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Biomedical subjects

R J Connolly

Publications and source records attributed to R J Connolly.

At least 37 records · Page 2Linked to original sources
PubMed1991

Increased in-vitro incubation time of endothelial cells on fibronectin-treated ePTFE increases cell retention in blood flow.

Endothelial cell (EC) seeding is postulated as a mechanism of improving patency of small calibre vascular grafts. However, the majority of seeded cells are lost within hours following restoration of blood flow. We postulated that incubating EC in-vitro on a graft will improve adherence and resistance to the sheer stresses of pulsatile blood flow. Fibronectin-treated ePTFE (5 cm x 4 mm ID) seeded with Indium-111-labelled autologous canine EC (1.5 x 10(5) cells/cm2) were incubated for four different time periods; 90 min, 24 h, 72 h and 6 days. Incubated grafts were subjected to blood flow of 75 ml/min for 6 h, in a canine ex-vivo arteriovenous shunt circuit. EC retention during perfusion was studied by measuring gamma activity emitted by the grafts. Cell morphology of non-perfused control groups and perfused groups was compared using scanning electron microscopy (SEM). SEM of control grafts showed progressive EC spreading on the ePTFE surface for up to 72 h incubation. Gamma activity was significantly higher at 6 h perfusion in grafts incubated for 72 h (82 +/- 4%) and 24 h (63 +/- 6%) vs. 90 min (34 +/- 13%, p less than 0.05), and between grafts incubated for 72 h vs. 6 days (55 +/- 7%, p less than 0.05). Perfused grafts incubated for 72 h showed unaltered EC morphology on SEM, few cells remained on 90 min incubated grafts. We conclude that incubating EC on fibronectin-treated ePTFE for 72 h in-vitro after seeding improves cell retention during blood flow.

Animals↗
PubMed1991

Staphylococcus epidermidis induces complement activation, tumor necrosis factor and interleukin-1, a shock-like state and tissue injury in rabbits without endotoxemia. Comparison to Escherichia coli.

Tumor necrosis factor (TNF) and IL-1 are thought to mediate many of the pathophysiologic changes of endotoxemia and Gram-negative bacteremia. In these studies, heat-killed Staphylococcus epidermidis were infused into rabbits to determine whether an endotoxin (LPS)-free microorganism also elicits cytokinemia and the physiologic abnormalities seen in Gram-negative bacteremia. S. epidermidis induced complement activation, circulating TNF and IL-1, and hypotension to the same degree as did one-twentieth the number of heat-killed Escherichia coli. Circulating IL-1 beta levels had a greater correlation coefficient (r = 0.81, P less than 0.001) with the degree of hypotension than TNF levels (r = 0.48, P less than 0.02). Leukopenia, thrombocytopenia, diffuse pulmonary capillary aggregation of neutrophils, and hepatic necrosis with neutrophil infiltration were observed to the same extent after either S. epidermidis or E. coli infusion. However, S. epidermidis infusion did not induce significant (less than 60 pg/ml) endotoxemia, whereas E. coli infusion resulted in high (11,000 pg/ml) serum endotoxin levels. S. epidermidis, E. coli, LPS, or S. epidermidis-derived lipoteichoic acid (LTA) induced TNF and IL-1 from blood mononuclear cells in vitro. E. coli organisms and LPS were at least 100-fold more potent than S. epidermidis or LTA. Thus, a shock-like state with similar levels of complement activation as well as circulating levels of IL-1 and TNF were observed following either S. epidermidis or E. coli. These data provide further evidence that host factors such as IL-1 and TNF are common mediators of the septic shock syndrome regardless of the organism.

Animals↗
PubMed1991

Modification of the thrombogenicity of a self-expanding vascular stent.

When placed in the iliac arteries of normal healthy animals, the Wall-stent self-expanding endovascular prosthesis exhibits minimal thrombogenicity, measured by 111In-labeled platelet uptake. Preliminary clinical reports suggest a greater thrombogenicity in diseased human arteries. When evaluated in an ex vivo shunt, these stents exhibit significant thrombogenicity. The ex vivo shunt may therefore provide a model to evaluate strategies to reduce thrombogenicity in the clinical setting. Stents were released into shunts and the uptake of In111-labeled platelets was measured by gamma imaging for 2 h at a flow rate of 100 mL/min. The effect of systemic heparin, 100 U/kg, oral aspirin, 325 mg, and local application of heparin-benzalkonium chloride complex were evaluated. At the end of each study the stents were fixed in situ and evaluated with scanning electron microscopy (SEM). Control stents exhibited a rapid, significant uptake of platelet associated 111In activity, which reached a maximum in approximately 1 h. Twenty-two percent of control stents occluded before 2 h. Aspirin reduced maximum platelet uptake by 46%. Systemic heparin, with a clotting time greater than five times control, reduced maximum platelet uptake by 86%. The benzalkonium-heparin complex coating, with no increase in clotting time, reduced maximum platelet uptake by 84%. No occlusions were observed with the anti-thrombotic regimes. SEM evaluation of the stents supports the results of the isotope uptake studies.

Animals↗
PubMed1991

Leukocyte redistribution and eicosanoid changes during the autoperfused working heart-lung preparation.

We studied the role of leukocyte redistribution and eicosanoid changes in the early stages of instituting 16 rabbit autoperfused working heart-lung preparations (AWHLP). Physiological changes occurring during the transition from the intact animal to the AWHLP may determine the survival and viability of the organ blocks for transplantation. White blood cell (WBC) count decreased from 5,160/microL to 1430/microL (P less than .01) at 60 min of autoperfusion. Differential WBC counts performed in ten of these AWHLP revealed a 63% decrease in lymphocyte count and an 88% decrease in the granulocyte count at 60 min. Thus, the predominant leukocyte remaining in the circulation was the lymphocyte. Blood samples were collected from the intact animal and from the AWHLP for assay of the stable metabolites of thromboxane A2 (TxA2) and prostacyclin (PGI2). Transition from the in situ heart-lung block to the in vitro AWHLP stage caused significant changes in these metabolites. The PGI2 metabolite 6-ketoprostaglandin F1a (6KPGF1a) increased from 2680 +/- 487 to 4339 +/- 478 (pg/mL), P less than .05, while the TxA2 metabolite, thromboxane B2 (TxB2) decreased from 618 +/- 105 to 289 +/- 63 (pg/mL). However, assays of 11-dehydro-TxB2 (11-DHT), a longer lived metabolite of TxA2 (n = 7) increased (668.4 +/- 84.6 to 946.4 +/- 43.7, P less than .05). The transition from the in situ heart-lung block of the intact animal to the AWHLP involves significant physiological changes. Redistribution of leukocytes occurs with a predominant decrease in the granulocyte count, while levels of bioactive lipid mediators show a distinct large rise in the PGI2 metabolites and a lesser increase in TxA2 metabolites.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Rapid in-line blood warming using microwave energy: preliminary studies.

The management of massive blood loss resulting from trauma or surgery necessitates rapid transfusion capability. Hypothermia secondary to shock, transfusion, and prolonged surgical procedures significantly increases morbidity and mortality in these patients. Transfusion at high flow rates frequently exceeds the warming capacity of conventional blood-warming devices, whose inherent resistance also limits the maximal flow rates. Microwave ovens are capable of blood warming, but have been associated with unacceptable hemolysis. We have investigated the possibility of using microwave energy to provide rapid in-line blood warming. Fresh blood from 10 human subjects was warmed from an average of 18 degrees C to temperatures ranging from 37 to 39 degrees C at flow rates from 250 to 500 mL/min. Laboratory analysis of free plasma hemoglobin, haptoglobin, hematocrit, hemoglobin, and electrolytes showed no difference between heated and control samples. LDH was elevated in those samples warmed repeatedly, but remained within the normal range. These data indicate the potential for further investigation utilizing properly controlled microwave energy for in-line blood and fluid warming.

Blood Transfusion↗
PubMed1990

Extended ex vivo preservation of the heart and lungs. Effects of acellular oxygen-carrying perfusates and indomethacin on the autoperfused working heart-lung preparation.

The autoperfused working heart-lung preparation has been proposed as a method for long-term heart-lung preservation. We investigated the effects of acellular oxygen-carrying perfusates (study 1) and the effect of donor pretreatment with indomethacin (study 2) on the working ex vivo heart-lung block. In study 1 perfusion with stroma-fee hemoglobin resulted in significantly reduced survival (118 +/- 46 minutes) compared with autologous blood (561 +/- 125 minutes, p less than 0.05) or perfluorocarbon (438 +/- 114 minutes, p less than 0.05). Decrease in survival with stroma-free hemoglobin perfusate is associated with a marked decrease in left ventricular performance and a significant increase in pulmonary vascular resistance. Perfusion with autologous blood is associated with a significant increase in pulmonary vascular resistance after 240 minutes of explantation, which is significantly delayed by perfusion with perfluorocarbon. Perfusion for 6 hours with blood pretreated with indomethacin (study 2) resulted in a decrease in the concentration of prostacyclin and thromboxane A2 metabolites but an increase in the prostaglandin/thromboxane A2 metabolite ratio. This is associated with abrogation of the increase in pulmonary vascular resistance (12,787 +/- 1682 dynes/sec/cm-5, T = 0; 13,134 +/- 2654 dynes/sec/cm-5, T = 360 minutes) observed in preparations perfused with autologous blood (13,194 +/- 1942 dynes/sec/cm-5, T = 0; 24,768 +/- 3325 dynes/sec/cm-5, T = 360 minutes, p less than 0.05). We conclude that alteration of the cellular and humoral components of autologous blood may prove advantageous for increasing the utility of the autoperfused working heart-lung preparation as a preservation technique.

Animals↗
PubMed1990

Scanning electron microscopy analysis of polyethylene oxide hydrogels for blood contact.

Hydrogels are a class of synthetic material, composed of a polymer-water matrix and have been proposed as tissue substitutes and drug delivery vehicles. Polyethylene oxide (PEO) hydrogels were synthesized and used to produce coated wires and conduits for baboon blood compatibility studies. Blood-material interactions were studied both by Scanning Electron Microscopy (SEM) and 111In labeled platelet deposition. SEM processing modifications were first evaluated in order to reduce shrinkage and surface distortion incurred during sample preparation of these high water content materials. Pretreatment with 1% tannic acid reduced bulk shrinkage associated with critical point drying by 10-20%. This effect is small, nevertheless, it prevented major sample disruption. Coated guidewires were exposed to baboon blood for one hour in the inferior vena cava and conduits were placed for either 30 or 60 minutes in an ex vivo femoral arteriovenous shunt. Reference materials included Gore-tex, polyethylene and silica-free polydimethyl siloxane (PDMS). In the guidewire studies, 111In labeled platelet levels were highest on Gore-tex (6568.97 platelets/1000 microns 2) and large thrombotic deposits were well visualized by SEM. Formulations containing PEO had low levels of platelet deposition and little evidence of platelet activation was noted by SEM. Shunt studies demonstrated that materials of high PEO content and molecular weight had the lowest levels of platelet deposition. After 60 minutes of blood flow, mean platelet deposition on PDMS and Gore-tex was 50 and 1000 fold higher than on a network composed of 65% PEO 20,000 (p less than 0.05). SEM confirmed these findings.

Analysis of Variance↗
PubMed1989

The effect of radiofrequency-generated thermal energy on the mechanical and histologic characteristics of the arterial wall in vivo: implications for radiofrequency angioplasty.

Abrupt reclosure of atherosclerotic vessels after percutaneous transluminal balloon angioplasty has been blamed on traumatic dissections and elastic recoil of the vessel wall. Thermal energy with compression produces fusion of separated arterial wall layers, and heat appears to alter the elastic recoil of the vessel wall. Radiofrequency (RF) thermal energy has been used to perform vascular anastomoses and thermal angioplasty. A simple in vivo experiment was designed to describe and quantitate vascular tissue weld strength produced by a range of RF thermal energy levels. Canine carotid arteries were compressed between a pair of modified bipolar forceps that applied RF energy, causing occlusive tissue welds between the apposed intimal surfaces. The strength of the welds was evaluated by measuring the perfusion pressure required to reopen the vessel lumen. A dosimetry range of 0 to 205 joules showed a typical dose-response curve for the relationship between energy applied and bond strength, plateauing at approximately 300 mm Hg. Light microscopy showed fusion of the inner surfaces of the vessel with preservation of vessel wall architecture. Additionally inflation of a bipolar RF balloon catheter in the normal canine carotid lumen produced an alteration of vessel profile angiographically and histologically. Results of these preliminary experiments suggest that balloon angioplasty with adjunctive RF thermal energy may have benefits in reducing the factors causing acute failure of conventional percutaneous transluminal balloon angioplasty.

Angiography↗
PubMed1989

Effects of atrial cardioplegia on the ischemic right ventricle after acute coronary artery occlusion and reperfusion.

Right atrial cardioplegia has been advocated as a simple method of delivering retrograde cardioplegia. Passive distention of the right heart inherent with right atrial cardioplegia has been shown to impair right ventricular function in a canine model of global ischemia. This study was designed to compare right ventricular performance after right atrial cardioplegia administered intermittently (n = 5) and continuously (n = 5) with coronary sinus retrograde cardioplegia (n = 5) and aortic root cardioplegia (n = 8) in a canine model of acute right ventricular ischemia and reperfusion. Right ventricular performance was assessed using the load-independent relationship of end-systolic pressure versus dimension (myocardial fiber length). Right ventricular performance was well preserved after reperfusion in those dogs protected with intermittent right atrial cardioplegia (95% of control). Results with continuous right atrial cardioplegia (66% of control) and coronary sinus retrograde cardioplegia (40% of control) demonstrated diminished postreperfusion right ventricular performance. Right ventricular performance in the group protected with aortic root cardioplegia was significantly impaired after reperfusion when compared with all retrograde groups (34% of control, p less than 0.05). In this model, postreperfusion right ventricular performance was preserved in the right atrial cardioplegia groups despite passive ventricular distention. All methods of retrograde cardioplegia resulted in superior preservation of right ventricular performance when compared with standard aortic root cardioplegia.

Animals↗
PubMed1989

Development and evaluation of a new polymeric material for small caliber vascular prostheses.

Polyethylene oxide (PEO), because of its low levels of protein and cellular adsorption, may provide a suitable coating for synthetic small caliber vascular prostheses. PEO/polysiloxane networks were synthesized via an acid-catalyzed epoxy/hydroxyl crosslinking reaction and used to produce conduits with a 4-mm internal diameter. Three networks with nominal PEO molecular weights of 2000, 8000, and 20,000 and all 65% PEO by weight were studied. Blood compatibility was assessed by measuring 111In-platelet and 125I-fibrinogen deposition in a baboon ex vivo shunt, over a 1-hr time period and at a flow rate of 50 ml/min. Differences in material performance were noted particularly after the initial 30-min blood contact period. Materials in the mid and high PEO molecular weight range (8000 and 20,000) had significantly lower levels of platelet adsorption than networks of low PEO molecular weight (2000) at 30 min (P less than 0.005) and 60 min (P less than 0.05). The lowest level of platelet deposition was noted on networks of high PEO molecular weight (20,000). During the observation period, platelet accumulation on this surface was less than one platelet per 1000 microns. Platelet deposition on Gore-Tex was two and three orders of magnitude greater than that on the high molecular weight PEO material at 30 and 60 min, respectively (P less than 0.001). Fibrinogen adsorption was also lower on materials of mid and high PEO molecular weights, when compared with low molecular weight networks (P less than 0.05) and Gore-Tex (P less than 0.05). Scanning electron micrographs confirmed these observations. Overall, platelet and fibrinogen depositions are low for PEO networks, particularly for materials of high PEO molecular weight. This latter observation may be related to increased surface molecular mobility and a relative enhancement of PEO content at the blood-material interface.

Animals↗
PubMed1989

Thermal compression and molding of atherosclerotic vascular tissue with use of radiofrequency energy: implications for radiofrequency balloon angioplasty.

The combined delivery of pressure and thermal energy may effectively remodel intraluminal atherosclerotic plaque and fuse intimal tears. To test these hypotheses with use of a non-laser thermal energy source, radiofrequency energy was delivered to postmortem human atherosclerotic vessels from a metal "hot-tip" catheter, block-mounted bipolar electrodes and from a prototype radiofrequency balloon catheter. Sixty-two radiofrequency doses delivered from a metal electrode tip produced dose-dependent ablation of atherosclerotic plaque, ranging from clean and shallow craters with histologic evidence of thermal compression at doses less than 40 J to tissue charring and vaporization at higher (greater than 80 J) doses. Lesion dimensions ranged between 3.14 and 3.79 mm in diameter and 0.20 and 0.47 mm in depth. Tissue perforation was not observed. To test the potential for radiofrequency fusion of intimal tears, 5 atm of pressure and 200 J radiofrequency energy were delivered from block-mounted bipolar electrodes to 48 segments of human atherosclerotic aorta, which had been manually separated into intima-media and media-adventitial layers. Significantly stronger tissue fusion resulted (28.5 +/- 3.3 g) with radiofrequency compared with that with pressure alone (4.8 +/- 0.26 g; p less than 0.0001). A prototype radiofrequency balloon catheter was used to deliver 3 atm of balloon pressure with or without 200 J radiofrequency energy to 20 postmortem human atherosclerotic arterial segments. In 10 of 10 radiofrequency-treated vessels, thermal "molding" of both normal and atherosclerotic vessel wall segments resulted with increased luminal diameter and histologic evidence of medial myocyte damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗
PubMed1988

Efficacy of retrograde coronary sinus cardioplegia in patients undergoing myocardial revascularization: a prospective randomized trial.

The efficacy of retrograde coronary sinus cardioplegia (RCSC) administered through the right atrium compared with aortic root cardioplegia (ARC) has not been examined critically in patients undergoing coronary artery bypass grafting (CABG). Twenty patients having elective CABG were randomized prospectively to receive cold blood ARC (Group I, 10 patients) or cold blood RCSC (Group II, 10 patients). Patient demographics were similar in both groups. Ventricular function was assessed preoperatively by radionuclide ventriculography and postoperatively by simultaneous hemodynamic and radionuclide ventriculographic studies with volume loading. There was no change in ejection fraction (EF) (preoperative versus postoperative value) in Group I (50 +/- 6% versus 53 +/- 6%) but in group II, at similar peak systolic pressure and similar left ventricular end-diastolic volume index (LVEDVI), LVEF improved significantly (49 +/- 6% versus 60 +/- 12%, p less than 0.05). Postoperative ventricular function (stroke work index versus EDVI) for the left ventricle and right ventricle were similar in both groups. Evaluation of postoperative LV systolic function (end-systolic blood pressure versus end-systolic volume index) and diastolic function (pulmonary capillary wedge pressure versus EDVI) were also similar in both groups. Retrograde coronary sinus cardioplegia is as effective as ARC for intraoperative myocardial protection, and provides excellent postoperative function in patients undergoing elective CABG.

Blood↗
PubMed1988

Interleukin 1 induces a shock-like state in rabbits. Synergism with tumor necrosis factor and the effect of cyclooxygenase inhibition.

In addition to activating T and B lymphocytes, interleukin 1 (IL-1) induces several hematologic and metabolic changes typical of host responses to infection and injury. We now report a new biological property, namely, the induction of hypotension. Rabbits given a single intravenous injection of recombinant human IL-1-beta (5 micrograms/kg) rapidly developed decreased systemic arterial pressure, which reached the lowest levels after 50-60 min and slowly returned to pre-IL-1 values after 3 h. Associated with the hypotension, systemic vascular resistance and central venous pressure fell, while cardiac output and heart rate increased. These responses were prevented by ibuprofen given 15 min before the IL-1. A bolus injection of IL-1 followed by a 2-h infusion sustained the hypotension and was associated with leukopenia and thrombocytopenia. Ibuprofen given at the mid-point of the infusion reversed the changes in all hemodynamic parameters, but had no effect on the leukopenia or thrombocytopenia. Tumor necrosis factor (TNF) also induced a shock-like state in rabbits. When the dose of IL-1 or TNF was reduced to 1 microgram/kg, no hemodynamic changes were observed; however, the combination of these low doses of both cytokines resulted in a profound shock-like state including histological evidence of severe pulmonary edema and hemorrhage. Pretreatment with ibuprofen prevented the hemodynamic, leukocyte, and platelet changes induced by the low-dose cytokine combination, and ameliorated the pulmonary tissue damage. These results demonstrate that IL-1, like TNF, possesses the ability to induce hemodynamic and hematological changes typical of septic shock, and that the combination of IL-1 and TNF is more potent than either agent alone. These effects seem to require cyclooxygenase products, and suggest that intravenous cyclooxygenase inhibitors may be of therapeutic value in patients with IL-1/TNF-mediated shock.

Animals↗
PubMed1988

Effects of nicotine on local cerebral glucose utilization in the rat.

We used the autoradiographic 2-deoxy-D-[1-14C]glucose (14C-DG) method of Sokoloff to identify brain areas with altered rates of local cerebral glucose utilization (LCGU) in vivo in response to peripheral I-nicotine administration (0.1, 0.3, 1.0, and 1.75 mg/kg, s.c.). Nicotine stimulated LCGU primarily in areas reported to contain nicotine binding sites, indicating that the sites are true receptors. Increases in LCGU of 100% or more over control were obtained in the medial habenula, fasciculus retroflexus, superior colliculus, and median eminence. Substantial stimulation (50-100% increases) also was obtained in the cerebellar vermis, interpeduncular nucleus, and anteroventral and interanteromedial thalamic nuclei. Moderate increases (20-50%) were observed in the reticular nucleus of the medulla, paramedian lobule, nucleus of the spinal tract of the trigeminal nerve, presubiculum, subiculum, red nucleus, ventral tegmental area, substantia nigra, nucleus ambiguus, nucleus tractus solitarius, dorsal lateral geniculate nucleus, mammillothalamic tract, and fornix. The greatest stimulation in most affected areas was obtained with 0.3 mg/kg nicotine administered at 2 min, but not longer, before 14C-DG. Effects of nicotine on LCGU were antagonized by mecamylamine. The findings indicate that the interaction of nicotine with specific binding sites is coupled to cerebral energy metabolism. The distribution of in vivo cerebral metabolic effects of nicotine implicates various brain regions in the behavioral and physiological effects of nicotine.

Animals↗
PubMed1986

Antiplatelet therapy and vascular grafts. Studies in a baboon ex vivo shunt.

Antiplatelet therapy is currently recommended in an effort to improve patency rates of small-caliber vascular grafts. The effect of aspirin and heparin on acute platelet deposition was studied in a baboon ex vivo shunt. Two grafts, expanded polytetrafluoroethylene and knitted Dacron, were exposed to a flow rate of 25 mL/min after administration of aspirin or heparin. Indium 111-labeled platelet uptake by the grafts was determined over 2 1/2 hours. The amount of platelet deposition in the treated groups was significantly less than that of controls after 2 1/2 hours. There was no difference between the aspirin and heparin groups. The finding that heparin inhibited platelet deposition to a degree comparable with aspirin suggests that it may not be necessary to start antiplatelet therapy preoperatively. Intraoperative systemic heparinization will provide sufficient inhibition of platelet deposition. A protocol for perioperative antiplatelet therapy is outlined.

Animals↗
PubMed1986

Endothelial cell seeding of small-caliber synthetic grafts in the baboon.

Endothelial cell (EC) seeding has been proposed as a method to improve the performance of small-caliber synthetic vascular prostheses. Seeding experiments to date have all been carried out in the dog. This study investigates EC seeding of small-caliber Dacron carotid interposition grafts compared with contralateral control grafts in the baboon. Surface thrombogenicity was assessed at 24 hours, 2 weeks, and 4 weeks after implantation with indium 111-labeled autologous platelets. Morphologic and immunohistochemical techniques were used to assess the identity and homogeneity of the EC inoculum before seeding and to identify cell types on the harvested grafts. There was no significant difference in patency rates between seeded and control grafts at 5 weeks. Platelet accumulation on seeded grafts was significantly less (p less than 0.05) than on paired controls at 2 and 4 weeks after implantation. The luminal lining of seeded grafts had more cellular ingrowth, less adherent thrombus, and more surface cells with the morphologic and histochemical characteristics of EC than did the lining of controls. EC seeding reduces the platelet reactivity and accelerates EC coverage of small-caliber grafts in the baboon.

Animals↗
PubMed1986

The effect of flow on vascular endothelial cells grown in tissue culture on polytetrafluoroethylene grafts.

Vascular grafts lined with endothelial cells (EC) grown to confluence in culture before implantation may provide a thromboresistant flow surface. Growth of EC on and their adherence to currently available prosthetic materials under conditions of flow are two impediments remaining in the development of such a graft. To address these problems, 22 polytetrafluoroethylene grafts (PTFE) (5 cm by 4 mm inside diameter) were pretreated with collagen and fibronectin, seeded with 2 to 3 X 10(6) bovine aortic EC per graft, and placed in tissue culture (seeded grafts). Twenty-two grafts pretreated with collagen and fibronectin alone served as controls. After 2 weeks morphologic studies revealed that 20/22 seeded grafts were lined with a confluent endothelial layer. Indium 111-oxine was then used to label the EC-seeded grafts. After exposure to either low (25 ml/min) or high (200 ml/min) flow rates for 60 minutes in an in vitro circuit, examination of the luminal surface of the graft by light microscopy and scanning electron microscopy revealed minimal loss of EC. These findings were corroborated by radionuclide scans that showed an insignificant loss of the EC-associated indium label during exposure to flow (7% low flow, 11% high flow). Pretreatment of PTFE grafts with collagen and fibronectin thus promotes both attachment and adherence of EC even under flow conditions.

Animals↗