RESUMO
OBJECTIVES: Our study aims at producing acellular extracellular matrix scaffolds from the human pancreas (hpaECMs) as a first critical step toward the production of a new-generation, fully human-derived bioartificial endocrine pancreas. In this bioartificial endocrine pancreas, the hardware will be represented by hpaECMs, whereas the software will consist in the cellular compartment generated from patient's own cells. BACKGROUND: Extracellular matrix (ECM)-based scaffolds obtained through the decellularization of native organs have become the favored platform in the field of complex organ bioengineering. However, the paradigm is now switching from the porcine to the human model. METHODS: To achieve our goal, human pancreata were decellularized with Triton-based solution and thoroughly characterized. Primary endpoints were complete cell and DNA clearance, preservation of ECM components, growth factors and stiffness, ability to induce angiogenesis, conservation of the framework of the innate vasculature, and immunogenicity. Secondary endpoint was hpaECMs' ability to sustain growth and function of human islet and human primary pancreatic endothelial cells. RESULTS: Results show that hpaECMs can be successfully and consistently produced from human pancreata and maintain their innate molecular and spatial framework and stiffness, and vital growth factors. Importantly, hpaECMs inhibit human naïve CD4 T-cell expansion in response to polyclonal stimuli by inducing their apoptosis and promoting their conversion into regulatory T cells. hpaECMs are cytocompatible and supportive of representative pancreatic cell types. DISCUSSION: We, therefore, conclude that hpaECMs has the potential to become an ideal platform for investigations aiming at the manufacturing of a regenerative medicine-inspired bioartificial endocrine pancreas.
Assuntos
Matriz Extracelular/metabolismo , Pâncreas , Engenharia Tecidual , Alicerces Teciduais , Humanos , Ilhotas Pancreáticas/metabolismo , Organogênese , Pâncreas/metabolismo , Regeneração , Engenharia Tecidual/métodosRESUMO
OBJECTIVE: To evaluate the mechanical property and biocompatibility of the Wnt pathway inhibitor (ICG-001) delivering collagen/poly(L-lactide-co-caprolactone) (P(LLA-CL)) scaffold for urethroplasty, and also the feasibility of inhibiting the extracellular matrix (ECM) expression in vitro and in vivo. METHODS: ICG-001 (1 mg (2 mM)) was loaded into a (P(LLA-CL)) scaffold with the co-axial electrospinning technique. The characteristics of the mechanical property and drug release fashion of scaffolds were tested with a mechanical testing machine (Instron) and high-performance liquid chromatography (HPLC). Rabbit bladder epithelial cells and the dermal fibroblasts were isolated by enzymatic digestion method. (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) assay) and scanning electron microscopy (SEM) were used to evaluate the viability and proliferation of the cells on the scaffolds. Fibrolasts treated with TGF-ß1 and ICG-001 released medium from scaffolds were used to evaluate the anti-fibrosis effect through immunofluorescence, real time PCR and western blot. Urethrography and histology were used to evaluate the efficacy of urethral implantation. RESULTS: The scaffold delivering ICG-001 was fabricated, the fiber diameter and mechanical strength of scaffolds with inhibitor were comparable with the non-drug scaffold. The SEM and MTT assay showed no toxic effect of ICG-001 to the proliferation of epithelial cells on the collagen/P(LLA-CL) scaffold with ICG-001. After treatment with culture medium released from the drug-delivering scaffold, the expression of Collagen type 1, 3 and fibronectin of fibroblasts could be inhibited significantly at the mRNA and protein levels. In the results of urethrography, urethral strictures and fistulas were found in the rabbits treated with non-ICG-001 delivering scaffolds, but all the rabbits treated with ICG-001-delivering scaffolds showed wide caliber in urethras. Histology results showed less collagen but more smooth muscle and thicker epithelium in urethras repaired with ICG-001 delivering scaffolds. CONCLUSION: After loading with the Wnt signal pathway inhibitor ICG-001, the Collagen/P(LLA-CL) scaffold could facilitate a decrease in the ECM deposition of fibroblasts. The ICG-001 delivering Collagen/P(LLA-CL) nanofibrous scaffold seeded with epithelial cells has the potential to be a promising substitute material for urethroplasty. Longer follow-up study in larger animals is needed in the future.
Assuntos
Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Pirimidinonas/farmacologia , Alicerces Teciduais , Estreitamento Uretral/metabolismo , Estreitamento Uretral/patologia , Via de Sinalização Wnt/efeitos dos fármacos , Animais , Compostos Bicíclicos Heterocíclicos com Pontes/administração & dosagem , Compostos Bicíclicos Heterocíclicos com Pontes/química , Proliferação de Células , Colágeno Tipo I/genética , Colágeno Tipo I/metabolismo , Constrição Patológica/tratamento farmacológico , Constrição Patológica/metabolismo , Preparações de Ação Retardada , Sistemas de Liberação de Medicamentos , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , Células Epiteliais/ultraestrutura , Fibrose/tratamento farmacológico , Masculino , Pirimidinonas/administração & dosagem , Pirimidinonas/química , Coelhos , Engenharia Tecidual , Alicerces Teciduais/química , Fator de Crescimento Transformador beta1/genética , Fator de Crescimento Transformador beta1/metabolismo , Uretra , Estreitamento Uretral/diagnóstico , Estreitamento Uretral/tratamento farmacológico , Estreitamento Uretral/cirurgiaRESUMO
BACKGROUND AND OBJECTIVE: Regenerative medicine involves the bioengineering of a functional tissue or organ by seeding living cells on a biodegradable scaffold cultured in a bioreactor. A major barrier to creating functional tissues, however, has been the inability to monitor the dynamic and complex process of scaffold maturation in real time, making control and optimization extremely difficult. Current methods to assess maturation of bioengineered constructs, such as histology or organ bath physiology, are sample-destructive. Optical coherence tomography (OCT) has recently emerged as a key modality for structural assessment of native blood vessels as well as engineered vessel mimics. The objective of this study was to monitor and assess in real time the development of a bioengineered blood vessel using a novel approach of combining both free-space and catheter-based OCT imaging in a new quartz-walled bioreactor. Development of the blood vessel was characterized by changes in thickness and scattering coefficient over a 30-day period. MATERIALS AND METHODS: We constructed a novel blood vessel bioreactor utilizing a rotating cylindrical quartz cuvette permitting free-space OCT imaging of an installed vessel's outer surface. A vascular endoscopic OCT catheter was used to image the lumen of the vessels. The quartz cuvette permits 360 degree, free-space OCT imaging of the blood vessel. Bioengineered blood vessels were fabricated using biodegradable polymers (15% PCL/collagen, â¼300 µm thick) and seeded with CH3 10t1/2 mesenchymal stem cells. A swept-source OCT imaging system comprised of a 20 kHz tunable laser (Santec HSL2000) with 1,300 nm central wavelength and 110 nm FWHM bandwidth was used to assess the vessels. OCT images were obtained at days 1, 4, 7, 14, 21, and 30. Free-space (exterior surface) OCT images were co-registered with endoscopic OCT images to determine the vessel wall thickness. DAPI-stained histological sections, acquired at same time point, were evaluated to quantify wall thickness and cellular infiltration. Non-linear curve fitting of free-space OCT data to the extended Huygen-Fresnel model was performed to determine optical scattering properties. RESULTS: Vessel wall thickness increased from 435 ± 15 µm to 610 ± 27 µm and Vessel scattering coefficient increased from 3.73 ± 0.32 cm⻹ to 5.74 ± 0.06 cm⻹ over 30 days. Histological studies showed cell migration from the scaffold surface toward the lumen and cell proliferation over the same time course. The imaging procedure did not have any significant impact on scaffold dimensions, cell migration, or cell proliferation. CONCLUSIONS: This study suggests that combination of free-space and catheter-based OCT for blood vessel imaging provides accurate structural information of the developing blood vessel. We determined that free-space OCT images could be co-registered with catheter-based OCT images to monitor structural features such as wall thickness or delamination of the developing tissue-engineered blood vessel within a bioreactor. Structural parameters and optical properties obtained from OCT imaging correlate with histological sections of the blood vessel and could potentially be used as markers to non-invasively and non-destructively assess regeneration of engineered tissues in real time.
Assuntos
Reatores Biológicos , Vasos Sanguíneos , Engenharia Tecidual/métodos , Alicerces Teciduais , Tomografia de Coerência Óptica/métodos , Vasos Sanguíneos/anatomia & histologia , Vasos Sanguíneos/fisiologia , Catéteres , Movimento Celular , Proliferação de Células , Humanos , Células-Tronco Mesenquimais , Quartzo , Engenharia Tecidual/instrumentação , Tomografia de Coerência Óptica/instrumentaçãoRESUMO
The reactive thermal-sensitive hydrogels, which combined the reversible thermosensitive and mild reactive property, were designed based on thiol-ene reaction in physiological conditions between thiol and acrylate capped thermosensitive Poloxamer 188. The modified P188A, P188SH, and their reactivity were characterized by (1)H NMR, FT-IR, GPC, DSC, Ellman method, and Rheometer. It was found that the thiol-ene reaction was pH and thermal-sensitive. There was 77.7% SH involved into the reaction at 37.0 degrees C and pH 7.4 within the first 30 min. The most of molecules reacted as CC/SH mol ratio was 1.5. The exothermic thiol-ene reaction was mild, with about DeltaH = -91.18 J/g changes. The multiblocks or network structure limited the dissolution of hydrogel, correspondingly the gel's duration and the release time of methylene blue were prolonged to 124 h. The experimental results indicated the reactive thermal-sensitive hydrogel's potential applications in drug delivery, tissue engineering, and cell encapsulation.
Assuntos
Acrilatos/química , Polietilenoglicóis/química , Polímeros/química , Propilenoglicóis/química , Compostos de Sulfidrila/química , Materiais Biocompatíveis/química , Varredura Diferencial de Calorimetria/métodos , Cromatografia Gasosa/métodos , Sistemas de Liberação de Medicamentos , Géis/química , Hidrogéis/química , Concentração de Íons de Hidrogênio , Espectroscopia de Ressonância Magnética , Conformação Molecular , Espectroscopia de Infravermelho com Transformada de Fourier , Engenharia Tecidual/métodosRESUMO
Real-time, quantitative measurement of muscle progenitor cell (myoblast) differentiation is an important tool for skeletal muscle research and identification of drugs that support skeletal muscle regeneration. While most quantitative tools rely on sacrificial approach, we developed a double fluorescent tagging approach, which allows for dynamic monitoring of myoblast differentiation through assessment of fusion index and nuclei count. Fluorescent tagging of both the cell cytoplasm and nucleus enables monitoring of cell fusion and the formation of new myotube fibers, similar to immunostaining results. This labeling approach allowed monitoring the effects of Myf5 overexpression, TNFα, and Wnt agonist on myoblast differentiation. It also enabled testing the effects of surface coating on the fusion levels of scaffold-seeded myoblasts. The double fluorescent labeling of myoblasts is a promising technique to visualize even minor changes in myogenesis of myoblasts in order to support applications such as tissue engineering and drug screening.
Assuntos
Corantes Fluorescentes/metabolismo , Desenvolvimento Muscular , Músculo Esquelético/metabolismo , Animais , Diferenciação Celular , Linhagem Celular , Camundongos , Músculo Esquelético/citologia , Músculo Esquelético/crescimento & desenvolvimento , Fator Regulador Miogênico 5/genética , Fator de Crescimento Transformador alfa/metabolismo , Proteínas Wnt/agonistasRESUMO
The argonaute protein from the thermophilic bacterium Thermus thermophilus shows DNA-guided DNA interfering activity at high temperatures, complicating its application in mammalian cells. A recent work reported that the argonaute protein from Natronobacterium gregoryi (NgAgo) had DNA-guided genome editing activity in mammalian cells. We compared the genome editing activities of NgAgo and Staphylococcus aureus Cas9 (SaCas9) in human HEK293T cells side by side. EGFP reporter assays and DNA sequencing consistently revealed high genome editing activity from SaCas9. However, these assays did not demonstrate genome editing activity by NgAgo. We confirmed that the conditions allowed simultaneous transfection of the NgAgo expressing plasmid DNA and DNA guides, as well as heterologous expression of NgAgo in the HEK293T cells. Our data show that NgAgo is not a robust genome editing tool, although it may have such activity under other conditions.
Assuntos
Proteínas Argonautas/genética , Natronobacterium/genética , Proteínas Argonautas/metabolismo , Western Blotting , Edição de Genes , Genoma Humano/genética , Células HEK293 , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Plasmídeos/genética , Staphylococcus aureus/genética , Staphylococcus aureus/metabolismo , Thermus thermophilus/genética , Thermus thermophilus/metabolismoRESUMO
Fluorescent protein imaging, a promising tool in biological research, incorporates numerous applications that can be of specific use in the field of regenerative medicine. To enhance tissue regeneration efforts, scientists have been developing new ways to monitor tissue development and maturation in vitro and in vivo. To that end, new imaging tools and novel fluorescent proteins have been developed for the purpose of performing deep-tissue high-resolution imaging. These new methods, such as intra-vital microscopy and Förster resonance energy transfer, are providing new insights into cellular behavior, including cell migration, morphology, and phenotypic changes in a dynamic environment. Such applications, combined with multimodal imaging, significantly expand the utility of fluorescent protein imaging in research and clinical applications of regenerative medicine.
RESUMO
ß-Cell replacement through transplantation is the only curative treatment to establish a long-term stable euglycemia in diabetic patients. Owing to the shortage of donor tissue, attempts are being made to develop alternative sources of insulin-secreting cells. Stem cells differentiation and reprograming as well as isolating pancreatic progenitors from different sources are some examples; however, no approach has yet yielded a clinically relevant solution. Dissociated islet cells that are cultured in cell numbers by in vitro proliferation provide a promising platform for redifferentiation towards ß-cells phenotype. In this study, we cultured islet-derived cells in vitro and examined the expression of ß-cell genes during the proliferation. Islets were isolated from porcine pancreases and enzymatically digested to dissociate the component cells. The cells proliferated well in tissue culture plates and were subcultured for no more than 5 passages. Only 10% of insulin expression, as measured by PCR, was preserved in each passage. High glucose media enhanced insulin expression by about 4-18 fold, suggesting a glucose-dependent effect in the proliferated islet-derived cells. The islet-derived cells also expressed other pancreatic genes such as Pdx1, NeuroD, glucagon, and somatostatin. Taken together, these results indicate that pancreatic islet-derived cells, proliferated in vitro, retained the expression capacity for key pancreatic genes, thus suggesting that the cells may be redifferentiated into insulin-secreting ß-like cells.
Assuntos
Proliferação de Células/fisiologia , Células Secretoras de Insulina/citologia , Insulina/metabolismo , Transplante das Ilhotas Pancreáticas/métodos , Ilhotas Pancreáticas/citologia , Animais , Diferenciação Celular , Células Cultivadas , Células Secretoras de Insulina/metabolismo , Ilhotas Pancreáticas/metabolismo , SuínosRESUMO
Fluorescent imaging is a useful tool to monitor and evaluate bioengineered tissues and organs. However, autofluorescence emitted from the scaffold can be comparable or even overwhelm signals generated by fluorescently labelled cells and biomarkers. Using standard fluorescent microscopy techniques, a simple and easy-to-measure signal to noise ratio metric was developed, which can facilitate the selection of fluorescent biomarkers and the respective biomaterials for tissue engineering studies. Endothelial cells (MS1) expressing green-fluorescent protein and red fluorescent protein (mKate) were seeded on poly(epsilon-caprolactone)-collagen hybrid scaffolds that were prepared by crosslinking with glutaraldehyde, genipin and ethyl(dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide. All scaffolds had comparable mechanical properties, which could meet the requirements for vascular graft applications. ethyl(dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide crosslinked scaffolds had a high signal to noise ratio value because of its low autofluorescence in green and red channels. Genipin crosslinked scaffolds had a high signal to noise ratio only in the green channel, while glutaraldehyde crosslinked scaffolds had a low signal to noise ratio in both green and red channels. The signal to noise ratio was independent of the exposure time. The data show that although similar in their mechanical properties and ability to support cell growth, scaffolds crosslinked with different agents have significant differences in causing autofluorescence of the scaffolds. This result indicates that scaffold's preparation method may have a significant impact on direct imaging of fluorescently labelled cells on scaffolds used for tissue engineering. Copyright © 2014 John Wiley & Sons, Ltd.
Assuntos
Bioprótese , Prótese Vascular , Reagentes de Ligações Cruzadas/química , Células Endoteliais/metabolismo , Engenharia Tecidual , Alicerces Teciduais/química , Animais , Linhagem Celular , Células Endoteliais/citologia , Camundongos , Microscopia de Fluorescência/métodosRESUMO
Corneal transplantation has become a common procedure to improve visual acuity by replacing the opaque or distorted host tissue with clear healthy donor corneal tissue. However, globally its wide spread clinical utility is limited due to a lack of supply of high quality corneas. Bioengineered neo-corneas using discarded human corneas to isolate corneal endothelial and epithelial cells, as well as corneal stroma as a scaffolding material, could help address this shortage. The objective of this study was to fabricate multilayered corneal equivalents that could be suitable for full thickness cornea transplantation. To achieve this goal human corneal endothelial cells (hCEC) and human limbal epithelial cells (hLEC) were isolated from discarded human corneas and expanded in vitro, maintaining their phenotype for at least 3 passages. We used our previously described process of human cornea decellularization to create corneal scaffolds that preserve the native extracellular matrix of the corneal stroma. The corneal scaffolds were seeded with hCEC and hLEC, using a special apparatus that enabled seeding both sides of the scaffold. The cell-seeded corneal constructs supported hCEC and hLEC growth and multi-cellular organization for 2 weeks in vitro. Immunohistochemical analysis showed expression of typical hCEC and hLEC markers on their corresponding sides. Importantly, the cell-seeded corneal constructs were more transparent than non-seeded corneal scaffolds. Taken together, this study demonstrates the feasibility of creating multilayered cornea equivalents, exclusively from human donor-derived materials. These constructs may be suitable for corneal transplantation, and as a short-term application, may serve for ophthalmological drug testing purposes.
Assuntos
Transplante de Córnea/métodos , Endotélio Corneano/citologia , Limbo da Córnea/citologia , Engenharia Tecidual/métodos , Técnicas de Cultura de Células , Separação Celular , Endotélio Corneano/metabolismo , Humanos , Imuno-Histoquímica , Limbo da Córnea/metabolismo , Teste de Materiais , Fenômenos Ópticos , Alicerces TeciduaisRESUMO
Cardiovascular disease (CVD) affecting blood vessel function is a leading cause of death around the world. A common treatment option to replace the diseased blood vessels is vascular grafting using the patient's own blood vessels. However, patients with CVD are usually lacking vessels for grafting. Recent advances in tissue engineering are now providing alternatives to autologous vascular grafts in the form of tissue-engineered blood vessels (TEBVs). In this review, we will describe the use of different scaffolding systems, cell sources and conditioning approaches for creating fully functional blood vessels. Additionally, we will present the methods used for assessing TEBV functions and describe preclinical and clinical trials for TEBV. Although the early results were encouraging, current designs of TEBV still fall short as a viable clinical option. Implementing the current knowledge in vascular development can lead to improved fabrication and function of TEBV and hasten clinical translation.
Assuntos
Vasos Sanguíneos/fisiologia , Engenharia Tecidual/métodos , Animais , Bioprótese , Prótese Vascular , Vasos Sanguíneos/citologia , Vasos Sanguíneos/transplante , Ensaios Clínicos como Assunto , HumanosRESUMO
Although one of the most transplanted tissues, a shortage of cadaveric corneas for transplantation still exists in the western society and elsewhere. The goal of this study was to develop a biological scaffold to support transfer of cultured human corneal endothelial cells (HCECs) into the anterior chamber of the eye, potentially a replacement for cadaveric donor tissue. A series of transparent scaffolds were fabricated from gelatin and modified with heparin. Mechanical parameters of the scaffolds, such as stiffness, affected cell proliferation, phenotype and cell surface marker expression were determined. The heparin-modified scaffolds had a greater capacity to absorb basic fibroblast growth factor (bFGF) and showed better release kinetics for up to 20 days. The release of bFGF from the scaffolds improved HCECs survival and reduced cellular loss. The scaffolds were flexible and could be folded and implanted in rabbits' eyes, through a small incision in the cornea. The scaffolds adhered to the inner surface of the corneal stroma and gradually integrated with the surrounding tissue. These results indicate that gelatin based corneal scaffolds modified to absorb and release growth factors and seeded with HCECs, might be a suitable alternative for cadaveric cornea transplantation.
Assuntos
Transplante de Células/métodos , Endotélio Corneano/citologia , Células Epiteliais/citologia , Gelatina/química , Heparina/química , Alicerces Teciduais/química , Animais , Proliferação de Células , Células Cultivadas , Cães , Humanos , Camundongos , Camundongos Endogâmicos BALB CRESUMO
Musculoskeletal disorders are a major cause of disability and effective treatments are currently lacking. Tissue engineering affords the possibility of new therapies utilizing cells and biomaterials for the recovery of muscle volume and function. A major consideration in skeletal muscle engineering is the integration of a functional vasculature within the regenerating tissue. In this study we employed fluorescent cell labels to track the location and differentiation of co-cultured cells in vivo and in vitro. We first utilized a co-culture of fluorescently labeled endothelial cells (ECs) and muscle progenitor cells (MPCs) to investigate the ability of ECs to enhance muscle tissue formation and vascularization in an in vivo model of bioengineered muscle. Scaffolds that had been seeded with both MPCs and ECs showed significantly greater vascularization, tissue formation and enhanced innervation as compared to scaffolds seeded with MPCs alone. Subsequently, we performed in vitro experiments using a 3-cell type system (ECs, MPCs, and pericytes (PCs)) to demonstrate the utility of fluorescent cell labeling for monitoring cell growth and differentiation. The growth and differentiation of individual cell types was determined using live cell fluorescent microscopy demonstrating the utility of fluorescent labels to monitor tissue organization in real time.
Assuntos
Diferenciação Celular , Células Endoteliais da Veia Umbilical Humana/citologia , Fibras Musculares Esqueléticas/citologia , Músculos/irrigação sanguínea , Músculos/inervação , Neovascularização Fisiológica , Engenharia Tecidual/métodos , Animais , Biomarcadores/metabolismo , Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Técnicas de Cocultura , Feminino , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Humanos , Implantes Experimentais , Camundongos , Camundongos Nus , Microscopia de Fluorescência , Fibras Musculares Esqueléticas/efeitos dos fármacos , Músculos/efeitos dos fármacos , Neovascularização Fisiológica/efeitos dos fármacos , Células-Tronco/citologia , Células-Tronco/efeitos dos fármacos , Sus scrofa , Fator A de Crescimento do Endotélio Vascular/farmacologiaRESUMO
A series of novel transparent shape memory co-polymers, made from (meth)acrylate monomers, intended to be used as intraocular lens, was synthesized. The thermo-mechanical properties, shape memory properties and optical properties of the co-polymers could be adjusted by using monomers with various alkyl chain lengths. The cytocompatibility of the prepared co-polymers to L929 mouse connective tissue fibroblasts was demonstrated in vitro, and the co-polymers exhibited favorable cytocompatibility, supporting cell viability and proliferation. This study showed that the prepared co-polymers, which exhibited good flexibility, adjustable shape memory properties, high transparency and favorable cytocompatibility, could find great promising applications as intraocular lens.
Assuntos
Materiais Biocompatíveis , Metacrilatos , Polímeros , Animais , Materiais Biocompatíveis/síntese química , Materiais Biocompatíveis/química , Varredura Diferencial de Calorimetria , Espectroscopia de Ressonância Magnética Nuclear de Carbono-13 , Linhagem Celular , Proliferação de Células/fisiologia , Sobrevivência Celular/fisiologia , Fibroblastos/fisiologia , Teste de Materiais , Metacrilatos/química , Camundongos , Implantes Orbitários , Maleabilidade , Polímeros/síntese química , Polímeros/química , Desenho de Prótese , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
The unique features of shape-memory polymers enables their use in minimally invasive surgical procedures with a compact starting material switching over to a voluminous structure in vivo. In this work, a series of transparent, thermoset (meth)acrylate shape-memory polymer networks with tailored thermomechanics have been synthesized and evaluated. Fundamental trends were established for the effect of the crosslinker content and crosslinker molecular weight on glass transition temperature, rubbery modulus and shape-recovery behavior, and the results are intended to help with future shape-memory device design. The prepared (meth)acrylate networks with high transparency and favorable biocompatibility are presented as a promising shape-memory ophthalmic biomaterial.
Assuntos
Materiais Biocompatíveis/química , Metacrilatos/química , Oftalmologia/instrumentação , Polímeros/química , Reagentes de Ligações Cruzadas/química , Elasticidade , Humanos , Teste de Materiais , Estresse Mecânico , Temperatura , Temperatura de TransiçãoRESUMO
Combination chemotherapy has been a primary management for cancer. Thus a drug delivery system which can administer several drugs simultaneously and control the drug release at the cancer site is desired. Here we synthesized hyperbranched poly(amine-ester) (HPAE) macromers with different degrees of terminal CC modification to make injectable hydrogels as a multi-drug delivery system. The aqueous solutions of the macromers were fast transformed into hydrogel at body temperature with a low concentration (0.05 wt%) of ammonium persulfate (APS) but no activator for accelerating the polymerization, since the HPAE macromer with tertiary amines and APS themselves formed a redox system as initiator. Three different types of drugs, doxorubicin hydrochloride (Dox), 5-fluorouracil (5FU) and leucovorin calcium (LC), were used as model drugs in this experiment. This system allows locally releasing single and/or combinations of anticancer drugs simultaneously by a controllable way. Behaviors of drug release can be controlled by the drug-loading methods or/and the CC modification degree of macromers loaded with the drug molecules. The drug release period could be prolonged when the drug was loaded into the macromers with high content of CC. The HPAE macromers exhibited good biocompatibility which was evaluated in L929 and MCF7 cell lines using MTT cell proliferation assay. The swelling behavior and degradation of HPAE hydrogels in vitro were also examined. These results suggest that the HPAE hydrogels hold great potential for use as injectable systems for locally delivering single and/or multiple drugs in chemotherapy of cancer.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Dendrímeros/química , Ésteres/química , Hidrogéis/química , Animais , Linhagem Celular , Preparações de Ação Retardada , Dendrímeros/síntese química , Doxorrubicina/farmacologia , Ésteres/síntese química , Fluoruracila/farmacologia , Humanos , Leucovorina/farmacologia , Espectroscopia de Ressonância Magnética , Teste de Materiais , Camundongos , Peso Molecular , Fatores de TempoRESUMO
Injectable acrylamide/N-vinylpyrrolidinone copolymers with pendent thiol groups were prepared by a radical polymerization and reductive dissolution reaction. The solution of copolymers was re-gelled through oxidation in air or the thiol-disulfide exchange reaction. The re-gelation time could be adjusted from several minutes to several hours by changing the amount of the disulfide exchange reagent. The re-gelled hydrogels possessed high transmittance in the visible region but could block out some of the ultraviolet radiation. Their refractive indexes ranged from 1.34 to 1.35, and their equilibrium water contents were over 95.0%. The morphologies of the hydrogels were analyzed and the porous structure, with pore sizes of 50-300 microm, was noted. The cytotoxicities of the hydrogels were clearly reduced compared with previous results. The experimental results indicated that the injectable copolymers could be used as an artificial vitreous substance or as a scaffold for lens regeneration.
Assuntos
Acrilamida/química , Polímeros/síntese química , Pirrolidinonas/química , Compostos de Sulfidrila/química , Dissulfetos/química , Olho , Hidrogel de Polietilenoglicol-Dimetacrilato/química , Concentração de Íons de Hidrogênio , Microscopia Eletrônica de Varredura , Estrutura Molecular , Polímeros/química , Soluções , Análise Espectral RamanRESUMO
The drawbacks of poloxamer hydrogel, such as dissolving quickly in aqueous solution, have limited its biomedical application. In order to improve the stability of hydrogel, a novel system was developed by combining the reversible thermo-sensitive property of poloxamer 407 and the thiol-ene reactivity between the acrylate and thiol groups. It was found that the sol-gel transition of the acrylate/thiol modified poloxamer 407 mixture could be achieved at body temperature even with a low concentration of 17.5 wt.%. Meanwhile, the reaction between the acrylate and thiol modified poloxamer 407s occurred spontaneously in mimic physiological conditions, thus the hydrogel with crosslinking structure was formed. As a result, the stability of the crosslinked hydrogel was enhanced remarkably, and the release time of the drug from the crosslinked hydrogel was about 4.0 times as long as that from the poloxamer 407 hydrogel. Invitro and invivo experiments revealed that the biocompatibilities of the modified poloxamer 407 hydrogel were similar to that of poloxamer 407. These results indicate that the modified poloxamer 407s have potential applications in controlled drug release, tissue engineering and cell encapsulation etc.