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1.
Materials (Basel) ; 13(6)2020 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-32245004

RESUMO

Due to increasing rates of periprosthetic joint infections (PJI), new approaches are needed to minimize the infection risk. The first goal of this study was to modify a well-established infection model to test surface-active antimicrobial systems. The second goal was to evaluate the antimicrobial activity of a silver multilayer (SML) coating. In vitro tests with SML items showed a >4 Log reduction in a proliferation assay and a 2.2 Log reduction in an agar immersion test (7 d). In the in vivo model blank and SML coated K-wires were seeded with ~2 × 104 CFU of a methicillin-sensitive Staphylococcus epidermidis (MSSE) and inserted into the intramedullary tibial canal of rabbits. After 7 days, the animals were sacrificed and a clinical, microbiological and histological analysis was performed. Microbiology showed a 1.6 Log pathogen reduction on the surface of SML items (p = 0.022) and in loosely attached tissue (p = 0.012). In the SML group 7 of 12 SML items were completely free of pathogens (cure rate = 58%, p = 0.002), while only 1 of 12 blank items were free of pathogens (cure rate = 8%, p = 0.110). No silver was detected in the blood or urine of the SML treated animals and only scarcely in the liver or adjacent lymph nodes. In summary, an in vivo infection model to test implants with bacterial pre-incubation was established and the antimicrobial activity of the SML coating was successfully proven.

2.
J Biomed Mater Res A ; 106(1): 180-191, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28884523

RESUMO

A wide variety of titanium implant modifications have been developed to improve tissue- or cell-material interactions including bone bonding, implant failure, and contact osteogenesis. Osteogenesis can be stimulated by mechanobiological signals such as topography though translation of in vivo reactions to in vitro bioactivity and stem cell culture data, and vice versa, is challenging. We hypothesized that a systematic in vitro approach comparing clinically well-accepted implant surface topographical modifications could shed light on potential cell biological mechanisms provoked by submicron-, micron- or macrostructured surfaces. In this study, we investigated the response of umbilical cord derived mesenchymal stromal cells (UC-MSCs) to anodized, particle blasted, and plasma sprayed highly porous Plasmapore surfaces, which is known to promote bony ingrowth in vivo. After 21 days, UC-MSCs undergo a morphological shift from a 2D to 3D behavior on micro- or macrostructures visualized by actin-vinculin fluorescence and are able to fill the porous surfaces completely. Cell viability after 7 days was significantly decreased on the micro- and macrostructured surfaces particle blasted and Plasmapore, compared to polished controls. The analysis of osteogenic differentiation under noninduced conditions revealed a significantly elevated ALP activity on Plasmapore, indicating a beneficial effect of this macrostructured surface toward osteogenic differentiation supported by late elevated gene expression of osteopontin evaluated by qPCR. Mineralization as well as in vitro bioactivity was pronounced on anodized surfaces. Our findings point to synergistic implant modification strategies allowing early contact osteogenesis and bone ingrowth for future implant designs. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 180-191, 2018.


Assuntos
Ligas/farmacologia , Células-Tronco Mesenquimais/efeitos dos fármacos , Titânio/farmacologia , Cordão Umbilical/citologia , Ligas/química , Adesão Celular/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Materiais Revestidos Biocompatíveis/química , Materiais Revestidos Biocompatíveis/farmacologia , Humanos , Osteogênese , Osteopontina/genética , Osteoprotegerina/genética , Porosidade , Propriedades de Superfície , Titânio/química
3.
Int J Mol Sci ; 17(2)2016 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-26805825

RESUMO

Drug-eluting stents (DES) have reduced in-stent-restenosis drastically. Yet, the stent surface material directly interacts with cascades of biological processes leading to an activation of cellular defense mechanisms. To prevent adverse clinical implications, to date almost every patient with a coronary artery disease is treated with statins. Besides their clinical benefit, statins exert a number of pleiotropic effects on endothelial cells (ECs). Since maintenance of EC function and reduction of uncontrolled smooth muscle cell (SMC) proliferation represents a challenge for new generation DES, we investigated the effect of atorvastatin (ATOR) on human coronary artery cells grown on biodegradable polymers. Our results show a cell type-dependent effect of ATOR on ECs and SMCs. We observed polymer-dependent changes in IC50 values and an altered ATOR-uptake leading to an attenuation of statin-mediated effects on SMC growth. We conclude that the selected biodegradable polymers negatively influence the anti-proliferative effect of ATOR on SMCs. Hence, the process of developing new polymers for DES coating should involve the characterization of material-related changes in mechanisms of drug actions.


Assuntos
Atorvastatina/farmacologia , Plásticos Biodegradáveis/farmacologia , Vasos Coronários/citologia , Miócitos de Músculo Liso/efeitos dos fármacos , Polímeros/farmacologia , Técnicas de Cultura de Células , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Doença da Artéria Coronariana/tratamento farmacológico , Vasos Coronários/efeitos dos fármacos , Stents Farmacológicos , Células Endoteliais/citologia , Células Endoteliais/efeitos dos fármacos , Humanos , Miócitos de Músculo Liso/citologia , Especificidade de Órgãos , Propriedades de Superfície
4.
PLoS One ; 10(12): e0142075, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26641662

RESUMO

PURPOSE: Drug-eluting stents (DES) based on permanent polymeric coating matrices have been introduced to overcome the in stent restenosis associated with bare metal stents (BMS). A further step was the development of DES with biodegradable polymeric coatings to address the risk of thrombosis associated with first-generation DES. In this study we evaluate the biocompatibility of biodegradable polymer materials for their potential use as coating matrices for DES or as materials for fully bioabsorbable vascular stents. MATERIALS AND METHODS: Five different polymers, poly(L-lactide) PLLA, poly(D,L-lactide) PDLLA, poly(L-lactide-co-glycolide) P(LLA-co-GA), poly(D,L-lactide-co-glycolide) P(DLLA-co-GA) and poly(L-lactide-co-ε-caprolactone), P(LLA-co-CL) were examined in vitro without and with surface modification. The surface modification of polymers was performed by means of wet-chemical (NaOH and ethylenediamine (EDA)) and plasma-chemical (O2 and NH3) processes. The biocompatibility studies were performed on three different cell types: immortalized mouse fibroblasts (cell line L929), human coronary artery endothelial cells (HCAEC) and human umbilical vein endothelial cells (HUVEC). The biocompatibility was examined quantitatively using in vitro cytotoxicity assay. Cells were investigated immunocytochemically for expression of specific markers, and morphology was visualized using confocal laser scanning (CLSM) and scanning electron (SEM) microscopy. Additionally, polymer surfaces were examined for their thrombogenicity using an established hemocompatibility test. RESULTS: Both endothelial cell types exhibited poor viability and adhesion on all five unmodified polymer surfaces. The biocompatibility of the polymers could be influenced positively by surface modifications. In particular, a reproducible effect was observed for NH3-plasma treatment, which enhanced the cell viability, adhesion and morphology on all five polymeric surfaces. CONCLUSION: Surface modification of polymers can provide a useful approach to enhance their biocompatibility. For clinical application, attempts should be made to stabilize the plasma modification and use it for coupling of biomolecules to accelerate the re-endothelialization of stent surfaces in vivo.


Assuntos
Materiais Biocompatíveis/administração & dosagem , Materiais Biocompatíveis/química , Polímeros/administração & dosagem , Polímeros/química , Propriedades de Superfície/efeitos dos fármacos , Trombose/induzido quimicamente , Animais , Linhagem Celular , Vasos Coronários/efeitos dos fármacos , Stents Farmacológicos/efeitos adversos , Fibroblastos/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Humanos , Camundongos , Stents/efeitos adversos
5.
Transl Vis Sci Technol ; 4(3): 14, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26175960

RESUMO

PURPOSE: A novel glaucoma drainage device (GDD) with local drug delivery (LDD) system was created and characterized for safety and effectiveness after implantation into the suprachoroidal space (SCS) of rabbit eyes. METHODS: Thin films of two different polymers, Poly(3-hydroxybutyrate) (P(3HB)) and Poly(4-hydroxybutyrate) (P(4HB)), containing the drugs mitomycin C (MitC) or paclitaxel (PTX) were attached to silicone-tubes to create LDD devices. The release kinetics of these drugs were explored in vitro using high performance liquid chromatography (HPLC). Twenty-four New Zealand white rabbits, randomly divided into eight groups, were implanted with different kinds of microstents into SCS. The intraocular pressure (IOP) was monitored noninvasively. After 6 weeks, rabbits were sacrificed and enucleated eyes were used for anterior segment optical coherence tomography (OCT), micro magnetic resonance imaging (MRI), and histology. RESULTS: In vitro, faster drug release from both polymers was observed for MitC compared to PTX. Comparing polymers, the release from P(3HB) matrix was slower for both drugs. MRI and OCT showed all implants maintained a proper location. An effective IOP reduction was observed for up to 6 weeks in eyes with microstents combined with a drug-releasing LDD system. Overall, the surrounding tissue revealed mild-to-moderate inflammation. No pronounced fibrosis was observed in any of the groups. However, both drugs caused damage to the neighboring retina. CONCLUSIONS: The suprachoroidal microstent reduced IOP with mild inflammation in rabbit eyes. To avoid negative effects on the retina, it is necessary to identify novel drugs with less cytotoxicity. Future studies are needed to explore the fibrotic process over the long-term. TRANSLATIONAL RELEVANCE: The presented data serve as a proof of principle study for the concept of a suprachoroidal drug eluting microstent. Future device improvements will be focused on the design of LDD systems and the use of specific anti-inflammatory or antifibrotic agents with less cytotoxicity compared to MitC or PTX. Long-term animal studies using a reliable glaucoma model will be a further step towards clinical application and improvement of surgical glaucoma therapy.

6.
J Control Release ; 214: 1-11, 2015 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-26160303

RESUMO

In this study we present the development of an injectable polymeric drug delivery system for subconjunctival treatment of primary open angle glaucoma. The system consists of hyaluronic acid sodium salt (HA), which is commonly used in ophthalmology in anterior segment surgery, and an isocyanate-functionalized 1,2-ethylene glycol bis(dilactic acid) (ELA-NCO). The polymer mixtures with different ratios of HA to ELA-NCO (1/1, 1/4, and 1/10 (v/v)) were investigated for biocompatibility, degradation behavior and applicability as a sustained release system. For the latter, the lipophilic latanoprost ester pro-drug (LA) was incorporated into the HA/ELA-NCO system. In vitro, a sustained LA release over a period of about 60days was achieved. In cell culture experiments, the HA/ELA-NCO (1/1, (v/v)) system was proven to be biocompatible for human and rabbit Tenon's fibroblasts. Examination of in vitro degradation behavior revealed a total mass loss of more than 60% during the observation period of 26weeks. In vivo, LA was continuously released for 152days into rabbit aqueous humor and serum. Histological investigations revealed a marked leuko-lymphocytic infiltration soon after subconjunctival injection. Thereafter, the initial tissue reaction declined concomitantly with a continuous degradation of the polymer, which was completed after 10months. Our study demonstrates the suitability of the polymer resulting from the reaction of HA with ELA-NCO as an injectable local drug delivery system for glaucoma therapy, combining biocompatibility and biodegradability with prolonged drug release.


Assuntos
Túnica Conjuntiva , Glaucoma de Ângulo Aberto/tratamento farmacológico , Animais , Humor Aquoso/metabolismo , Materiais Biocompatíveis , Células Cultivadas , Preparações de Ação Retardada , Portadores de Fármacos , Sistemas de Liberação de Medicamentos , Olho/patologia , Glaucoma de Ângulo Aberto/patologia , Humanos , Ácido Hialurônico/administração & dosagem , Ácido Hialurônico/uso terapêutico , Injeções , Latanoprosta , Fármacos Neuroprotetores/administração & dosagem , Fármacos Neuroprotetores/uso terapêutico , Polímeros , Pró-Fármacos/administração & dosagem , Prostaglandinas F Sintéticas/administração & dosagem , Prostaglandinas F Sintéticas/uso terapêutico , Coelhos
7.
PLoS One ; 10(3): e0116080, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25734818

RESUMO

Drug-coated balloons (DCB), which have emerged as a therapeutic alternative to drug-eluting stents in percutaneous cardiovascular intervention, are well described with regard to clinical efficacy and safety within a number of clinical studies. In vitro studies elucidating the correlation between coating additive and DCB performance are however rare but considered important for the understanding of DCB requirements and the improvement of established DCB. In this regard, we examined three different DCB-systems, which were developed in former studies based on the ionic liquid cetylpyridinium salicylate, the body-own hydrogel hyaluronic acid and the pharmaceutically well-established hydrogel polyvinylpyrrolidone, considering coating morphology, coating thickness, drug-loss, drug-transfer to the vessel wall, residual drug-concentration on the balloon surface and entire drug-load during simulated use in an in vitro vessel model. Moreover, we investigated particle release of the different DCB during simulated use and determined the influence of the three coatings on the mechanical behavior of the balloon catheter. We could show that coating characteristics can be indeed correlated with the performance of DCB. For instance, paclitaxel incorporation in the matrix can reduce the drug wash-off and benefit a high drug transfer. Additionally, a thin coating with a smooth surface and high but delayed solubility can reduce drug wash-off and decrease particle burden. As a result, we suggest that it is very important to characterize DCB in terms of mentioned properties in vitro in addition to their clinical efficacy in order to better understand their function and provide more data for the clinicians to improve the tool of DCB in coronary angioplasty.


Assuntos
Antineoplásicos Fitogênicos/química , Materiais Revestidos Biocompatíveis/química , Stents Farmacológicos , Hidrogel de Polietilenoglicol-Dimetacrilato/química , Líquidos Iônicos/química , Paclitaxel/química , Angioplastia Coronária com Balão , Materiais Revestidos Biocompatíveis/síntese química , Ácido Hialurônico/química , Líquidos Iônicos/síntese química , Microscopia Confocal , Microscopia Eletrônica de Varredura , Modelos Biológicos , Povidona/química , Propriedades de Superfície
8.
Acta Biomater ; 10(12): 5081-5089, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25204522

RESUMO

As it has been demonstrated that bioactive substances can be delivered locally using coated surgical suture materials, the authors developed a vascular endothelial growth factor (VEGF)-releasing suture material that should promote vascularization and potentially wound healing. In this context, the study focused on the characterization of the developed suture material and the verification of its biological activity, as well as establishing a coating process that allows reproducible and stable coating of a commercially available polydioxanone suture material with poly(l-lactide) (PLLA) and 0.1µg and 1.0µg VEGF. The in vitro VEGF release kinetics was studied using a Sandwich ELISA. The biological activity of the released VEGF was investigated in vitro using human umbilical vein endothelial cells. The potential of the VEGF-releasing suture material was also studied in vivo 5days after implantation in the hind limb of Wistar rats, when the histological findings were analyzed. The essential results, enhanced cell viability in vitro as well as significantly increased vascularization in vivo, were achieved using PLLA/1.0µg VEGF-coated suture material. Furthermore, ELISA measurements revealed a high reproducibility of the VEGF release behavior. Based on the results achieved regarding the dose-effect relationship of VEGF, the stability during its processing and the release behavior, it can be predicted that a bioactive suture material would be successful in later in vivo studies. Therefore, this knowledge could be the basis for future studies, where bioactive substances with different modes of action are combined for targeted, overall enhancement of wound healing.


Assuntos
Indutores da Angiogênese/administração & dosagem , Vasos Sanguíneos/crescimento & desenvolvimento , Implantes de Medicamento/administração & dosagem , Células Endoteliais/fisiologia , Neovascularização Fisiológica/fisiologia , Suturas , Fator A de Crescimento do Endotélio Vascular/administração & dosagem , Indutores da Angiogênese/química , Animais , Vasos Sanguíneos/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Difusão , Implantes de Medicamento/química , Células Endoteliais/citologia , Células Endoteliais/efeitos dos fármacos , Humanos , Técnicas In Vitro , Masculino , Ratos , Ratos Wistar , Resultado do Tratamento , Fator A de Crescimento do Endotélio Vascular/química
9.
Eur J Pharm Biopharm ; 87(3): 570-8, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24801065

RESUMO

In vitro drug release testing is an appropriate approach to identify critical parameters helping to predict drug release from drug-eluting stents (DES) prior to studying drug release behavior under in vivo conditions. Drug release and distribution from DES coated with a fluorescent model substance were studied in vitro using the vessel-simulating flow-through cell equipped with different long-term stable hydrogel compartments composed of agarose, polyacrylamide or poly(vinyl alcohol). The obtained experimental results were compared with the results of finite-element modeling obtained using experimentally determined diffusion coefficients and partition coefficients. In spite of differences regarding these parameters, experimental and mathematical data yielded only minor differences between the different gels regarding the release and distribution behavior and reasonable agreement between the modeling and the experiment was obtained. In an attempt to further elucidate the dosage form behavior, the diffusion coefficients in the gel as well as in the stent coating were systematically varied in the finite-element model. Changes in the diffusivity in the stent coating mainly impacted on the initial concentrations. Slower diffusion inside the hydrogel yielded a retarded elution from the stent coating and a higher model substance accumulation in the gel compartment at late time points.


Assuntos
Stents Farmacológicos , Hidrogel de Polietilenoglicol-Dimetacrilato/química , Hidrogel de Polietilenoglicol-Dimetacrilato/metabolismo , Preparações Farmacêuticas/química , Preparações Farmacêuticas/metabolismo , Resinas Acrílicas/química , Materiais Revestidos Biocompatíveis/química , Materiais Revestidos Biocompatíveis/metabolismo , Difusão , Álcool de Polivinil/química , Sefarose/química , Distribuição Tecidual
10.
J Mater Sci Mater Med ; 25(8): 2003-15, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24811954

RESUMO

The high degree of clinical routine in percutaneous transluminal coronary angioplasty (PTCA) with and without stenting has not changed the fact that a large number of coronary heart disease patients are still affected by post-operative complications such as restenosis and thrombosis. Because re-endothelialization is the crucial aspect of wound healing after cardiovascular implant surgery, there is a need for modern biomaterials to aid endothelial cells in their adhesion and functional recovery post-stenting. This study systematically examines the potential of numerous chemical polymer modifications with regard to endothelialization. Poly(ε-caprolactone) (PCL) and its chemically activated forms are investigated in detail, as well as the impact of polymer surface morphology and precoating with matrix protein. Human umbilical vein endothelial cells (HUVECs) are used to characterize endothelial cell responses in terms of in vitro viability and adhesion. As a potential component in drug eluting implants, VEGF is applied as stimulus to boost endothelial cell proliferation on the polymer. In conclusion, plasma chemical activation of PCL combined with VEGF stimulation best enhances in vitro endothelialization. Examining the impact of morphological, chemical and biological modifications of PCL, this study makes an important new contribution towards the existing body of work on polymer endothelialization.


Assuntos
Endotélio Vascular/efeitos dos fármacos , Poliésteres/química , Fator A de Crescimento do Endotélio Vascular/farmacologia , Materiais Biocompatíveis , Endotélio Vascular/citologia , Células Endoteliais da Veia Umbilical Humana , Humanos , Microscopia Eletrônica , Propriedades de Superfície
11.
Mol Pharm ; 11(3): 665-72, 2014 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-24495124

RESUMO

Enhanced proliferation of human coronary artery smooth muscle cells (HCASMCs) and thereby formation of neointima is one of the factors contributing to failure of coronary stents. Even if the use of drug eluting stents (DES) and thereby the local delivery of cytotoxic compounds has significantly improved the clinical outcome, unselective cytotoxic effects are assumed to hamper clinical success. Novel pharmacological approaches are required to enhance cellular selectivity of locally delivered drugs. Cell specific overexpression of a drug transporter could be used to enhance cellular accumulation and therefore cell specificity. In the herein reported study we tested the possibility of cell specific transporter expression to enhance drug effects in HCASMCs. We generated adenoviral constructs to overexpress the organic cation transporter 1 (OCT1) under control of the promoter of SM22α, which had been previously reported as muscle cell specific gene. First the activity of the SM22α-promoter was assessed in various cell types supporting the notion of muscle cell specificity. Subsequently, the activity of the transporter was compared in infected HCAECs and HCASMCs revealing enhanced accumulation of substrate drugs in HCASMCs in presence of the SM22α-promoter. Testing the hypothesis that this kind of targeting might serve as a mechanism for cell-specific drug effects, we investigated the impact on paclitaxel treatment in HCASMC and HCAECs, showing significantly increased antiproliferative activity of this substrate drug on muscle cells. Taken together, our findings suggest that cell-specific expression of transport proteins serves as mechanism governing the uptake of cytotoxic compounds for a selective impact on targeted cells.


Assuntos
Vasos Coronários/metabolismo , Endotélio Vascular/metabolismo , Células Madin Darby de Rim Canino/metabolismo , Proteínas dos Microfilamentos/genética , Proteínas Musculares/genética , Músculo Liso Vascular/metabolismo , Miócitos Cardíacos/metabolismo , Transportador 1 de Cátions Orgânicos/metabolismo , Adenoviridae/genética , Animais , Antineoplásicos Fitogênicos/farmacologia , Western Blotting , Fármacos Cardiovasculares/farmacologia , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Vasos Coronários/citologia , Vasos Coronários/efeitos dos fármacos , Cães , Sistemas de Liberação de Medicamentos , Endotélio Vascular/citologia , Endotélio Vascular/efeitos dos fármacos , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Humanos , Células Madin Darby de Rim Canino/citologia , Células Madin Darby de Rim Canino/efeitos dos fármacos , Camundongos , Músculo Liso Vascular/citologia , Músculo Liso Vascular/efeitos dos fármacos , Miócitos Cardíacos/citologia , Miócitos Cardíacos/efeitos dos fármacos , Transportador 1 de Cátions Orgânicos/genética , Paclitaxel/farmacologia , Regiões Promotoras Genéticas/genética , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa
12.
Eur Heart J ; 35(12): 808-20, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24334406

RESUMO

BACKGROUND: Impaired re-endothelialization and stent thrombosis are a safety concern associated with drug-eluting stents (DES). PI3K/p110α controls cellular wound healing pathways, thereby representing an emerging drug target to modulate vascular homoeostasis after injury. METHODS AND RESULTS: PI3K/p110α was inhibited by treatment with the small molecule inhibitor PIK75 or a specific siRNA. Arterial thrombosis, neointima formation, and re-endothelialization were studied in a murine carotid artery injury model. Proliferation and migration of human vascular smooth muscle cell (VSMC) and endothelial cell (EC) were assessed by cell number and Boyden chamber, respectively. Endothelial senescence was evaluated by the ß-galactosidase assay, endothelial dysfunction by organ chambers for isometric tension. Arterial thrombus formation was delayed in mice treated with PIK75 when compared with controls. PIK75 impaired arterial expression and activity of tissue factor (TF) and plasminogen activator inhibitor-1 (PAI-1); in contrast, plasma clotting and platelet aggregation did not differ. In VSMC and EC, PIK75 inhibited expression and activity of TF and PAI-1. These effects occurred at the transcriptional level via the RhoA signalling cascade and the transcription factor NFkB. Furthermore, inhibition of PI3K/p110α with PIK75 or a specific siRNA selectively impaired proliferation and migration of VSMC while sparing EC completely. Treatment with PIK75 did not induce endothelial senescence nor inhibit endothelium-dependent relaxations. In line with this observation, treatment with PIK75 selectively inhibited neointima formation without affecting re-endothelialization following vascular injury. CONCLUSION: Following vascular injury, PI3K/p110α inhibition selectively interferes with arterial thrombosis and neointima formation, but not re-endothelialization. Hence, PI3K/p110α represents an attractive new target in DES design.


Assuntos
Stents Farmacológicos , Inibidores de Fosfoinositídeo-3 Quinase , Trombose/enzimologia , Animais , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Quimiotaxia/efeitos dos fármacos , Endotélio Vascular/enzimologia , GTP Fosfo-Hidrolases/metabolismo , Hidrazonas/farmacologia , Imunossupressores/farmacologia , Leucócitos Mononucleares/enzimologia , Masculino , Camundongos Endogâmicos C57BL , Músculo Liso Vascular/efeitos dos fármacos , Neointima/enzimologia , Óxido Nítrico/biossíntese , Paclitaxel/farmacologia , Inibidor 1 de Ativador de Plasminogênio/metabolismo , Inibidores de Proteínas Quinases/farmacologia , Proteínas Serina-Treonina Quinases/metabolismo , Interferência de RNA , RNA Interferente Pequeno/farmacologia , Sirolimo/farmacologia , Sulfonamidas/farmacologia , Fator de Necrose Tumoral alfa/metabolismo
13.
J Biomed Mater Res B Appl Biomater ; 102(2): 345-55, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24000221

RESUMO

Aiming at a speed up of the re-endothelialization process of biodegradable endovascular implants, novel approaches for the functionalization of poly(l-lactide) (PLLA) with anti-CD34 antibodies were established. We propose a three-step process involving PLLA surface activation with functional amino groups, attachment of a protein repelling peptide spacer, and covalent random or site-selective immobilization of the antibodies. Obtainable antibody surface densities and antigen binding capacities were thoroughly evaluated by means of enzyme-linked immunosorbent assay. Results indicate that a lower amount of anchoring sites on the antibody favors high coupling efficiency, while localization of the anchoring sites, facing the antigen binding moiety, strongly enhances the antigen capture capacity of the support. Besides minimization of physisorption and cell adhesion exemplarily shown with bovine serum albumin, avidin, and human umbilical vein endothelial cells, respectively, the inclusion of the protein-repelling spacer strengthened this effect, yielding antigen capture capacities exceeding values so far reported in literature. In contrast, the number of amino groups on the PLLA surfaces, which is indeed highly dependent on the applied activation procedure, does not seem to influence antibody coupling efficiency and antigen capture capacity considerably. This allows the choice of surface activation treatment, plasma or wet-chemical, regarding other processing parameters as for instance sterilizability or favored modification depth.


Assuntos
Anticorpos/química , Antígenos CD34 , Prótese Vascular , Proteínas Imobilizadas/química , Poliésteres/química , Desenho de Prótese , Animais , Bovinos , Humanos , Camundongos , Peptídeos/química
14.
Acta Biomater ; 10(2): 688-700, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24148751

RESUMO

Despite the development of new coronary stent technologies, in-stent restenosis and stent thrombosis are still clinically relevant. Interactions of blood and tissue cells with the implanted material may represent an important cause of these side effects. We hypothesize material-dependent interaction of blood and tissue cells. The aim of this study is accordingly to investigate the impact of vascular endothelial cells, smooth muscle cells and platelets with various biodegradable polymers to identify a stent coating or platform material that demonstrates excellent endothelial-cell-supportive and non-thrombogenic properties. Human umbilical venous endothelial cells, human coronary arterial endothelial cells and human coronary arterial smooth muscle cells were cultivated on the surfaces of two established biostable polymers used for drug-eluting stents, namely poly(ethylene-co-vinylacetate) (PEVA) and poly(butyl methacrylate) (PBMA). We compared these polymers to new biodegradable polyesters poly(l-lactide) (PLLA), poly(3-hydroxybutyrate) (P(3HB)), poly(4-hydroxybutyrate) (P(4HB)) and a polymeric blend of PLLA/P(4HB) in a ratio of 78/22% (w/w). Biocompatibility tests were performed under static and dynamic conditions. Measurement of cell proliferation, viability, glycocalix width, eNOS and PECAM-1 mRNA expression revealed strong material dependency among the six polymer samples investigated. Only the polymeric blend of PLLA/P(4HB) achieved excellent endothelial markers of biocompatibility. Data show that PLLA and P(4HB) tend to a more thrombotic response, whereas the polymer blend is characterized by a lower thrombotic potential. These data demonstrate material-dependent endothelialization, smooth muscle cell growth and thrombogenicity. Although polymers such as PEVA and PBMA are already commonly used for vascular implants, they did not sufficiently meet the criteria for biocompatibility. The investigated biodegradable polymeric blend PLLA/P(4HB) evidently represents a promising material for vascular stents and stent coatings.


Assuntos
Plaquetas/citologia , Comunicação Celular/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana/citologia , Miócitos de Músculo Liso/citologia , Polímeros/farmacologia , Stents , Biomarcadores/metabolismo , Plaquetas/efeitos dos fármacos , Plaquetas/metabolismo , Plaquetas/ultraestrutura , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Materiais Revestidos Biocompatíveis/farmacologia , Glicocálix/metabolismo , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana/enzimologia , Humanos , Miócitos de Músculo Liso/efeitos dos fármacos , Miócitos de Músculo Liso/metabolismo , Óxido Nítrico Sintase Tipo III/metabolismo , Selectina-P/metabolismo , Adesividade Plaquetária/efeitos dos fármacos , Agregação Plaquetária/efeitos dos fármacos , Molécula-1 de Adesão Celular Endotelial a Plaquetas/metabolismo , Reologia/efeitos dos fármacos , Estresse Mecânico , Propriedades de Superfície
15.
Biomacromolecules ; 14(11): 3985-96, 2013 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-24088140

RESUMO

Novel biodegradable materials with tunable hydrolytic degradation rate are prepared by grafting of phosphonoethylated polyglycidols with polyesters. First, the hydrolytically degradable polyester grafts are attached to polyglycidols partially grafted with phosphonoethylated diethyl esters through chemical-catalyzed grafting using tin(II) octanoate, then the diethyl ester groups are chemoselectively converted to the corresponding monoester (mixed phosphonate/phosphonic acid) using alkali metal halides. The products are characterized by means of (1)H, (13)C, and (31)P NMR spectroscopy, as well as size-exclusion chromatography and differential scanning calorimetry. The in vitro degradation of the copolymers is studied in phosphate buffered solution at 55 °C. The copolymers are of the same architecture, molecular weight, and crystallinity, only differing in the pendant phosphonate and mixed phosphonate/phosphonic acid groups, respectively. On the basis of mass loss, decrease of the molecular weight, and morphological analysis of the copolymers, the strong impact of mixed phosphonate/phosphonic acid groups on the hydrolytic degradation rate is demonstrated.


Assuntos
Ésteres/química , Poliésteres/química , Propilenoglicóis/química , Animais , Fibroblastos , Hidrólise , Camundongos , Estrutura Molecular , Propilenoglicóis/síntese química
16.
Mater Sci Eng C Mater Biol Appl ; 33(7): 4244-50, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23910339

RESUMO

Drug-coated balloons (DCB), which have emerged as therapeutic alternative to drug-eluting stents in percutaneous cardiovascular intervention, are well described with regard to clinical efficiency and safety within a number of clinical studies. In vitro studies elucidating the correlation of coating method and composition with DCB performance are however rare but considered important for the understanding of DCB requirements and the improvement of established DCB. In this context, we evaluated the applicability of a pipetting, dip-coating, and spray-coating process for the establishment of DCB based on paclitaxel (PTX) and the ionic liquid cetylpyridinium salicylate (Cetpyrsal) as novel innovative additive in three different compositions. Among tested methods and compositions, the pipetting process with 50 wt.% PTX resulted in most promising coatings as drug load was less controllable by the other processes and higher PTX contents led to considerable drug crystallization, as visualized by electron microscopy, accelerating PTX loss during short-term elution. Applying these conditions, homogeneous coatings could be applied on balloon catheter, whose simulated use in an in vitro vessel model revealed percental drug losses of 36 and 28% during transit and percental drug transfers of 12 and 40% under expansion for coatings applied in expanded and folded balloon condition, respectively. In comparison to literature values, these results support the high potential of Cetpyrsal as novel DCB matrix regarding low drug loss and efficient drug transfer.


Assuntos
Angioplastia com Balão , Cateterismo , Cetilpiridínio/química , Cetilpiridínio/síntese química , Materiais Revestidos Biocompatíveis/síntese química , Modelos Teóricos , Paclitaxel/farmacologia , Materiais Revestidos Biocompatíveis/química , Simulação por Computador , Humanos , Microscopia Eletrônica de Varredura , Tamanho da Partícula , Silicones
17.
AAPS PharmSciTech ; 14(3): 1209-18, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23918507

RESUMO

The vessel-simulating flow-through cell (vFTC) has been used to examine release and distribution from drug-eluting stents in an in vitro model adapted to the stent placement in vivo. The aim of this study was to examine the effect of the admixture of different hydrophobic additives to the vessel wall simulating hydrogel compartment on release and distribution from model substance-coated stents. Four alginate-based gel formulations containing reversed-phase column microparticles LiChroprep® RP-18 or medium-chain triglycerides in form of preprocessed oil-in-water emulsions Lipofundin® MCT in different concentrations were successfully developed. Alginate and modified gels were characterized regarding the distribution coefficient for the fluorescent model substances, fluorescein and triamterene, and release as well as distribution of model substances from coated stents were investigated in the vFTC. Distribution coefficients for the hydrophobic model substance triamterene and the hydrophobized gel formulations were up to four times higher than for the reference gel. However, comparison of the obtained release profiles yielded no major differences in dissolution and distribution behavior for both fluorescent model substances (fluorescein, triamterene). Comparison of the test results with mathematically modeled data acquired using finite element methods demonstrated a good agreement between modeled data and experimental results indicating that gel hydrophobicity will only influence release in cases of fast releasing stent coatings.


Assuntos
Alginatos/química , Stents Farmacológicos , Hidrogéis/química , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Interações Hidrofóbicas e Hidrofílicas
18.
Biomed Tech (Berl) ; 58(5): 417-27, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23979120

RESUMO

Implants providing controlled, local release of active substances are of interest in different medical applications. Therefore, the focus of the present article is the development of implant-associated diffusion- or chemically controlled local drug delivery (LDD) systems based on biodegradable polymeric drug carriers. In this context, we provide new data and review our own recently published data concerning the drug release behavior of diffusion-controlled LDD systems in relation to the kind of polymer, drug content, coating mass/thickness, and layer composition. We demonstrate that polymers allow a wide range of control over the drug release characteristics. In this regard, we show that the glass transition temperature of a polymer has an impact on its drug release. Additionally, the blending of hydrophobic, semicrystalline polymers with amorphous polymers leads to an increase in the rate of drug release compared with the pure semicrystalline polymer. Moreover, the percentage loading of the embedded drug has a considerable effect on the rate and duration of drug release. Furthermore, we discuss chemically controlled LDD systems designed for the release of biomolecules, such as growth factors, as well as nanoparticle-mediated LDD systems. With our own published data on drug-eluting stents, microstents, and cochlear implants, we highlight exemplary implant-associated LDD systems designed to improve implant performance through the reduction of undesirable effects such as in-stent restenosis and fibrosis.


Assuntos
Implantes Absorvíveis , Preparações de Ação Retardada/administração & dosagem , Preparações de Ação Retardada/química , Stents Farmacológicos , Polímeros/síntese química , Difusão , Desenho de Fármacos , Teste de Materiais , Desenho de Prótese
19.
J Mater Sci Mater Med ; 24(11): 2589-600, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23846839

RESUMO

Within the context of novel stent designs we developed a dual drug-eluting stent (DDES) with an abluminally focussed release of the potent anti-proliferative drug sirolimus and a luminally focussed release of atorvastatin with stabilizing effect on atherosclerotic deposits and stimulating impact on endothelial function, both from biodegradable poly(L-lactide)-based stent coatings. With this concept we aim at simultaneous inhibition of in-stent restenosis as a result of disproportionally increased smooth muscle cell proliferation and migration as well as thrombosis due to failed or incomplete endothelialisation. The especially adapted spray-coating processes allowed the formation of smooth form-fit polymer coatings at the abluminal and luminal side with 70% respectively 90% of the drug/polymer solution being deposited at the intended stent surface. The impacts of tempering, sterilization, and layer composition on drug release are thoroughly discussed making use of a semi-empirical model. While tempering at 80 °C seems to be necessary for the achievement of adequate and sustained drug release, the coating sequence for DDES should be rather abluminal-luminal than luminal-abluminal, as reduction of the amount of sirolimus eluted luminally could then potentially minimize the provocation of endothelial dysfunction. In vitro proliferation and viability assays with smooth muscle and endothelial cells underline the high potential of the developed DDES.


Assuntos
Stents Farmacológicos , Ácidos Heptanoicos/administração & dosagem , Pirróis/administração & dosagem , Sirolimo/administração & dosagem , Atorvastatina , Varredura Diferencial de Calorimetria , Proliferação de Células , Células Cultivadas , Ácidos Heptanoicos/farmacologia , Humanos , Técnicas In Vitro , Microscopia Eletrônica de Varredura , Peso Molecular , Pirróis/farmacologia , Sirolimo/farmacologia
20.
Curr Eye Res ; 38(10): 1057-63, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23885713

RESUMO

PURPOSE: For developing injectable lenses the retention properties of the capsular bag are important. Therefore the apparent permeability coefficients of sodium fluorescein and fluorescent dextrans of different sizes were determined for the human anterior lens capsule to calculate a molecular weight cutoff from these data. In addition, permeability coefficients of drugs helpful for the suppression of secondary cataract were determined. MATERIALS AND METHODS: Capsulorhexis specimens were fixed in a specially designed two compartment diffusion chamber to investigate the permeation of sodium fluorescein and fluorescent dextrans of different sizes (10, 40, 70 and 150 kDa) for 24 h (n ≥ 3) and of the antiproliferative drugs actinomycin D and methotrexate for 0.5, 24, 48 and 72 h (n ≥ 3). RESULTS: The molecular weight cutoff of the anterior lens capsule was found to be 166 ± 82 kDa. After 0.5 h, no passage of actinomycin D and methotrexate was detectable through the lens capsule. The apparent permeability coefficients for actinomycin D and methotrexate were calculated to 0.71 ± 0.02 µm/s and to 0.80 ± 0.13 µm/s, respectively. CONCLUSIONS: The capsular bag retains fluorescent dextrans with a molecular weight of >166 kDa. Hence, prepolymers are required to polymerize rapidly to be retained inside of the capsular bag. In addition, low-molecular substances intended as antiproliferative drugs for secondary cataract prevention should be applied within a time frame of five minutes in such a way that cells adjacent to the capsular bag will not be damaged.


Assuntos
Catarata/tratamento farmacológico , Catarata/metabolismo , Corantes Fluorescentes/farmacocinética , Cápsula do Cristalino/metabolismo , Metotrexato/farmacocinética , Modelos Biológicos , Catarata/prevenção & controle , Dextranos/química , Dextranos/farmacocinética , Cultura em Câmaras de Difusão , Corantes Fluorescentes/química , Humanos , Imunossupressores/química , Imunossupressores/farmacocinética , Cápsula do Cristalino/efeitos dos fármacos , Metotrexato/química , Peso Molecular , Permeabilidade , Polímeros/metabolismo
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