RESUMO
Adaptive drug release can combat coagulation and inflammation activation at the blood-material interface with minimized side effects. For that purpose, poly(styrene-alt-maleic-anhydride) copolymers were conjugated to heparin via coagulation-responsive linker peptides and shown to tightly adsorb onto poly(ethersulfone) (PES)-surfaces from aqueous solutions as monolayers. Coagulation-responsive release of unfractionated as well as low molecular weight heparins from the respective coatings was demonstrated to be functionally beneficial in human plasma and whole blood incubation with faster release kinetics resulting in stronger anticoagulant effects. Coated poly(ethersulfone)/poly(vinylpyrrolidone) (PES/PVP) flat membranes proved the technology to offer an easy, effective and robust anticoagulant interfacial functionalization of hemodialysis membranes. In perspective, the modularity of the adaptive release system will be used for inhibiting multiple activation processes.
Assuntos
Coagulação Sanguínea , Polímeros , Humanos , Polímeros/química , Heparina/química , Anticoagulantes/farmacologia , EstirenoRESUMO
Hydrogel coatings can improve the biocompatibility of medical devices. However, stable surface bonding and homogeneity of hydrogel coatings are often challenging. This study exploits the benefits of biohybrid hydrogels of crosslinked four-armed poly(ethylene glycol) and heparin to enhance the hemocompatibility of cobaltchromium (CoCr) vascular stents. A bonding layer of dual silane and poly(ethylene-alt-maleic anhydride) (PEMA) treatment was applied to the stent to provide covalent immobilization and hydrophilicity for the homogeneous spreading of the hydrogel. A spray coating technology was used to distribute the aqueous solution of the reactive hydrogel precursors onto the sub-millimeter struts of the stents, where the solution polymerized to a homogeneous hydrogel film. The coating was mechanically stable on the stent after ethanol dehydration, and the stents could be stored in a dry state. The homogeneity and stability of the coating during stent expansion were verified. Quasistatic and dynamic whole blood incubation experiments showed substantial suppression of the pro-coagulant and inflammatory activity of the bare metal by the coating. Translation of the technology to industrial coating devices and future surface modification of stents with anti-inflammatory hydrogels are discussed.
Assuntos
Heparina , Hidrogéis , Interações Hidrofóbicas e Hidrofílicas , Polietilenoglicóis , StentsRESUMO
Poly(ethylene glycol) (PEG)-glycosaminoglycan (GAG) hydrogel networks are established as very versatile biomaterials. Herein, the synthetic gel component of the biohybrid materials is systematically varied by combining different poly(2-alkyl-2-oxazolines) (POx) with heparin applying a Michael-type addition crosslinking scheme: POx of gradated hydrophilicity and temperature-responsiveness provides polymer networks of distinctly different stiffness and swelling. Adjusting the mechanical properties and the GAG concentration of the gels to similar values allows for modulating the release of GAG-binding growth factors (VEGF165 and PDGF-BB) by the choice of the POx and its temperature-dependent conformation. Adsorption of fibronectin, growth of fibroblasts, and bacterial adhesion scale with the hydrophobicity of the gel-incorporated POx. In vitro hemocompatibility tests with freshly drawn human whole blood show advantages of POx-based gels compared to the PEG-based reference materials. Biohybrid POx hydrogels can therefore enable biomedical technologies requiring GAG-based materials with customized and switchable physicochemical characteristics.
Assuntos
Heparina , Hidrogéis , Materiais Biocompatíveis , Glicosaminoglicanos , Humanos , PolietilenoglicóisRESUMO
Precision surface engineering is key to advanced biomaterials. A new platform of PEGylated styrene-maleic acid copolymers for adsorptive surface biofunctionalization is reported. Balanced amphiphilicity renders the copolymers water-soluble but strongly affine for surfaces. Fine-tuning of their molecular architecture provides control over adsorptive anchorage onto specific materials-which is why they are referred to as "anchor polymers" (APs)-and over structural characteristics of the adsorbed layers. Conjugatable with an array of bioactives-including cytokine-complexing glycosaminoglycans, cell-adhesion-mediating peptides and antimicrobials-APs can be applied to customize materials for demanding biotechnologies in uniquely versatile, simple, and robust ways. Moreover, homo- and heterodisplacement of adsorbed APs provide unprecedented means of in situ alteration and renewal of the functionalized surfaces. The related options are exemplified with proof-of-concept experiments of controlled bacterial adhesion, human umbilical vein endothelial cell, and induced pluripotent cell growth on AP-functionalized surfaces.
Assuntos
Materiais Biocompatíveis/química , Polímeros/química , Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Materiais Biocompatíveis/farmacologia , Adesão Celular/efeitos dos fármacos , Citocinas/química , Glicosaminoglicanos/química , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana , Humanos , Células-Tronco Pluripotentes Induzidas/citologia , Células-Tronco Pluripotentes Induzidas/metabolismo , Maleatos/química , Oligopeptídeos/química , Polietilenoglicóis/química , Polímeros/farmacologia , Estireno/química , Propriedades de SuperfícieRESUMO
The mechanical properties of cancer cells and their microenvironment contribute to breast cancer progression. While mechanosensing has been extensively studied using 2D substrates, much less is known about it in a physiologically more relevant 3D context. Here it is demonstrated that breast cancer tumor spheroids, growing in 3D polyethylene glycol-heparin hydrogels, are sensitive to their environment stiffness. During tumor spheroid growth, compressive stresses of up to 2 kPa build up, as quantitated using elastic polymer beads as stress sensors. Atomic force microscopy reveals that tumor spheroid stiffness increases with hydrogel stiffness. Also, constituent cell stiffness increases in a Rho associated kinase (ROCK)- and F-actin-dependent manner. Increased hydrogel stiffness correlated with attenuated tumor spheroid growth, a higher proportion of cells in G0/G1 phase, and elevated levels of the cyclin-dependent kinase inhibitor p21. Drug-mediated ROCK inhibition not only reverses cell stiffening upon culture in stiff hydrogels but also increases tumor spheroid growth. Taken together, a mechanism by which the growth of a tumor spheroid can be regulated via cytoskeleton rearrangements in response to its mechanoenvironment is revealed here. Thus, the findings contribute to a better understanding of how cancer cells react to compressive stress when growing under confinement in stiff environments.
Assuntos
Inibidor de Quinase Dependente de Ciclina p21/genética , Regulação Neoplásica da Expressão Gênica , Hidrogéis/farmacologia , Mecanotransdução Celular/genética , Esferoides Celulares/efeitos dos fármacos , Quinases Associadas a rho/genética , Resinas Acrílicas/química , Resinas Acrílicas/farmacologia , Actinas/genética , Actinas/metabolismo , Fenômenos Biomecânicos , Técnicas de Cultura de Células , Proliferação de Células/efeitos dos fármacos , Inibidor de Quinase Dependente de Ciclina p21/metabolismo , Feminino , Pontos de Checagem da Fase G1 do Ciclo Celular/genética , Heparina/química , Heparina/farmacologia , Humanos , Hidrogéis/síntese química , Células MCF-7 , Polietilenoglicóis/química , Polietilenoglicóis/farmacologia , Análise de Célula Única/métodos , Esferoides Celulares/metabolismo , Esferoides Celulares/patologia , Microambiente Tumoral/efeitos dos fármacos , Microambiente Tumoral/genética , Quinases Associadas a rho/metabolismoRESUMO
We present the synthesis of hydrogel microbeads based on telechelic poly(2-oxazoline) (POx) crosslinkers and the methacrylate monomers (HEMA, METAC, SPMA) by inverse emulsion polymerization. While in batch experiments only irregular and ill-defined beads were obtained, the preparation in a microfluidic (MF) device resulted in highly defined hydrogel microbeads. Variation of the MF parameters allowed to control the microbead diameter from 50 to 500 µm. Microbead elasticity could be tuned from 2 to 20 kPa by the POx:monomer composition, the POx chain length, net charge of the hydrogel introduced via the monomer as well as by the organic content of the aqueous phase. The proliferations of human mesenchymal stem cells (hMSCs) on the microbeads were studied. While neutral, hydrophilic POx-PHEMA beads were bioinert, excessive colonization of hMSCs on charged POx-PMETAC and POx-PSPMA was observed. The number of proliferated cells scaled roughly linear with the METAC or SPMA comonomer content. Additional collagen I coating further improved the stem cell proliferation. Finally, a first POx-based system for the preparation of biodegradable hydrogel microcarriers is described and evaluated for stem cell culturing.