ICAM-1 deficiency reduces atherosclerotic lesions in double-knockout mice (ApoE(-/-)/ICAM-1(-/-)) fed a fat or a chow diet.

Intercellular adhesion molecule (ICAM)-1, a major adhesion molecule, plays a critical role in the homing of leukocytes to sites of atherosclerotic lesions. However, very little is known on the role of ICAM-1 in initiating and perpetuating vascular lesions in ApoE(-/-) mice fed a chow or a fat diet. This study has investigated the mean aortic lesions in mice (C57BL6 background) with a single-knockout (ApoE(-/-)) or double-knockout (DKO; ApoE(-/-), ICAM-1(-/-)) fed a chow or a fat diet over a period of 3, 6, 15, and 20 weeks. A 3-fold reduction in lesion size was observed at all time points in DKO mice fed a chow diet. However, in DKO mice fed a fat diet, a marked reduction in the aortic lesion was observed at 3 and 15 weeks, which did not reach a significant level at 6 and 20 weeks. This study shows in essence that DKO mice are protected from developing significant lesions for up to 6 weeks when fed a chow diet and from 3 to 6 weeks when fed a fat diet. After 6 weeks, the lesion size of the DKO mice follows that of the single-knockout mice when fed a chow diet and gets to the same level in mice fed a fat diet. Plasma cholesterol levels were not altered as a result of ICAM-1 deficiency. These studies show that ICAM-1 is implicated in the formation and progression of atherosclerotic lesions.

Modulation of expression of endothelial intercellular adhesion molecule-1, platelet-endothelial cell adhesion molecule-1, and vascular cell adhesion molecule-1 in aortic arch lesions of apolipoprotein E-deficient compared with wild-type mice.

Human vascular adhesion molecules, such as intercellular adhesion molecule-1 (ICAM-1), platelet-endothelial cell adhesion molecule-1 (PECAM-1), and vascular cell adhesion molecule-1 (VCAM-1), are thought to play a critical role in the homing of leukocytes to sites of atherosclerotic lesions. However, very little is known about the expression of adhesion molecules in the vasculature of mice models, such as apolipoprotein E knockout (apoE(-/-)) mice, the lesions of which closely mimic human atherosclerotic lesions. This study has first quantitatively characterized the mean expression of endothelial adhesion molecules, lining the whole vessel intimal circumference, over a period of time (0 to 20 weeks of diet) in aortic arch lesions of male apoE-deficient compared with wild-type (C57BL/6) mice. These animals were fed a chow or a cholesterol-rich diet. ApoE(-/-) animals showed first an increase (at 6 weeks) and then a reduction (at 16 weeks) in the mean expression of ICAM-1 (P<0.05) and PECAM-1 (P<0.05) but not VCAM-1 levels. Such modulation of the mean expression of adhesion molecules was not observed in wild-type mice. Confirmation of immunohistochemistry results on ICAM-1 was obtained by Northern blots performed on the aortic arch of apoE and C57BL6 chow-fed mice over a period of 20 weeks. Moreover, the presence of VCAM-1 was also confirmed at the RNA level, on aortas of control and apoE mice, by reverse transcription-polymerase chain reaction. In the second part of the study, we assayed the levels of adhesion molecules, in different types of histologically defined atherosclerotic lesions, in apoE(-/-) animals fed for 20 weeks. All 3 adhesion molecules (ICAM-1, PECAM-1, and VCAM-1) were observed to be reduced in fibrofatty and complex lesions but not in fatty streaks or in areas without lesions. These results indicate that the expression of these adhesion molecules in apoE-deficient animals varies with the evolution of the plaque from a fatty to a fibrous stage.

Enhanced expression of P-selectin (CD62P) by endothelial cells seeded onto synthetic arterial prostheses (PET, Dacron) is correlated with leukocyte interactions.

This study evaluated the expression by seeded endothelial cells (S-EC) of P-selectin (CD62P/GMP-140/PADGEM), an adhesion molecule implicated in endothelial-leukocyte interactions. Endothelial cells were seeded onto knitted polyethylene terephthalate (PET, Dacron(R)) prostheses and compared with control endothelial cells (C-EC) cultured in flasks to the same stage. Using flow cytometry techniques, we observed that CD62P expression by PET S-EC was significantly increased (p<0.05) compared to C-EC. Moreover, RT PCR techniques showed that the CD62P RNA level was higher on S-ECs compared to C-ECs. Following adhesion assays, increased polymorphonuclear neutrophil (PMN) attachment to the PET-seeded prostheses as compared to control cultures (p<0.001) was observed. PMN adherence was enhanced by TNFalpha activation. PMN adhesion was decreased significantly (p<0.001) after the incubation of resting EC or TNFalpha-activated EC-seeded prostheses with a blocking monoclonal antibody (LYP20) directed against the P-selectin. Such results suggest that: (1) PET prosthetic material may induce the expression of P-selectin by S-EC; (2) seeding conditions provoke an increase in PMN adhesion; (3) increased PMN interactions with seeded PET material is partially dependent upon P-selectin expression by the S-EC.

Identification and cloning of a new gene (2A3-2), homologous to human translational elongation factor, upregulated in a proliferating rat smooth muscle cell line and in carotid hyperplasia.

Smooth muscle cells (SMCs), before migration and proliferation in the intima of the vessel wall, change from a normal contractile to a pathological proliferating phenotype. The molecular regulatory mechanisms implicated in such phenotypic changes remain poorly understood. In this study, using differential display, we have isolated for the first time a new gene (2A3-2) that is overexpressed in a rapidly proliferating, but not synthetic, rat SMC line. This was further confirmed by northern blot performed on the 2 cell types. Moreover, balloon catheter injury of rat carotids showed, by a virtual northern technique, an upregulation of this new gene in hyperplasia vessels. This new gene (2A3-2, 1.2 kb) was present in skeletal muscle, heart, aorta, lung, liver, kidney, and spleen. In addition, 5' rapid amplification of cDNA ends (5' RACE) allowed the cloning and sequencing of this 1.2-kb gene. Comparison of this newly identified gene sequence with data banks showed a strong homology to human and bovine mitochondrial translational elongation factor. The 2A3-2 gene, identified in this study, may play a vital role in the cascade of events implicated in switching SMC phenotype from a quiescent to a proliferate one.

Effect of a micronized purified flavonoid fraction on in vivo platelet functions in the rat.

The aim of this study was to investigate the effects of a micronized purified flavonoid fraction (MPFF) on in vivo rat platelet functions. Platelet aggregation and disaggregation were evaluated by a noninvasive, automated isotope monitoring system (AimsPlus). Indium-labeled platelets were injected into anesthetized rats and stimulated by adenosine diphosphate (ADP) (10 microg/kg, i.v.) or collagen (50 microg/kg, i.v.). Fibrinogen binding to ex vivo ADP-activated platelets was determined by flow cytometry. MPFF (100 mg/kg, p.o.) significantly reduced ADP-induced platelet aggregation (p<0.05) and increased platelet disaggregation (p<0.05) compared with controls. Moreover, MPFF inhibited collagen-induced platelet aggregation (p<0.001) and increased platelet disaggregation (p<0.01). In addition, fibrinogen binding to 2.5 or 5 microM ADP-stimulated platelets also was reduced significantly (p<0.05 and 0.01, respectively). These results show that MPFF inhibits in vivo rat platelet functions.

Effect of naftazone on in vivo platelet function in the rat.

The aim of this study was to investigate the in vivo effects of 50 mg/kg (i.p.) naftazone or ticlopidine on platelet functions in the rat. An automated isotope monitoring system (Aims plus) was used to determine the height of platelet aggregation and disaggregation (measured by the area under the curve, AUC) of 111indium-labelled platelets activated by ADP (10 microg/kg i.v.) or collagen (50 microg/kg i.v.). Fibrinogen-binding experiments were carried out with activated platelets in whole blood and measured by flow cytometry. Naftazone reduced the height of platelet aggregation induced by ADP compared with controls (P = 0.024). Ticlopidine-treated rats gave similar results (P = 0.008). Platelet disaggregation, following the aggregation induced by collagen, was significantly increased in naftazone-treated rats compared with controls (P = 0.003). Similar results were observed with ticlopidine-treated rats (P = 0.002). Fibrinogen binding to 2.5 or 5 microM ADP-stimulated platelets, from naftazone-treated rats, were significantly reduced compared with controls (P = 0.05 and 0.04 respectively). These results show that naftazone has similar inhibitory effects on rat platelet functions as ticloplidine. In conclusion, naftazone could be a useful agent to modulate platelet function in patients with cardiovascular disease.

Mapping the epitope of a functional P-selectin monoclonal antibody (LYP20) to a short complement-like repeat (SCR 4) domain: use of human-mouse chimaera and homologue-replacement mutagenesis.

P-selectin (CD62P), an adhesion molecule localized in platelet alpha-granules and endothelial cell Weibel-Palade bodies, is rapidly expressed on the surface of activated cells. This adhesion molecule, a member of the selectin family, mediates leucocyte interactions with activated platelets or endothelial cells. The aim of this study was to identify and characterize the epitope of a functional blocking P-selectin monoclonal antibody (mAb), LYP20. LYP20 recognizes human or rat, but not mouse, P-selectin. Human/mouse chimaeras and wild-type constructs, modified by homologue replacement mutagenesis, were expressed in COS cells. Blocking anti-(P-selectin) mAbs (G1, G3 or CLB-thromb/6) were observed, by flow cytometry, to bind to the lectin-like domain. In contrast, LYP20 was found to bind to one of the P-selectin short complement-like repeats (SCR domain 4). Homologue replacement mutagenesis of SCR domain 4 (region delineated by amino acid residues 359-457) identified three amino acids (Cys412-->Ser, Cys416-->Ser or Arg415-->Lys) as being implicated in the LYP20 epitope. Deleting the region bearing the LYP20 epitope, from a wild-type CD62P construct, showed a decrease in polymorphonuclear leucocyte (PMNL) binding to transfected COS cells. In addition, mutation of one of the three amino acids, implicated in the LYP20 epitope, markedly affected PMNL binding to transfected COS cells but did not affect the binding of mAbs G1 and CLB-thromb/6. These results are the first to indicate (1) that a functional blocking anti-P-selectin mAb binds to SCR 4, a site other than the lectin-like/epidermal growth factor-like domain, and (2) that SCR domain 4 has a functional role in P-selectin-leucocyte interactions.

Venous thrombosis generation by means of high-intensity focused ultrasound.

Sclerotherapy of superficial varicose veins is now performed with chemical agents since physical agents have given only poor clinical results. We investigated the possibility of using high intensity focused ultrasound energy to achieve this goal in an animal model, the rat femoral vein. A specially designed probe delivering ultrasonic energy at a central frequency of 7.31 MHz was constructed and evaluated. Femoral veins of six rats were surgically exposed to a set of between four and seven 3-s exposures at 1-mm increments at a power level of 167 W/cm2. At 2 days following the irradiation, control veins were patent while occlusive thrombus was documented by Doppler flow and histological studies in all six of the irradiated veins. No damage to the surrounding soft tissues was noted. We concluded that high-intensity focused ultrasound can be used to induce thrombosis in this animal model.

Two sites (23-30, 76-90) on rat P-selectin mediate thrombin activated platelet-neutrophil interactions.

The lectin-like domain of P-selectin, an adhesive receptor (also known as PADGEM, GMP-140 or CD62) is implicated in platelet or endothelial cell interactions with leukocytes. The aim of this study was to characterize the lectin-like domain of rat P-selectin by the use of synthetic peptides. The lectin and EGF-like domains of rat P-selectin were cloned in our laboratory and shown to present very strong homologies to its human counterpart. Peptides corresponding with the lectin-like domain of P-selectin were tested for their ability to inhibit thrombin-activated platelets rosetting to neutrophils. Peptides 23-30 (A) and 76-90 (C), but not peptide 51-61 (B), inhibited thrombin activated rat platelets interactions with rat neutrophils (A = 33%, C = 46%, P < 0.05). Using a combination of peptides (A+B = 35%, P = 0.008 and A+C = 62%, P < 0.001), we observe different degrees of inhibition of platelets binding to neutrophils. The IC50 of peptides A+C was 0.11 mM. LYP-20, an anti-human P-selectin monoclonal antibody, was also observed to inhibit thrombin-activated rat platelets binding to rat neutrophils in a very significant manner (57% of inhibition, P < 0.001). Moreover, heparin inhibited thrombin-stimulated platelet/neutrophils rosetting (36% of inhibition, P < 0.01). These results show the importance of two sites (23-30 and 76-90) on the lectin-like domain of P-selectin in mediating platelet-neutrophil interactions in rats. Such peptides may be potent in vivo inhibitors of cell-cell interactions involving P-selectin.

A P-selectin/CD62P monoclonal antibody (LYP-20), in tandem with flow cytometry, detects in vivo activated circulating rat platelets in severe vascular trauma.

P-selectin, also known as CD62P, GMP140 or PADGEM, is present in platelet alpha-granules and endothelial cell Weibel-Palade bodies and is very rapidly expressed on the surface of these cells on activation. In this study, an anti P-selectin monoclonal antibody (LYP20) was used, in tandem with flow cytometry, to identify activated platelets at the site of induced vascular trauma or in peripheral blood. Moreover, electron microscopy was performed to characterize sites of vascular trauma and quantify the number of adhering platelets. The same induced vascular trauma was observed to result into animals responding in 2 different ways (Group I, Group II) following the degree of platelet activation. Five rats, out of 14 with induced vascular trauma, had more than half of their circulating platelets expressing P-selectin when drawn at the site of the trauma (67.4% +/- 3.44) or in peripheral blood (78.5% +/- 2.5) (Group I). In the remaining 9 animals a much smaller proportion of circulating platelets expressed P-selectin when assayed from trauma sites (18% +/- 3.34) or in peripheral blood (18.0% +/- 4.30) (Group II). Enhanced P-selectin expression by circulating platelets in Group I, compared to Group II, appears to be linked to the degree of activated platelets adhering at sites of trauma (171 +/- 15 x 10(3) platelets versus 48 +/- 31 x 10(3) platelets per mm2). In the 5 control animals, that were not operated on, platelets expressing P-selectin when drawn at the site of a mock trauma (7.0% +/- 1.84) or in the peripheral blood (11.2% +/- 3.30) showed little activation.(ABSTRACT TRUNCATED AT 250 WORDS)

Thrombospondin in human glomerulopathies. A marker of inflammation and early fibrosis.

Extensive damage is thought to occur to endothelial cells in renal vasculitis and other glomerulopathies. The state of inflammation of these endothelial cells was investigated through the use of a panel of monoclonal antibodies (MAb) directed against thrombospondin (TSP), von Willebrand factor (vWF), integrins (alpha IIb beta 3, alpha v beta 3), CD36, and classical markers of inflammation (P-selectin, E-selectin, ICAM-1, VCAM). Results show that the anti-TSP MAb (LYP10) stains large areas of interstitium in focal sclerosis, vasculitis, membranous glomerulonephritis (GN), and diabetic GN but does not in normal kidney. In contrast, very limited areas are stained by LYP10 in minimal change nephropathy and Berger's disease. On paraffin-embedded specimens these areas stained by LYP10 appear edematous and early fibrous. Up-regulation of vWF and ICAM-1 is matched by an increased binding of LYP10 to the interstitium. In addition, fibrous crescents in injured glomeruli are stained by LYP10. This study reports for the first time an increased TSP secretion in glomerulopathies. Such TSP secretion may be part of physiological adaptive changes associated with inflammation and early fibrosis.

Dacron vascular biomaterial triggers macrophage ectoenzyme activity without change in cell membrane fluidity.

Biomaterials induce an inflammatory reaction characterized by a rapid recruitment at the implantation site of polymorphonuclear cells and macrophages. In the course of the inflammatory response, the cellular activation triggers expression of a number of enzymes, such as 5'-nucleotidase, which is widely distributed in animal cell membranes as an ectoenzyme. It is now well established that 5'-nucleotidase activity decreases following the contact of inflammatory cells with foreign particles. In this paper we investigate a possible correlation between the enzymatic activities and the dynamic properties of the cell membrane bilayer. Dacron pieces were introduced into rats' peritoneal cavities for a period of 6 h, after which the peritoneal cells were harvested, and various enzyme assays performed, including those for cytoplasmic, lysosomal, and ectoenzymes. In parallel, we studied cell membrane fluidity, using fluorescence polarization of 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH), and cellular ultrastructural alteration resulting from the cell-biomaterial interactions using scanning and transmission electron microscopy. Our results show that: 1) macrophages spread around the Dacron fibers with cytoplasmic finger-like projections, but no phagolysosomes, 2) 5'-nucleotidase levels decrease with surgical trauma in comparison with the resident cell exudate, 3) implantation of biomaterials slightly modify the 5'-nucleotidase levels observed in the sham animal, 4) no differences in the anisotropy values indicating that membrane lipid order within the cells could not account for the observed decrease of 5'-nucleotidase activity. Thus, we can suggest that 5'-nucleotidase expression may reflect a particular feature of cell activation without a phagocytic process.

A member of the selectin family (GMP-140/PADGEM) is expressed on thrombin-stimulated rat platelets in vitro.

1. Granule membrane protein (GMP-140) is an integral alpha-granule membrane glycoprotein, expressed on the surface of human platelets following degranulation, and is part of a new family of adhesion molecules (selectins) related to the endothelial leukocyte adhesion molecule (ELAM-1) and to the lymphocyte homing receptors in man (Leu-8/TQ1) and in mouse (gp90MEL-14). 2. The cross-reactivity with rat platelets of the monoclonal antibodies (MAb), LYP20 and S12, directed against human GMP-140 was examined, with the purpose of assessing the homology of GMP-140 between human and rat platelets and of using positive MAbs to detect platelet activation in vivo in response to vascular disease in rats. 3. By ELISA technique, LYP20 gave a greater OD reading with thrombin-stimulated rat platelets than with resting platelets. 4. 125I-LYP20 bound significantly more to thrombin-stimulated rat platelets (3875 +/- 750 molecules/platelet) than to resting platelets (645 +/- 240 molecules/platelet, P less than 0.01) with 50% maximum binding at 0.13 +/- 0.02 microgram/ml; 125I-S12 did not bind to rat platelets. 5. By fluorescence-activated flow cytometry there were significantly more fluorescent thrombin-stimulated platelets (56 +/- 7% of total), compared with resting platelets (8 +/- 1% of total, P less than 0.001). 6. Western blots of rat platelet lysates showed that LYP20 bound to a single band identified, under non-reducing conditions, as having the same apparent M(r) as GMP-140. 7. LYP20 immunoprecipitated a protein which became radiolabelled on the surface of thrombin-activated rat platelets; S12 did not recognize any protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of subintimal hyperplasia of autologous vein bypass grafts by nimodipine in rats: a placebo-controlled study.

An arterial bypass may be required for the management of neoplastic or cerebrovascular disease. When an arterial graft is not suitable, autologous vein grafts are the most commonly used conduits; however, as many as 20% of the vein grafts used in vascular surgery may occlude as a result of subintimal hyperplasia. Although the mechanism initiating subintimal hyperplasia remains unclear, it is known that subintimal hyperplasia is dependent upon smooth muscle cell proliferation and migration from the media to the intimal layer. The present study focused on the prevention of smooth muscle cell proliferation using a calcium antagonist. Forty rats received an autologous vein bypass graft from the jugular vein to reconstruct the abdominal aorta. They were randomly divided into two groups of 20 rats each. Animals in the treated group received a calcium antagonist (nimodipine), and those in the control group received a placebo. Nine months after grafting, the group receiving the calcium antagonist presented no or only slight sub intimal hyperplasia as compared with the placebo-treated group (P less than 0.001). These data suggest that a calcium antagonist could be used for the prevention of venous graft disease.

Effect of nimodipine on subintimal hyperplasia of autologous vein bypass grafts in rats: a placebo-controlled study.

Autologous vein grafts are commonly used conduits for coronary bypass grafts. However, as many as 20% of the grafts may occlude in the first year to a subintimal hyperplasia. Although the initiating mechanism remains unclear, it has been demonstrated that subintimal hyperplasia is dependent upon smooth muscle cell proliferation and migration from the medial to the intimal layer. The present study focused on the prevention of smooth muscle cell proliferation using a calcium antagonist. A vein bypass graft from the jugular vein on the abdominal aorta was performed in 40 rats, divided into two groups of 20. Animals in the treated group received nimodipine (15 mg/kg of body weight), and those of the control group received a placebo. Nine months after grafting, the results showed that the group receiving nimodipine presented no or only slight subintimal hyperplasia as compared with the placebo group (p less than 0.001). The data presented in this study show that nimodipine can reduce subintimal hyperplasia in rats and strongly suggest that a calcium antagonist could be employed in the prevention of venous graft disease.

Peritoneal macrophage response: an in vivo model for the study of synthetic materials.

This study was designed to validate an in vivo model in rat to study cell-implant interactions. Pieces of Dacron and Goretex and polydimethylsiloxane (reference material) precoated or not were implanted in the peritoneal cavity. In some cases the peritoneal cells were stimulated before the implantation. Macrophage phagocytosis and fibrinocoagulolytic activities were investigated in parallel with morphological studies 6 h after implantation. A graded cell response related to the different situations was observed, providing a measure of the material's behaviour. Using this model, other investigations of macrophage/polymer can be conducted, especially to explain implant encapsulation.

Assessment of a potentially noninvasive method for monitoring aortic blood flow in children.

Ultrasonic methods have rendered possible noninvasive quantitative blood flow measurement. In this work, a method is proposed to measure aortic blood flow in children by means of a specially designed miniaturized esophageal probe and an autonomous apparatus combining an M-mode imaging system and a pulsed Doppler. In vivo experimental results in animals are presented and demonstrate the interest of simultaneous and continuous measurement of aortic diameter and blood flow velocity giving accurate measurements. A 0.94 correlation coefficient is found when comparing blood flow in the descending aorta measured using this method and using an electromagnetic flowmeter.

Lipid accumulation in prosthetic vascular grafts. Experimental study.

The present study demonstrates that the endoprosthetic tissue, developed at the contact of Dacron and Gore-Tex vascular prostheses replacing the infrarenal aortae of healthy dogs, presents a particular lipidic pattern as compared with the adjacent intimal arterial layer. The modified lipidic pattern is characterized by a significant increase in the total amounts of cholesterol, phospholipids, and triglycerides, despite a normal lipidic plasma profile. Histochemical studies showed that lipid droplets are accumulated in the cytoplasm of deeply situated cells and in the extracellular matrix. These findings support the idea that lipids may be trapped within the pseudo-intima of synthetic vascular grafts, even in the absence of a major plasma lipid disorder, and contribute to the prosthesis failure.

[The neoartery, myth or reality? Study of 79 explanted arterial prostheses]. / La néo-artère, mythe ou réalité? Etude de 79 prothèses artérielles explantées.

This study represents the third stage of a personal study on the long term fate of reconstruction and arterial restoration materials presented to the Academie de Chirurgie. 79 explanted prostheses were studied. First of all by an in depth histological study (8 cases selected from 70 reinterventions carried out before 1980), and then by a more complete protocol: scanning electron microscopy, resistance testing, programmed differential calorimetry, X-ray diffraction and biochemical analysis (71 reinterventions carried out after 1980). Our findings agree with the studies of R. Guidoin. With the exception of structural manufacturing defects or defects related to surgical manipulation, mechanical fatigue in a Dacron (PET) arterial prosthesis is inevitable: on average by the 7th to 10th year, a prosthesis looses one half of its mechanical resistance. The covering tissue, like that of the external capsule, which has poor mechanical properties, cannot compensate for prosthetic deterioration which may be considered to be complete by the 25th year. Knitted arterial prostheses, especially aortic, more rapidly undergo dilatation than woven prostheses which are much more resistant. On the other hand, the poor compliance of the latter compared with the recipient artery, perhaps favorises late anastomotic rupture. At internal capsule or pseudo-intimal level, endothelium is never present, but rather there is a permanent turnover with a variable time course, the mechanisms of which are poorly understood (role of prostaglandins?). Rather than a neo-artery, the vascular surgeon is only capable of producing an imperfect arterial tube, fragile from many points of view, and having an evolution which remains poorly understood.

Characterization of the tissue proliferated at the blood interface of carbon/ceramic composites.

The present study focuses on cell adhesion/differentiation and material stability of surfaces of the three carbon/ceramic composites implanted in intra-atrial position in dogs for 1 year. Before implantation their surface was characterized by scanning electron microscopy. After harvesting, the tissue proliferated on the blood interface was examined by histology, scanning, and transmission electron microscopy, wavelength dispersive and x-ray spectrometry, electrophoretic and enzymatic characterization of glycosaminoglycans (GAGs) which were compared to endocardiac tissue as control samples. One year after implantation, the pattern of GAGs in the newly developed tissue was characterized by: 1) a constant increase of the total GAGs present on all carbon composites, 2) a significant increase of dermatan sulfate (p less than 0.05), 3) a significant increase of chondroitin sulfate (p less than 0.05), 4) a significant decrease of heparan sulfate in Group 1, whereas this GAG fraction was increased in Groups 2 and 3. Cellular surface differentiation towards endothelial-like cells occurred in places particularly in groups 1 and 3, whereas only fibrous tissue was found covering the implants in Group 2. Fibroblastic cells with dense intracellular deposits, which produced emission of Si, Ca, and C energy as well as extracellular lipidic containing inclusions were observed. The macromolecular modifications were associated with 1) the absence of endothelial lining, 2) the migration of carbon and silicon particles, and 3) the occurrence of calcifications and lipidic inclusions. These results suggest that the relative smoothness of these materials could be responsible for the development of a tissue that did not adhere to the biomaterial, indicating that cell adhesion and functional differentiation are in intimal relationship with the physical-chemical structure of the material surface.