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PubMed1995

In vitro evaluation of the efficacy and biocompatibility of new, synthetic ABO immunoabsorbents.

Synthetic ABO immunoabsorbents (known as Synsorbs) were in use for several years to specifically eliminate ABO antibodies from the patient's circulation before ABO-incompatible organ or bone marrow transplantation. Because Synsorbs are no longer available, we have developed new ABO immunoabsorbents. These substances, termed BioSorbents A and B, respectively, consist of synthetic A or B trisaccharides covalently coupled to macroporous glass beads via polyacrylamide. Here we report the evaluation of BioSorbents in regard to efficacy, specificity, and biocompatibility. Using a closed-circuit in vitro system, representing a 1:10-1:20 scale as compared with the immunoabsorption procedure with an adult patient, blood group O plasma was run through columns filled with ethylene oxide-sterilized BioSorbent. Hemagglutination was reduced by 4 titer steps after absorption, and anti-A and/or anti-B IgM/G/A, as measured by ABO ELISA, dropped by 85% or more, while no nonspecific absorption of immunoglobulins occurred. No significant changes could be observed for complement (C3, C4, and total hemolytic complement of the classical pathway) or for coagulation parameters (fibrinogen, prothrombin time, activated partial thromboplastin time). As monitored by immunoblotting, neither factor XII nor high molecular weight kininogen was cleaved. In addition, a monocyte phagocytosis inhibition test provided evidence that no significant aggregation of IgG had occurred during absorption. We conclude that BioSorbents A and B are efficient, specific, and biocompatible with human plasma.

ABO Blood-Group System↗

PubMed2002

In-vivo biocompatibility evaluation of stents coated with a new biodegradable elastomeric and functional polymer.

BACKGROUND: In-stent restenosis may be prevented by impregnating an antiproliferative agent in a polymer from a stent platform. This approach requires both an antiproliferative agent effective in small doses and a biocompatible polymer. METHODS: A series of new biodegradable elastomeric poly(ester-amide)(co-PEA) polymers having functional carboxyl groups for drug conjugation were synthesized from non-toxic building blocks. The in-vivo biocompatibility was tested in porcine coronary arteries, by comparing the polymer-coated stents with bare metal stents in 10 pigs. RESULTS: All animals survived until sacrifice 28 days later and follow-up angiography prior to sacrifice revealed identical diameter stenosis (21 +/- 23%) in both groups. Histology confirmed similar injury scores (0.34 +/- 0.34 compared with 0.34 +/- 0.32), inflammatory reaction (1.18 +/- 0.38 compared with 1.11 +/- 0.32) and area stenosis (26 +/- 17% compared with 28 +/- 22%). CONCLUSIONS: This study suggests that the newly developed copoly(ester-amide) elastomers may be suitable for stent-based local drug delivery.

Absorbable Implants↗

PubMedDate not supplied

In vivo performance and biocompatibility of the MagScrew ventricular assist device.

Currently available ventricular assist devices (VADs) have limitations in long-term durability and blood compatibility. We evaluated a prototype of a pulsatile MagScrew VAD for in vivo hemodynamic performance and biocompatibility. The device is composed of an actuator, blood pump housing, diaphragm, pusher plate, and bioprosthetic valves. Its protein-coated ("biolized") blood-contacting surface inhibits clot formation. Forces between moving parts of the actuator are transmitted magnetically, eliminating a primary source of friction and wear. The pump fills passively and is highly preload sensitive. The device was implanted into three calves for 90, 10, and 57 days, respectively. No anticoagulants were given postoperatively. The device functioned without technical problems during the entire course of each experiment, with mean device flow ranging between 5.4 and 9.0 L/min. Autopsy of the first two calves revealed no sign of embolization and clean blood-contacting surfaces of the devices. The third experiment was complicated by a prosthetic valve endocarditis with infectious embolization, and a few small depositions were found in the pump. In conclusion, the MagScrew VAD has demonstrated a high level of performance and biocompatibility in three calves studied for 10-90 days. Vigorous development is in progress to bring this device to preclinical readiness and thus provide surgeons with the VAD of choice for permanent implantation.

Animals↗

PubMed2001

The biocompatibility, integrity, and positional stability of an injectable microstimulator for reanimation of the paralyzed larynx.

The biocompatibility, integrity, positional stability, and potential use of hermetically sealed injectable wireless micromachined microstimulators were investigated for reanimation of the paralyzed larynx. The device, consisting of silicon and glass, has been tested and proven to be biocompatible with no evidence of pathological tissue reaction or rejection up to one-year implantation in the rat dorsum and canine larynx. By one month, each unit was encapsulated by a thin membrane, which thickened to form a fibrous layer of less than 500 microm at 6-12 months. The microstimulators demonstrated long-term in vivo durability: the hermetic seal of only one in ten devices was breached. Once implanted, migration of the device varied from 0 to 3 cm, depending upon the extent of surgical dissection. No discernable migration was noted when the tissue dissection was minimal. Studies utilizing a modified device equipped with electrodes indicated that migration was nominal with sufficient positional stability to ensure activation of target muscles for glottis opening. This study supported the feasibility of using a microstimulator for reanimation of paralyzed laryngeal muscles that open the airway during breathing. This innovative approach to treatment would alleviate the need for a tracheotomy or surgical resection of the vocal fold.

Animals↗

PubMed2005

Evaluation of biocompatibility of mineral trioxide aggregate with an improved rabbit ear chamber.

In the present study, the biocompatibility of mineral trioxide aggregate (MTA) to the revascularization of the connective tissues was evaluated by using the improved rabbit ear chamber, in vivo. Twenty improved rabbit ear chamber was prepared from 12 male albino-rabbit by using a well through which a material could be introduced into the living vascular tissue. Ten chambers were provided for MTA, and the remaining 10 chambers were used for a calcium hydroxide-containing root canal sealer (Sealapex), as a comparator. A volume of about 1.5 mm(3) of the materials were inserted into the chamber and the interaction between the vascular tissue and materials was observed by using a biomicroscope immediately after application, at 1, 3, 5.5, 8, 24, 48, 72 h, and once a week up to 4 weeks. The results revealed that revascularization of connective tissue took place with complete recovery of microcirculation within 4 weeks in both MTA and Sealapex. However, the precipitate-barrier and brown zone around periphery of Sealapex was not observed in MTA treated samples. It can be concluded that MTA is biocompatible and does not produce any adverse site effect on microcirculation of the connective tissue.

Aluminum Compounds↗

PubMed2006

In vivo evaluation of the biocompatibility of three current bonding agents.

The aim of this in vivo study was to evaluate the biocompatibility of three current bonding agents and calcium hydroxide cement. Sixty polyethylene tubes filled with the following materials: Group 1: Prime & Bond NT (PB-Dentsply, US; Group 2: Bond 1 (BO-Jeneric/Pentron, US); Group 3: Optibond Solo (OP-Kerr, US); and Group 4 (control): calcium hydroxide cement - Dycal (CH-Dentsply, US) were implanted into the connective tissue of 30 rats. After 15, 30 and 60 days, the implants were excised and the animals sacrificed. The biopsies were immersed in Karnovsky (pH, 7.2) fixative solution for 48 hours, and processed using routine histological technique. Six-micron-thick sections were cut and stained with hematoxilin and eosin and Masson's trichome technique. Microscopic evaluation was used to compare the connective tissue reactions caused by the experimental and control materials adjacent to the tube opening. At 15 days, the experimental and control materials triggered a moderate to intense inflammatory response which gave rise to a thick capsule adjacent to the tube opening. With time, the inflammatory reaction decreased. At 60 days, the connective tissue adjacent to the bonding agents exhibited a persistent inflammatory response mediated by macrophages and giant cells which were engulfing displaced resin components. On the other hand, for the control group (calcium hydroxide) no inflammatory response associated with a thin capsule adjacent to the material was observed even at the 30-day period. The hard-setting calcium hydroxide cement allowed complete healing and was considered more biocompatible than the bonding agents.

Animals↗

PubMed1989

Biocompatibility of urinary catheters. Effect on complement activation.

The ability of 2 brands of urinary catheters to activate the complement system in vitro as a marker of biocompatibility was investigated. Pieces of a silicone/latex catheter and an all-silicone catheter were incubated in human serum. Complement activation was tested in 2 enzyme immunoassays, one evaluating C3 activation and the other the terminal complement complex (TCC) formation. The silicone/latex catheter caused considerably more complement activation in both assays than did the all-silicone one. The findings are in agreement with previous results of tissue toxicity tests. The methods presented may prove valuable for the practical purpose of testing the biocompatibility of urinary catheters.

Biocompatible Materials↗

PubMed1991

Activation of complement, kallikrein-kinin, fibrinolysis and coagulation systems by urinary catheters. Effect of time and temperature in biocompatibility studies.

Urethral strictures induced by the use of latex catheters and combined silicone/latex catheters following open-heart surgery have been reported. These strictures differ from the post-catheterisation type in affecting a greater length of urethra. Recently it was shown that complement was activated by catheters which cause inflammation, in contrast to clinically silent catheters. The present study was designed to investigate a possible association between catheter-induced inflammation and activation of another mediator of inflammation, the contact system. We also investigated various in vitro conditions to optimise biocompatibility studies. Our data indicate that both the complement and the kallikrein-kinin system are activated by potentially harmful silicone/latex catheters and may be involved in the pathophysiology of catheter-induced urethral strictures. In vitro biocompatibility tests may be performed at both 20 and 37 degrees C. Glass test tubes may be used for in vitro complement but not for kallikrein-kinin investigations.

Adult↗

PubMed2006

Biocompatible properties of surgical mesh using an animal model.

AIM: To study the biocompatibility of surgical meshes for use in pelvic reconstructive surgery using an animal model. METHODS: Eight different types of mesh: Atrium, Dexon, Gynemesh, IVS tape, Prolene, SPARC tape, TVT tape and Vypro II, were implanted into the abdominal walls of rats for 3 months' duration. Explanted meshes were assessed, using light microscopy, for parameters of rejection and incorporation. RESULTS: Type 1 (Atrium, Gynemesh, Prolene, SPARC and TVT) and type 3 (Vypro II, Dexon and IVS) meshes demonstrated different biocompatible properties. Inflammatory cellular response and fibrosis at the interface of mesh and host tissue was most marked with Vypro II and IVS. All type 1 meshes displayed similar cellular responses despite markedly different mesh architecture. CONCLUSIONS: The inflammatory response and fibrous reaction in the non-absorbable type 3 meshes tested (IVS and Vypro II) was more marked than the type 1 meshes. The increased inflammatory and fibrotic response may be because of the multifilamentous polypropylene components of these meshes. Material and filament composition of mesh is the main factor in determining cellular response.

Absorbable Implants↗

PubMed1987

Failure of platelet markers to evaluate membrane biocompatibility during a combined hemodialysis-hemoperfusion treatment.

Plasma levels of the platelet markers beta-thromboglobulin (beta-TG) and platelet factor 4 (PF4) are among the most sophisticated indexes of biocompatibility available to evaluate new members for hemodialysis. This investigation was designed to determine the extent of platelet activation by measuring the alpha-granule release products, beta-TG and PF4; anticoagulation and thrombogenesis by monitoring plasma heparin; and fibrinopeptide A (FPA) and thromboxane B2 (TX B2) levels during treatment with a combined hemodialysis-hemoperfusion system. Both in vivo and in vitro results showed that the platelet markers had a pattern different from that generally observed during treatment with hemodialysis alone. This is due to the avidity of charcoal for the markers studied, which therefore cannot be used to evaluate the biocompatibility of the system.

Biocompatible Materials↗

PubMed1992

Evaluation of two epoxy ether compounds for biocompatible potential.

Bovine arterial tissue exposed to two epoxy ether compounds (Denacol EX-313 and Denacol EX-810) was evaluated for its biocompatible potential by in vitro and in vivo test procedures. The battery of test procedures included percent Inhibition of Cell Growth, Medium Eluate Method (MEM), Agar Overlay (AO), Blood Compatibility, Acute Mouse Systemic Injection, Rabbit Intracutaneous Irritation, Rabbit Subcutaneous Implantation, Guinea Pig Maximization, and Ames Tests. The epoxy exposed tissue was found to be noncytotoxic, nonmutagenic, and biocompatible by the test methods employed. In addition, the maximum concentrations of the unreacted Denacol EX-313 and EX-810 solutions found to demonstrate noncytotoxic reactions by the MEM and AO procedures were identified as 55 and 60 ppm for the MEM and 150 and 200 ppm for the AO procedure, respectively. These studies suggest that Denacol EX-313 and EX-810 are acceptable solutions for the processing of implantable tissue provided the epoxy residuals remain below those levels found to be cytotoxic.

Animals↗

PubMed1993

Lipid apheresis by hemoperfusion: in vitro efficacy and ex vivo biocompatibility of a new low-density lipoprotein adsorber compatible with human whole blood.

To date, selective extracorporeal low-density lipoprotein (LDL) removal can only be performed from plasma; that is, a plasma-cell separation step using a centrifuge or a plasma membrane separator is necessary initially. This article characterizes a new polyacrylate-based LDL adsorber directly applicable to whole blood. In vitro single-pass hemoperfusion tests using pooled donor blood showed quantitative adsorption of atherogenic LDL-cholesterol (LDL-C) and complete recovery of protective high-density lipoprotein C. Fibrinogen, another independent risk factor of atherosclerosis, was also adsorbed to a lesser extent. Single-pass ex vivo biocompatibility using fresh donor blood on-line was excellent and resulted in minimal cell loss. Neither signs of hemolysis nor activation of monocytes (interleukin-1 production) were detected. Only slight activation of leukocytes (elastase release) and thrombocytes (platelet factor 4 secretion) as well as of coagulation (thrombin-antithrombin complex formation) and complement (C3a, C5a generation) was observed. Under the experimental conditions used, the optimal anticoagulation regimen was 0.5 IU heparin plus 0.375 mg citrate/ml blood. Priming the column with a buffer of pH 7.4 containing heparin, citrate, and Ca2+ is recommended. In conclusion, this new adsorber exhibited selective LDL-C adsorption in vitro combined with excellent ex vivo biocompatibility and thus holds great promise for a successful clinical application in a closed-loop system in patients.

Acrylic Resins↗

PubMed1995

Biocompatibility in hemodialysis: clinical relevance in 1995.

Hemodialysis therapy for end-stage renal disease is still empirical even after more than 30 years of experience. Although long-term survival can now be assured in selected patients, clinical results tend to be disappointing. Hemodialysis therapy needs to be improved. Zealots of the biocompatibility school believe that this improvement will come from reducing undesirable consequences of blood membrane interaction, particularly complement activation. However, there is controversy over the clinical meaningfulness of biocompatibility when exclusively related to blood membrane interactions. Another dimension needs to be added, namely ultrapure dialysate to avoid subclinical chronic effects of activation of the cytokine cascade by bacterial fragments present in dialysate. While the pathogenesis of acute anaphylactoid reactions are understood and largely preventable, the relation of the chronic syndromes such as amyloidosis to the use of a particular membrane remain unproven. Prospective studies that will occupy at least a decade will be necessary to decide these issues.

Bacterial Toxins↗

PubMed1995

A new model for evaluation of biocompatibility: combined determination of neoepitopes in blood and on artificial surfaces demonstrates reduced complement activation by immobilization of heparin.

An in vitro technique was developed for assessment of the biocompatibility of materials for use in clinical applications. Artificial materials were exposed to blood, and the resulting complement activation was quantified both in the plasma and on the material surface by enzyme immunoassays based on monoclonal antibodies specific for neoepitopes exposed in complement activation products. Several materials were evaluated, and the effect of surface modifications, including end-point immobilized heparin, was studied. The results revealed widely varying complement activation properties of the different materials and confirmed that heparin markedly improves biocompatibility. The present method is superior to analysis limited to either the fluid phase or solid phase since certain materials adsorb activation products (exemplified by Tecoflex) whereas others do not although activation was evident from fluid-phase assay (silicone). Furthermore, direct determination of activation-specific neoepitopes on the surface represents an improvement compared with previously described methods for detection of adsorbed components.

Biocompatible Materials↗

PubMed1996

Simple evaluation method of biocompatibility of artificial oxygenator hollow fiber.

We made miniature modules filled with artificial oxygenator hollow fibers and conducted a simple experiment to study the effect of different membrane structures on the blood. Three types of modules were made: one filled with polyolefin, one filled with polypropylene, and a blank module. The 3 modules were connected through 3 fine tubings to one needle so that the same blood that passed through the 3 modules could be analyzed simultaneously. Nonheparinized blood was continuously withdrawn from 6 healthy volunteers using a small pump and passed through the circuit by a single pass (10 ml/min, for 10 min). Platelet count, thrombin-antithrombin complex, and complement-3 were measured in the blood collected at 10 min from the outlet of each module. The results showed significantly better biocompatibility of polyolefin than polypropylene, which is attributable to the dense layer of the blood contact surface of polyolefin fibers. This method is useful in assessing biocompatibility of various hollow fibers in a simple and safe manner.

Analysis of Variance↗

PubMed1997

Hemodialysis urea rebound and membrane biocompatibility: accuracy of Kt/V estimations.

To date, the magnitude, causes, and factors that govern urea rebound are not clearly defined. This study was undertaken to determine the possible influence of the biocompatibility of dialyzer membrane on urea rebound and to assess the participation of rebound in the calculation of Kt/V-urea by different methods. Blood urea samples were obtained before, and at 2, 30, and 60 min posthemodialysis in 8 patients undergoing dialysis with 2 different membranes, Cuprophan and polyacrylonitrile (24 sessions with each membrane). Urea rebound was documented in all patients. The degree of rebound was large, 20%, and it was achieved within 30 min after the end of dialysis. Urea rebound was observed with both Cuprophan and polyacrylonitrile membranes, without significant differences. Kt/V-urea significantly decreased (p < 0.001) by all methods when urea rebound was incorporated. We conclude that urea rebound is clinically very important and is not influenced by the biocompatibility of the dialyzer membrane. This phenomenon must be taken into account in the calculation of Kt/V; otherwise, it might be overestimated.

Acrylic Resins↗

PubMed1997

Biocompatibility of heparin-coated circuits in pediatric cardiopulmonary bypass.

In this study, we evaluated the biocompatibility of heparin-coated circuits in pediatric cardiopulmonary bypass (CPB). Eight patients were divided into 2 groups: the control group (Group C) and heparin-coated group (Group H). In Group H, CPB circuits, including the arterial pump, oxygenator, and cannulas were heparin-coated. Before, during, and after CPB, blood samples were obtained to assess the platelet counts (Plat), alpha 2-plasmin plasminogen inhibitor complex (PIC), thrombin-antithrombin III complex (TAT), C3 activation products (C3a), interleukin (IL)-6, IL-8, and polymorphonuclear neutrophil leukocyte (PMN) elastase. There was no significant difference in Plat, PIC, or TAT between groups. Group H showed significantly low levels of C3a (during and after CPB), PMN elastase (during CPB), and IL-6 (after CPB). These data demonstrated that in pediatric CPB, heparin-coated CPB circuits reduced the activation of complements and the production of PMN elastase and IL-6, suggesting the superior biocompatibility of the heparin-coated circuits.

Anticoagulants↗

PubMed2005

Study on biocompatibility of complexes of collagen-chitosan-sodium hyaluronate and cornea.

In this study we investigated the biocompatibility of collagen-chitosan-sodium hyaluronate (Col-Chi-NaHA) complexes and cornea tissue, and the feasibility of Col-Chi-NaHA complexes as substrates for cultivating rabbit corneal cells. Different components of Col-Chi-NaHA complexes were prepared and tested. A circular complex film with a diameter of 6 mm was inserted into rabbit stomal pocket and traced for a period of 5 months. Clinical examination was made. Rabbit limbal corneal epithelial cells, corneal endothelial cells, and keratocytes were cultured primarily on complexes. Phase contrast microscope examination was made daily. Histological, immunohistochemical, and scanning electron microscopic examinations were carried out. The complexes of 20% collagen, 10% chitosan, and 0.5% sodium hyaluronate showed rather weak corneal edema and other responses. The degradation of materials was obvious after 5 months. Corneas were transparent and translucent. Cells seeded on Col-Chi-NaHA were allowed to proliferate and partly form confluent monolayer after 9 days in culture. Cultured cells were well attached to the complexes of 20% collagen, 10% chitosan, and 0.5% sodium hyaluronate, or 10% chitosan and 0.5% sodium hyaluronate. The results showed that Col-Chi-NaHA complexes had good biocompatibility with cornea. The complexes can degrade and be absorbed in cornea. Col-Chi-NaHA complex may be a suitable substrate for cultivating corneal cells and a feasible material as a scaffold of tissue-engineered cornea.

Animals↗