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Biomedical subjects

J Ellinger

Publications and source records attributed to J Ellinger.

At least 19 recordsLinked to original sources
PubMed1995

In vivo platelet deposition on polytetrafluoroethylene coated with fibrin glue containing fibroblast growth factor 1 and heparin in a canine model.

BACKGROUND: We previously reported that the coating of expanded polytetrafluoroethylene (ePTFE) with fibrin glue containing fibroblast growth factor 1 (FGF-1) and heparin accelerates endothelial coverage of grafts implanted into animals. We report here the effect of this surface modification on early platelet deposition. MATERIALS AND METHODS: Nine dogs received 7-cm ePTFE grafts, 60-microns internodal distance, 4-mm internal diameter, as bilateral aortoiliac implants, one coated (luminal cross section and abluminal surface) with fibrin glue (fibrinogen 32.1 mg/mliters, thrombin 0.32 U/mliters) containing FGF-1 (11 ng/mliters and heparin (250 U/mliters), the other uncoated. After 5, 30, or 120 minutes of circulation with blood containing autologous platelets radiolabelled with indium 111, gamma emissions were quantitated on explants and correlated to surface areas measured by computerized planimetry. RESULTS: Both global and segmental comparisons showed significantly (P < 0.05, Student's t-test) less platelet deposition on coated than on uncoated grafts after 120 minutes of circulation, but no difference at 5 and 30 minutes. CONCLUSIONS: In this model, ePTFE coating with fibrin glue containing FGF-1 and heparin shows no adverse effect on early platelet deposition.

Animals↗
PubMed1993

Kinetics of cell proliferation as a function of vascular graft material.

Bioresorbable vascular grafts constructed for polyglactin 910 (PG910) and polydioxanone (PDS) and nonresorbable Dacron were interposed into the infrarenal abdominal aortas of New Zealand White rabbits. The prosthesis/tissue complexes were harvested after 2, 3, 4, 12, and 52 weeks. Seventeen, 9, and 1 h prior to sacrifice, animals received tritiated thymidine (0.5 mCi/kg/dose). All specimens were studied grossly and by light and transmission electron microscopy. Mitotic indices (MI's) were determined by autoradiography for inner capsule myofibroblasts at the proximal, mid, and distal segments of each prosthesis. There were no aortic-related deaths. All grafts were patent with no aneurysmal dilatation. At 4 weeks, PG910 resorption was evidenced by macrophage phagocytosis, less so in PDS while Dacron remained intact. At 12 weeks, the PG910 was completely resorbed while PDS resorption continued. The latter was completely resorbed by 52 weeks. There was no significant difference in MI's between proximal, mid, and distal regions for each graft type. The mitotic index paralleled the rate of prosthetic resorption in both PG910 and PDS groups, as high as 28.34 +/- 23.21 in the former 3 weeks after implantation and significantly higher at 4 weeks (7.58 +/- 2.02 and 7.50 +/- 2.66, respectively) than at 52 weeks (0.72 +/- 0.98 and 1.00 +/- 0.22, respectively) in both groups. The mitotic index in the Dacron group never surpassed 1.22 +/- 0.90. We conclude that higher levels of early cell proliferation in bioresorbable grafts closely parallel the kinetics of prosthetic resorption.

Animals↗
PubMed1991

The effects of an atherogenic diet on macrophage/biomaterial interactions.

We previously reported that biomaterials differentially induced macrophages to secrete growth factors that mediate reendothelialization. The present study evaluates the effect of an atherogenic diet on macrophage/biomaterial interactions. Female New Zealand white rabbits were fed an atherogenic diet. Peritoneal macrophages were harvested from these as well as rabbits fed a normal diet and cultured in Minimum Essential Medium with platelet-poor serum. Dacron or polyglactin 910 were added to two of three conditions of both cell groups in passage 2. Conditioned media were collected weekly through week 15. Mitogenicity assays were performed with quiescent mouse embryonal (BALB/c3T3) fibroblasts, atherosclerotic rabbit aortic smooth muscle cells, and murine capillary lung (LE-II) endothelial cells. Mitogenic activity was assayed by scintillation counting of tritiated thymidine incorporation into deoxyribonucleic acid (DNA). Results showed increased mitogenic activity released by macrophages from atherosclerotic rabbits, in the absence of prosthetic material, when assayed against every cell line. In normal diet macrophages, polyglactin 910 stimulated mitogen release for every cell line, and Dacron yielded minimal mitogen release. In lipid diet macrophages polyglactin 910 slightly increased mitogen release for all three cell lines, whereas Dacron resulted in stimulation of DNA synthesis in smooth muscle cells and BALB/c3T3 cells but less DNA synthesis in LE-II cells than in control, no graft material, media. Western blotting demonstrated immunoreactivity to basic fibroblast growth factor in media from normal diet macrophages but only in the presence of polyglactin 910 or Dacron. Radioimmunoassay for platelet-derived growth factor B chain was negative in all groups, and polymerase chain reaction techniques to amplify transforming growth factor-beta messenger ribonucleic was negative. These data demonstrate the effect of in vivo dietary manipulation on macrophage activation as well as the effect of an atherogenic diet in modulating macrophage/biomaterial interactions. Additionally, different biomaterials differentially induce macrophages to release factors that stimulate and inhibit growth.

Animals↗
PubMed1989

Hemodynamic effects on endothelial cell monolayer detachment from vascular prostheses.

The establishment of an early blood-contacting endothelialized surface may improve the graft-host relationship. This study evaluated the adherence of indium 111-radiolabeled endothelial cells that were cultured to confluence on fibronectin-treated polyester elastomer (Hytrel) grafts that were perfused for two hours on a pulse duplicator apparatus under high- and low-shear conditions. Perfusate samples were serially assayed for radioactivity. After perfusion, grafts were sectioned into four segments and assayed for retained radioactivity. All graft segments were hematoxylin stained and examined under light microscopy for evaluation of cell density. Excellent endothelial cell adherence (90%) was observed under both hemodynamic conditions at 120 minutes, with most losses occurring within the first 15 minutes. No differences were seen between high- and low-shear conditions or proximal vs distal graft segments.

Animals↗
PubMed1989

Plasma polymerized tetrafluoroethylene/polyethylene terephthalate vascular prostheses.

Tetrafluoroethylene (TFE) was discharged onto woven polyethylene terephthalate (PET) prostheses, and the PET prostheses (50 mm long) with or without TFE were implanted into canine carotid arteries and aortas. Additional controls included polytetrafluoroethylene and Dacron. Specimens were explanted after one to 12 months, photographed, and sectioned for light and scanning and transmission electron microscopy, and thrombus-free surface areas calculated by computerized planimetry. Results showed no significant patency differences among carotid or aortic groups. However, both PET carotid groups had significantly greater thrombus-free surface areas. Histologically, both PET groups appeared identical. An endothelialized neointima covered PET carotid specimens by six months, compared with three months in the aortic position, with greater pannus ingrowth in both PET groups. Plasma polymerized TFE offered no additional advantage in these long-term experiments.

Animals↗
PubMed1989

Macrophage/biomaterial interactions: the stimulation of endothelialization.

This current study analyzed macrophage/biomaterial interactions as modulators of endothelial cell proliferation. Rabbit peritoneal macrophages were harvested and seeded (1 x 10(6) cells/ml) into culture flasks with Dulbecco's modified Eagle medium and 10% platelet-poor, plasma-derived equine serum. Macrophages were identified by morphologic characteristics, nonspecific esterase, and Fc (immunoglobulin G) receptors on the cell membranes. Culture conditions were (1) no prosthetic material, (2) Dacron, or (3) Polyglactin 910 (PG910) (Ethicon, Inc., Somerville, N.J.). Both prosthetic materials were finely shredded into the media. After 5 weeks in culture, PG910 inclusions were seen within macrophage cytoplasm. No intracytoplasmic Dacron was observed. Conditioned media from all three groups were collected weekly from week 5 to week 10, centrifuged, filtered, and added in serial dilutions to cultured quiescent murine capillary lung endothelial cells. Quiescence was achieved by serum deprivation and verified by [3H]thymidine incorporation. Sixteen hours after addition of conditioned media, [3H]thymidine was measured in and expressed as percent increase above quiescent levels. Mitogenic activity in the PG910 group progressively increased from weeks 6 to 10. At week 10, the PG910 group (1:10 dilution) yielded a 620% increase in DNA synthesis. The Dacron group never varied from the control group (no prosthetic). The mean increases in [3H]thymidine incorporations over weeks 7 to 10 were PG910, 540% +/- 65%; Dacron, 323% +/- 65%, and control, 343% +/- 26% (PG910 vs Dacron, p less than or equal to 0.004). These studies suggest macrophage activation by bioresorbable prostheses, yielding growth factor release with subsequent enhanced endothelial cell proliferation.

Animals↗
PubMed1988

Polyglactin 910/polydioxanone bicomponent totally resorbable vascular prostheses.

Previous studies from our laboratory have shown that bioresorbable vascular prostheses woven from lactide-glycolide copolymers and implanted into arteries of several animal models become replaced by cellular tissues; the rate of replacement parallels the kinetics of prosthetic resorption. This study evaluates the efficacy of bicomponent resorbable prostheses as a method of augmenting resistance to dilatation during the resorption period of the more rapidly resorbed component. Bicomponent prostheses (n = 37) were woven from compound yarns containing 74% polyglactin 910 (PG910) and 26% polydioxanone (PDS) and were interposed into adult white New Zealand rabbit infrarenal aortas. Resultant prosthesis-tissue complexes were harvested after 2 weeks to 12 months. Specimens were photographed and sectioned for light, scanning, and transmission electron microscopy. Randomly selected fresh explants at 1 and 3 months and control aortic segments from the same rabbits were simultaneously perfused with culture media (37 degrees C, 100/80 mm Hg, 60 ml/min) and perfusates assayed by means of tritiated radioimmunoassay techniques for the stable prostacyclin metabolite 6-keto-PGF1 alpha before and after the addition of sodium arachidonate (10 micrograms/ml) to the media. Results showed 100% patency, no aneurysms, and stenosis in 1 of 37 prostheses (3%). PG910 was totally resorbed by 2 months and PDS by 6 months. By 1 month inner capsule thickness was 303 +/- 30 microns. In contrast to previous reports this was significantly thicker than that within 100% PDS (230 +/- 40 microns) and significantly less thick than in 100% PG910 (530 +/- 62 microns). Inner capsules in all three groups stabilized at similar thicknesses (417 to 502 microns).(ABSTRACT TRUNCATED AT 250 WORDS)

6-Ketoprostaglandin F1 alpha↗
PubMed1988

Derivation of neointima in vascular grafts.

Vascular prostheses woven from absorbable lactide/glycolide copolymers are replaced by myofibroblast-laden tissue conduits lined by endothelium. When these prostheses are implanted in arteries of animal models, the absorption-replacement reactions are inhibited by Dacron. To determine whether these reactions resulted primarily from transanastomotic pannus ingrowth, prostheses (30 mm x 4 mm) were constructed of three 10-mm long segments with Dacron segments on both ends and a middle polyglactin 910 (PG910) segment. The prostheses were implanted in the aortas of 15 adult New Zealand White rabbits. Resultant prosthesis/tissue complexes were harvested in triplicate at 2 weeks and at 1, 2, 3, and 4 months after implantation. Explants were photographed and sectioned for light microscopy and for scanning and transmission electron microscopy, which showed 100% patency with no aneurysms or stenoses. Inner-capsule thickness in the PG910 segments increased only during the interval from 2 weeks to 2 months; this thickness was statistically greater than either Dacron segment at 1 and 2 months (p less than or equal to 0.004 and p less than or equal to 0.0001, respectively). Proximal and distal Dacron segments did not differ from each other in thickness. Inner capsules of PG910 segments at 1 month were composed predominantly of myofibroblasts, whereas inner capsules of Dacron segments were composed of fibrin coagulum beyond the initial 2 mm of endothelial pannus ingrowth. These data suggest that transanastomotic pannus ingrowth is not the primary source of cells replacing absorbable vascular prostheses.

Absorption↗
PubMed1987

Arterial regeneration over polydioxanone prostheses in the rabbit.

We analyzed histologic, ultrastructural, and functional characteristics of rabbit aortic conduits regenerated over absorbable polydioxanone prostheses. Twenty-eight polydioxanone-elicited prosthesis/tissue complexes harvested two weeks to 12 months following implantation were analyzed grossly; photographed; sectioned for light, scanning, and transmission electron microscopy; and studied for compliance, bursting strength, and prostacyclin and thromboxane metabolite contents. No aortic-related deaths or hemorrhages occurred. Smooth regenerated conduits without stenoses were seen in 27 of 28 specimens, with one small aneurysm. Transprosthetic myofibroblast migration and proliferation paralleled the kinetics of macrophage-mediated prosthetic dissolution, which was consequently delayed compared with polyglycolic acid prostheses. Confluent endothelial-like luminal surfaces were present after two weeks. Progressive inner capsular thickening ended after three months at 420 micron. Ex vivo compliance curves resembled arterial elasticity. Regenerated tissue withstood 1200 mm Hg of systolic pressure, and 6-keto-prostaglandin F1 alpha to thromboxane B2 ratios did not differ from normal control specimens.

6-Ketoprostaglandin F1 alpha↗
PubMed1987

Biomaterial pretreatment with ECGF to augment endothelial cell proliferation.

ECGF, a polypeptide of bovine hypothalamic derivation, is the most potent endothelial cell mitogen known, with mitogenic and chemotactic effects well demonstrated in vitro on human endothelial cells. These effects are synergized by heparin. In vivo re-endothelialization of blood-contacting biomaterials may be enhanced by bonding ECGF and heparin to prosthetic surfaces. Long woven Dacron (24 mm) and woven PDS vascular prostheses were treated first with human plasma fibronectin (10 micrograms/cm2). Porcine sodium heparin (20 micrograms/cm2) was added by means of fibronectin's heparin affinity. Pure 125I-ECGF (95% alpha, 5% beta; 1 ng/cm2) was next fixed by the heparin affinity of ECGF and followed by a second heparin layer (20 micrograms/cm2) to synergize with and stabilize ECGF. 125I-ECGF adherences were determined by scintillation counts. Attachment efficiency averaged 25%. Prostheses were interposed into rabbit aortas and harvested in triplicate from 0 to 30 days to establish in vivo washout curves. After explantation, residual 125I-ECGF was eluted from prostheses, and intact ECGF was identified by SDS gel electrophoresis. Similarly prepared but nonradioiodinated Dacron and PDS prostheses were explanted after 7 days and their ECGF eluted off for in vitro activity documentation. This ECGF retained its mitogenic properties, causing a 1000% to 1200% increase in 3H-thymidine incorporation into newly synthesized DNA in test murine LE-II cells. Fibronectin-heparin-ECGF fixation to blood-contacting biomaterials may enhance spontaneous re-endothelialization and/or hasten the confluence of transplanted endothelial cells.

Animals↗
PubMed1987

Compound polyglactin 910/polypropylene small vessel prostheses.

This study evaluated morphologic and functional characteristics of tissue reactions to compound prostheses of 69% absorbable polyglactin 910 (PG910) and 31% nonabsorbable polypropylene in the rabbit. Forty-two woven PG910/polypropylene prostheses (24 X 4 mm internal diameter) implanted into rabbit infrarenal aortas were harvested after 2 weeks to 12 months. Each explant was photographed and sectioned for light microscopy and transmission and scanning electron microscopy. Randomly selected explants underwent either compliance and bursting strength measurements or assays of production of prostacyclin and thromboxane metabolites by luminal surfaces of both regenerated conduits and normal control aortas in response to administered sodium arachidonate. Results showed 100% patency with no aneurysms and 2% stenoses (1 of 42 prostheses). Confluent endothelial-like cellular luminal surfaces covering oriented smooth muscle-like myofibroblasts comprised the inner capsules whose thicknesses stabilized at 1 to 2 months. Only residual polypropylene remained in the prostheses after 2 months. Compliance studies reflected a 0.65 mm (14%) change over a pressure range of 0 to 160 mm Hg. All regenerated prosthesis-tissue complexes had bursting strengths greater than the proximal perianastomotic native aortas, which burst between 600 and 2000 mm Hg. At 1 month the rate of production of 6-keto-PGF1 alpha per square millimeter of surface area of experimental segments was normal. Production of 6-keto-PGF1 alpha by experimental segments at 3 months had increased fourfold whereas thromboxane B2 (TxB2) production remained unchanged. The 6-keto-PGF1 alpha/TxB2 ratio increased from 1 to 4 months. This study demonstrates clinically efficacious morphologic, mechanical, and biochemical characteristics of PG910/polypropylene-elicited vascular prosthesis-tissue complexes.

6-Ketoprostaglandin F1 alpha↗
PubMed1986

Dacron inhibition of arterial regenerative activities.

These biocompatibility studies evaluate the effects of Dacron, absorbable polymeric, and compound prostheses containing both elements in various constructions on the migration, proliferation, and functional characteristics of regenerating endothelial and smooth muscle-like cells in the rabbit aorta model. Prosthesis/tissue complexes explanted after 2 weeks to 9 months were studied grossly, photographed, sectioned for light microscopy and scanning and transmission electron microscopy, and assayed for 6-keto-PGE1 alpha contents in inner capsular tissues. Polyglycolic acid, polyglactin 910, or polydioxanone prostheses elicited a transinterstitial migration and proliferation of primitive mesenchymal cells that differentiated into smooth muscle-like myofibroblasts and a surface repopulation of confluent endothelial-like cells paralleling the time course of macrophage-mediated prosthetic dissolution. Even small Dacron components (20%) woven into or surrounding the absorbable polymer significantly inhibited these processes, yielding significantly thinner, less cellular inner capsules with lower 6-keto-PGF1 alpha contents. These studies show the augmentation of clinically efficacious arterial regenerative activities by polymers phagocytosed by macrophages and the inhibition of these activities by Dacron.

6-Ketoprostaglandin F1 alpha↗
PubMed1983

Morphological evidence of the shedding of chondrocytes from the articular surface in neonatal rats: relationship to the interlacunar network.

The superficial zone of the femoral head articular cartilage of 5- to 15-day old rats was examined by light and electron microscopy for evidence of shedding into the joint space. Chondrocytes deepest in the superficial zone were round, surrounded by a capsule, and connected to adjacent chondrocytes by the interlacunar network, whereas cells in the middle of the zone appeared similar but with less cytoplasm. At the circular surface, chondrocytes were small, with pyknotic nuclei and poorly defined organelles. These cells occasionally protruded from the articular surface but maintained at least partial connection with the network and their capsule. Depressions in the articular surface were lined with material similar to that of the network and were the only locations found where the network did not terminate at a cell surface. This static evidence suggested at least two hypotheses: 1) Degenerating chondrocytes moved up through the superficial zone to the articular surface and were shed into the joint space. This movement may be facilitated by the network as part of neonatal cartilage development. 2) During joint formation, the surface of the articular cartilage was eroded down to the chondrocytes, which were exposed to the joint fluid, causing cell degeneration, death, and shedding. Evidence of cell shedding was rarely seen after 2 weeks of age. Likewise, the interlacunar network disappeared from the superficial zone during this period. A physiological as well as structural relationship may exist between the chondrocytes and interlacunar network.

Animals↗
PubMed1981

Glycol methacrylate in light microscopy: nucleic acid cytochemistry.

Techniques utilizing Feulgen, azure B bromide, methyl green-pyronin, gallocyanin chromalum and cresyl violet stains have been modified and adapted for visualizing nucleic acids in 0.5-2.0 micrometer sections of tissues embedded in glycol methacrylate (GMA). Methods for evaluating the stain specificity for DNA and RNA using deoxyribonuclease and ribonuclease digestions, aldehyde blocking, and acid extractions are also described. The specificity of the stains in GMA embedded tissues is comparable to that reported for paraffin-embedded tissues.

Acrylates↗
PubMedDate not supplied

Platelet interactions with heparin binding growth factor and fibronectin.

A fibronectin (Fn)/heparin/heparin binding growth factor (HBGF)/heparin (FHHH) complex can be affixed to vascular grafts. This study examines the effect of HBGF, Fn, and FHHH on platelet adhesion and aggregation. Expanded polytetrafluoroethylene (PTFE) grafts (5 cm X 4 mm) were treated with Fn (n = 9), FHHH (n = 9), or neither (n = 10) and interposed into canine aortoiliac systems, using each dog as its own control. Autogenous radiolabeled (111In oxine-650 muCi) platelets were injected IV prior to re-establishment of circulation. Blood flow was determined by electromagnetic flowmetry and perfusion maintained for 30 min. Grafts were removed with native aorta and ipsilateral iliac arteries (IIA). Specimens, excluding anastomoses, were sectioned for gamma counting and computerized planimetry. Results showed that FHHH and Fn treated grafts contained significantly more radioactivity than control segments, when normalized to their IIA. FHHH treated grafts contained 27 +/- 16 times more radioactivity per mm2 than IIA, Fn treated prostheses 12 +/- 8 times more, and untreated PTFE 4 +/- 3 times more. FHHH was significantly more radioactive than Fn alone (p less than or equal to 0.03). Platelet aggregation in response to either Fn or HBGF was studied in vitro. Aggregation was not activated by either Fn (1-100 micrograms/100 microliters) or HBGF (25-2,500 ng/100 microliters). These data suggest that Fn and HBGF promote platelet adhesion but not aggregation.

Animals↗
PubMedDate not supplied

Biomaterial-induced macrophage activation and monokine release.

This study quantifies macrophage acid phosphatase release as a marker of cell activation when cultured with or without biomaterials. Peritoneal macrophages were harvested from six New Zealand White rabbits and cultured in minimum essential media with 10% equine serum. After cell identification by morphology, nonspecific esterase, and RAM 11 immunoperoxidase, cells were passaged twice, and second-passage macrophages were seeded in 96-well plates (5,000 cells/well) and grown to confluence. After collection of day zero media, circular disks of polyglactin 910 and two types of commercially available polyethylene terephthalate with different construction and sterilization characteristics were placed on the cell monolayer. Controls without biomaterials were also established. Media was collected and pooled for each group and time point beginning on day 2 and continuing every other day for 22 days. Conditioned media were quantitatively assayed for acid phosphatase colorimetrically at 402 nm using p-nitrophenylphosphate as the substrate. Acid phosphatase activity increased progressively at late time points for each group but no difference was noted between groups at any time point. These data show that the activation of cultured macrophages with time is not altered differentially by the presence of biomaterials. The previously demonstrated monokine release following biomaterial exposure is therefore a specific event and not simply part of the generalized activation phenomenon.

Acid Phosphatase↗
PubMedDate not supplied

Kinetics of collagen deposition within bioresorbable and nonresorbable vascular prostheses.

This study compares the kinetics of collagen deposition within the prosthesis/tissue complexes formed following implantation of either polyglactin 910 (PG910), polydioxanone (PDS), or Dacron prostheses into rabbit infrarenal aortas. The grafts were explanted in triplicate at 1, 3, and 12 months, and then processed for spectrophotometric hydroxyproline quantitation. A 2 mm longitudinal strip from each sample was processed for histologic evaluation by light and electron microscopy. Results showed more extensive collagen deposition within the prosthesis/tissue complexes of both PG910 and PDS continuing throughout 3 months, as compared to less collagen deposition in Dacron grafts at all time points. Differences between PG910 and Dacron, and between PDS and Dacron at each time point were statistically significant. When correlated with previous related studies done in our laboratory, data showed that in resorbable grafts the rate of collagen deposition parallels the kinetics of cellular proliferation, tissue thickening, and graft resorption.

Animals↗