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1.
Angew Chem Int Ed Engl ; 63(27): e202404775, 2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-38758087

RESUMO

The surface structure and chemical properties of Y-stabilized zirconia (YSZ) have been subjects of intense debate over the past three decades. However, a thorough understanding of chemical processes occurring at YSZ powders faces significant challenges due to the absence of reliable reference data acquired for well-controlled model systems. Here, we present results from polarization-resolved infrared reflection absorption spectroscopy (IRRAS) obtained for differently oriented, Y-doped ZrO2 single-crystal surfaces after exposure to CO and D2O. The IRRAS data reveal that the polar YSZ(100) surface undergoes reconstruction, characterized by an unusual, red-shifted CO band at 2132 cm-1. Density functional theory calculations allowed to relate this unexpected observation to under-coordinated Zr4+ cations in the vicinity of doping-induced O vacancies. This reconstruction leads to a strongly increased chemical reactivity and water spontaneously dissociates on YSZ(100). The latter, which is an important requirement for catalysing the water-gas-shift (WGS) reaction, is absent for YSZ(111), where only associative adsorption was observed. Together with a novel analysis Scheme these reference data allowed for an operando characterisation of YSZ powders using DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy). These findings facilitate rational design and tuning of YSZ-based powder materials for catalytic applications, in particular CO oxidation and the WGS reaction.

2.
Cell Chem Biol ; 30(9): 1115-1134.e10, 2023 09 21.
Artigo em Inglês | MEDLINE | ID: mdl-37467751

RESUMO

The immune checkpoint protein PD-L1 plays critical roles in both immune system homeostasis and tumor progression. Impaired PD-1/PD-L1 function promotes autoimmunity and PD-L1 expression within tumors promotes immune evasion. If and how changes in metabolism or defined metabolites regulate PD-L1 expression is not fully understood. Here, using a metabolomics activity screening-based approach, we have determined that hydroxyproline (Hyp) significantly and directly enhances adaptive (i.e., IFN-γ-induced) PD-L1 expression in multiple relevant myeloid and cancer cell types. Mechanistic studies reveal that Hyp acts as an inhibitor of autophagic flux, which allows it to regulate this negative feedback mechanism, thereby contributing to its overall effect on PD-L1 expression. Due to its prevalence in fibrotic tumors, these findings suggest that hydroxyproline could contribute to the establishment of an immunosuppressive tumor microenvironment and that Hyp metabolism could be targeted to pharmacologically control PD-L1 expression for the treatment of cancer or autoimmune diseases.


Assuntos
Antígeno B7-H1 , Interferon gama , Autofagia , Antígeno B7-H1/genética , Antígeno B7-H1/metabolismo , Linhagem Celular Tumoral , Hidroxiprolina , Interferon gama/farmacologia , Interferon gama/metabolismo , Humanos
3.
Leukemia ; 37(6): 1298-1310, 2023 06.
Artigo em Inglês | MEDLINE | ID: mdl-37106163

RESUMO

Although the landscape for treating acute myeloid leukemia (AML) patients has changed substantially in recent years, the majority of patients will eventually relapse and succumb to their disease. Allogeneic stem cell transplantation provides the best anti-AML treatment strategy, but is only suitable in a minority of patients. In contrast to B-cell neoplasias, chimeric antigen receptor (CAR) T-cell therapy in AML has encountered challenges in target antigen heterogeneity, safety, and T-cell dysfunction. We established a Fab-based adapter CAR (AdCAR) T-cell platform with flexibility of targeting and control of AdCAR T-cell activation. Utilizing AML cell lines and a long-term culture assay for primary AML cells, we were able to demonstrate AML-specific cytotoxicity using anti-CD33, anti-CD123, and anti-CLL1 adapter molecules in vitro and in vivo. Notably, we show for the first time the feasibility of sequential application of adapter molecules of different specificity in primary AML co-cultures. Importantly, using the AML platform, we were able to demonstrate that chronic T-cell stimulation and exhaustion can be counteracted through introduction of treatment-free intervals. As T-cell exhaustion and target antigen heterogeneity are well-known causes of resistance, the AdCAR platform might offer effective strategies to ameliorate these limitations.


Assuntos
Leucemia Mieloide Aguda , Exaustão das Células T , Humanos , Linhagem Celular Tumoral , Leucemia Mieloide Aguda/metabolismo , Imunoterapia Adotiva , Linfócitos T
4.
Angew Chem Int Ed Engl ; 62(1): e202214048, 2023 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-36315420

RESUMO

A frontier challenge in single-atom (SA) catalysis is the design of fully inorganic sites capable of emulating the high reaction selectivity traditionally exclusive of organometallic counterparts in homogeneous catalysis. Modulating the direct coordination environment in SA sites, via the exploitation of the oxide support's surface chemistry, stands as a powerful albeit underexplored strategy. We report that isolated Rh atoms stabilized on oxygen-defective SnO2 uniquely unite excellent TOF with essentially full selectivity in the gas-phase hydroformylation of ethylene, inhibiting the thermodynamically favored olefin hydrogenation. Density Functional Theory calculations and surface characterization suggest that substantial depletion of the catalyst surface in lattice oxygen, energetically facile on SnO2 , is key to unlock a high coordination pliability at the mononuclear Rh centers, leading to an exceptional performance which is on par with that of molecular catalysts in liquid media.

5.
Nanoscale ; 14(37): 13551-13560, 2022 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-36000554

RESUMO

Converting CO2 into value-added chemicals and fuels, such as methanol, is a promising approach to limit the environmental impact of human activities. Conventional methanol synthesis catalysts have shown limited efficiency and poor stability in a CO2/H2 mixture. To design improved catalysts, crucial for the effective utilization of CO2, an in-depth understanding of the active sites and reaction mechanism is desired. The catalytic performance of a series of carbon-supported Cu catalysts, with Cu particle sizes in the range of 5 to 20 nm, was evaluated under industrially relevant temperature and pressure, i.e. 260 °C and 40 bar(g). The CO2 hydrogenation reaction exhibited clear particle size effects up to 13 nm particles, with small nanoparticles having the lower activity, but higher methanol selectivity. MeOH and CO formation showed a different size-dependence. The TOFCO increased from 1.9 × 10-3 s-1 to 9.4 × 10-3 s-1 with Cu size increasing from 5 nm to 20 nm, while the TOFMeOH was size-independent (8.4 × 10-4 s-1 on average). The apparent activation energies for MeOH and CO formation were size-independent with values of 63 ± 7 kJ mol-1 and 118 ± 6 kJ mol-1, respectively. Hence the size dependence was ascribed to a decrease in the fraction of active sites suitable for CO formation with decreasing particle size. Theoretical models and DFT calculations showed that the origin of the particle size effect is most likely related to the differences in formate coverage for different Cu facets whose abundancy depends on particle size. Hence, the CO2 hydrogenation reaction is intrinsically sensitive to the Cu particle size.

6.
Proc Natl Acad Sci U S A ; 119(4)2022 01 25.
Artigo em Inglês | MEDLINE | ID: mdl-35046020

RESUMO

Water influences critically the kinetics of the autocatalytic conversion of methanol to hydrocarbons in acid zeolites. At very low conversions but otherwise typical reaction conditions, the initiation of the reaction is delayed in presence of H2O. In absence of hydrocarbons, the main reactions are the methanol and dimethyl ether (DME) interconversion and the formation of a C1 reactive mixture-which in turn initiates the formation of first hydrocarbons in the zeolite pores. We conclude that the dominant reactions for the formation of a reactive C1 pool at this stage involve hydrogen transfer from both MeOH and DME to surface methoxy groups, leading to methane and formaldehyde in a 1:1 stoichiometry. While formaldehyde reacts further to other C1 intermediates and initiates the formation of first C-C bonds, CH4 is not reacting. The hydride transfer to methoxy groups is the rate-determining step in the initiation of the conversion of methanol and DME to hydrocarbons. Thus, CH4 formation rates at very low conversions, i.e., in the initiation stage before autocatalysis starts, are used to gauge the formation rates of first hydrocarbons. Kinetics, in good agreement with theoretical calculations, show surprisingly that hydrogen transfer from DME to methoxy species is 10 times faster than hydrogen transfer from methanol. This difference in reactivity causes the observed faster formation of hydrocarbons in dry feeds, when the concentration of methanol is lower than in presence of water. Importantly, the kinetic analysis of CH4 formation rates provides a unique quantitative parameter to characterize the activity of catalysts in the methanol-to-hydrocarbon process.

7.
Nat Chem Biol ; 17(6): 684-692, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33846619

RESUMO

Heparan sulfate (HS) proteoglycans bind extracellular proteins that participate in cell signaling, attachment and endocytosis. These interactions depend on the arrangement of sulfated sugars in the HS chains generated by well-characterized biosynthetic enzymes; however, the regulation of these enzymes is largely unknown. We conducted genome-wide CRISPR-Cas9 screens with a small-molecule ligand that binds to HS. Screening of A375 melanoma cells uncovered additional genes and pathways impacting HS formation. The top hit was the epigenetic factor KDM2B, a histone demethylase. KDM2B inactivation suppressed multiple HS sulfotransferases and upregulated the sulfatase SULF1. These changes differentially affected the interaction of HS-binding proteins. KDM2B-deficient cells displayed decreased growth rates, which was rescued by SULF1 inactivation. In addition, KDM2B deficiency altered the expression of many extracellular matrix genes. Thus, KDM2B controls proliferation of A375 cells through the regulation of HS structure and serves as a master regulator of the extracellular matrix.


Assuntos
Proteínas F-Box/antagonistas & inibidores , Estudo de Associação Genômica Ampla , Heparitina Sulfato/metabolismo , Histona Desmetilases com o Domínio Jumonji/antagonistas & inibidores , Algoritmos , Sistemas CRISPR-Cas , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Descoberta de Drogas , Matriz Extracelular/genética , Ensaios de Triagem em Larga Escala , Humanos , Ligação Proteica/genética , RNA-Seq , Sulfotransferases/antagonistas & inibidores
8.
Viruses ; 13(4)2021 04 02.
Artigo em Inglês | MEDLINE | ID: mdl-33918368

RESUMO

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) causes COVID-19 and is responsible for the ongoing pandemic. Screening of potential antiviral drugs against SARS-CoV-2 depend on in vitro experiments, which are based on the quantification of the virus titer. Here, we used virus-induced cytopathic effects (CPE) in brightfield microscopy of SARS-CoV-2-infected monolayers to quantify the virus titer. Images were classified using deep transfer learning (DTL) that fine-tune the last layers of a pre-trained Resnet18 (ImageNet). To exclude toxic concentrations of potential drugs, the network was expanded to include a toxic score (TOX) that detected cell death (CPETOXnet). With this analytic tool, the inhibitory effects of chloroquine, hydroxychloroquine, remdesivir, and emetine were validated. Taken together we developed a simple method and provided open access implementation to quantify SARS-CoV-2 titers and drug toxicity in experimental settings, which may be adaptable to assays with other viruses. The quantification of virus titers from brightfield images could accelerate the experimental approach for antiviral testing.


Assuntos
Antivirais/farmacologia , Aprendizado Profundo , Avaliação Pré-Clínica de Medicamentos/métodos , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos , Aprendizado de Máquina , SARS-CoV-2/efeitos dos fármacos , Monofosfato de Adenosina/análogos & derivados , Monofosfato de Adenosina/farmacologia , Alanina/análogos & derivados , Animais , COVID-19 , Chlorocebus aethiops , Proteínas do Nucleocapsídeo de Coronavírus , Fosfoproteínas , Células Vero , Carga Viral/efeitos dos fármacos
9.
Science ; 369(6506): 993-999, 2020 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-32820126

RESUMO

Stimulator of interferon genes (STING) links innate immunity to biological processes ranging from antitumor immunity to microbiome homeostasis. Mechanistic understanding of the anticancer potential for STING receptor activation is currently limited by metabolic instability of the natural cyclic dinucleotide (CDN) ligands. From a pathway-targeted cell-based screen, we identified a non-nucleotide, small-molecule STING agonist, termed SR-717, that demonstrates broad interspecies and interallelic specificity. A 1.8-angstrom cocrystal structure revealed that SR-717 functions as a direct cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) mimetic that induces the same "closed" conformation of STING. SR-717 displayed antitumor activity; promoted the activation of CD8+ T, natural killer, and dendritic cells in relevant tissues; and facilitated antigen cross-priming. SR-717 also induced the expression of clinically relevant targets, including programmed cell death 1 ligand 1 (PD-L1), in a STING-dependent manner.


Assuntos
Antineoplásicos/farmacologia , Materiais Biomiméticos/farmacologia , Proteínas de Membrana/metabolismo , Nucleotídeos Cíclicos/farmacologia , Animais , Antígeno B7-H1/metabolismo , Materiais Biomiméticos/química , Linfócitos T CD8-Positivos/efeitos dos fármacos , Linfócitos T CD8-Positivos/imunologia , Cristalografia por Raios X , Células Dendríticas/efeitos dos fármacos , Células Dendríticas/imunologia , Humanos , Células Matadoras Naturais/efeitos dos fármacos , Células Matadoras Naturais/imunologia , Camundongos , Nucleotídeos Cíclicos/química , Conformação Proteica/efeitos dos fármacos
10.
Mater Sci Eng C Mater Biol Appl ; 106: 110268, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31753373

RESUMO

Microfiber yarns (MY) have been widely employed to construct tendon tissue grafts. However, suboptimal ultrastructure and inappropriate environments for cell interactions limit their clinical application. Herein, we designed a modified electrospinning device to coat poly(lactic-co-glycolic acid) PLGA nanofibers onto polylactic acid (PLA) MY to generate PLGA/PLA hybrid yarns (HY), which had a well-aligned nanofibrous structure, resembling the ultrastructure of native tendon tissues and showed enhanced failure load compared to PLA MY. PLGA/PLA HY significantly improved the growth, proliferation, and tendon-specific gene expressions of human adipose derived mesenchymal stem cells (HADMSC) compared to PLA MY. Moreover, thymosin beta-4 (Tß4) loaded PLGA/PLA HY presented a sustained drug release manner for 28 days and showed an additive effect on promoting HADMSC migration, proliferation, and tenogenic differentiation. Collectively, the combination of Tß4 with the nano-topography of PLGA/PLA HY might be an efficient strategy to promote tenogenesis of adult stem cells for tendon tissue engineering.


Assuntos
Nanofibras/química , Poliésteres/química , Copolímero de Ácido Poliláctico e Ácido Poliglicólico/química , Timosina/química , Engenharia Tecidual , Tecido Adiposo/citologia , Diferenciação Celular/efeitos dos fármacos , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Humanos , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/metabolismo , Tendões/citologia , Tendões/metabolismo , Timosina/metabolismo , Timosina/farmacologia , Alicerces Teciduais/química
11.
Proc Natl Acad Sci U S A ; 116(13): 6435-6440, 2019 03 26.
Artigo em Inglês | MEDLINE | ID: mdl-30846550

RESUMO

Glioblastoma multiforme (GBM; grade IV astrocytoma) is the most prevalent and aggressive form of primary brain cancer. A subpopulation of multipotent cells termed GBM cancer stem cells (CSCs) play a critical role in tumor initiation, tumor maintenance, metastasis, drug resistance, and recurrence following surgery. Here we report the identification of a small molecule, termed RIPGBM, from a cell-based chemical screen that selectively induces apoptosis in multiple primary patient-derived GBM CSC cultures. The cell type-dependent selectivity of this compound appears to arise at least in part from redox-dependent formation of a proapoptotic derivative, termed cRIPGBM, in GBM CSCs. cRIPGBM induces caspase 1-dependent apoptosis by binding to receptor-interacting protein kinase 2 (RIPK2) and acting as a molecular switch, which reduces the formation of a prosurvival RIPK2/TAK1 complex and increases the formation of a proapoptotic RIPK2/caspase 1 complex. In an orthotopic intracranial GBM CSC tumor xenograft mouse model, RIPGBM was found to significantly suppress tumor formation in vivo. Our chemical genetics-based approach has identified a drug candidate and a potential drug target that provide an approach to the development of treatments for this devastating disease.


Assuntos
Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Neoplasias Encefálicas/tratamento farmacológico , Neoplasias Encefálicas/patologia , Animais , Astrócitos , Linhagem Celular Tumoral , Modelos Animais de Doenças , Sistemas de Liberação de Medicamentos , Avaliação Pré-Clínica de Medicamentos , Feminino , Glioblastoma , Xenoenxertos , Ensaios de Triagem em Larga Escala , Humanos , MAP Quinase Quinase Quinases/metabolismo , Camundongos , Camundongos Nus , Células-Tronco Neoplásicas/efeitos dos fármacos , Piroptose/efeitos dos fármacos , Proteína Serina-Treonina Quinase 2 de Interação com Receptor , Proteína Serina-Treonina Quinases de Interação com Receptores/metabolismo
12.
Haematologica ; 104(1): 59-69, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30171030

RESUMO

Hematologic responses to hypomethylating agents are often delayed in patients with myelodysplastic syndrome or acute myeloid leukemia. Fetal hemoglobin is a potential novel bio-marker of response: recently, we demonstrated that a high fetal hemoglobin level prior to decitabine treatment was associated with superior outcome. Here we investigated whether early fetal hemoglobin induction during decitabine treatment also had prognostic value, and studied the potential of decitabine to induce erythroid differentiation and fetal hemoglobin expression in vitro Fetal hemoglobin levels were measured by high-performance liquid chromatography in patients with higher-risk myelodysplastic syndrome (n=16) and acute myeloid leukemia (n=37) before treatment and after each course of decitabine. Levels above 1.0% were considered induced. Patients achieving complete or partial remission as best response had attained a median fetal hemoglobin of 1.9% after two courses of treatment, whereas the median value in patients who did not reach complete or partial remission was 0.8% (P=0.015). Fetal hemoglobin induction after two courses of decitabine treatment was associated with early platelet doubling (P=0.006), and its subsequent decrease with hematologic relapse. In patients with myelodysplastic syndrome, induction of fetal hemoglobin after course 2 of treatment was associated with longer overall survival: median of 22.9 versus 7.3 months in patients with or without induction of fetal hemoglobin, respectively [hazard ratio=0.2 (95% confidence interval: 0.1-0.9); P=0.03]. In vitro decitabine treatment of two bi-potential myeloid leukemia cell lines (K562 and HEL) resulted in induction of an erythroid (not megakaryocytic) differentiation program, and of fetal hemoglobin mRNA and protein, associated with GATA1 gene demethylation and upregulation. In conclusion, fetal hemoglobin may provide a useful dynamic biomarker during hypomethylating agent therapy in patients with myelodysplastic syndrome or acute myeloid leukemia.


Assuntos
Biomarcadores Tumorais/sangue , Decitabina/administração & dosagem , Hemoglobina Fetal/metabolismo , Síndromes Mielodisplásicas , Proteínas de Neoplasias/sangue , Idoso , Feminino , Humanos , Células K562 , Leucemia Mieloide Aguda/sangue , Leucemia Mieloide Aguda/tratamento farmacológico , Masculino , Pessoa de Meia-Idade , Síndromes Mielodisplásicas/sangue , Síndromes Mielodisplásicas/tratamento farmacológico
13.
J Hand Surg Am ; 44(8): 699.e1-699.e10, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30502017

RESUMO

PURPOSE: The aim of this study was to assess the treatment and complications of a distinct type of partial intra-articular distal radius fracture. METHODS: Seven patients treated by the senior author between 2008 and 2013 for a partial intra-articular distal radius fracture with isolated involvement of the volar lunate facet were included. All fragments had the distinctive shape of a triangular-base pyramid (tetrahedron) extending from the metaphysis distally. All fractures were preoperatively assessed with computed tomography (CT) scans. Patients underwent surgical treatment using a standard flexor carpi radialis approach (2 patients) or a volar ulnar approach (5 patients) and were followed postoperatively for a minimum of 12 months. RESULTS: Patient age ranged from 33 to 66 years. On average, fragments measured 34 ± 6 mm in length (range, 27-43 mm) and were 48% as wide as the distal radius (range, 40% to 56%) and 58% as deep as the anterior-posterior dimension of the lesser sigmoid notch (range, 33% to 83%). Loss of reduction requiring revision surgery occurred at 4 weeks in 1 patient who underwent internal fixation through the flexor carpi radialis approach. The remaining cases healed uneventfully. At the final follow-up, all, except the patient requiring revision surgery, had a painless wrist. Average total wrist motion measured 87% of the opposite side. Radiographic healing with anatomic wrist alignment was observed in all except the patient requiring revision. This patient had persistent joint subluxation. The remaining patients all achieved good or excellent functional outcomes. CONCLUSIONS: Isolated tetrahedron volar lunate facet fractures of the distal radius are rare. In our experience, the use of a volar ulnar approach leads to satisfactory fixation and outcomes, yielding excellent radiographic and clinical outcomes. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic V.


Assuntos
Fixação Interna de Fraturas/métodos , Fraturas Intra-Articulares/cirurgia , Fraturas do Rádio/cirurgia , Ulna/cirurgia , Adulto , Idoso , Feminino , Humanos , Fraturas Intra-Articulares/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Complicações Pós-Operatórias/cirurgia , Fraturas do Rádio/diagnóstico por imagem , Amplitude de Movimento Articular , Reoperação/estatística & dados numéricos , Tomografia Computadorizada por Raios X , Ulna/diagnóstico por imagem
14.
Bioorg Med Chem Lett ; 28(16): 2675-2678, 2018 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-29731362

RESUMO

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy that is extremely refractory to the therapeutic approaches that have been evaluated to date. Recently, it has been demonstrated that PDAC tumors are dependent upon a metabolic pathway involving aspartate aminotransferase 1, also known as glutamate-oxaloacetate transaminase 1 (GOT1), for the maintenance of redox homeostasis and sustained proliferation. As such, small molecule inhibitors targeting this metabolic pathway may provide a novel therapeutic approach for the treatment of this devastating disease. To this end, from a high throughput screen of ∼800,000 molecules, 4-(1H-indol-4-yl)-N-phenylpiperazine-1-carboxamide was identified as an inhibitor of GOT1. Mouse pharmacokinetic studies revealed that potency, rather than inherent metabolic instability, would limit immediate cell- and rodent xenograft-based experiments aimed at validating this potential cancer metabolism-related target. Medicinal chemistry-based optimization resulted in the identification of multiple derivatives with >10-fold improvements in potency, as well as the identification of a tryptamine-based series of GOT1 inhibitors.


Assuntos
Aspartato Aminotransferases/antagonistas & inibidores , Inibidores Enzimáticos/uso terapêutico , Indóis/uso terapêutico , Compostos de Fenilureia/uso terapêutico , Piperazinas/uso terapêutico , Transaminases/antagonistas & inibidores , Animais , Aspartato Aminotransferase Citoplasmática , Carcinoma Ductal Pancreático/tratamento farmacológico , Descoberta de Drogas , Estabilidade de Medicamentos , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacocinética , Feminino , Indóis/síntese química , Indóis/química , Indóis/farmacocinética , Camundongos , Compostos de Fenilureia/síntese química , Compostos de Fenilureia/química , Compostos de Fenilureia/farmacocinética , Piperazinas/síntese química , Piperazinas/química , Piperazinas/farmacocinética , Relação Estrutura-Atividade
15.
Biofabrication ; 9(4): 044106, 2017 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-29134948

RESUMO

Engineered tendon grafts offer a promising alternative for grafting during the reconstruction of complex tendon tears. The tissue-engineered tendon substitutes have the advantage of increased biosafety and the option to customize their biochemical and biophysical properties to promote tendon regeneration. In this study, we developed a novel centrifugal melt electrospinning (CME) technique, with the goal of optimizing the fabrication parameters to generate fibrous scaffolds for tendon tissue engineering. The effects of CME processing parameters, including rotational speed, voltage, and temperature, on fiber properties (i.e. orientation, mean diameter, and productivity) were systematically investigated. By using this solvent-free and environmentally friendly method, we fabricated both random and aligned poly (L-lactic acid) (PLLA) fibrous scaffolds with controllable mesh thickness. We also investigated and compared their morphology, surface hydrophilicity, and mechanical properties. We seeded human adipose derived mesenchymal stem cells (HADMSC) on various PLLA fibrous scaffolds and conditioned the constructs in tenogenic differentiation medium for up to 21 days, to investigate the effects of fiber alignment and scaffold thickness on cell behavior. Aligned fibrous scaffolds induced cell elongation and orientation through a contact guidance phenomenon and promoted HADMSC proliferation and differentiation towards tenocytes. At the early stage, thinner scaffolds were beneficial for HADMSC proliferation, but the scaffold thickness had no significant effects on cell proliferation for longer-term cell culture. We further co-seeded HADMSC and human umbilical vein endothelial cells (HUVEC) on aligned PLLA fibrous mats and determined how the vascularization affected HADMSC tenogenesis. We found that co-cultured HADMSC-HUVEC expressed more tendon-related markers on the aligned fibrous scaffold. The co-culture systems promoted in vitro HADMSC differentiation towards tenocytes. These aligned fibrous scaffolds fabricated by CME technique could potentially be utilized to repair and regenerate tendon defects and injuries with cell co-culture and controlled vascularization.


Assuntos
Tecido Adiposo/citologia , Diferenciação Celular , Técnicas de Cocultura/métodos , Células-Tronco Mesenquimais/citologia , Poliésteres/química , Tendões/citologia , Engenharia Tecidual/métodos , Alicerces Teciduais/química , Proliferação de Células , Centrifugação , Células Endoteliais da Veia Umbilical Humana/citologia , Humanos
16.
Acta Biomater ; 62: 102-115, 2017 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-28864251

RESUMO

Non-woven nanofibrous scaffolds have been developed for tendon graft application by using electrospinning strategies. However, electrospun nanofibrous scaffolds face some obstacles and limitations, including suboptimal scaffold structure, weak tensile and suture-retention strengths, and compact structure for cell infiltration. In this work, a novel nanofibrous, woven biotextile, fabricated based on electrospun nanofiber yarns, was implemented as a tissue engineered tendon scaffold. Based on our modified electrospinning setup, polycaprolactone (PCL) nanofiber yarns were fabricated with reproducible quality, and were further processed into plain-weaving fabrics interlaced with polylactic acid (PLA) multifilaments. Nonwoven nanofibrous PCL meshes with random or aligned fiber structures were generated using typical electrospinning as comparative counterparts. The woven fabrics contained 3D aligned microstructures with significantly larger pore size and obviously enhanced tensile mechanical properties than their nonwoven counterparts. The biological results revealed that cell proliferation and infiltration, along with the expression of tendon-specific genes by human adipose derived mesenchymal stem cells (HADMSC) and human tenocytes (HT), were significantly enhanced on the woven fabrics compared with those on randomly-oriented or aligned nanofiber meshes. Co-cultures of HADMSC with HT or human umbilical vein endothelial cells (HUVEC) on woven fabrics significantly upregulated the functional expression of most tenogenic markers. HADMSC/HT/HUVEC tri-culture on woven fabrics showed the highest upregulation of most tendon-associated markers than all the other mono- and co-culture groups. Furthermore, we conditioned the tri-cultured constructs with dynamic conditioning and demonstrated that dynamic stretch promoted total collagen secretion and tenogenic differentiation. Our nanofiber yarn-based biotextiles have significant potential to be used as engineered scaffolds to synergize the multiple cell interaction and mechanical stimulation for promoting tendon regeneration. STATEMENT OF SIGNIFICANCE: Tendon grafts are essential for the treatment of various tendon-related conditions due to the inherently poor healing capacity of native tendon tissues. In this study, we combined electrospun nanofiber yarns with textile manufacturing strategies to fabricate nanofibrous woven biotextiles with hierarchical features, aligned fibrous topography, and sufficient mechanical properties as tendon tissue engineered scaffolds. Comparing to traditional electrospun random or aligned meshes, our novel nanofibrous woven fabrics possess strong tensile and suture-retention strengths and larger pore size. We also demonstrated that the incorporation of tendon cells and vascular cells promoted the tenogenic differentiation of the engineered tendon constructs, especially under dynamic stretch. This study not only presents a novel tissue engineered tendon scaffold fabrication technique but also provides a useful strategy to promote tendon differentiation and regeneration.


Assuntos
Células Endoteliais da Veia Umbilical Humana/metabolismo , Células-Tronco Mesenquimais/metabolismo , Nanofibras/química , Tendões/metabolismo , Tenócitos/metabolismo , Têxteis , Engenharia Tecidual , Alicerces Teciduais/química , Células Endoteliais da Veia Umbilical Humana/citologia , Humanos , Células-Tronco Mesenquimais/citologia , Poliésteres/química , Tendões/citologia , Tenócitos/citologia
17.
J Bone Joint Surg Am ; 99(18): 1524-1531, 2017 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-28926381

RESUMO

BACKGROUND: Total elbow arthroplasty is commonly considered for elderly patients with comminuted distal humeral fractures. Satisfactory short-term outcomes have been reported, but long-term outcomes are unknown. Our purpose was to assess the long-term outcomes of total elbow arthroplasty after distal humeral fracture and to determine differences between elbows with or without inflammatory arthritis at the time of fracture. METHODS: Forty-four total elbow arthroplasties were performed after distal humeral fracture; those patients were followed for a minimum of 10 years and were evaluated with regard to pain, motion, Mayo Elbow Performance Scores, complications, and reoperations. The outcomes in elbows with and without inflammatory arthritis were compared. Kaplan-Meier survivorship analysis was performed. RESULTS: Total elbow arthroplasty provided good pain relief and motion; the mean visual analog scale for pain was 0.6, the mean flexion was 123°, and the mean loss of extension was 24°. The mean Mayo Elbow Performance Score was 90.5 points, with 3 patients scoring <75 points. Five elbows (11%) developed deep infection, treated surgically with component retention (3 acute) or resection (2 chronic). Implant revision or resection was performed in 8 elbows (18%): 3 for infections (1 reimplantation and 2 resections), 3 for ulnar loosening (associated with periprosthetic fracture in 1), and 2 for ulnar component fractures. Additional periprosthetic fractures were observed in 5 elbows. The survival rates for elbows with rheumatoid arthritis were 85% at 5 years and 76% at 10 years, and the survival rates for elbows without rheumatoid arthritis were 92% at both 5 and 10 years. The most relevant risk factor for revision was male sex (hazard ratio, 12.6 [95% confidence interval, 1.7 to 93.6]). CONCLUSIONS: Selective use of total elbow arthroplasty to treat fractures of the distal part of the humerus for infirm, less active older patients and patients with inflammatory arthritis has acceptable longevity in surviving patients, but at the cost of a number of major complications. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.


Assuntos
Artroplastia de Substituição do Cotovelo , Fraturas do Úmero/cirurgia , Idoso , Idoso de 80 Anos ou mais , Artrite Reumatoide/cirurgia , Articulação do Cotovelo/cirurgia , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Medição da Dor , Amplitude de Movimento Articular , Estudos Retrospectivos
18.
Br J Haematol ; 176(4): 609-617, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-27905102

RESUMO

Although azanucleoside DNA-hypomethylating agents (HMAs) are routinely used for the treatment of myelodysplastic syndrome/acute myeloid leukaemia (MDS/AML), very few outcome predictors have been established. Expression of the ß-like globin gene locus is tightly regulated by DNA methylation, is HMA-sensitive in vitro, and fetal haemoglobin (HbF) expression is under study as a potential biomarker for response of MDS patients to azacitidine. We determined HbF expression in 16 MDS and 36 AML patients receiving decitabine (DAC). Pre-treatment HbF was already elevated (>1·0% of total haemoglobin) in 7/16 and 12/36 patients, and HbF was induced by DAC in 81%/54% of MDS/AML patients, respectively. Elevated pre-treatment HbF was associated with longer median overall survival (OS): 26·6 vs. 8·6 months for MDS (hazard ratio [HR] 8·56, 95% confidence interval [CI] 1·74-42·49, P = 0·008, with similarly longer progression-free and AML-free survival), and 10·0 vs. 2·9 months OS for AML (HR 3·01, 95% CI 1·26-7·22, P = 0·014). In a multivariate analysis, the prognostic value of HbF was retained. Time-dependent Cox models revealed that the prognostic value of treatment-induced HbF induction was inferior to that of pre-treatment HbF. In conclusion, we provide first evidence for in vivo HbF induction by DAC in MDS/AML, and demonstrate prognostic value of elevated pre-treatment HbF, warranting prospective, randomized studies.


Assuntos
Azacitidina/análogos & derivados , Hemoglobina Fetal/análise , Leucemia Mieloide Aguda/tratamento farmacológico , Síndromes Mielodisplásicas/tratamento farmacológico , Idoso , Idoso de 80 Anos ou mais , Antimetabólitos Antineoplásicos/uso terapêutico , Azacitidina/administração & dosagem , Azacitidina/farmacologia , Azacitidina/uso terapêutico , Biomarcadores/análise , Metilação de DNA/efeitos dos fármacos , Decitabina , Intervalo Livre de Doença , Feminino , Hemoglobina Fetal/efeitos dos fármacos , Humanos , Leucemia Mieloide Aguda/mortalidade , Masculino , Pessoa de Meia-Idade , Síndromes Mielodisplásicas/mortalidade , Prognóstico , Análise de Sobrevida
19.
Curr Opin Struct Biol ; 40: 104-111, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27639240

RESUMO

Diverse glycans on proteins impact cell and organism physiology, along with drug activity. Since many protein-based biotherapeutics are glycosylated and these glycans have biological activity, there is a desire to engineer glycosylation for recombinant protein-based biotherapeutics. Engineered glycosylation can impact the recombinant protein efficacy and also influence many cell pathways by first changing glycan-protein interactions and consequently modulating disease physiologies. However, its complexity is enormous. Recent advances in glycoengineering now make it easier to modulate protein-glycan interactions. Here, we discuss how engineered glycans contribute to therapeutic monoclonal antibodies (mAbs) in the treatment of cancers, how these glycoengineered therapeutic mAbs affect the transformed phenotypes and downstream cell pathways. Furthermore, we suggest how systems biology can help in the next generation mAb glycoengineering process by aiding in data analysis and guiding engineering efforts to tailor mAb glycan and ultimately drug efficacy, safety and affordability.


Assuntos
Anticorpos Monoclonais/genética , Anticorpos Monoclonais/metabolismo , Neoplasias/fisiopatologia , Polissacarídeos/metabolismo , Engenharia de Proteínas/métodos , Animais , Anticorpos Monoclonais/uso terapêutico , Humanos , Neoplasias/metabolismo , Neoplasias/terapia
20.
Int J Shoulder Surg ; 10(1): 21-7, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26980986

RESUMO

PURPOSE: The purpose of this study is to assess the outcomes of a consecutive series of patients who underwent revision surgery after humeral head resurfacing (HHR). Our joint registry was queried for all patients who underwent revision arthroplasty for failed HHR at our institution from 2005 to 2010. Eleven consecutive patients (average age 54 years; range 38-69 years) that underwent revision of 11 resurfacing arthroplasties were identified. The primary indication for resurfacing had been osteoarthritis in six, glenoid dysplasia in two, a chondral lesion in two, and postinstability arthropathy in one patient. The indication for revision was pain in 10 and infection in one patient. Seven patients had undergone an average of 1.9 surgeries prior to resurfacing (range 1-3). MATERIALS AND METHODS: All patients were revised to stemmed arthroplasties, including one hemiarthroplasty, two reverse, and eight anatomic total shoulder arthroplasties at a mean 33 months after primary resurfacing (range 10-131 months). A deltopectoral approach was used in seven patients; four patients required an anteromedial approach due to severe scarring. Subscapularis attenuation was found in four cases, two of which required reverse total shoulder arthroplasty. Bone grafting was required in one glenoid and three humeri. RESULTS: At a mean follow-up of 3.5 years (range 1.6-6.9 years), modified Neer score was rated as satisfactory in five patients and unsatisfactory in six. Abduction and external rotation improved from 73° to 88° (P = 0.32) and from 23° to 32° (P = 0.28) respectively. Reoperation was required in two patients, including one hematoma and one revision for instability. CONCLUSION: Outcomes of revision of HHR arthroplasty in this cohort did not improve upon those reported for revision of stemmed humeral implants. A comparative study would be required to allow for definitive conclusions to be made.

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