Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 75
Filtrar
Mais filtros

Base de dados
País/Região como assunto
Tipo de documento
País de afiliação
Intervalo de ano de publicação
1.
J Mater Sci Mater Med ; 35(1): 41, 2024 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-39073502

RESUMO

As an acne sequela, post-acne scarring (PSA) has huge negative impact on sufferers' quality of life because of aesthetical embarrassment. Transdermal delivery of botulinum toxin-A (BTXA) is a promising strategy for PAS treatment, but currently reported approaches are far from satisfactory. In this work, phosphatidylcholine/cholesterol (PC/Chol) nanoliposomes were utilized for encapsulation and transdermal delivery of BTXA. The composition, structure, morphology, size, size distribution, etc. of as-prepared BTXA@liposome nanoparticles were investigated in detail. Simulated transdermal delivery assay indicated that the diffusion depth of the BXTA@liposome nanoparticles was nearly 8 times that of pure BTXA and reached 380 µm. 12 facial PSA patients were recruited to evaluate the curative effect of the BTXA@liposome nanoparticles on PSA. Through ECCA (échelle d'évaluation clinique des cicatrices d'acné) scoring and self-evaluation of patients, the resultant data indicated that compared to hyaluronic acid (HA) hydrogel treatment the BTXA@liposome/HA hydrogel treatment could better relieve PSA to some extent but didn't show significant advantage. Further work is needed to verify the feasibility and curative effect of this method in PSA treatment in the future.


Assuntos
Administração Cutânea , Toxinas Botulínicas Tipo A , Colesterol , Lipossomos , Nanopartículas , Fosfatidilcolinas , Lipossomos/química , Humanos , Fosfatidilcolinas/química , Colesterol/química , Toxinas Botulínicas Tipo A/administração & dosagem , Toxinas Botulínicas Tipo A/química , Nanopartículas/química , Cicatriz/tratamento farmacológico , Adulto , Feminino , Masculino , Hidrogéis/química , Sistemas de Liberação de Medicamentos
2.
Biomacromolecules ; 22(8): 3474-3485, 2021 08 09.
Artigo em Inglês | MEDLINE | ID: mdl-34291920

RESUMO

Three-dimensional (3D) multicellular spheroids are a new generation in vitro cell model, however, their applications are severely limited by difficulties in their generation. Here patterned poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogel films were synthesized for their generation. Instead of polymerization of HEMA monomers in the presence of a cross-linker, here the PHEMA films were synthesized by cross-linking furan-functionalized linear PHEMA, PHEMA-furan, and maleimide-functionalized linear PHEMA, PHEMA-mal, via Diels-Alder (DA) reaction between furan and maleimide groups. A thermal treatment temperature of 75 °C was chosen for the cross-linking reaction. The occurrence of DA reaction was confirmed by IR spectra. Using this method, cross-linked PHEMA films with smooth surface were successfully synthesized in situ in the well of cell culture plates. The films were then patterned by simply adding water to swell them. Highly ordered, honeycomb-like wrinkling patterns were successfully obtained by adjusting the furan and maleimide contents in the precursor linear polymers. The patterned hydrogel films were used to generate multicellular spheroids. Guided by the patterns, 3D spheroids with narrow size distribution, tunable size, and high cell viability were successfully obtained. The patterned PHEMA films reported here exhibited a lot of advantages. The patterning method was quite simple and required no template or special equipment. They were synthesized in situ in commercial cell culture plates. Particularly, thanks to the clean nature of the DA reaction, no low molecular weight monomer, cross-linker, initiator, or catalyst, which were potentially cytotoxic, was involved in the film synthesis, and no byproduct was produced and left in the film. The resulting films presented a high biocompatibility, allowing the avoidance of the tedious washing step. The films synthesized here were expected to have high potential for massive production of well-defined multicellular spheroids.


Assuntos
Poli-Hidroxietil Metacrilato , Esferoides Celulares , Hidrogéis , Metilgalactosídeos
3.
Biomacromolecules ; 15(12): 4495-508, 2014 Dec 08.
Artigo em Inglês | MEDLINE | ID: mdl-25279766

RESUMO

Injectable hydrogels as an important biomaterial class have been widely used in regenerative medicine. A series of injectable poly(l-glutamic acid)/alginate (PLGA/ALG) hydrogels were fabricated by self-cross-linking of hydrazide-modified poly(l-glutamic acid) (PLGA-ADH) and aldehyde-modified alginate (ALG-CHO). Both the degree of PLGA modification and the oxidation degree of ALG-CHO could be adjusted by the amount of activators and sodium periodate, respectively. The effect of the solid content of the hydrogels and oxidation degree of ALG-CHO on the gelation time, equilibrium swelling, mechanical properties, microscopic morphology, and in vitro degradation of the hydrogels was examined. Encapsulation of rabbit chondrocytes within hydrogels showed viability of the entrapped cells and good biocompatibility of the injectable hydrogels. A preliminary study exhibited injectability and rapid in vivo gel formation, as well as mechanical stability, cell ingrowth, and ectopic cartilage formation. The injectable PLGA/ALG hydrogels demonstrated attractive properties for future application in a variety of pharmaceutical delivery and tissue engineering, especially in cartilage tissue engineering.


Assuntos
Alginatos/química , Cartilagem/química , Ácido Glutâmico/química , Hidrogéis/química , Engenharia Tecidual/métodos , Animais , Materiais Biocompatíveis/química , Sobrevivência Celular , Condrócitos/citologia , Reagentes de Ligações Cruzadas/química , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Camundongos , Camundongos Nus , Coelhos , Alicerces Teciduais/química
4.
Eur Spine J ; 23(11): 2423-31, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25001891

RESUMO

PURPOSE: Spinal epidural fibrosis and adhesion are implicated as one of the key factors of failed back surgery syndrome, which may cause dura mater compression or peridural tethering, resulting in persistent backache and leg pain. Various materials or drugs have been used to inhibit formation of epidural fibrosis and reduce the compressive effect on neural structures. Nevertheless, the effects are not satisfied. In this study, we investigated the prevention effect of poly (L-glutamic acid)/chitosan (PLGA/CS) barrier on epidural fibrosis developing post-laminectomy in a rabbit model. METHODS: Sixteen rabbits were divided randomly into two equal groups: group A (experimental group, n = 8) and group B (non-treatment group, n = 8). In both groups, total L5-6 laminectomy was performed; further both ligamentum flavum and epidural fat were removed gently. In experimental group, the laminectomy sites were treated with PLGA/CS barriers, while no additional treatment was received in non-treatment group. At 1, 12 and 24 weeks post-surgery, the animals were subjected to magnetic resonance imaging (MRI) evaluation. Following last MRI examination, all rabbits were sacrificed and their spinal columns were totally removed for further macroscopic and histological evaluation. RESULTS: MRI showed that rabbits treated with PLGA/CS barrier at 12 and 24 weeks post-surgery had less epidural fibrosis or scar tissue, peridural adhesion, foreign body reaction and low pressure of spinal cord in comparison with the non-treatment group. In consistence with the radiographic results, macroscopic analysis and histological examination showed that the amount of scar tissue and the extent of epidural adhesion decreased significantly in experimental groups. Concerning the fibroblast density evaluated, the scores were significantly lower in experimental group compared with those in non-treatment group. CONCLUSION: The results of our study demonstrate that PLGA/CS barrier is effective in inhibiting epidural fibrosis and peridural adhesions in post-laminectomy rabbit model.


Assuntos
Materiais Biocompatíveis/farmacologia , Quitosana/farmacologia , Espaço Epidural/patologia , Laminectomia , Ácido Poliglutâmico/farmacologia , Animais , Contagem de Células , Modelos Animais de Doenças , Fibroblastos/metabolismo , Fibrose , Reação a Corpo Estranho/prevenção & controle , Imageamento por Ressonância Magnética , Próteses e Implantes , Coelhos , Aderências Teciduais/prevenção & controle
5.
Medicine (Baltimore) ; 102(9): e32839, 2023 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-36862855

RESUMO

BACKGROUND: Coronary pseudoaneurysm (CPA) are associated with iatrogenic coronary artery dissection or perforation, which rarely reported formation early after percutaneous coronary intervention (PCI) for chronic total occlusion (CTO). This study reported a case of CPA that developed 4 weeks after PCI for CTO. CASE REPORT: A 40-year-old man was admitted with unstable angina and diagnosed with CTO of the left anterior descending artery (LAD) and right coronary artery. The CTO of the LAD was successfully treated by PCI. However, reexamination by coronary arteriography and optical coherence tomography after 4 weeks confirmed a CPA at the stented middle segment of the LAD. The CPA was treated surgically by the implantation of a Polytetrafluoroethylene-coated stent. reexamination at the 5-month follow-up revealed a patent stent in the LAD and no CPA-like manifestations. Intravascular ultrasound showed no intimal hyperplasia or in-stent thrombogenesis. CONCLUSION: CPA might develop within weeks after PCI for CTO. While it could be successfully treated by the implantation of a Polytetrafluoroethylene-coated stent.


Assuntos
Falso Aneurisma , Cardiomiopatias , Intervenção Coronária Percutânea , Doenças Vasculares , Masculino , Humanos , Adulto , Intervenção Coronária Percutânea/efeitos adversos , Falso Aneurisma/diagnóstico por imagem , Falso Aneurisma/etiologia , Falso Aneurisma/cirurgia , Angina Instável , Politetrafluoretileno
6.
Front Med (Lausanne) ; 10: 1174502, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37181367

RESUMO

Introduction: Urolithiasis is one of the most common diseases for urologists and it is a heavy burden for stone formers and society. The theory of the oral-genitourinary axis casts novel light on the pathological process of genitourinary system diseases. Hence, we performed this study to characterize the crosstalk between oral health conditions and urolithiasis to provide evidence for prevention measures and mechanisms of stone formation. Materials and methods: This population-based cross-sectional study included 86,548 Chinese individuals who had undergone a comprehensive examination in 2017. Urolithiasis was diagnosed depending on the results of ultrasonographic imaging. Logistic models were utilized to characterize the association between oral health conditions and urolithiasis. We further applied bidirectional Mendelian randomization to explore the causality between oral health conditions and urolithiasis. Results: We observed that presenting caries indicated a negative correlation with the risk for urolithiasis while presenting gingivitis [OR (95% CI), 2.021 (1.866-2.187)] and impacted tooth [OR (95% CI), 1.312 (1.219-1.411)] shown to be positively associated with urolithiasis. Furthermore, we discovered that genetically predicted gingivitis was associated with a higher risk of urolithiasis [OR (95% CI), 1.174 (1.009-1.366)] and causality from urolithiasis to impacted teeth [OR(95% CI), 1.207 (1.027-1.418)] through bidirectional Mendelian randomization. Conclusion: The results cast new light on the risk factor and pathogenesis of kidney stone formation and could provide novel evidence for the oral-genitourinary axis and the systematic inflammatory network. Our findings could also offer suggestions for tailored clinical prevention strategies against stone diseases.

7.
Acta Biomater ; 151: 491-500, 2022 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-35948176

RESUMO

Current vaccination schedules, including COVID-19 vaccines, require multiple doses to be administered. Single injection vaccines eliciting equivalent immune response are highly desirable. Unfortunately because unconventional release kinetics are difficult to achieve it still remains a huge challenge. Herein a single-injection COVID-19 vaccine was designed using a highly programmable release system based on dynamic layer-by-layer (LBL) films. The antigen, S1 subunit of SARS-CoV-2 spike protein, was loaded in CaCO3 microspheres, which were further coated with tannic acid (TA)/polyethylene glycol (PEG) LBL films. The single-injection vaccine was obtained by mixing the microspheres coated with different thickness of TA/PEG films. Because of the unique constant-rate erosion behavior of the TA/PEG coatings, this system allows for distinct multiple pulsatile release of antigen, closely mimicking the release profile of antigen in conventional multiple dose vaccines. Immunization with the single injection vaccine induces potent and persistent S1-specific humoral and cellular immune responses in mice. The sera from the vaccinated animal exhibit robust in vitro viral neutralization ability. More importantly, the immune response and viral inhibition induced by the single injection vaccine are as strong as that induced by the corresponding multiple dose vaccine, because they share the same antigen release profile. STATEMENT OF SIGNIFICANCE: Vaccines are the most powerful and cost-effective weapons against infectious diseases such as COVID-19. However, current vaccination schedules, including the COVID-19 vaccines, require multiple doses to be administered. Herein a single-injection COVID-19 vaccine is designed using a highly programmable release system. This vaccine releases antigens in a pulsatile manner, closely mimicking the release pattern of antigens in conventional multiple dose vaccines. As a result, one single injection of the new vaccine induces an immune response and viral inhibition similar to that induced by the corresponding multiple-dose vaccine approach.


Assuntos
COVID-19 , Vacinas Virais , Animais , COVID-19/prevenção & controle , Vacinas contra COVID-19 , Humanos , Imunidade , Camundongos , Polietilenoglicóis , SARS-CoV-2 , Glicoproteína da Espícula de Coronavírus , Taninos , Vacinas de Subunidades Antigênicas
8.
Biomater Adv ; 137: 212812, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35929251

RESUMO

Single-injection vaccines may overcome issues, such as high cost and poor patient compliance, of the multi-bolus regimes dominantly used in vaccination. However no such vaccine has been commercialized because time-controlled release, an unconventional release kinetics, is difficult to achieve. Here a new time-controlled release system using dynamic layer-by-layer (LBL) film as erodible coating was used to design single-injection vaccine. Unlike commonly used degradable polymers, dynamic LBL film disintegrates at a constant rate, thus allowing distinct pulsatile release of antigen at predetermined intervals. The release pattern of the single-injection vaccine mimics closely to that of ordinary multi-dose regimes. It elicits both humoral and cellular immune responses which are comparable to or even stronger than the corresponding multi-dose regime. In addition, it inhibits tumor growth more effectively. The new vaccine will not only improve patient compliance but also therapeutic outcome.


Assuntos
Vacinas , Preparações de Ação Retardada , Humanos , Injeções , Polímeros , Vacinação
9.
ACS Appl Mater Interfaces ; 13(35): 42052-42062, 2021 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-34435780

RESUMO

Ideal conductive hydrogels for flexible, wearable strain sensors should be tough, highly resilient, adhesive, and anti-freezing. However, such hydrogels are difficult to design. Herein, a multifunctional macromolecular cross-linker (MC) based on poly(hydroxyethyl-l-glutamine) was designed and used to synthesize the hydrogels. Cross-linking with the MC leads to a reduced inhomogeneity of the gel network. Therefore, the mechanical properties of the gels are significantly improved compared with the ordinary hydrogels cross-linked with the conventional cross-linker N,N-methylenebisacrylamide (BIS). The MC-cross-linked gels also exhibit high resilience. At the same time, replacing BIS with MC significantly improves the adhesive properties of the gel, which is attributed to the introduction of a large amount of adhesive groups with the MC. The gels can stick to various substrates including skin. The good tissue adhesiveness of the gel allows it to stick to skin by itself without using any straps or adhesive tapes when used as a flexible wearable strain sensor. Both large and subtle human movements were successfully monitored using the sensor. The signals are highly stable and reliable, thanks to the high resilience of the gel. The introduction of the polar groups also improved dramatically the anti-freezing properties of the gels. Even at -20 °C, the gels still remained highly flexible and stretchable, therefore allowing the gel-based sensor to work at sub-zero temperatures. The excellent toughness, resilience, tissue-adhesiveness, and anti-freezing properties of the gel make it a good choice for a flexible wearable sensor.


Assuntos
Reagentes de Ligações Cruzadas/química , Hidrogéis/química , Peptídeos/química , Dispositivos Eletrônicos Vestíveis , Resinas Acrílicas/síntese química , Resinas Acrílicas/química , Adesividade , Humanos , Hidrogéis/síntese química , Monitorização Fisiológica/instrumentação , Movimento , Maleabilidade , Resistência à Tração
10.
Cell Transplant ; 29: 963689720973647, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33300392

RESUMO

The healing of tendon-bone in the rotator cuff is featured by the formation of the scar tissues in the interface after repair. This study aimed to determine if the 3D-printed poly lactic-co-glycolic acid (PLGA) scaffolds loaded with bone marrow-derived mesenchymal stem cells (BMSCs) could augment the rotator cuff repair in the rabbits. PLGA scaffolds were generated by the 3D-printed technology; Cell Counting Kit-8 assay evaluated the proliferation of BMSCs; the mRNA and protein expression levels were assessed by quantitative real-time polymerase chain reaction and western blot, respectively; immunohistology evaluated the rotator cuff repair; biomechanical characteristics of the repaired tissues were also assessed. 3D-printed PLGA scaffolds showed good biocompatibility without affecting the proliferative ability of BMSCs. BMSCs-PLGA scaffolds implantation enhanced the cell infiltration into the tendon-bone injunction at 4 weeks after implantation and improved the histology score in the tendon tissues after implantation. The mRNA expression levels of collagen I, III, tenascin, and biglycan were significantly higher in the scaffolds + BMSCs group at 4 weeks post-implantation than that in the scaffolds group. At 8 and 12 weeks after implantation, the biglycan mRNA expression level in the BMSCs-PLGA scaffolds group was significantly lower than that in the scaffolds group. BMSCs-PLGA scaffolds implantation enhanced collagen formation and increased collagen dimeter in the tendon-bone interface. The biomechanical analysis showed that BMSCs-PLGA scaffolds implantation improved the biomechanical properties of the regenerated tendon. The combination of 3D-printed PLGA scaffolds with BMSCs can augment the tendon-bone healing in the rabbit rotator cuff repair model.


Assuntos
Células da Medula Óssea/citologia , Células-Tronco Mesenquimais/citologia , Copolímero de Ácido Poliláctico e Ácido Poliglicólico/química , Lesões do Manguito Rotador/terapia , Alicerces Teciduais/química , Cicatrização/fisiologia , Animais , Células da Medula Óssea/fisiologia , Células-Tronco Mesenquimais/fisiologia , Coelhos
11.
Acta Biomater ; 83: 334-348, 2019 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-30366135

RESUMO

Hypoxia is not merely a tumor microenvironment byproduct, but rather an active participant in tumor development, invasion, and metastasis. Hypoxia contributes to poor outcomes in tumor treatment and has currently emerged as an important therapeutic target. In this work, a facile hypoxia-responsive liposomal drug delivery system was developed by incorporating derivatized nitroimidazole into liposome membranes. Under hypoxic conditions, hypoxia-induced reductive metabolism of the nitroimidazole derivative facilitated disassembly of the liposomes for triggered drug release. The liposomes showed high sensitivity to hypoxia, even at the cellular level, and could release payload in an oxygen-dependent manner, leading to high cytotoxicity in hypoxic conditions. In vivo fluorescence imaging revealed that there was a selective release of the liposomes at the hypoxic tumor site. As a result, the liposomes exhibited enhanced therapeutic efficacy in treating a hypoxic tumor in both cell line-derived and clinically relevant patient-derived xenograft models. Thus, hypoxia-responsive liposomes are a promising drug delivery system for hypoxia targeted tumor therapy. STATEMENT OF SIGNIFICANCE: 1. A facile but smart hypoxia-responsive liposomal drug delivery system is developed by incorporating nitroimidazole derivative, one of representative hypoxia-responsive moieties, into phospholipid bilayer of the liposomes. 2. The liposomes show extremely high sensitivity to hypoxia and can selectively release payload in hypoxic cells and hypoxic tumor. 3. The liposomes show enhanced therapeutic efficacy not only in cell line-derived xenograft model but also in clinically relevant patient-derived xenograft model, indicating their promising prospect in clinical application.


Assuntos
Neoplasias/tratamento farmacológico , Nitroimidazóis , Animais , Hipóxia Celular/efeitos dos fármacos , Preparações de Ação Retardada/química , Preparações de Ação Retardada/farmacocinética , Preparações de Ação Retardada/farmacologia , Xenoenxertos , Humanos , Lipossomos , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Transplante de Neoplasias , Neoplasias/metabolismo , Neoplasias/patologia , Nitroimidazóis/química , Nitroimidazóis/farmacocinética , Nitroimidazóis/farmacologia , Ensaios Antitumorais Modelo de Xenoenxerto
12.
Int J Biol Macromol ; 138: 79-88, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31295489

RESUMO

This study investigates if the application of bone marrow-derived mesenchymal stem cells (BM-MSCs) loaded 3D-printed scaffolds could improve rotator cuff repair. The polylactic-co-glycolic acid (PLGA) scaffolds were fabricated by 3D print technology. Rabbit BM-MSCs were transfected with a recombinant adenovirus encoding bone morphogenic protein 12 (BMP-12). The effect of BM-MSCs loaded PLGA scaffolds on tendon-bone healing was assessed by biomechanical testing and histological analysis in a rabbit rotator cuff repair model. We found that the PLGA scaffolds had good biocompatible and biodegradable property. Overexpression of BMP-12 increased the mRNA and protein expression of tenogenic genes in BM-MSCs cultured with DMEM medium and seeded in PLGA scaffolds. When BMP-12-overexpressing BM-MSCs-loaded PLGA scaffolds were implanted into the injured rabbit supraspinatus tendon-bone junctions, the tendon-bone healing was improved. Our results suggest that application of BMP-12 overexpressing BM-MSCs loaded 3D-printed PLGA scaffolds promote the healing of tendon-bone interface, improve collagen organization and increase fibrocartilage in the rabbit rotor cuff repair. Rotator cuff regeneration achieved by BMP-12-overexpressing BM-MSCs-loaded PLGA scaffolds may represent a novel approach for the management of rotator cuff defect.


Assuntos
Proteínas Morfogenéticas Ósseas/genética , Células-Tronco Mesenquimais/metabolismo , Copolímero de Ácido Poliláctico e Ácido Poliglicólico/química , Impressão Tridimensional , Manguito Rotador/fisiologia , Alicerces Teciduais/química , Animais , Biomarcadores/metabolismo , Adesão Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Expressão Gênica , Células-Tronco Mesenquimais/química , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/efeitos dos fármacos , Copolímero de Ácido Poliláctico e Ácido Poliglicólico/farmacologia , Coelhos , Regeneração , Tendões/fisiologia
13.
Biomaterials ; 29(10): 1464-72, 2008 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-18155136

RESUMO

Tissue engineering offers a new approach for the construction of vascular substitutes in vitro with proper mechanical properties. Although success has been made in the engineering of small blood vessels (<6mm in diameter), it remains a challenge to engineer large vessels (>6mm in diameter) due to their insufficient biomechanical property. In the current study, an elastic large vessel wall (6mm in diameter) was engineered by loading a polyglycolic acid (PGA) unwoven fiber scaffold seeded with smooth muscle cells (SMCs) on a vessel reactor designed with dynamic culture conditions. SMCs were isolated from canine carotid artery and expanded before seeding on a PGA fiber mesh. The cell-seeded PGA mesh was then loaded on a vessel reactor and subjected to pulsatile stimuli. Grossly, an elastic vessel wall was formed after 8 weeks of dynamic engineering. Histological examination showed well-orientated smooth muscle cells and collagenous fibers in the group with dynamic culture. In addition, the phenotype of SMCs was confirmed by positive staining of smooth muscle alpha-actin and calponin. On the contrary, disorganized smooth muscle cells and collagenous fibers were observed in the group under static culture without stimuli. Furthermore, the engineered vessels under dynamic culture exhibited significant improvements on biomechanical property over the one from static culture. Our results indicate that the approach developed in the current work is efficient for large vessel engineering. This approach may also be suitable for the engineering of other tissues with muscular tubular structure.


Assuntos
Reatores Biológicos , Vasos Sanguíneos , Ácido Poliglicólico/química , Engenharia Tecidual/métodos , Animais , Fenômenos Biomecânicos , Células Cultivadas , Cães , Microscopia Eletrônica de Varredura , Miócitos de Músculo Liso/metabolismo , Miócitos de Músculo Liso/ultraestrutura
14.
Biomaterials ; 29(14): 2183-92, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-18289667

RESUMO

In vivo niche plays an important role in determining the fate of implanted mesenchymal stem cells (MSCs) by directing committed differentiation. An inappropriate in vivo niche can also alter desired ultimate fate of exogenous MSCs even they are in vitro induced to express a specific phenotype before in vivo implantation. Studies have shown that in vitro chondrogenically differentiated MSCs are apt to lose their phenotype and fail to form stable cartilage in subcutaneous environment. We hypothesized that failure of maintaining the phenotype of induced MSCs in subcutaneous environment is due to the insufficient chondrogenic differentiation in vitro and fully differentiated MSCs can retain their chondrocyte-like phenotype and form stable ectopic cartilage. To test this hypothesis, extended in vitro chondrogenic induction and cartilage formation were carried out before implantation. Human bone marrow stem cells (hBMSCs) were seeded onto polylactic acid coated polyglycolic acid scaffolds. The cell-scaffold constructs were chondrogenically induced from 4 to 12 weeks for in vitro chondrogenesis, and then implanted subcutaneously into nude mice for 12 or 24 weeks. The engineered cartilages were evaluated by gross view, glycosaminoglycan content measurement, and histological staining before and after implantation. Histological examination showed typical cartilage structure formation after 8 weeks of induction in vitro. However, part of the constructs became ossified after implantation when in vitro induction lasted 8 weeks or less time. In contrast, those induced for 12 weeks in vitro could retain their cartilage structure after in vivo implantation. These results indicate that a fully differentiated stage achieved by extended chondrogenic induction in vitro is necessary for hBMSCs to form stable ectopic chondrogenesis in vivo.


Assuntos
Cartilagem Articular/citologia , Condrócitos/citologia , Condrogênese , Células-Tronco Mesenquimais/citologia , Adolescente , Adulto , Animais , Fenômenos Biomecânicos , Técnicas de Cultura de Células , Diferenciação Celular , Células Cultivadas , Criança , Condrócitos/fisiologia , Glicosaminoglicanos/análise , Humanos , Imuno-Histoquímica , Ácido Láctico/química , Transplante de Células-Tronco Mesenquimais/métodos , Células-Tronco Mesenquimais/ultraestrutura , Camundongos , Camundongos Nus , Poliésteres , Ácido Poliglicólico/química , Polímeros/química , Fatores de Tempo , Engenharia Tecidual/métodos
15.
Biomacromolecules ; 9(10): 2653-61, 2008 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-18754685

RESUMO

We synthesized methoxy poly(ethylene glycol)-b-poly(alpha,L-glutamic acid) (mPEGGA) diblock copolymer by ring-opening polymerization of N-carboxy anhydride of gamma-benzyl-L-glutamate (NCA) using amino-terminated methoxy polyethylene glycol (mPEG) as macroinitiator. Polyelectrolyte complexation between mPEGGA as neutral-block-polyanion and chitosan (CS) as polycation has been scrutinized in aqueous solution as well as in the solid state. Water-soluble polyelectrolyte complexes (PEC) can be formed only under nonstoichiometric condition while phase separation is observed when approaching 1:1 molar mixing ratio in spite of the existence of hydrophilic mPEG block. This is likely due to mismatch in chain length between polyanion block of the copolymer and the polycation or hydrogen bonding between the components. Hydrodynamic size of primary or soluble PEC is determined to be about 200 nm, which is larger than those reported in some literatures. The increase in polyion chain length of the copolymer leads to the increase in the hydrodynamic size of the water-soluble PEC. Formation of spherical micelles by the mPEGGA/CS complex at nonstoichiometirc condition has been confirmed by the scanning electron microscopy observation and transmission electron microscopy observations. The homopolymer CS experiences attractive interaction with both mPEGA and PGA blocks within the copolymer. Competition of hydrogen bonding and electrostatic force in the system or hydrophilic mPEG segments weakens the electrostatic interaction between the oppositely charged polyions. The existence of hydrogen bonding restrains the mobility of mPEG chains of the copolymer and completely prohibits crystallization of mPEG segments. In vitro culture of human fibroblasts indicates that mPEGGA/CS-based materials have potential in biomedical application, especially in tissue engineering.


Assuntos
Materiais Biocompatíveis/química , Quitosana/química , Eletrólitos/química , Polietilenoglicóis/química , Ácido Poliglutâmico/análogos & derivados , Ânions , Fibroblastos/metabolismo , Humanos , Concentração de Íons de Hidrogênio , Espectroscopia de Ressonância Magnética , Teste de Materiais , Micelas , Modelos Químicos , Ácido Poliglutâmico/química , Polímeros/química , Espectroscopia de Infravermelho com Transformada de Fourier
16.
Zhonghua Yi Xue Za Zhi ; 88(13): 914-8, 2008 Apr 01.
Artigo em Zh | MEDLINE | ID: mdl-18756959

RESUMO

OBJECTIVE: To examine the feasibility of using human dermal fibroblasts (DFbs) and polyglycolic acids (PGA) to engineer tendon in vitro. METHODS: Human dermal fibroblasts (DFbs) were isolated from the foreskin tissues of children obtained during operation with collagenase and cultured in vitro. Human tendon was obtained from a patient undergoing amputation during operation to isolate tenocytes. The DFbs of second passage were seeded on PGA fibers to form cell-scaffold constructs in shape of tendons. Those constructs were divided into 4 groups: experimental group (n = 15) with the DFbs inoculated on PGA scaffold under constant tension generated by a U-shaped spring, control group 1 (n = 15) with the DFbs inoculated on PGA scaffold without tension, control group 2 (n = 3), i. e., cell-free pure PGA scaffolds under tension, and control group 3 (n = 5), i. e., tenocyte-scaffold constructs under tension that was harvested only at the ninth week. Samples were harvested 2, 5, 9, 14, and 18 weeks later to undergo histological examination and biomechanical test. RESULTS: Two weeks later histological examination showed that the constructs were mainly composed of PGA fibers in both the experimental group and the group without tension. Transmission electron microscopy showed fine cell attachment and stretching on the scaffold. By the 5th week, a neo-tendon was formed in all groups except for the cell-free group, and histology revealed the formation of collagen fibers. At the 9th week, the PGA fibers of the cell-free group were broken and partially degraded, the neo-tendon's diameter of the experimental group was (1.18 +/- 0.25) mm, significantly thinner than that of the group without tension[ (2.43 +/- 0.49) mm, P = 0.017]. The gross morphology of tendons of the experimental group and tenocyte group were similar to each other except for more cells in the experimental group. In experimental group, immunohistochemistry revealed the production of fibers of collagen type I & III that were aligned longitudinally along the force axis like the normal tendon pattern. An irregular collagen pattern was observed in the group without tension. The maximum tensile stress of the experimental group was (2.75 +/- 0.59) MPa, similar to that of the tenocyte group [(3.08 +/- 0.30) MPa, P = 0.439], and significantly greater than that of the group without tension [(0.82 +/- 0.21) MPa, P = 0.006]. At the 14th week the PGA fibers of the cell-free group were mostly degraded. In addition, more dead cells and tissue atrophy were observed in the experimental group, and the tensile stress was higher than that of the same group by the 9th week. In the 18th week the number of hollow fiber of the experimental group was more obvious, the number of dead cells increased, and the tensile stress was lower, however, there was no significant difference in other characteristics compared with those in the 14th week. CONCLUSIONS: DFbs can be used for in vitro tendon engineering as tenocytes. Mechanical stimulation by statistic strain is beneficial for tissue formation, but the effect may not be optimal if the tension is applied for too long.


Assuntos
Fibroblastos/citologia , Tendões , Engenharia Tecidual/métodos , Implantes Absorvíveis , Técnicas de Cultura de Células , Criança , Derme/citologia , Prepúcio do Pênis/citologia , Humanos , Masculino , Ácido Poliglicólico/química , Alicerces Teciduais/química
17.
Mol Med Rep ; 17(1): 1537-1544, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29257226

RESUMO

The aim of the present study was to regulate the transformation of bone marrow mesenchymal stem cells (BMMSCs) to osteoblasts to promote bone formation and osseointegration surrounding oral implants. BMMSCs were cultured using the whole bone marrow adherence method. Cell surface markers were detected by flow cytometry, and multi­lineage differentiation potential was detected by osteogenic and adipogenic tests. miR­122­modified cell sheets were prepared by non­viral transfection and complexed with micro­arc titanium oxide implants to construct a gene­modified tissue­engineered implant, with its surface morphology observed by scanning electron microscopy (SEM). In vitro osteogenic activity of the implant was determined by alkaline phosphatase (ALP), Sirius Red, alizarin red staining, polymerase chain reaction and western blot analysis. The BMMSCs were spindle­ or triangular­shaped. Surface markers, cluster of differentiation 29 (CD29), CD90 and CD105 were positively expressed, whereas blood cell markers CD34, CD45 and CD31 were negatively expressed. Osteogenic staining exhibited deposition of calcified nodules, while adipogenic staining demonstrated the formation of lipid droplets. miR­122 modification significantly enhanced the in vitro osteogenic activity of the sheets. On day 3 of osteogenic induction, runt-related transcription factor 2, osterix, osteocalcin, collagen I, ALP and bone morphogenetic protein 2 expression levels of the experimental group were 2.0, 3.1, 4.6, 3.2, 10.5 and 4.5 times those of the blank control group, respectively. SEM imaging of the modified sheet demonstrated close adhesion and fitting between abundant cellular and extracellular matrices, and the porous surface of the implant. In vitro osteogenesis of the complex was promoted and accelerated. Thus, miR­122 effectively promoted osteogenic differentiation of the BMMSC sheet. Therefore, it is feasible to construct gene­modified tissue­engineered implants by complexing miR­122­modified sheets with micro­arc titanium oxide implants.


Assuntos
Engenharia Celular/métodos , Implantes Dentários , Células-Tronco Mesenquimais/citologia , MicroRNAs/genética , Osteoblastos/citologia , Osteogênese , Animais , Células Cultivadas , Regulação da Expressão Gênica , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais/metabolismo , Osseointegração , Osteoblastos/metabolismo , Ratos , Ratos Sprague-Dawley , Engenharia Tecidual/métodos , Titânio/química , Transfecção/métodos
18.
Biomater Sci ; 6(10): 2738-2749, 2018 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-30175347

RESUMO

Shape memory scaffolds are minimally invasive cell carriers that are promising biomaterials for tissue regeneration. Since cell fate is critical for successful regeneration, the influence of mechanostructural stimuli induced by shape memory on cell fate is worthy of investigation. In this study, we developed a poly(l-glutamic acid)-based (PLGA-based) shape memory porous scaffold by cross-linking PLGA with poly(ε-caprolactone)-diols (PCL-diols) and by using the particle leaching method. After regulating the cross-linking density and molecular weight of the PCL-diols, the scaffolds exhibited excellent shape memory properties around physiological temperatures. The interconnected porous structure not only enabled the scaffold to be deformed to 20% of its original size but also supported tissue invasion. In vivo results demonstrated that the PLGA-based scaffold degraded within 6 months. Cell fate studies indicated that large dimensional deformation of the porous structure during the shape memory process induced significant death, detachment and reorganization of stem cells but had negligible effects on stemness and proliferation. These results indicate that the PLGA-based shape memory porous scaffold is a potential cell carrier for tissue regeneration, and they are also meaningful to investigate the effects of mechanostructural stimuli on stem cell fate in porous structures.


Assuntos
Ácido Láctico/química , Ácido Poliglutâmico/química , Ácido Poliglicólico/química , Células-Tronco/citologia , Alicerces Teciduais , Tecido Adiposo/citologia , Animais , Materiais Biocompatíveis/química , Proliferação de Células , Sobrevivência Celular , Humanos , Copolímero de Ácido Poliláctico e Ácido Poliglicólico , Porosidade , Ratos Sprague-Dawley , Engenharia Tecidual
19.
Biomaterials ; 28(6): 1005-13, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17092556

RESUMO

Tissue engineering has become a new approach for repairing bone defects. Previous studies have been limited to the use of slow-degradable scaffolds with bone marrow stromal cells (BMSCs) in mandibular reconstruction. In this study, a 30 mm long mandibular segmental defect was repaired by engineered bone graft using osteogenically induced autologous BMSCs seeded on porous beta-tricalcium phosphate (beta-TCP, n=5). The repair of defects was compared with those treated with beta-TCP alone (n=6) or with autologous mandibular segment (n=4). In the BMSCs/beta-TCP group, new bone formation was observed from 4 weeks post-operation, and bony-union was achieved after 32 weeks, which was detected by radiographic and histological examination. In contrast, minimal bone formation with almost fibrous connection was observed in the group treated with beta-TCP alone. More importantly, the engineered bone with BMSCs/beta-TCP achieved a satisfactory biomechanical property in terms of bending load strength, bending displacement, bending stress and Young's modulus at 32 weeks post-operation, which was very close to those of contralateral edentulous mandible and autograft bone (p>0.05). Based on these results, we conclude that engineered bone from osteogenically induced BMSCs and biodegradable beta-TCP can well repair the critical-sized segmental mandibular defects in canines.


Assuntos
Células da Medula Óssea/patologia , Transplante de Medula Óssea/métodos , Substitutos Ósseos/uso terapêutico , Fosfatos de Cálcio/uso terapêutico , Fraturas Mandibulares/patologia , Fraturas Mandibulares/cirurgia , Engenharia Tecidual/métodos , Animais , Materiais Biocompatíveis/química , Materiais Biocompatíveis/uso terapêutico , Bioprótese , Substitutos Ósseos/química , Fosfatos de Cálcio/química , Células Cultivadas , Cães , Osteogênese/fisiologia , Células Estromais/transplante , Resultado do Tratamento
20.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi ; 24(1): 76-80, 2007 Feb.
Artigo em Zh | MEDLINE | ID: mdl-17333896

RESUMO

In order to prepare three-dimensional scaffolds with "ideal pore-structure" for tissue engineering, a novel water dissoluble adhesive was developed, and the property of adhesive as well as influence of experimental condition on bonded porogen assembly was investigated. Experimental results showed that it was possible to fabricate large dimensional porogen assembly with homogenous and controllable bonding extent by this adhesive, and a large dimensional (45 mm in diameter, 55mm in thickness) biodegradable poly(D,L-lactic acid)(PDLLA) scaffold resulting from bonded porogen was formed. The scaffolds with high porosity as well as with controllable and homogeneous inner-structure can be easily formed. In addition, pore size of scaffolds as well as diameter of openings can be controlled by adjusting the porogen size and bonding degree in bonded porogen assembly.


Assuntos
Adesivos/química , Ácido Láctico/química , Polímeros/química , Engenharia Tecidual , Alicerces Teciduais/química , Poliésteres , Porosidade , Solubilidade , Propriedades de Superfície
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA