External Biodegradable Supporting Conduit Protects Endothelium in Vein Graft in Arterial Interposition

The prevention of circumferential distension could reduce structural damage in arteriovenous grafts. We studied the effect of an external biodegradable supporting conduit on the endothelium and extracellular matrix in vein graft in a pig model. Cephalic vein control grafts (Group I) and jugular veins wrapped in a vicryl mesh tube (I.D. 4mm) (Group II) were implanted into autologous carotid arteries (n=14). The grafts were explanted after 1 and 24 hours and at 1 and 3 weeks and evaluated by ELISA for endothelial DNA synthesis and by immunohistoenzymic assays for cells and extracellular matrix. In group I an initial loss of endothelial and smooth muscle cells along with elastin breakdown was followed by an impaired endothelial regeneration and significant graft wall thickening. The elastic tissue was replaced by collagen type I and chondroitin sulfate accumulations, which included a disarray of α-smooth muscle actin positive cells. The endothelium was preserved in group II. After 3 weeks the circumferential elastin layers were densified, distended and separated from the endothelium by a neointimal growth of irregular thickness. Biodegradable perivenous conduit minimized endothelial injury and allowed the partial preservation of elastin fibers and smooth muscle cells in the arteriovenous graft. It did not however, prevent myofibroblastic cell proliferation and triggered a macrophagic reaction.

Human Vascular Endothelial Cells on Expanded Ptfe Precoated with An Engineered Protein Adhesion Factor

To elucidate the role of the molecular structure of adhesive proteins in an endothelialization of synthetic vascular prosthesis in vitro, a recombinant fibronectin-like engineered adhesion factor (FP) constructed from the specific Arg-Gly-Asp cell adhesion repeats was assayed as adhesive substrate to culture human saphenous vein endothelial cells on ePTFE. ePTFE samples (1 cm2) inserted into cell culture chambers were coated by incubation with increasing amounts of FP (up to 100 μg/cm2) prior to cell seeding. At 24 hours after low density cell seeding and 20 μg/ml/cm2 FP concentration, the number of adhered cells reached a plateau and the adhered cells did not proliferate up to 6 days of culture. At 24 hours after high density seeding (105 cells/cm2), the number of adhered cells was significantly higher on ePTFE with preadsorbed FP than on fibronectin coated PTFE. About 55% of the initially adhered cells survived up to 7 days on FP, whereas cell debris and free nuclei were predominant on fibronectin coated PTFE. In the investigated model the engineered RGD polymer potentialized a short-term adhesion of vascular endothelial cells to PTFE, nevertheless it did not ensure proliferation and long-term survival of these cells.

Pseudointima in Inflow and Outflow Conduits of a Left Ventricular Assist System: Possible Role in Clinical Outcome

Activation of blood coagulation and thromboemboli have been shown to present significant clinical risks in patients supported with an left ventricular assist system (LVAS). The interaction of pseudointima (PI) with blood in the conduits of the device could be involved in these clinical complications. Our aim was to study the morphology of the PI versus duration of circulatory support. Novacor N 100 PC LVASs were explanted from 10 men and 2 women after a mean of 209 days (range 23-560 days) of circulatory assistance. PI in the inflow and outflow conduits were investigated with immunohistochemical assays. In the inflow conduits, a loosely adherent PI had built up from collagen type I and III fibers growing into and between fibrin deposits. Disorganized collagenous matrix and longitudinally oriented collagen fibers included alpha-smooth muscle actin positive cells with random orientation. Macrophages were concentrated in the fibrin and were dispersed throughout the extracellular matrix. In the outflow conduits, a thin, adherent PI was composed of regular collagen type I and III layers. Collagen type I fibers had grown into the woven Dacron and alpha-smooth muscle actin positive cells were oriented in the axis of the blood flow. Macrophages were concentrated in the Dacron and reached the inner collagen layers. Venous blood flow in the inflow conduits allows the development of a non endothelialized irregular collagenous matrix intermingled with fibrin and invaded by macrophages. These persistent structural features progress with duration of circulatory assistance and reflect matrix degradation and remodeling. The potential to release thromboembolic fragments from the non stable, thrombogenic PI may be involved in the thromboembolic or neurologic complications sustained by 5 of 12 patients who were on circulatory support for as long as 200 days.

Effect of an alpha-blocker (Nicergoline) and of a beta-blocker (Acebutolol) on the in vitro biosynthesis of vascular extracellular matrix

The effect of an alpha-blocking agent and of a beta-blocking agent on the biosynthesis of extracellular matrix macromolecules of the arterial wall was investigated. Rabbit aorta explants were cultured up to 48 hours with radioactive proline, lysine or glucosamine. In presence of these drugs, at concentration shown to be effective for the inhibition of platelet-endothelial cell interactions (10(-7) M), the incorporation of 14C proline in total macromolecular proline was higher than in macromolecular hydroxyproline suggesting a relatively higher rate of biosynthesis of non-collagenous proteins as compared to collagens. The alpha-blocking increased the incorporation of 14C proline in collagenous and non-collagenous proteins after 18 hours of incubation. beta-blocking also increased the incorporation of proline in macromolecular proline and hydroxyproline as compared to control cultures. Both increased the incorporation of 3H glucosamine in newly synthesised glycosaminoglycans. beta-blocking increased mainly the neosynthesis of heparan sulphate, alpha-blocking that of hyaluronan. The incorporation of 14C-lysine in crosslinked, insoluble elastin was not modified. These experiments confirm that alpha and beta-blocking agents can influence not only the tonus of aortic smooth muscle cells but also the relative rates of biosynthesis of extracellular matrix macromolecules. This effect should be taken in consideration for the evaluation of the long range effect of alpha and beta-blocking drugs on the vascular wall.

Effect of variation in systemic blood flow on plasma TNF-alpha in a pig model with left ventricular assist device

Tumor necrosis factor-alpha (TNF-alpha) release has been implicated in a sepsis-like syndrome following cardiopulmonary bypass (CPB). This also may be important in patients who have had a left ventricular assist device (LVAD) implanted. This report investigates the effect of reducing systemic blood flow on hemodynamic response, mixed venous oxygen saturation (SvO(2)), and the release of TNF-alpha. LVADs were implanted in 9 pigs. The aorta was clamped, and thus the LVAD flow represented the entire systemic blood flow. Plasma TNF-alpha in the femoral artery (FA) and superior mesenteric vein (SMV) was measured at baseline and following systemic blood flow changes. Simultaneously, hemodynamic parameters and oxygen saturation in the pulmonary artery (SvO(2)) were measured. Following reductions in systemic blood flow, plasma TNF-alpha increased gradually to a maximum level at a systemic blood flow of 20%. There was no significant difference between TNF-alpha levels in the SMV and the FA. There was a significant (p < 0.05) correlation between cardiac index, stroke volume index, and TNF-alpha. The SvO(2) decreased significantly (p < 0.05) at a systemic blood flow of 30 and 20%. A rise in TNF-alpha occurred when the SvO(2) was less than 75%. The data demonstrate that a reduction in systemic blood flow causes an increase in plasma TNF-alpha. This can lead to the development of a sepsis-like syndrome in a group of patients who already are hemodynamically compromised. While weaning short-term LVAD support, rapid diminution of the cardiac output and the pump flow must be avoided.

Intestinal tissue oxygenation and tumor necrosis factor-alpha release during systemic blood flow changes in pigs with left ventricular assist devices

We previously demonstrated that tumor necrosis factor-alpha (TNF-alpha) increased following a reduction in systemic blood flow to 60% or less of the original cardiac output using a left ventricular assist device (LVAD). The aim of this study was to investigate the effect of reducing systemic blood flow on tissue oxygenation in the gastrointestinal tract (GIT) and the consequences of this on TNF-alpha release. LVADs were implanted in 9 pigs. The aorta was clamped, and thus the LVAD flow represented the entire systemic blood flow. Plasma TNF-alpha of the superior mesenteric vein was measured at baseline and during systemic blood flow changes. Simultaneously, pH, lactate, oxygen delivery index (DO(2)I), oxygen consumption index (VO(2)I), and oxygen extraction (O(2)ER) in the GIT were measured. The pH decreased and the lactate level increased significantly (p < 0.05) at a systemic blood flow of 50% or less. The VO(2)I was positively correlated with DO(2)I. The O(2)ER increased significantly (p < 0.05) with reductions in systemic blood flow to 30% or less. There was a significant (p < 0.01) correlation between TNF-alpha and O(2)ER at levels higher than 55%. These data demonstrate that the GIT oxygenation is inadequate with a reduction in systemic blood flow to 50% and that GIT oxygenation becomes critical at a reduction of 30%. During LVAD weaning, careful attention must be given to the GIT. The pH and lactate may be good markers of the adequacy of tissue oxygenation in the GIT.

New agents for the treatment of infarcted myocardium

Local delivery of angiogenic growth factors for the treatment of myocardial ischemia has been well documented in various animal models, and clinical trials are now in progress. Our strategy was radically different, based on selective protection of some of the growth factors naturally present within the injured tissue. This protection was obtained by applying a chemically defined substitute for Dextran called RGTA11 (for ReGeneraTing Agent). RGTA is a family of agents, which has properties mimicking those of heparan sulfates toward heparin-binding growth factors (HBGF) and which stimulate tissue repair and protection. Indeed, we have previously shown that RGTA prevents most of the damage resulting from acute skeletal muscle ischemia [FASEB J. (1999) 13, 761-766]. We now show that the same agent can be used for the treatment of myocardial infarction. Acute myocardial infarction was induced in pigs by ligation of the left circumflex artery. One hour later, a single injection of 10 mg of RGTA11 was made in the center of the infarcted area. Three weeks later we observed 1) recovery of 84% of the initial left ventricular ejection fraction (only 55% in saline-treated controls), 2) an almost 50% reduction in the infarct size, 3) a reduction in fibrotic tissue formation, 4) significant preservation of myocytes, and 5) an increase in the number of blood vessels. The treatment of ischemic heart disease with RGTA would have clear advantages over other therapies such as growth factor, gene, or cell transplants, based on a stable, simple, and easy-to-develop chemical product.

Structural changes in porcine bioprosthetic valves of a left ventricular assist system in human patients

BACKGROUND AND AIM OF THE STUDY

Porcine, specially manufactured bioprosthetic valves regulate blood flow from the left ventricle to pump sac (inflow valve) and from the pump to the aorta (outflow valve) in a wearable, electrically powered left ventricular support system (LVAS, Novacor). The increased need for long-term circulatory assistance requires information on the evolution of these valves when exposed to specific hemodynamic conditions and inflammatory reactions in the device. The study aim was to examine structural changes in valves from explanted LVASs.

METHODS

Thirteen patients (11 males, two females; mean age 42 years (range: 17-64 years) were supported for a mean of 285 days (range: 37-1,293 days) with LVAS. Histologic sections from explanted inflow and outflow valves were studied immunohistochemically using peroxidase-labeled antibodies and avidin-biotinylated peroxidase complex for detection.

RESULTS

In the macroscopically normal inflow valves (11/13), the outflow surface (facing the pump) was covered with a discontinuous deposit of fibrin, macrophages and granulocyte elastase. Fibrinogen, IgG, complement proteins C1q and C3 had infiltrated the extracellular matrix (ECM) between 37 and 1,293 days. The crevices were enlarged during circulatory support, and fibrinogen/fibrin insudations were detected in the spongiosa. The collagen layers in the fibrosa were disrupted after 293 days, and eroded on the inflow surface in the ventricularis after 1,293 days. In a deteriorated valve from a patient with endocarditis, Gram-positive bacteria and metalloproteinases were concentrated in the ECM. In the macroscopically normal (11/13) outflow valves, fibrin and complement proteins had penetrated the ECM from the inflow side (facing the pump), while macrophages and granulocytes were localized mainly on the outflow surface. IgG and complement proteins were detected on and beneath the cusp surface up to 200 days and covered the disrupted ECM as implant time progressed.

CONCLUSIONS

Structural changes appear to progress more rapidly in the inflow than in the outflow of bioprosthetic valves. This difference indicates that the effects of biological factors are modulated by mechanical stress.

Pseudointima in inflow conduits of left ventricular assist devices

BACKGROUND

Explant analysis of left ventricular assist systems (LVAS) should permit a better evaluation of long-term evolution of materials and tissue healing in patients supported by mechanical devices and a precise understanding of embolic phenomena, observed clinically.

METHODS

Five Novacor LVAS and their conduits have been explanted after 156 days (range 61-226 days) of mechanical support. The pseudo-intima (PI) developed in the inflow and outflow conduits was characterized microscopically, using monoclonal antibodies.

RESULTS

The morphological aspects of PI were quite different in the inflow and outflow conduits. Blood coagulation between the basal surface of the PI and the Dacron tube, irregular collagen type I matrix with plasma infiltration, macrophages, and neutrophil granulocyte elastase characterized the nonadherent, loose, and potentially thrombogenic PI growth in the inflow conduit. The PI from collagen types I and IV with circumferentially oriented alpha-smooth muscle cell actin-positive cells was anchored to the outflow conduits.

CONCLUSIONS

The observations, which have to be confirmed by a more extensive study on a larger number of specimens, suggest the role of the biomaterial itself, as well as the configuration, physical characteristics, and rheology in the conduit. They also suggest that thromboembolic complications of LVAS may eventually be related to this host tissue response.

Inflammatory response to cardiopulmonary bypass using two different types of heparin-coated extracorporeal circuits

Previous reports have highlighted the disparity in biocompatibility of two differently engineered heparin coatings during the cardiopulmonary bypass (CPB) procedure. The aim of this prospective study was to evaluate the impact of the difference in haemocompatibility provided by either the Duraflo II equipment or the Carmeda equipment in the terminal inflammatory response observed after coronary artery surgery. Thirty patients were randomly allocated to two groups to be operated on using either Duraflo II equipment (group I) or Carmeda equipment (group 2) for extracorporeal circulation (ECC). Initial inflammatory response was assessed by terminal complement complex activation (SC5b-9). The late inflammatory response observed in the postoperative period was assessed by measuring cytokine production (tumour factor necrosis (TNF alpha), interleukin IL-6, interleukin IL-8) and circulating concentrations of adhesion molecules (ELAM-1, ICAM-1). The release of SC5b-9 after CPB and after protamine administration was lower in group 2 than in group 1 (p = 0.0002 and p = 0.006, respectively). A significant production of cytokines was detected in both groups with peak values observed within the time range of 4-6 h after the start of CPB.

External biodegradable supporting conduit protects endothelium in vein graft in arterial interposition

The prevention of circumferential distension could reduce structural damage in arteriovenous grafts. We studied the effect of an external biodegradable supporting conduit on the endothelium and extracellular matrix in vein graft in a pig model. Cephalic vein control grafts (Group I) and jugular veins wrapped in a vicryl mesh tube (I.D. 4 mm) (Group II) were implanted into autologous carotid arteries (n = 14). The grafts were explanted after 1 and 24 hours and at 1 and 3 weeks and evaluated by ELISA for endothelial DNA synthesis and by immunohistoenzymic assays for cells and extracellular matrix. In group I an initial loss of endothelial and smooth muscle cells along with elastin breakdown was followed by an impaired endothelial regeneration and significant graft wall thickening. The elastic tissue was replaced by collagen type I and chondroitin sulfate accumulations, which included a disarray of alpha-smooth muscle actin positive cells. The endothelium was preserved in group II. After 3 weeks the circumferential elastin layers were densified, distended and separated from the endothelium by a neointimal growth of irregular thickness. Biodegradable perivenous conduit minimized endothelial injury and allowed the partial preservation of elastin fibers and smooth muscle cells in the arteriovenous graft. It did not however, prevent myofibroblastic cell proliferation and triggered a macrophagic reaction.

Immunoglobulins and complement deposits in mitroflow pericardial bioprosthetic heart valves--a contributing factor to structural deterioration

BACKGROUND AND AIMS OF THE STUDY

Twenty-two bovine pericardial Mitroflow prostheses were explanted after 73-114 months from either the aortic or mitral position because of clinical failure. All the samples exhibited cuspal tears and foldings. Eleven prostheses were calcified. The aim was to study biological factors involved in the structural deterioration.

METHODS

Histologic and biochemical assays were carried out on the deteriorated, non-calcified and on the calcified leaflets. Labelled antibodies and avidinbiotinyilated peroxydase complex were used to detect plasma proteins and cells in the cusps.

RESULTS

Fibrin covered the cuspal surface and accumulated in the deep disrupted layers (19/22). Scattered fibronectin filaments were seen across the transversal sections (20/22). IgG, complement fractions C1q, C3, C4 (20/22), macrophages (sixteen) and cells containing granulocyte elastase were revealed in the altered matrix. These plasma proteins and cells were detected in the disintegrated matrix of non-calcified and of calcified leaflets. IgA was present in amorphous cuspal thickenings with lipid infiltration (12/22). Western blot analysis of the PBS-2% SDS extracts from the leaflets indicated the breakdown of fibrinogen/fibrin, fibronectin and of complement proteins C3, C4 and C5.

CONCLUSIONS

The results suggest the activation of the complement by the non-hemocompatible, chemically processed bovine pericardium. The bioactive peptides generated in this process can stimulate monocyte migration, phagocytosis and exocytosis of proteases able to degrade the glutaraldehyde cross-linked macromolecular matrix. These biological factors can contribute, together with the mechanical stress, to the structural deterioration of the bioprosthesis.

Complement activation is involved in the structural deterioration of bovine pericardial bioprosthetic heart valves

Disintegrated collagen fibers surrounded with protein deposits are a morphologic feature in torn, folded, and disrupted cusps of pericardial prostheses explanted for clinical dysfunction. New technologies for valve bioprostheses with improved durability require further investigation of molecular mechanisms initiating the deterioration of bioprosthetic valves. The authors' aim was to obtain experimental evidence of biologic factors contributing to the degradation of the bioprosthetic matrix. Clinically failed Mitroflow (22), Hancock (3), Ionescu-Shiley (2), and Sorin (1) valves were explanted after 69-170 months. Non calcific deterioration of the prosthetic matrix was studied with labeled antibodies to plasma proteins and cells. IgG, and complement proteins C1q, C3, and C4 were accumulated close to dissociated collagen bundles (26/28) throughout the prostheses. Fibrin was identified on the cuspal surface and in the deep disrupted areas. The fibrin peptides and proteolytic breakdown products of the complement components, the latter consistent with complement activation and chemotaxis for monocytes, were shown by immunoenzymic assay on Western blots from the valve extracts. The complement activation triggered by the IgG aggregates generates bioactive peptide signals that can activate macrophages (22/28) and neutrophil granulocyte elastase (22/24) able to cooperate with the mechanical stress in the breakdown of the chemically processed, non hemocompatible, and non-self macromolecular matrix.

The superiority of hollow fiber membrane over bubble oxygenator in a perfusion circuit for the evaluation of small caliber endothelialized arterial prostheses

A perfusion circuit was constructed from a pneumatic ventricular assist device, 2 compliance chambers, 4 small-diameter silicone tubes (ID 4 mm) simulating shear inducing vascular prostheses, and an oxygenator with a heat exchanger. A bubble oxygenator (in a BO circuit) and a hollow fiber membrane oxygenator (in an MO circuit) were studied. The circuits were perfused with 30% human serum containing culture medium for 7 days at 37 degrees C. The pH, Po2, PCo2, Na+, K+, Ca2+, Cl, glucose, and total protein concentrations remained the same in BO and MO circuits during the 7 days of perfusion. The differences between the values measured in the perfusion medium and in the medium maintained in the static conditions of cell culture were not significant. In the BO circuit, the amount of cholesterol and triglyceride concentrations decreased whereas the relative amounts of albumin, alpha 1, alpha 2, beta, and gamma globulins remained stable in the perfusion medium. The medium from the BO circuit did not promote the proliferation of cultured human saphenous vein endothelial cells. In the medium from the MO circuit, the cholesterol and triglyceride concentrations did not change with perfusion time; the proliferation rate and anticoagulant function of endothelial cells were maintained. The hollow fiber membrane oxygenator preserves the biological characteristics of the cell culture medium in a perfusion circuit. The MO circuit permits the performance of relevant studies on shear stress resistance and functional activity of human endothelial cells seeded onto vascular prostheses.

Effects of cryopreservation on the proliferation and anticoagulant activity of human saphenous vein endothelial cells

Human saphenous veins were cryopreserved in 4% human albumin and 10% dimethyl sulfoxide. The effect of cryopreservation on endothelial cells was studied in terms of the anticoagulant activity of thrombomodulin and in terms of cell proliferation. After storage for 2 weeks at -150 degrees C, 0.45 +/- 0.07 x 10(5) endothelial cells/cm2 were detected in cryopreserved veins and 1.03 +/- 0.04 x 10(5) endothelial cells/cm2 in fresh veins (p < 0.01). The thrombin-catalyzed activation of protein C decreased after cryopreservation, indicating altered thrombomodulin activity in the endothelial cells. On a cell number basis, the release of soluble thrombomodulin was three times higher from the cryopreserved endothelium than from the fresh endothelium (p < 0.05). The amount of spontaneous release of von Willebrand factor from the endothelial surface was not significantly different between fresh and cryopreserved veins. Endothelial cells were cultured from fresh veins and from their cryopreserved counterparts. On plating of endothelial cells in primary culture, the number of adhered cells was 0.9 +/- 0.09 x 10(3) cells/cm2 from fresh veins and 0.25 +/- 0.03 x 10(3) cells/cm2 from cryopreserved veins (p < 0.01). The positive immunohistochemical stain for von Willebrand factor indicated that the endothelial cell character was maintained after cryopreservation. The endothelial desquamation with loss of anticoagulant function and the slow proliferation of surviving cells in vitro suggest an impaired endothelial healing in vivo. The loss of anticoagulant activity complicates the problems of the exposure of thrombogenic subendothelial matrix to blood in implanted cryopreserved veins.

Congenital soft tissue dysplasias: a morphological and biochemical study

The term congenital soft tissue dysplasias (CSTDs) regroups some localized malformations of covering soft tissues in children, presenting as various clinical entities, either recognized as particular syndromes (e.g., Parkes-Weber, Klippel-Trenaunay, Proteus) or, most often, appearing less stereotyped (e.g., segmental hypertrophy or gigantism, lymphedema, angiodysplasia, phakomatosis), with a common histopathological lesion, the hamartoma. The aim of this paper is to report a morphological and biochemical study of the extracellular matrix of skin and subcutaneous tissue in children with CSTD. For every patient, pathological tissues were compared with contralateral, symmetrical tissues, taken as controls. In all CSTDs, pathological samples were characterized by an increase in water and total glycosaminoglycan (GAG) content with a decrease in collagen content. Other results lead the authors to distinguish two main entities, segmental dysplasia (SeD) and neuroectodermal dysplasia (NeD). Elastic fiber content was increased in SeD and decreased in NeD. Hyaluronic acid (HA) and dermatan sulfate (DS) were increased in NeD, whereas in SeD, HA was decreased with an increase in the DS/HA ratio. Cultured fibroblasts from dysplastic skin had slower proliferation in vitro than fibroblasts from control skin, whereas their biosynthetic activity concerning collagen and GAGs was greater. The difference in the composition of extracellular matrix supports the clinical classification of CSTDs in two main groups: segmental dysplasia with or without gigantism and neuroectodermal dysplasia (in von Recklinghausen's disease and nevi).

Deterioration of bioprosthetic heart valves

The aim of this study was to detect biologic factors in the structural deterioration of bioprosthetic heart valves. Prostheses were removed from patients after 4-8 years of implantation and submitted to biochemical and morphologic assays. Successive staining of biologic sections revealed colocalization of lipids and glycosaminoglycans underneath calcifications in the disintegrated extracellular matrix. On biochemical assays, the amidolysis of synthetic peptide substrates indicated thrombin, plasmin, and tissue plasminogen activator activities in the nonhemocompatible leaflets; 0.15 mol NaCl, 0.05 mol Tris, and 5 mmol CaCl2 extracts from the prostheses cleaved the peptide substrate for collagenase and lysed gelatin gels. Polyacrylamide gel electrophoresis in sodium dodecyl sulfate disclosed the presence of low molecular mass polypeptides in extracts of the deteriorated prostheses. The detection of plasmin and collagenolytic enzyme(s), and the known broad proteolytic activity of plasmin, may point to the role of activation of the fibrinolytic system in the proteolytic degradation of bioprosthetic valves.

Human vascular endothelial cells on expanded PTFE precoated with an engineered protein adhesion factor

To elucidate the role of the molecular structure of adhesive proteins in an endothelialization of synthetic vascular prosthesis in vitro, a recombinant fibronectin-like engineered adhesion factor (FP) constructed from the specific Arg-Gly-Asp cell adhesion repeats was assayed as adhesive substrate to culture human saphenous vein endothelial cells on ePTFE. ePTFE samples (1 cm2) inserted into cell culture chambers were coated by incubation with increasing amounts of FP (up to 100 micrograms/cm2) prior to cell seeding. At 24 hours after low density cell seeding and 20 micrograms/ml/cm2 FP concentration, the number of adhered cells reached a plateau and the adhered cells did not proliferate up to 6 days of culture. At 24 hours after high density seeding (10(5) cells/cm2), the number of adhered cells was significantly higher on ePTFE with preadsorbed FP than on fibronectin coated PTFE. About 55% of the initially adhered cells survived up to 7 days on FP, whereas cell debris and free nuclei were predominant on fibronectin coated PTFE. In the investigated model the engineered RGD polymer potentialized a short-term adhesion of vascular endothelial cells to PTFE, nevertheless it did not ensure proliferation and long-term survival of these cells.

Accumulation of heparan sulfate in the culture of human melanoma cells with different metastatic ability

Glycosaminoglycans were metabolically labeled in subconfluent cultures of highly metastatic 7Gp122 and poorly metastatic IC8 variants and of the low metastatic parental M4Be human melanoma cell line. Proteoglycans were separated by DEAE Trisacryl chromatography from the culture medium, from the heparin extract of the cell layer and from the heparin-extracted cell residue lyzed with detergents. Glycosaminoglycans were released from the proteoglycans by reductive alkaline hydrolysis and heparan sulfate (HS) was detected by deaminative cleavage with nitrous acid. Expressed on cell protein basis, the labeled HS content in the medium and in the cell layer decreased with increasing metastatic ability. The extraction of HS with heparin from the 7Gp122 cells indicated that this variant was enriched in (polypeptide bound) HS non inserted into the plasma membrane, compared with the low metastatic IC8 and M4Be cells. The HS fraction in heparin extract and in the heparin-extracted cell residue exhibited molecular mass heterogeneity on gel permeation chromatography and it contained HS fragments. Scission with nitrous acid followed by molecular sieve chromatography of the degradation products indicated that the tetra- and disaccharide repeats separated by the N-sulfated glucosamine residue were present in about equal amounts and constituted 60% of the HS chains in the IC8 and M4Be cells. HS from 7Gp122, IC8 and M4Be cells did not bind antithrombin III with high affinity but it was capable of binding bFGF in in vitro assay.

Stimulation of cell proliferation by hyaluronidase during in vitro aging of human skin fibroblasts

The effect of the degradation of extracellular hyaluronan on the proliferation of human skin fibroblasts in serial cultures during in vitro aging was investigated. Human skin fibroblasts at different time intervals from 3rd to 36th passages were exposed after plating to bovine testicular hyaluronidase. The enzyme treatment resulted in an increase in cell proliferation (cell number vs. time) as compared to the untreated control fibroblasts. The effect was dose dependent, reversible, and was independent of the type of the glycosidic linkage cleaved in hyaluronan. The increased proliferation was observed at all passages when untreated cells underwent mitosis. The degradation of hyaluronan induced cell proliferation up to the presenescent phase. Depletion of hyaluronan did not induce proliferation of postmitotic fibroblasts. The incorporation of 3H-glucosamine into hyaluronan decreased with increasing cell passages (increase of the number of population doublings). Twenty-fourth passage fibroblasts accumulated about two time less hyaluronan in the medium than ninth passage cultures. Following hyaluronidase treatment, the amount of newly synthesized, labeled hyaluronan increased in the medium. Accordingly, the fibroblasts restored the degraded hyaluronan even in the declining phase of proliferation (phase III according to Hayflick).

Increased synthesis of extracellular spleen glycosaminoglycans in an experimental myeloproliferative syndrome

The changes occurring in the hematopoietic extracellular matrix in an experimental myeloproliferative syndrome were explored by comparing the glycosaminoglycan (GAG) composition of normal mouse spleens and spleens infected with myeloproliferative sarcoma virus (MPSV). Large quantities of hyaluronate and of sulfated GAGs accumulated in the extracellular matrix of infected spleens, as shown by histoimmunoassay and alcian blue staining, respectively. The splenic GAGs were either labeled with 35S-sulfate injected in vivo or unlabeled. The spleens were fractionated to separate hematopoietic cells from the stromal component containing extracellular matrix material and fibroblasts, and the GAGs were extracted from each fraction. Specific degradative treatments and electrophoresis indicated that sulfated GAGs were mostly chondroitin sulfate and heparan sulfate. Three hours after in vivo injection of 35S-sulfate, the amount of 35S-GAGs was increased approximately fivefold per mg stromal proteins. The bulk of these 35S-GAGs (70%) was recovered in the stromal fraction. The higher amount of sulfated GAGs in leukemic spleen was due both to the presence of more producer cells (infected fibroblasts and hematopoietic cells) and to a stimulation of GAG synthesis per cell, as evidenced 35S-labeling in in vitro experiments. Chondroitin sulfate was the main sulfated GAG present in the culture medium of both hematopoietic and fibroblastic cells and in the pericellular material released by trypsin from fibroblastic cells. High amounts of chondroitin sulfate, which has a possible role in the detachment of hematopoietic cells from the stromal cells, may favour the release of hematopoietic cells from the spleen into the peripheral blood. Heparan sulfate was produced by fibroblastic cells and it was principally present in their pericellular material. Considering the capacity of heparan sulfate to retain cytokines, as demonstrated by others in vitro, large amounts of heparan sulfate may result in the retention of large amounts of the cytokines, which production is enhanced in the infected spleen. This phenomenon may contribute to promote the hematopoietic stem cell proliferation characteristic of the MPSV-induced myeloproliferative disease.

Differential expression of proteoglycans on the surface of human melanoma cells characterized by altered experimental metastatic potential

Heparan sulphate (HS) and chondroitin sulphate (CS) proteoglycans (PGs) frequently have opposite biologic functions in cell-matrix adhesion as well as in the regulation of cell proliferation. Data revealed that sulphated glycosaminoglycans (sGAGs) (sugar chains of PGs) are differently expressed in tumor cells characterized by different metastatic potential; the more metastatic cells contain a higher HS/CS ratio. As the proliferative capacity of tumor cells is also frequently altered in parallel with their metastatic potential, it was not clear whether observed PG alterations reflect changes in cell proliferation or metastatic potential. The cell-associated PG expression and sGAG biosynthesis was studied in tumor cells of human melanoma lines characterized by different experimental metastatic potential to the mouse liver but similar in vitro/in vivo proliferation rates. Using antibodies against PGs we found different expression of PG epitopes in melanoma lines, except from the melanoma antigen. Unlike the low CSPG (melCSPG) metastatic melanoma cells, the cell line with high metastatic capacity contained a higher proportion of positive cells for surface-HSPG without the coexpression of certain cartilage-type CSPG epitopes (recognized by MAb HSFPG 529) as well as by an increased pericellular HS/CS ratio due to intracellular accumulation/retention of CS. Immunocytochemistry of adherent cells revealed HSPGs at substrate-attached membrane areas only in cases of highly metastatic melanoma cells. These data further support our view that the absolute or relative dominance of HSPGs over CSPGs at the cell surface of metastatic tumor cells can be considered a marker of a more metastatic phenotype.

N-oleoyl heparin inhibits the amidolytic activity of plasmin and urokinase

N-desulphated heparin, partially N-acylated on average with three oleoyl chains per molecule, inhibits the amidolytic activity of plasmin (IC50 16 nM) and urokinase (IC50 10mM) when assayed on N-p-tosyl-Gly-Pro-Lys-4-nitroanilide and benzoyl-Ala-Gly-Arg-4-nitroanilide substrates respectively. N-desulphated heparin is not inhibitory. This effect requires the covalent binding of oleoyl residues to heparin and it decreases with increasing concentration of Tris-HCl and non-ionic detergents.

Comparative study of the precipitation of low density lipoproteins by aortic proteodermatan sulphate and heparin

The aortic proteoglycans and heparin were shown to form insoluble complexes with human low density lipoproteins (LDL). The effect of temperature, polyethylene glycol and ionic strength on the formation of complexes between porcine aortic proteodermatan sulphate (PDS) and LDL has been studied by laser nephelometry and comparisons made with heparin LDL complexes. Turbidity was a nonlinear function of the quantity of LDL precipitated by PDS. The turbidity of aggregates was constant at temperatures between 2 degrees C and 30 degrees C but increased with temperature above 30 degrees C up to 50 degrees C. The formation of insoluble complexes decreased rapidly with increasing NaCl concentration. Polyethylene glycol enhanced the turbidity at 20 degrees C but not at 37 degrees C. It also increased the resistance of complexes to dissociation by increasing ionic strength. The turbidity of heparin--LDL complexes was linearly correlated with the quantity of precipitated LDL. The heparin-LDL aggregates were less sensitive to modification of temperature and ionic strength than the PDS-LDL aggregates. These results suggest that ionic interactions are weaker in PDS-LDL complexes than in the heparin-LDL complexes. Non-coulombic interactions and/or temperature dependent conformational changes may be involved in the stabilization of supramolecular PDS-LDL aggregates. No such interactions or changes appear to be involved in complex formation between heparin and LDL.

Hyaluronate-binding proteins in weakly and highly metastatic variants of rat rhabdomyosarcoma cells

Weakly (RMS8) and highly (RMS0) metastatic rat rhabdomyosarcoma cells were assayed for their interaction with hyaluronate. The cells in subconfluent cultures were incubated with 35S methionine, the cells were fractionated and the labelled proteins were separated by affinity chromatography on hyaluronate-Sepharose and by HPLC. The RMS8 cells expressed about twice the amount of labelled hyaluronate-binding proteins seen in the RMS0 cells. The molecular sizes of the main hyaluronate-binding proteins were similar in both cell types. Unlike the RMS0 cells, the RMS8 cells took up exogenous, radioactively labelled hyaluronate at 4 degrees C in a saturable and specific way with high affinity. Cells were also incubated with 3H glucosamine. The isolation of the glycosaminoglycans from these cultures by ion-exchange chromatography indicated that the RMS8 cells retained more endogenous 3H hyaluronate in their pericellular domain than did the RMS0 cells. The attachment of trypsinized cells could be inhibited with exogenous hyaluronate, indicating that the proteins with affinity for hyaluronate may act as hyaluronate-binding sites on these cells.

Effect of testicular hyaluronidase on hyaluronate synthesis by human skin fibroblasts in culture

The effect of hyaluronidase treatment on the incorporation of [3H]glucosamine into hyaluronate in human skin fibroblast cultures was investigated. Fourth passage cells in confluent cultures were treated with hyaluronidase from bovine tests, Streptomyces and leech in Dulbecco's minimum essential medium in the presence of 3% fetal calf serum. The medium was removed from the control (non-treated) and the treated cultures and the washed cell layers were incubated with [3H]glucosamine and [35S]sulfate. [3H]Hyaluronate was separated by DEAE Trisacyl chromatography and identified by specific enzymic assays. Hyaluronidase treatment induced an increase in the amount of labelled hyaluronate secreted into the medium and into the pericellular compartment. This amount reached a plateau with increasing enzyme concentration and with the time of treatment. Oligosaccharides derived from hyaluronate did not produce this effect. The maximal increase was about 3-fold, and was not inhibited by exogenous hyaluronate (25-100 micrograms/ml) or by oligosaccharides from hyaluronate. Cycloheximide (0.03 mM) inhibited hyaluronate synthesis by 18% or less in the control cells and by 50% in the hyaluronidase-pretreated fibroblasts. No significant difference was found in the hyaluronate synthase activity between control and treated cells, at 60 min following treatment, indicating the reversibility of the effect. The persistence of the stimulation required the presence of hyaluronidase. The treatment of cells with specific hyaluronidases (from Streptomyces and leech) or with testicular hyaluronidase did not modify the labelling of the sulfated glycosaminoglycans. The incorporation kinetics of the [3H]glucosamine into labeled hyaluronate and the increased amount of non-labelled hyaluronate determined by radiometric assay indicated a specific stimulation of hyaluronate synthesis in the hyaluronidase-pretreated fibroblast cultures.

Biochemical characterization of elastin in neointimal hyperplasia of rabbit aorta

Elastin synthesized in response to vascular injury was characterized in terms of its amino acid composition, the biosynthetic labeling of the desmosines and of the heat coacervable polypeptides present in the 2 M urea extract. Neointimal hyperplasia of the chronic variety was induced in rabbit aorta by superficial mechanical lesions. At 4 months following injury the reendothelialized neointimal thickening and the media were excised. Aliquot samples were incubated with [3H] lysine, extracted with 2 M urea, 0.1 M Tris, pH 7.4 and hydrolysed with collagenase. In the residue of the digests the [3H] desmosines were quantified after electrophoretic separation. Elastin was purified from the nonlabeled aliquots of the media and neointimal hyperplasia. It accounted for 60% and 25% of the dry weight of the media and the neointima respectively. Elastin isolated from the media and the neointima had essentially the same amino acid composition. The incorporation of [3H] lysine into desmosines and into coacervable polypeptides indicated that the synthesis of crosslinked elastin is still active in the hyperplasia at 4 months following injury.

Solubilization and degradation of extracellular matrix by various metastatic cell lines derived from a rat rhabdomyosarcoma

Examination by use of WAG syngeneic female rats was made on 4 rat rhabdomyosarcoma sublines expressing different metastatic potentials for their abilities to degrade proteoglycans and glycoproteins of the extracellular matrix (ECM), deposited by corneal endothelial cells and metabolically labeled with [3H]glycosamine and [35S]sulfate. Of the label incorporated in ECM, 10-20% was released in the culture medium in 3 days by the cell lines studied. The proteoglycans, glycosaminoglycans, and glycoproteins released by the cells from ECM were separated and partially characterized. Most of the ECM glycoproteins were recovered in the region of 200,000 (200K) on gel chromatography. Glycopeptides of 10K-20K apparent molecular weight were minor components. The glycosaminoglycan chains of the proteoheparan sulfate were partially hydrolyzed to 20K fragments. Tumor cells increased also the solubilization of the nondegraded matrix macromolecules. About 5-8% of the radioactivity of the ECM remained associated with the tumor cells detached from the ECM. ECM degrading activity of the sublines did not correlate with their ability to colonize the lungs after iv injection but did correlate with their ability to metastasize to the lungs from the primary subcutaneous site.

Proteoglycans from pig aorta. Comparative study of their interactions with lipoproteins

Different proteoglycans (PGs) were isolated from pig aorta for aggregation studies with hyaluronic acid and human low-density lipoproteins (LDL). Extraction of the intima-media with 4M-guanidinium chloride and digestion of the residue with collagenase solubilized 91% of aortic hexuronic acid content. From the guanidinium chloride extract two PGs were isolated by ion-exchange and gel-permeation chromatography: proteochondroitin sulphate (PGI) with a protein-core apparent Mr of 250 000 and proteodermatan-chondroitin sulphate (PGII) with a protein-core apparent Mr of 55 000. Only PGI forms high-Mr aggregates with hyaluronic acid. From the collagenase digest two other PGs were isolated: proteoheparan sulphate and proteochondroitin sulphate (PGIII and PGIV respectively). PGIV had a smaller hydrodynamic size than PGI. PGI and PGII formed insoluble complexes with human LDL in the presence of Ca2+. PGIII or PGIV did not form precipitates with the LDL. PGI and PGII, but neither PGIII nor PGIV, were bound to LDL-Sepharose. The main peaks of PGI and PGII were eluted from LDL-Sepharose with 60 mM- and 90 mM-NaCl respectively. The results indicate that aortic PGs have different interacting potentials with lipoproteins, depending on their Mr and their glycosaminoglycan composition.

Biosynthesis of hyaluronic acid, heparan sulfate and structural glycoproteins in hamster lung explants during elastase induced emphysema

Hyaluronic acid (HA), heparan sulfate (HS) and structural glycoproteins (SGP) were investigated in explant cultures of hamster lungs by studying incorporation of 14C-glucosamine (14C GlcN) on the first and on the 24th day after intratracheal administration of pancreatic elastase. The different 14C radiolabeled macromolecules were extracted sequentially by 0.4 M guanidinium chloride (0.4 M GUA), 4 M GUA and collagenase digestion. At one day following elastase injury, a 4.2 fold increase of 14C GlcN incorporation into HA released in 0.4 M GUA extract and a 2.6 fold increase into HS released in the collagenase digests were observed compared to control tissues; at 24 days, the increased 14C GlcN incorporation into HA and HS persist but to a lesser extent. Polyacrylamide gel electrophoresis and isoelectric focusing carried out on 4 M GUA extracts, demonstrated identical quantitative and qualitative distribution of 14C GlcN between the major SGP (140 and 110 K with pI 7.8 and 4.5 respectively) in the normal and the experimental groups. These results indicate that pulmonary SGP biosynthesis is not modified at one and 24 days after elastase injury, whereas HA and HS biosynthesis are consistently increased. These results suggest a specific role of these macromolecules in emphysematous injury of the lung.

The effect of procyanidolic oligomers on the composition of normal and hypercholesterolemic rabbit aortas

Rabbits were fed with normal (group 1 and 2) and cholesterol rich diets (group 3 and 4) concomitantly to a daily peroral administration of 50 mg/kg procyanidolic oligomers (PCO) to groups 2 and 4. After 10 weeks, the cholesterol content of the blood serum and the excised aortic intima-media were significantly higher in groups 3 and 4 than in groups 1 and 2. The DNA, hydroxyproline, uronic acid contents were similar in aortic dry weight basis in all four groups. The intima-media samples were extracted successively with 0.15 M NaCl, 0.02 M sodium phosphate pH 7.4 (NaCl extract) and with 4 M guanidinium chloride, 0.05 M sodium acetate pH 5.8 prior (G1 extract) and following (G2 extract) hydrolysis of the collagen with collagenase. The cholesterol contents of G1 extracts were higher in groups 2 and 4 than in groups 1 and 3. The cholesterol content of aortic elastin increased with cholesterol feeding (group 3). With simultaneous administration of cholesterol and PCO the cholesterol content of aortic elastin in group 4 was significantly lower than in group 3. The uronic acid contents increased in G1 extracts and in the collagenase digest with PCO treatment of both normal and hypercholesterolemic rabbits. The ratio of dermatan-sulphate to chondroitin-sulphate decreased with hypercholesterolemia (group 3) and with PCO (group 2 and 4). The parallelism between increased cholesterol and uronic acid contents and modified glycosaminoglycan composition in G1 extract, indicate that the interaction of cholesterol with macromolecules of the aorta can be modulated by PCO. This drug modifies the extractibility of aortic cholesterol and glycosaminoglycans and reduces the association of cholesterol to elastin.

Vascular substitute from human placental arteries: glycosaminoglycan and elastin synthesis in the neo-intimal hyperplasia

Heparinized human placental arteries (internal diameter less than or equal to 1 mm) were cross-linked with glutaraldehyde and implanted in infrarenal aortas in rats (n = 78). At three months and one year following aortic replacement, the neo-intimal hyperplasia covering the patent conduits and the host intima media were excised. Glycosaminoglycans (GAGs) and elastin were metabolically labelled in vitro with radioactive glucosamine and valine, respectively. The incorporation of 3H glucosamine into GAGs decreased sixfold in both neo-intima and host intima media from three months to one year. At three months, the 3H label of hyaluronic acid accounted for 66 per cent and 43 per cent of the 3H GAGs in the neo-intima and host aorta, respectively. At one year, 55 per cent of the 3H GAG label were identified as 3H heparan sulphate in the neo-intima and host intima media. From three months to one year, the ratio of chondroitin 4 sulphate (CS 4) to chondroitin 6 sulphate (CS 6) decreased from 6 to 1.5 in the neo-intima, whilst the ratio of CS 4 to CS 6 (0.6) was constant in the host aorta during the experimental period. At one year, the neo-intima contained elastin. The radioactive incorporation pattern of GAGs and the biosynthetic label of valylproline dipeptides indicated a decrease in biosynthetic activity in neo-intimal and the host aortic cells with progressing time in vivo.

[Experimental study of a biological micro-arterial prosthesis]

An arterial prosthesis prepared from human placental arteries, diameter 1.0 mm, length 20 mm, was evaluated after implantation into the infrarenal region of the aorta of the rat. The permeability rate after one year (70%) compares favorably with results after fresh arterial autografts. Histology showed that the prosthesis acted as a matrix colonizable by the tissues of the recipient. The internal surface of the tube was covered by a tissular layer in which fibrillary elements suggestive of elastic fibers were developing.

Structural glycoproteins from rabbit aortic media

Rabbit aortic intima-media fragments were incubated with [14C]mannose and [3H]fucose for 6 h to detect glycoproteins synthesized in situ. The radioactively labelled and the non-labelled samples were extracted with 0.2 mM-CaCl2/0.5 mM-dithiothreitol/0.5 mM-ATP and chloroform/methanol/water (4:4:1, by vol.). The delipidated residue was extracted with 5 M-guanidinium chloride/0.05 M-dithiothreitol/0.1 M-Tris/0.4% Na2EDTA, pH 7.5, before (extract 1) and after hydrolysis with collagenase (extract 2). The proteins in extracts 1 and 2 were S-carboxamidomethylated and separated by molecular-sieve chromatography, polyacrylamide-gel electrophoresis and isoelectric focusing in sucrose gradients in urea. The apparent molecular weights of glycoproteins were 36 000 (glycoprotein I) from extract 1, 50 000 (glycoprotein II) and 130 000 (glycoprotein III) from extract 2. The molecular weights of the non-labelled and radioactively labelled glycoproteins were identical. Glycoproteins I, II and III contain large amounts of polar amino acids and methionine. They contain neither hydroxyproline nor 3-methylhistidine. A hydroxyproline-containing component of 160 000-apparent-mol.wt. relatively rich in polar amino acids and labelled with incorporated sugars was isolated from extract 1. The incorporation in vitro of radioactive sugars into glycoproteins I, II, III and collagenous glycoproteins indicates that they are synthesized in the surviving aorta by the smooth-muscle cells.

Healing of biodegradable vascular prosthesis. Incorporation of 3H-valine into proteins in the subendothelial scar and host intima-media of rat aorta

Heparin treated and aldehyde crosslinked rat aorta segments were implanted in infrarenal aorta of homologous rats. One year following aortic replacement, the subendothelial scar and the prosthetic remnants were excised. The scar and the host intima-media were incubated with 3H-valine for 4 h and extracted with 5 M guanidinium chloride--0.05 M dithiothreitol--0.1 M Tris--0.1% EDTANa2 at pH 7.5 prior (Extract 1) and following (Extract 2) hydrolysis of collagen. The radioactivity of extract 1 accounted for approximately 80% of the total label incorporated in the scar and host intima-media. The 3H-label of extract 1 adjusted for the tissue collagen content was about twenty times higher in the scar than in the host aorta. The major 3H protein peaks from Extract 1 of scar and host aorta were of 130 K, 100 K and 70 K apparent molecular weight, based on polyacrylamide gel electrophoresis in SDS. Hydrolysis with 2N KOH of the extraction residue from the host aorta and scar yielded 3H-val-pro dipeptides and hydrolysis with 6N HCl desmosines. The incorporation pattern of 3H-valine into proteins and the presence of elastin synthesized de novo in the scar replacing the prosthesis indicate macromolecular repair of the host aortic wall.

Isolation and characterization of lung connective-tissue glycoproteins

1. Glycoproteins of hamster, rat and baboon lung parenchyma were investigated by using [14C]glucosamine incorporation in vitro followed by sequential extraction of the macromolecular components and characterization of the glycoproteins in the extracts. 2. Slices of lung parenchyma maintained in vitro incorporated [U-14C]glucosamine linearly with time into non-diffusible macromolecules for up to 5h. All the macromolecule-associated 14C label was present as [14C]glucosamine. 3. These 14C-labelled macromolecules were extracted from previously delipidated and salt-extracted lung by 5M-guanidinium chloride in the presence of dithiothreitol and proteinase inhibitors before (extract A1) and after (extract A2) hydrolysis of the collagen by collagenase. The [14C]glucosamine-labelled glycoproteins in extracts A1 and A2 contained 55 and 5% respectively of the total [14C]glucosamine incorporated in the lung of all three species studied. 4. The [14C]glucosamine-labelled glycoproteins were analysed by gel-filtration chromatography, sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and isoelectric focusing. The major [14C]glucosamine-labelled glycoproteins of baboon lung parenchyma had apparent mol.wts. of about 400 000, 140 000 and 65 000 with isoelectric points respectively of 4.8, 5.4 and 5.4. The hamster lung glycoproteins with isoelectric points of 4.1 and 5.8 were devoid of hydroxyproline and contained galactose, mannose and N-acetylglucosamine. These experiments indicate that several distinct glycoproteins are synthesized in situ by the cells of pulmonary parenchyma and may well play a role in its structure and function.

Effect of lysosomotropic amine, chloroquine, on the radioactive incorporation pattern of glycosaminoglycans in human skin fibroblasts

Control and chloroquine treated fibroblast cultures were incubated with 14C-glucosamine. The cells were separated from the medium and the pericellular matrix. The S-carboxymethylproteins in the medium were hydrolysed with trypsin and pronase. The glycosaminoglycans were treated with hyaluronidase, chondroitin AB-lyase and chondroitin ABC-lyase. The macromolecular 14C label per cell in the medium was higher in the chloroquine treated cultures than in the controls. The incorporation of the 14C-hexosamines per cell into the pericellular and intracellular compartment was not modified. The increased 14C-label in the medium of fibroblast exposed to chloroquine accounted for the increased incorporation of the 14C precursor into chondroitin 4 and 6 sulfates and dermatan sulfate.

Partial characterization of peptide fragment purified by isoelectrofocusing after organo alkaline hydrolysis of bovine ligamentum nuchae elastin

Highly purified elastin from bovine ligamentum nuchae was submitted to partial alkaline hydrolysis (37 degree C, 72 H, 1 N KOH in 80 p. 100 aqueous ethanol). The non-coacervable fractions were submitted to isoelectrofocusing and five kappa-elastin fractions were obtained. The amino-acid compositions, the N-terminal amino-acids, the molecular weights and the thermolysin digests of each fraction were determined by various techniques. The average MW was about 14,500 (150 - 166 amino-acids). These results suggest that the distribution of cross-linking agents in fibrous elastin may not be uniform. The results also show that in certain cross-linked regions of similar molecular weight and size appearing to be composed of different polypeptides sequences containing different amounts of cross-links.

Biodegradable arterial prosthesis from rat aorta

The preparation and potential clinical use of biodegradable microarterial grafts from rat aorta were investigated. Trypsin treated arterial segments were coated with heparin or chondroitin sulfate to reduce thrombogenicity. The samples were crosslinked with formaldehyde vapors at 4 degrees C. 50 - 100 microgram glycosaminoglycans taken up per mg aorta dry weight were resistant to washing with water for 24 hrs. The covalent crosslinks introduced by formaldehyde and resistance of the grafts to proteolytic degradation. The treated grafts were implanted on 70 rats in an infrarenal aortic position. The permeability of the aldehyde crosslinked prosthesis after 21 days by patency test was lower than the patency ratio measured with fresh autologous grafts. The glycosaminoglycans associated with the prosthesis improve the patency of the crosslinked grafts by about 48%. The resistance to bacterial collagenase of the excised grafts decreased with progressing time of implantation. In the permeable prosthesis and in the contiguous aorta, elastolytic activity was demonstrated by radial diffusion in elastin-agar gels. The grafts removed after 21 days of implantation were surrounded with scar tissue. In contrast to fresh aorta, the macromolecular hydroxyprolin in the scar was readily solubilized with pepsin. The presence of the fragmented elastin and collagen fibers in the excised graft is in favour of their resorption "in vivo".