Cytotoxicity of Poly(Alkyl Cyanoacrylate) Nanoparticles

Although nanotoxicology has become a large research field, assessment of cytotoxicity is often reduced to analysis of one cell line only. Cytotoxicity of nanoparticles is complex and should, preferentially, be evaluated in several cell lines with different methods and on multiple nanoparticle batches. Here we report the toxicity of poly(alkyl cyanoacrylate) nanoparticles in 12 different cell lines after synthesizing and analyzing 19 different nanoparticle batches and report that large variations were obtained when using different cell lines or various toxicity assays. Surprisingly, we found that nanoparticles with intermediate degradation rates were less toxic than particles that were degraded faster or more slowly in a cell-free system. The toxicity did not vary significantly with either the three different combinations of polyethylene glycol surfactants or with particle size (range 100–200 nm). No acute pro- or anti-inflammatory activity on cells in whole blood was observed.

Comparison of 2-Ethyl-Cyanoacrylate and 2-Butyl-Cyanoacrylate for Use on the Calvaria of CD1 Mice

Short-chain cyanoacrylates (SCCA), such as ethyl-2-cyanoacrylate (KrazyGlue, Aron Alpha, Columbus, OH) are commonly used as commercial fast-acting glues. Although once used in clinical medicine as skin adhesives, these products caused tissue toxicity and thus their use in live tissue was discontinued. SCCA were replaced by longer-chain versions (LCCA), such as butyl-cyanoacrylate (Vetbond, 3M, St Paul, Minnesota), which were found to be less toxic than the short-chain formulations. Some researchers prefer to use SCCA due to the belief that they create a stronger bond than do the longer-chain counterparts. In survival surgeries, we compared the bone thickness, bone necrosis, fibrosis, inflammation, and bone regeneration in the calvaria of control (naïve), surgery-only, SCCA-treated, and LCCA-treated mice (n = 20 per group). At 1 and 14 d after surgery, all mice except those treated with SCCA showed statistically similar bone measurements to those of the naive control group. The SCCA group had significantly less bone regeneration than did all other groups. These results suggest that the application of SCCA causes bone damage resulting in the loss of bone regeneration. This finding may assist investigators in choosing a tissue glue for their studies and may support the IACUC in advocating the use of pharmaceutical-grade tissue glues.

Cytotoxicity and cellular uptake of newly synthesized fucoidan-coated nanoparticles

The aim was to synthesize and characterize fucoidan-coated poly(isobutylcyanoacrylate) nanoparticles. The nanoparticles were prepared by anionic emulsion polymerization (AEP) and by redox radical emulsion polymerization (RREP) of isobutylcyanoacrylate using fucoidan as a new coating material. The nanoparticles were characterized, and their cytotoxicity was evaluated in vitro on J774 macrophage and NIH-3T3 fibroblast cell lines. Cellular uptake of labeled nanoparticles was investigated by confocal fluorescence microscopy. Results showed that both methods were suitable to prepare stable formulations of fucoidan-coated PIBCA nanoparticles. Stable dispersions of nanoparticles were obtained by AEP with up to 100% fucoidan as coating material. By the RREP method, stable suspensions of nanoparticles were obtained with only up to 25% fucoidan in a blend of polysaccharide composed of dextran and fucoidan. The zeta potential of fucoidan-coated nanoparticles was decreased depending on the percentage of fucoidan. It reached the value of -44 mV for nanoparticles prepared by AEP with 100% of fucoidan. Nanoparticles made by AEP appeared more than four times more cytotoxic (IC(50) below 2 μg/mL) on macrophages J774 than nanoparticles made by RREP (IC(50) above 9 μg/mL). In contrast, no significant difference in cytotoxicity was highlighted by incubation of the nanoparticles with a fibroblast cell line. On fibroblasts, both types of nanoparticles showed similar cytotoxicity. Confocal fluorescence microscopy observations revealed that all types of nanoparticles were taken up by both cell lines. The distribution of the fluorescence in the cells varied greatly with the type of nanoparticles.

Enhancing the tolerance of poly(isobutylcyanoacrylate) nanoparticles with a modular surface design

Polymer nanoparticles are designed as nanovehicles to carry drugs in the body in a controlled manner increasing the concentration of the biologically active substance in the diseased organs and cells. The safety and biocompatibility of these nanosystems are those of the many properties that nanoparticles must meet to be used in vivo. Here we show that the cytotoxicity profile of poly(isobutylcyanoacrylate) (PIBCA) nanoparticles is affected by the way the nanosystems were produced and by the design of their surface. It was found that the tolerance of PIBCA nanoparticles by cells could be improved up to 100-fold by coating their surface with polysaccharides and haemoglobin.

SURGICAL APPLICATIONS OF CYANOACRYLATE ADHESIVES: A REVIEW OF TOXICITY

Cyanoacrylate (CA) and its homologues have a variety of medical and commercial applications as biological adhesives and sealants. Homologues of CA are being widely promoted in surgery as a tissue adhesive to replace traditional suturing techniques. Potential benefits of using CA adhesives include better cosmetic results, more rapid wound closure, and perhaps most significantly, the potential for significant reductions in percutaneous injuries from suture needles, which would in turn also reduce the risk of transmission of infectious diseases. Nevertheless, certain concerns have been raised regarding the potential toxicity of CA within patients, as well as among health professionals who are occupationally exposed when using CA compounds. Reported toxicity of CA in the workplace may result in dermatological, allergic and respiratory conditions. To help reduce the occupational burden, therefore, medical staff using CA adhesives should avoid direct contact with the compound and use appropriate personal protective measures at all times. Maintaining higher levels of humidity, optimizing room ventilation and using special air conditioning filters in surgical suites and operating theatres may also be useful in minimizing the exposure to volatile CA adhesives.

In vitro toxicity test of ethyl 2-cyanoacrylate, a tissue adhesive used in cardiovascular surgery, by fibroblast cell culture method

BACKGROUND

The aim of this study was to evaluate the cytotoxicity of cyanoacrylate polymers (ethyl 2-cyanoacrylate) by an elution test system. In such systems, the material is extracted with a cell culture medium, which is subsequently added onto cultured cells, resulting in an indirect contact between the biomaterial and cells.

METHODS

A cell line commonly utilized for cytotoxicity experiments; L929 mouse fibroblasts were used in this study. The effects of extract dilutions on cells were evaluated by two experiments: (a) The cells were suspended and seeded in a medium containing the extract, followed by a short incubation to observe the effects on cell attachment; (b) cells were seeded in a normal medium. Following cell attachment, this was replaced with a medium containing the extract and long-term effects on cell proliferation were measured. The cytotoxicity was quantified using a cell viability assay, well established for use in the evaluation of cell-biomaterial interactions.

RESULTS

These results indicate that, in the test system utilized, a tenfold dilution of the extract results in an approximately 10% decrease in cells; this increases to between 30% and 45% in a 1:1 dilution. When a large number of cells (3000/well) were used, proliferation of cells overcame the cytotoxic effect and consistent results could not be observed.

CONCLUSIONS

In this study, the observed outcomes follow a similar trend on cell attachment and proliferation with acute effects (4 hours incubation) of the extracts on the cells, producing slightly higher toxicity. Our findings are parallel with the literature findings.

Occupational exposure to airborne solvents during nail sculpturing

This study describes occupational exposure to acrylates and other solvents during nail sculpturing, including comparative measurements of the exposure using four different sculpturing methods: The acrylic method, the UV-gel method, the acrylic powder method and the resin method. Thirty-two nail technicians working in 22 different salons participated in the study. In total, 92 measurements were performed, comprising 70 solvent measurements and 22 measurements of ethyl 2-cyanoacrylate. The solvents most frequently present in all samples were acetone, ethyl acetate, toluene and n-butyl acetate, measured in 96%, 94%, 91% and 81% of the samples, respectively. The study shows that the overall solvent exposure was low, with all measurements calculated as the additive effect (n = 70) below 20% of the OEL (arithmetic mean 0.06 and range 0.01-0.19). No statistically significant difference between sculpturing methods were observed (p = 0.05).

Comparison of antisense oligonucleotide drug delivery systems

Antisense oligonucleotides (AS-ONs) are specific drugs to inhibit gene expression at the transcriptional level. They possess a poor bioavailability and can be degraded by nucleases very rapidly. Therefore, a strong need for the development of oligonucleotide drug delivery systems exists. In the present study, two commercially available liposomes (DOTAP, lipofectin), one artificial virus capsoid (polyoma VP1), two cationic acrylate nanoparticles and two protamine-based nanoparticle preparations (proticles) were compared. Physical parameters of all carrier systems including z-average size, size distribution and surface charge regarding were determined. Cellular uptake was measured by a microplate fluorescence quantification method and, in addition, was visualized in mouse fibroblasts by confocal laser scan microscopy (CLSM). A comparison of cytotoxicity of the different drug delivery systems was performed in vitro using a MTT assay. Mouse fibroblasts which were stable transfected with the cDNA of a N-methyl-D-aspartate (NMDA) receptor also served as functional antisense oligonucleotide test system based on excitotoxicity (cell death). In addition, the efficiency of our oligonucleotide delivery systems was compared on the level of protein expression by Western blotting. Concluding the results, an increased uptake of the ON was found (2-18-fold) for all delivery systems compared to the free ON. Protamine-based nanoparticles showed a very low cytotoxicity in contradiction to all other carrier systems. Lipofectin could be identified as the most potent delivery system in terms of antisense effect, followed by protamine nanoparticles and DOTAP. Sequence-specific antisense effects up to 80% were observed in the functional cell death assay. The highest reduction of NMDA expression was obtained from liposomal preparations with approximately 60% analyzed by Western blot.

Incorporation of biodegradable nanoparticles into human airway epithelium cells-in vitro study of the suitability as a vehicle for drug or gene delivery in pulmonary diseases

PURPOSE

Nanoparticles are able to enhance drug or DNA stability for purposes of optimised deposition to targeted tissues. Surface modifications can mediate drug targeting. The suitability of nanoparticles synthesised out of porcine gelatin, human serum albumin, and polyalkylcyanoacrylate as drug and gene carriers for pulmonary application was investigated in vitro on primary airway epithelium cells and the cell line 16HBE14o-.

METHODS

The uptake of nanoparticles into these cells was examined by confocal laser scan microscopy (CLSM) and flow cytometry (FACS). Further the cytotoxicity of nanoparticles was evaluated by an LDH-release-test and the inflammatory potential of the nanoparticles was assessed by measuring IL-8 release.

RESULTS

CLSM and FACS experiments showed that the nanoparticles were incorporated into bronchial epithelial cells provoking little or no cytotoxicity and no inflammation as measured by IL-8 release.

CONCLUSIONS

Based on their low cytotoxicity and the missing inflammatory potential in combination with an efficient uptake in human bronchial epithelial cells, protein-based nanoparticles are suitable drug and gene carriers for pulmonary application.

Toxicity of cyanoacrylate adhesives and their occupational impacts for dental staff

Cyanoacrylate (CA) and its homologues have a variety of medical, dental and commercial applications as adhesives. The increasing use of CA in dentistry, particularly as an adhesive and sealing glue, has raised concerns regarding its potential toxicity in humans. Reported toxicity of CA is uncommon in the dental workplace, but may manifest as conditions such as urticaria, contact dermatitis and other dermatoses. Dental staff using CA adhesives should avoid direct contact with CA and use appropriate personal protective measures. Maintaining higher levels of humidity, optimizing room ventilation and using special air conditioning filters in the working environment may be useful in minimising the toxicity of volatile CA adhesives.

A New Acrylic Tissue Adhesive for Conjunctival Surgery: Experimental Study

PURPOSE

To evaluate the clinical efficacy and the clinical and histopathologic tolerance of a new acrylic tissue adhesive (ADAL-2) versus 8/0 polyglactin sutures (Vicryl) for its use in conjunctival surgery.

METHOD

Experimental study performed on New Zealand albino rabbits. The animals were divided into two groups. Surgery consisted of a conjunctival peritomy of 8 mm in the superior limbus followed by extensive subconjunctival dissection and creation of a flap by two radial cuts. The conjunctiva was then attached to the limbus again by the proposed acrylic tissue adhesive (ADAL-2) or 8/0 polyglactin suture depending on the group. Clinical efficacy of the closure of the conjunctival wound, either with adhesives or sutures, and the clinical and histopathologic tolerance were also evaluated 1, 7, 28 and 42 days after surgery.

RESULTS

Both conjunctival surgical closure methods were found to be equal in efficacy concerning their ability to fix the conjunctiva to the limbus. There were no significant clinical and histopathologic tolerance differences between the new tissue adhesive investigated (ADAL-2) and 8/0 polyglactin sutures (Vicryl). Histopathology showed no presence of the adhesive 28 days postoperatively.

CONCLUSIONS

ADAL-2 tissue adhesive is an efficient conjunctival closure method, very well tolerated by the ocular surface. Its sealing efficiency and its tolerance are similar to 8/0 polyglactin sutures. This new acrylic adhesive has a potential as an alternative for surgical conjunctival sealing in ophthalmic surgery.

Cytotoxic effects of cyanoacrylates used as retrograde filling materials: an in vitro analysis

Cyanoacrylate has been used in medicine and dentistry for many years. It has been used as a postextraction dressing and retrograde filling material in endodontic surgery. The aim of this study was to evaluate the cytotoxic effects of Histoacryl and other two homologue ethyl cyanoacrylates, Super Bonder and Ultrabond, on cultured fibroblasts, using the Trypan blue dye exclusion assay. The cyanoacrylates were applied to round glass coverslips, which were placed in contact with NIH 3T3 cells. After 0, 6, 12 and 24 h (short-term assay; viability) and 1, 3, 5 and 7 days (long-term assay; survival), the cells were examined under phase light microscopy and counted. The data were compared by the Kruskal-Wallis test. In the short-term experiments, only the cultures of the Ultrabond group (GIV) presented significant smaller percentages of cell viability than the cultures of the other groups (GI: control; GII: Super Bonder; GIII: Histoacryl). Although the cultures of the Super Bonder group (GII) presented smaller percentages of cell viability than cultures of the other groups (GI, GIII, GIV) at the long-term assay, this group was the only experimental group presenting a continuous and progressive cell growth. Our results have shown an in vitro biocompatibility of Histoacryl and ethyl cyanoacrylate homologues. These cyanoacrylates could therefore be of importance for endodontic purposes.

Efficacy and low vascular toxicity of embolization with radical versus anionic polymerization of n-butyl-2-cyanoacrylate (NBCA). An experimental study in the swine

BACKGROUND AND PURPOSE

To compare the efficacy and vascular toxicity of embolization with radical (NBCA+metacryloxysulpholane=CS) versus conventional anionic (NBCA alone=CA) polymerization of NBCA.

MATERIALS AND METHODS

Under continuous digital subtracted angiography (DSA) recordings, a 0.2 mL volume of identical glue mixtures were injected in a single-step procedure, concomitantly, in left and right (with CS and CA, respectively) renal arterial branches (RAB) and ascending pharyngeal arteries (APA) in 8 swines. Arterial histopathology and morphometry of inflammation were investigated at 2 weeks.

RESULTS

Complete embolization was achieved with equivalent cast homogeneity on DSA with both NBCA mixtures in RAB and APA. Inflammatory crowns in APA and RAB were significantly lower in CS - than in CA-treated sites (p<0.001). CS plug was scarcely adhesive to the vascular wall, and pulled apart from the wall by a residual thrombotic lining; in contrast with CA casts that were strongly adhesive to walls with endothelium stripping.

CONCLUSIONS

Anionic and radical polymerization of NBCA embolization was identical with regards to occlusion rate; whereas radical pathway of polymerization with cyanoacrylates lowered histotoxicity with a less sustained adhesiveness of casts against vascular walls.

In vitro and in vivo studies for modified ethyl cyanoacrylate regimens for sclerotherapy

Cyanoacrylates have known for their ability to polymerize rapidly in the presence of traces of weakly basic moieties such as water. The tissue adhesive, Histoacryl(R) (N-butyl 2-cyanoacrylate), has been reported to control bleeding through endoscopic sclerotherapy. But the commercially available Histoacryl(R) is expensive, and it has the problem like other cyanoacrylates that the glue tends to flow/run away from the point of application, which is inherent to the low viscosity, making precise application difficult. In this study, ethyl cyanoacrylate (ECA), the main constituent of "super glue," was employed instead of Histoacryl(R) due to its lower cost. The aim of the research is to modify the compositions of ECA regimen and evaluate its feasibility for sclerosant application through both in vitro flow circuit model and in vivo animal tests. It was noted that the difference in the relative hardening rate between the in vitro Hepes-Tyrodes buffer flowing model and the in vivo rat model for the ECA and Histoacryl(R) was related to the existence of the blood protein, such as albumin, in the physiological milieu. It was also noticed that the ECA setting rate was greatly increased either in Hepes-Tyrodes buffer or in blood (to a comparable rate as Histoacryl(R) in vivo) by adding a few doses of caffeine, which acts as a polymerization initiator. This would lead to far better injection precision during sclerotherapy. Furthermore, in vivo histological examination for the occluded lumen of the rat's inferior vena cava and a clinical piglet portal vein occlusion experiment have suggested this new sclerosant regimen, caffeine/ECA, is of great promise in endoscopic sclerotherapy.

Non-adhesive cyanoacrylate as an embolic material for endovascular neurosurgery

Endovascular neurosurgery is now becoming available as one of strategies for the treatment of cerebro-spinal arterio-venous malformations and aneurysms. For this treatment, a microcatheter is advanced into or close to a lesion and then an embolic material is administered through it to obliterate the lesion. N-butyl-2-cyanoacrylate (NBCA) has preferentially been used as an embolic material in Europe and America. However, its exceptionally strong adhesive force sometimes causes adhesion between the tip of the microcatheter and the artery. In this study, a new non-adhesive cyanoacrylate, isostearyl-2-cyanoacrylate (ISCA), was developed. It carries a long hydrophobic side isostearyl group with lower reactivity and adhesion than other cyanoacrylates. Its polymerization rate is, however, too low to obliterate a vascular lesion with a rapid blood flow. To increase the polymerization rate. ISCA was mixed with NBCA. As a result, the adhesive force of the mixture became extremely low, compared with that of NBCA. The viscosity of the mixture was low enough to allow its' use as an embolic material. Tissue reactions against the mixture was milder than those against NBCA. Radio-angiography became possible by mixing further with Lipiodol. The evaluation of this new embolic material with a rabbit renal artery showed that the obliteration effect of the mixture of ISCA and NBCA was excellent to use as an embolic material for clinical applications.

Cytotoxicity of cyanoacrylate adhesives to cultured tendon cells

The in vitro cytotoxicity of four cyanoacrylate adhesives was tested using cultures of cells derived from human tendons. All four were found to be cytotoxic, even at concentrations as low as 1.7%, over the experimental period of up to 18 weeks. This study shows that such adhesives in their present state may not be suitable for re-joining cut tendons as their initial and long-term toxicity may hinder the slow healing process of tendons.

Histological changes in the rat common carotid artery following simultaneous topical application of cotton sheet and cyanoacrylate glue

Histological changes in and around the arterial walls of rats were investigated following simultaneous topical application of cotton sheet and cyanoacrylate glue. The bilateral common carotid arteries were exposed using sterile techniques, and the test materials were applied to the right artery. The left artery served as a control. Changes in arterial histology were evaluated at 2 weeks, 1 month, 2 months, and 3 months after surgery. Extensive inflammation consisting primarily of histiocytes and multinuclear giant cells was observed around the materials, but tended to decrease by 3 months. Necrosis in the media and fibrosis in the adventitia initially appeared around 2 weeks, and became advanced by 2-3 months. At 2-3 months, disruption of elastic fibers and marked fibrosis in the media were seen, and endothelial proliferation in the intima appeared. Intimal proliferation was observed at both the experimental and other sites of the vessels. The present results suggest that simultaneous use of the test materials can cause the arterial occlusive lesions observed following aneurysmal surgery.

Histopathological changes following the use of biological and synthetic glue for dural grafts: an experimental study

Dural defects and CSF leaks are common neurosurgical problems and the search for a suitable sealant continues. The effects of such sealants on meninges and brain have not been previously studied. To study the effect of two commonly used sealants, burrholes were made in 20 rats, with the creation of dural tears which were covered with human cadaveric dura smeared with synthetic (cyanoacrylate) glue and gelatine (GRG) glue. Plain dura, placed in one of the burrholes served as a control. An intense inflammatory reaction was observed with both glues, which was found to persist till the eleventh week.

Interaction between polyalkylcyanoacrylate nanoparticles and peritoneal macrophages: MTT metabolism, NBT reduction, and NO production

PURPOSE

The nature of interactions between macrophages and drug carriers is of primordial importance either in the design of more effective therapeutic strategies for macrophage-associated pathogenesis or in establishing new approaches for pharmacological action avoiding macrophages.

METHODS

Polyalkylcyanoacrylate nanoparticles (PMCA, PECA, PBCA and PIBCA nanoparticles) were assayed for their toxicity on peritoneal resident and thioglycolate-elicited macrophages. Cellular viability was assessed by MTT tetrazolium salt assay, oxidative burst by NBT reduction and NO production by nitrite evaluation.

RESULTS

The nanoparticles tested led to cellular morphological modifications and induced toxicity in both types of macrophages in culture. The polyalkylcyanoacrylate nanoparticles uptake by peritoneal macrophages caused an increase in respiratory burst, as assessed by the NBT reduction assay, and induced the release of soluble toxic factors to the culture medium. The association of LPS with the PMCA nanoparticles significantly stimulated the production of nitric oxide (NO) by resident macrophages. In contrast, the association of PBCA nanoparticles with LPS does not increase the nitrite production as compared with LPS alone, which may be due to a different physico-chemical interaction between LPS and the two types of polymers.

CONCLUSIONS

In cultured mice peritoneal macrophages, nanoparticles of PACA induce the production of oxygen reactive products, which cause changes in the cell metabolism of both resident and elicited macrophages. PMCA nanoparticles in association with LPS significantly increase the expression of the inducible isoform of nitric oxide synthase, leading to the release of large amount of NO, which may be highly cytotoxic to the cultured cells in the presence of peroxide generated from the oxidative burst.

Evaluation of liver toxicological effects induced by polyalkylcyanoacrylate nanoparticles

Intravenous administration of drug-loaded polyalkylcyanoacrylate (PACA) nanoparticles is followed by a rapid uptake by the tissues of the reticuloendothelial system, mainly the liver. Nevertheless, it is so far unknown whether chronic administration of nanoparticles can lead to damage to the liver cells. We have studied the subacute toxicological effects of these drug carriers in a rat in vivo/ex vivo model. Nanoparticles were administered intravenously at a total dose of 200 mg/kg for 14 days (10 individual doses of 20 mg/kg). Hepatocytes were then isolated. Levels of alpha 1-acid glycoprotein secretion increased while albumin secretion decreased in hepatocytes from rats treated with PACA nanoparticles. In addition, glucose production due to the fructose metabolism was lowered. Treated rats induced a temporary increase and hyposialyation of serum alpha 1-acid glycoprotein. These effects were reversible 15 days after the treatment was concluded. Finally, the involvement of Kupffer cells and polymer degradation products was studied in vitro. Modifications of hepatocyte protein synthesis related to the treatments were only observed when direct contact between nanoparticles and hepatocytes existed. Kupffer cells and polymer degradation products did not mediate the hepatocyte response to nanoparticles in vitro. In conclusion, modifications in hepatic function after chronic administration of PACA nanoparticles have been detected by the use of very sensitive models for detecting hepatoxicity. These effects were, however, found to be reversible when the treatment was stopped.

Acute renal toxicity of doxorubicin (adriamycin)-loaded cyanoacrylate nanoparticles

Acute doxorubicin-loaded nanoparticle (DXNP) renal toxicity was explored in both normal rats and rats with experimental glomerulonephritis. In normal rats, 2/6 rats given free doxorubicin (DX) (5 mg/kg) died within one week, whereas all control animals and all rats having received free NP or DXNP survived. A 3 times higher proteinuria appeared in animals treated with DXNP than in those treated with DX. Free NP did not provoke any proteinuria. Two hr post-injection, DXNP was 2.7 times more concentrated in kidneys than free DX (p < 0.025). In rats with immune experimental glomerulonephritis, 5/6 rats given DX died within 7 days, in contrast to animals treated by DXNP, NP, or untreated, which all survived. Proteinuria appeared in all series, but was 2-5 times more intense (p > 0.001) and prolonged after doxorubicin treatment (400-700 mg/day), without significant difference between DXNP and DX. Rats treated by unloaded NP behaved as controls. These results demonstrate that, in these experimental conditions, DXNP killed less animals than free DX, despite of an enhanced renal toxicity of the former. Both effects (better survival and nephrosis) are most probably related to an enhanced capture of DXNP by cells of the mononuclear phagocyte system, including mesangial cells.

Toxicity of cyanoacrylates in vitro using extract dilution assay on cell cultures

Comparative cytotoxicity testing of four cyanoacrylate adhesives suggested for orthopaedic applications was performed. These substances were placed in complete culture medium with serum and the resulting extraction fluids were tested on L 929 cells and human lymphocytes. Testing procedures include cell morphology assessment using light microscopy and vital dyes, cell counting using a computer-assisted image analysis system, cell growth measurement using total protein content assay and cell viability assessment using the MTT method. Quantitation of the toxicity of the degradation products released by cyanoacrylates in the extracts was achieved and differences in the cytopathic effect related to the chemical composition of the cyanoacrylates were found. A toxicity rating of the assayed cyanoacrylate adhesives was obtained as follows (in order of increasing toxicity): BCA < xCA < ECAg < ECAl.

Cytotoxicity testing of cyanoacrylates using direct contact assay on cell cultures

The use of a tissue adhesive for surgical procedures has prompted a large number of clinical and experimental studies. Alkyl-2-cyanoacrylate esters constitute a family of adhesives with good mechanical properties but their biological compatibility has to be assessed. In this study the cytotoxicity of three commercially available cyanoacrylates and one of unknown composition has been determined. The first part of the study deals with direct contact testing procedures using L 929 cells challenged with drops of adhesives: cell morphology, cell growth and bacterial growth inhibition were assayed. Testing methods included cell viability assay using vital dyes, cell growth measurement using crystal violet staining uptake and bacterial growth assay using S. aureus growth inhibition. All the cyanoacrylate adhesives tested were found to be cytotoxic and to inhibit cell proliferation: differences between the cyanoacrylates were found.

In vitro evaluation of cell/biomaterial interaction by MTT assay

The tetrazolium-based colorimetric assay (MTT test) measures only in vitro living cells and the results are directly related to the number of viable cultured cells. It has been adopted in immunological investigations, cancer research and, recently, biocompatibility evaluation. We used the MTT method with minor modifications to fit it to an in vitro study of biomaterial-cell interactions. The MTT assay was confirmed to be feasible, rapid and reproducible. Moreover, it showed a good correlation with other in vitro proliferation assays, such as the 3H-thymidine uptake assay. By using the MTT method and the ASTM procedure for extracting biomaterials, we quantified the in vitro cell compatibility of different metals and polymers.

Toxicity test of biodegradable polymers by implantation in rabbit cornea

To evaluate whether or not the corneal micropocket implantation is effective for determining the toxicity of polymeric materials, currently used biodegradable polymers such as poly(lactic acid) (PLA), poly(glycolic acid) (PGA), LA-GA copolymers, and three kinds of poly(2-cyano-acrylate)s (PCA) were implanted in a rabbit corneal pouch and the tissue responses were observed macroscopically and microscopically. It was found that PLA induced no vascularization, whereas a residual solvent and ethylene oxide gas remaining in the PLA matrix invoked vascularization. Vascularization clearly took place when PGA was implanted in the cornea, which became opaque, probably because of cellular infiltration. In the case of PCA implantation, severe inflammation as well as vascular invasion occurred in the initial stage. It is likely that these tissue reactions were caused by the leachables from the implanted materials, the extent being dependent on the leaching rate and the toxicity. It was concluded that the corneal micropocket assay is a good means to detect trace amounts of leachables from implanted materials without sacrificing the animals with the implanted materials.

The current status of cyanoacrylate and fibrin tissue adhesives

Surgical tissue adhesives could simplify complex surgical procedures by stabilizing tissue surfaces through hemostasis, sealing wounds, and fixating tissue in areas inaccessible to suture placement. The most common surgical tissue adhesives available to the surgeon include the cyanoacrylate derivatives and the fibrin tissue adhesives. Butyl-2 cyanoacrylate (Histoacryl) is a cyanoacrylate derivative that is frequently used in Canada and Europe. This adhesive has excellent binding strength for skin closure; however, subcutaneous implantation can result in inflammation and foreign body giant cell reaction. Fibrin tissue adhesives use a fibrin clot as the binding moiety and vary in adhesive strength depending on the fibrinogen concentration of the preparation. Autologous fibrin tissue adhesives are prepared using one of several different methods, which vary in fibrinogen yield and concentration. The currently available autologous fibrin tissue adhesives demonstrate good hemostatic properties with relatively low binding strengths. This article reviews the status of cyanoacrylate adhesives and the preparation, efficacy, and clinical applications of the fibrin tissue adhesives.

In vitro toxicity test of 2-cyanoacrylate polymers by cell culture method

The inhibition of Swiss 3T3 cell growth by the microspheres prepared from various 2-cyanoacrylate polymers was investigated to assess their cell toxicity. Poly(ethoxy-ethyl 2-cyanoacrylate) and poly(methyl 2-cyanoacrylate) microspheres inhibited cell growth in a smaller amount than poly-(isobutyl 2-cyanoacrylate) and poly (ethyl 2-cyanoacrylate) microspheres. The extent of cell growth inhibition by the microspheres decreased with the increasing molecular weight, regardless of the kind of polymers used. Every kind of the microspheres was degraded releasing formaldehyde in the culture medium. The cell growth inhibition by the medium containing the microspheres was observed within 24 h for poly(ethoxyethyl 2-cyanoacrylate) and poly(methyl 2-cyanoacrylate). The extent of inhibition was in a linear proportion with the amount of formaldehyde released. It is concluded that the cell toxicity of 2-cyanoacrylate polymers is attributed to formaldehyde released upon polymer degradation.

Histotoxicity of cyanoacrylate tissue adhesives. A comparative study

Cyanoacrylate derivatives have been used as surgical adhesives for many years. Shorter-chain derivatives (methyl- and ethyl-cyanoacrylate) have proved to be histotoxic. Longer-chain derivatives (butyl- and isobutyl-cyanoacrylate) are much less histotoxic. Many surgeons continue to use ethyl-2-cyanoacrylate (Krazy Glue) despite the availability of a less toxic derivative, butyl-2-cyanoacrylate (Histoacryl). In this study, the histotoxicity and bone graft-cartilage binding ability of Krazy Glue and Histoacryl were compared. Bone grafts harvested from the anterior wall of the maxillary sinus were placed in a subcutaneous pocket and glued to auricular cartilage in the rabbit. Krazy Glue and Histoacryl were used in opposite ears, harvesting specimens at 1, 2, 4, 12, 24, and 48 weeks. The Krazy Glue-treated ears developed seromas with histologic evidence of acute inflammation, tissue necrosis, and chronic foreign body giant cell reaction. The Histoacryl-treated ears showed mild acute inflammation and mild foreign body giant cell reaction. The Krazy Glue was completely degraded within 12 months, while some Histoacryl was still present at 1 year. Histoacryl had minimal histotoxic effect and good bone graft-cartilage binding ability, whereas Krazy Glue demonstrated severe histotoxicity.

Prothrombotic cytotoxicity of cyanoacrylate tissue adhesive

Alkyl-2-cyanoacrylates exhibit properties suggestive of their use as surgical adhesives; however, their cytotoxic and proinflammatory properties have prevented their widespread application. The question of whether cyanoacrylate cytotoxicity may be due to eicosanoid production was investigated. Endothelial cells from rats were exposed to increased concentrations of isobutyl-2-cyanoacrylate. The products from this exposure promoted enhanced, concentration-dependent thromboxane biosynthesis as detected by platelet aggregation. When platelets were pretreated with 1-carboxyheptylimidazole (2.0 mM), an inhibitor of thromboxane biosynthesis, up to 80% less aggregation was observed. Such aggregation was inhibited using 1-carboxyheptylimidazole in a dose-dependent manner. Treatment of endothelial cells with isobutyl-2-cyanoacrylate and 1-carboxyheptylimidazole did not significantly alter the amount of platelet aggregation. A soluble metabolite of isobutyl-2-cyanoacrylate appeared to activate platelet aggregation. The cytotoxicity associated with the surgical use of alkyl-2-cyanoacrylates may be mediated by enhanced local thromboxane production.

Cytotoxicity of alkyl-2-cyanoacrylate adhesives

The cytotoxicity of methyl- and isobutyl-2-cyanoacrylate adhesives was determined using a rat polymorphonuclear leukocyte suspension. Cell degranulation increased and migration decreased on addition of the alkyl-2-cyanoacrylates to the suspension in a concentration-dependent manner. When acetylsalicylic acid or indomethacin, inhibitors of prostaglandin H synthase, were present, the cytotoxicity observed on addition of the adhesives to the leukocytes decreased up to eightfold in a dose-dependent manner as detected by trypan blue exclusion. Likewise, glutathione peroxidase and superoxide dismutase lowered such cytotoxicity resulting from the cyanoacrylates up to eight- and sevenfold, respectively. The data suggested that the adhesives may have generated lipid hydroperoxides that activated prostaglandin and thromboxane biosynthesis, and participated in membranal oxidation and lysis. Such a mechanism may contribute to understanding the thrombotic events associated with the necrosis observed on application of these adhesives to tissues in vivo.

[Experimental renal insufficiency in rabbits produced by the intrarenal injection of cyanoacrylic ester]

Through a percutaneous intrarenal injection of 2 ml cyanoacrylic ester to each kidney, acute renal failure was induced in 10 experimental rabbits. Seven of the animals died as a consequence of uremia before a period of 64 hours. The other three remained alive for 96 hours although suffering from stable renal failure. Cyanoacrylic ester solidifies immediately after injection, leading to a hardened body which fills the renal pelvis, ureters and also the renal vessels. Each injection induces hydronephrosis and necrotic-hemorrhagic lesions, and infarcts in the case of vascular injection. With this simple technique immediate acute renal failure can be obtained experimentally without causing trauma or involving extrarenal structures.

Cyanoacrylates and corneal abrasion

Cyanoacrylate-containing adhesives such as Super Glue, Krazy Glue, and a vast array of artificial nail adhesives are monomers which rapidly polymerize and bond in the presence of water or weak bases. Inadvertent contact with skin or tissue can also cause rapid bonding with resultant irritation. To assess the magnitude of problems associated with ocular contamination involving cyanoacrylates, a 12-month prospective study was conducted. 34 cases (21 adult and 13 pediatric) were collected. In all cases, contaminated eyes were thoroughly irrigated with tepid water for 15 minutes. 15 patients (44%) suffered a corneal abrasion, as determined by ophthalmic exam, necessitating treatment with antibiotics, cycloplegics, and patching. Individuals reporting complete resolution were irrigated with 20 minutes of exposure, while patients suffering mechanical injury delayed decontamination for a minimum of 15 minutes. In addition to immediate irrigation of eyes exposed to cyanoacrylates, we recommend an ophthalmologic evaluation to rule out the possibility of mechanical injury.

Retinal toxicity of cyanoacrylate tissue adhesive in the rabbit

N-butyl-2-cyanoacrylate tissue adhesive was injected into the preretinal space of rabbit eyes to study potential toxicity to the retina. Application of 3.3-10.0 ul of cyanoacrylate tissue adhesive showed localized but definite retinal toxicity. White halos appeared surrounding the preretinal cyanoacrylate immediately after injection with a gradual evolution of the white areas into pigmentary scars by 1 month. Histological examination confirmed severe focal necrosis of the retina. No identifiable distant toxic effects or electrophysiologic changes were observed during the 6-month follow-up period.

Synthesis and bioevaluation of a rapidly biodegradable tissue adhesive: 1,2-isopropylidene glyceryl 2-cyanoacrylate

A rapidly biodegradable tissue adhesive, 1,2-isopropylidene glyceryl 2-cyanoacrylate, was synthesized and characterized by NMR. Bond strength was determined. Three types of corresponding polymers were prepared and evaluated for in vitro and in vivo toxicity. The polymers were generally found to be in the moderately toxic and toxic groups similar to the lower alkyl 2-cyanoacrylates.

The histotoxicity of cyanoacrylates. A selective review

Cyanoacrylates, a group of rapidly polymerizing adhesives, have found widespread uses in oral and general surgery as well as surgical subspecialties, for example as hemostatic and anastomotic agents. They have been utilized most recently as materials for embolotherapy of complex cerebral and extra-cerebral vascular anomalies. The histopathology that results from their deposition in human tissues is thus an important consideration, and the subject of this review. Particular attention is given to the fate of cyanoacrylates in cerebral lesions after iatrogenic embolization procedures. The apparent toxicity of these plastics on blood vessel walls is discussed in relation to experimental observations. It is imperative that clinicians who use this group of substances evaluate their potential functions in the light of the pathologic findings.

Toxicity and association of polycyanoacrylate nanoparticles with hepatocytes

The degradation of polybutylcyanoacrylate (PBC) and polyhexylcyanoacrylate (PHC) nanoparticles, together with their association with and toxicity towards isolated hepatocytes, were determined. Nanoparticles were not taken up by rat hepatocytes at a significant level. The LD50S of PBC and PHC nanoparticles towards hepatocytes were 0.4 mg/2 x 10(6) cells and greater than 1 mg/2 x 10(6) cells respectively. This hepatocyte toxicity cannot be attributed solely to the formaldehyde formed during degradation.

Bioadhesive and histotoxic properties of ethyl-2-cyanoacrylate

Ethyl-2-cyanoacrylate was applied to the cortex of rabbits to evaluate its bioadhesive and histotoxic behavior. The animals were killed at 4 or 10 days. Half of the animals were pretreated with dexamethasone. Our results indicate that the application of ethyl-2-cyanoacrylate to brain tissue produced severe superficial cortical necrosis but not bioadhesion. Pretreatment with steroids did not provide a significant protective effect.

Neural and vascular tissue reaction of cyanoacrylate adhesives: a further report

The effect of a new tissue adhesive, carbohexoxymethyl 2-cyanoacrylate monomer (Ethicon CHC), was evaluated in six cats divided into two groups. With the cats under barbiturate anesthesia. Ethicon CHC was applied to the left cruciate cortex and the left femoral neurovascular bundle. Normal saline was applied to the right side for control. The first group (n = 4) and the second group (n = 2) were killed 4 and 7 days, respectively, after application of the adhesive. Neuropathological examination revealed meningeal astrocytosis, vascular wall degeneration, hemorrhage, and inflammatory reaction in both groups. This adhesive does not display the ideal property of inertness, which would permit its safe use. Focal tissue reactions caused by the adhesives in sensitive areas of the cortex can result in significant neurological deficit.

[Experimental test of two tissue adhesives (GRF and IBC 2) in vascular microsurgery in the rat (author's transl)]

Tissues adhesives have been evaluated on rats, during microvascular surgery: the IBC 2 and the GRF glues. The short and long term evolution is studied. The patency rate of the anastomosis is analyzed and the histological aspect is studied. The GRF glue exhibits a rapid resorption rate, but the long term results show a high toxicity against the muscular layers of the artery. The IBC 2 glue has a slower resorption rate and its long term effect are restricted to a foreign body reaction.

Neurosurgical applications of the cyanoacrylate adhesives

The cyanoacrylate adhesives are a biologically heterogenous group, some of which are potentially valuable additions to the neurosurgical armamentarium. The commercially available cyanoacrylates usually contain the more toxic methyl and ethyl monomers. The safe butyl monomer, isobutyl 2-cyanoacrylate, is approved in the United States by the Food and Drug Administration for investigational use only. Isobutyl 2-cyanoacrylate may prove to be useful for the extravascular reinforcement of intracranial aneurysms and for the intravascular occlusion of carotid-cavernous fistulae. Safe and effective alternatives exist for the management of these two problems. The sealing of certain cerebrospinal fluid fistulae and the intravascular occlusion of certain arteriovenous malformations may be more effectively accomplished with isobutyl 2-cyanoacrylate than with other currently available techniques. The ultimate role of this and of other as yet untested cyanoacrylates in neurosurgery remains to be determined.

Experimental internal iliac artery embolization: evaluation of low viscosity silicone rubber, isobutyl 2-cyanoacrylate, and carbon microspheres

The angiographic, morphologic, and histologic effects of carbon microspheres, isobutyl 2-cyanoacrylate (IBC), and low viscosity silicone rubber (LVSR) were compared. Carbon spheres did not effectively occlude the internal iliac artery, but resulted in small vessel occlusions leading to the most frequent complications. IBC was effective in causing occlusion but resulted in significant inflammatory changes within the thrombus and vessel wall. LVSR gave satisfactory occlusion without inciting vessel wass inflammatory reaction. Two of 4 animals developed a hind extremity paralysis. None of these materials is approved for general intravascular usage.