported studies of successful myocardial transfection were performed using open chest surgery to visualize the heart for direct injection of DNA constitutes a potential limitation to clinical applications of myocardial gene transfer. The objectives of the present study were: (a) to determine the extent to which gene expression is altered by varying the amount of DNA and the volume of the delivery vehicle; (b) to study whether protracted expression of DNA persists after direct myocardial transfection; and (c) to test the feasibility of percutaneous, transthoracic myocardial injection of DNA. EXPERIMENTAL DESIGN: New Zealand white rabbits (N = 30) were transfected with the firefly (Photinus pyralis) luciferase reporter gene. Twenty-three rabbits were segregated into 5 groups according to the amount of DNA and volume of delivery vehicle injected. These rabbits were sacrificed at 5 days posttransfection to measure the level of luciferase gene expression. Three more rabbits were designated exclusively for in situ hybridization. Two rabbits were sacrificed at 5 and 6 months, respectively to evaluate long-term expression. Two additional rabbits were used as controls. Yucatan microswine (N = 4) were used to evaluate the feasibility of percutaneous, transthoracic myocardial transfection with beta-galactosidase or luciferase reporter genes. Microswine were sacrificed immediately post-sham transfection (N = 2), or 5 days postmyocardial transfection (N = 2). RESULTS: Among 11 rabbits, transfection with 10 micrograms of DNA (N = 4), 25 micrograms of DNA (N = 3), and 50 micrograms of DNA (N = 4) in 100 microL of injectate yielded a step-wise but statistically insignificant increase in luciferase activity. Among 16 rabbits, transfection with 50 micrograms of DNA in injectate volumes of 50 microliters (N = 4), 100 microliters (N = 4), 150 microliters (N = 4), and 300 microliters (N = 4) yielded a statistically significant (p < 0.05) increase in luciferase activity in those hearts transfected with 300 microliters compared with those hearts transfected with either 50 or 100 microliters. Luciferase activity at 5 and 6 months postmyocardial transfection was 7.14 and 68.8 Turner light units, respectively. In situ hybridization confirmed that myocytes represented the site of luciferase expression. Percutaneous myocardial transfection was successfully accomplished with both reporter genes. CONCLUSIONS: The results of the present study demonstrate that increasing the amount of DNA employed for direct myocardial transfection fails to produce a statistically significant increase in the level of gene expression. In contrast, increasing the volume of injectate used to directly transfect a constant amount of DNA (50 micrograms) produced significantly augmented expression of the reporter luciferase gene. Luciferase expression was detected 6 months posttransfection. Successful transfection after fluoroscopic-guided direct percutaneous delivery suggests that it may be feasible to deliver genetic material into the myocardium of patients in a similar fashion.

Animals↗
PubMed1992

Smooth muscle cell outgrowth from human atherosclerotic plaque: implications for the assessment of lesion biology.

OBJECTIVES: The purpose of this study was to determine whether the kinetics of smooth muscle cell outgrowth from in vitro explants of human atherosclerotic tissue is dependent on the nature of the atherosclerotic lesion in vivo. BACKGROUND: The use of techniques for percutaneous in vivo extraction of atherosclerotic plaque has provided the opportunity to study human atheroma-derived smooth muscle cells in culture. However, because of cell selection and changes in phenotype, in vitro findings may not always reflect the biologic properties of the vessel wall, particularly if cells are in culture for prolonged periods. In contrast, studies with nonhuman cells have suggested that the rate at which cells grow out of tissue explants is closely related to the status of the cells in vivo. METHODS: Atherosclerotic tissue from 41 lesions, including primary plaques (from peripheral arteries and venous bypass conduits) and restenotic lesions (from peripheral arteries and venous conduits) were divided into a total of 1,596 fragments and placed in culture on fibronectin-coated wells. Explant outgrowth was scored over the ensuing 1 month to determine the prevalence and time course of smooth muscle cell outgrowth and the total cellular accumulation. RESULTS: Explant fragments from 40 (98%) of the 41 lesions yielded an outgrowth of smooth muscle cells, confirmed by immunocytochemistry. The mean proportion of adherent explant fragments yielding outgrowth, per lesion, was 69 +/- 4% and was higher in restenotic tissue (81 +/- 3%) than in primary tissue (56 +/- 6%, p < 0.001). For primary lesions, initiation of outgrowth was half-maximal by 8.7 +/- 0.4 days; for restenotic explants, initiation of outgrowth was considerably faster (half-maximal by 5.9 +/- 0.6 days, p < 0.001). Similarly, accumulation of smooth muscle cells around an explant was significantly greater for restenotic lesions (2,791 +/- 631 cells/explant) than for primary lesions (653 +/- 144 cells/explant, p < 0.01). Labeling of first-passage cells with [3H]-thymidine indicated that cells from restenotic lesions had a 1.3-fold greater incorporation rate than did cells from primary lesions (p < 0.05). CONCLUSIONS: Smooth muscle cells may be reliably cultivated by explant outgrowth from a variety of human atherosclerotic plaque types obtained intraoperatively or percutaneously. The kinetics of outgrowth from restenotic tissue is distinctly different from that of outgrowth from primary tissue, suggesting a relation between the in vitro outgrowth behavior and the biology of the lesion in vivo. Assessment of smooth muscle cell outgrowth from human atherosclerotic plaque may thus represent a practical and reliable means to investigate the biologic behavior, including growth characteristics, of individual atherosclerotic lesions from human subjects. This technique may also offer a suitable assay system for evaluating therapies designed to inhibit lesion proliferation.

Analysis of Variance↗