RESUMEN
The peripheral immune system is important in neurodegenerative diseases, both in protecting and inflaming the brain, but the underlying mechanisms remain elusive. Alzheimer's Disease is commonly preceded by a prodromal period. Here, we report the presence of large Aß aggregates in plasma from patients with mild cognitive impairment (n = 38). The aggregates are associated with low level Alzheimer's Disease-like brain pathology as observed by 11C-PiB PET and 18F-FTP PET and lowered CD18-rich monocytes. We characterize complement receptor 4 as a strong binder of amyloids and show Aß aggregates are preferentially phagocytosed and stimulate lysosomal activity through this receptor in stem cell-derived microglia. KIM127 integrin activation in monocytes promotes size selective phagocytosis of Aß. Hydrodynamic calculations suggest Aß aggregates associate with vessel walls of the cortical capillaries. In turn, we hypothesize aggregates may provide an adhesion substrate for recruiting CD18-rich monocytes into the cortex. Our results support a role for complement receptor 4 in regulating amyloid homeostasis.
Asunto(s)
Enfermedad de Alzheimer , Péptidos beta-Amiloides , Disfunción Cognitiva , Humanos , Enfermedad de Alzheimer/patología , Integrina alfaXbeta2 , Monocitos/patologíaRESUMEN
This is a case report of a hospitalised 62-year-old male patient with COVID-19, who received unilateral neuromuscular electrical stimulation treatment with a customised anti-embolic compression stocking and maintained muscle mass as well as maximum voluntary quadriceps contraction and balance during six days of illness-induced immobilisation. This illustrates, that short durations of neuromuscular electrical stimulation can help maintaining muscle mass and physical function in patients with SARS-CoV-2.
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COVID-19 , Terapia por Estimulación Eléctrica , Estimulación Eléctrica , Humanos , Masculino , Persona de Mediana Edad , Músculo Esquelético , Músculo Cuádriceps , SARS-CoV-2RESUMEN
A thorough understanding of the aortic root structure and biomechanics is necessary when performing aortic valve-sparing procedures in patients with aortic root aneurysms. This study aimed to evaluate the amount of collagen and biomechanics at different levels and segments of the aortic root. Ten aortic roots from healthy pigs were excised including the aortic annulus, the sinuses of Valsalva, and the sinotubular junction (STJ). Specimens were further divided into three circumferential segments; left coronary (LC)-, right coronary (RC)-, and non-coronary (NC) sinus. Collagen was determined using hydroxyproline analysis and specimens were tested biomechanically for stress-strain relations. The annulus showed significantly larger average maximum stiffness (9.6 ± 4.5 N/mm) compared with the sinus (4.5 ± 2.0 N/mm) and STJ (4.8 ± 1.8 N/mm). The average collagen content was likewise higher in the annulus (4.0 ± 1.0 mg/ml) compared with the sinus (2.4 ± 0.6 mg/ml) and STJ (2.2 ± 0.5 mg/ml) for all three segments. The NC sinus segment exhibited a significantly larger maximum stiffness and stress under static conditions compared with the RC. These results suggest that the aortic root is heterogeneous in both structure and biomechanical properties and that it varies both in levels and segments of the aortic root. Future surgical approaches should consider enhanced strength parameters for specific areas of the aortic root to achieve the best results when performing aortic valve-sparing techniques. From this study, we conclude that the aortic annulus needs special attention to imitate normal physiologic properties during aortic valve-sparing surgery due to its higher maximum stiffness, stress, and load. Modified future surgical procedures could potentially prevent recurrent aneurysmal formation.
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Insuficiencia de la Válvula Aórtica , Seno Aórtico , Animales , Aorta , Válvula Aórtica/cirugía , Fenómenos Biomecánicos , Colágeno , Humanos , Seno Aórtico/cirugía , PorcinosRESUMEN
The combination of modern interventional and preventive medicine has led to an epidemic of ageing. While this phenomenon is a positive consequence of an improved lifestyle and achievements in a society, the longer life expectancy is often accompanied by decline in quality of life due to musculoskeletal pain and disability. The Aarhus Regenerative Orthopaedics Symposium (AROS) 2015 was motivated by the need to address regenerative challenges in an ageing population by engaging clinicians, basic scientists, and engineers. In this position paper, we review our contemporary understanding of societal, patient-related, and basic science-related challenges in order to provide a reasoned roadmap for the future to deal with this compelling and urgent healthcare problem.
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Envejecimiento/fisiología , Sistema Musculoesquelético/fisiopatología , Medicina Regenerativa/métodos , Animales , Comorbilidad , Modelos Animales de Enfermedad , Humanos , Regeneración/fisiologíaRESUMEN
PURPOSE: To evaluate the ability of nm-scaled iron oxide particles conjugated with Azure A, a classic histological dye, to accumulate in areas of angiogenesis in a recently developed murine angiogenesis model. MATERIALS AND METHODS: We characterised the Azure A particles with regard to their hydrodynamic size, zeta potential, and blood circulation half-life. The particles were then investigated by Magnetic Resonance Imaging (MRI) in a recently developed murine angiogenesis model along with reference particles (Ferumoxtran-10) and saline injections. RESULTS: The Azure A particles had a mean hydrodynamic diameter of 51.8 ± 43.2 nm, a zeta potential of -17.2 ± 2.8 mV, and a blood circulation half-life of 127.8 ± 74.7 min. Comparison of MR images taken pre- and 24-h post-injection revealed a significant increase in R2(*) relaxation rates for both Azure A and Ferumoxtran-10 particles. No significant difference was found for the saline injections. The relative increase was calculated for the three groups, and showed a significant difference between the saline group and the Azure A group, and between the saline group and the Ferumoxtran-10 group. However, no significant difference was found between the two particle groups. CONCLUSION: Ultrahigh-field MRI revealed localisation of both types of iron oxide particles to areas of neovasculature. However, the Azure A particles did not show any enhanced accumulation relative to Ferumoxtran-10, suggesting the accumulation in both cases to be passive.
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Imagen por Resonancia Magnética/métodos , Nanopartículas de Magnetita/química , Nanopartículas de Magnetita/ultraestructura , Nanocápsulas/química , Nanocápsulas/ultraestructura , Neovascularización Patológica/metabolismo , Neovascularización Patológica/patología , Animales , Medios de Contraste/síntesis química , Masculino , Ratones , Tamaño de la Partícula , Distribución TisularRESUMEN
Bone tissue engineering implants with sustained local drug delivery provide an opportunity for better postoperative care for bone tumor patients because these implants offer sustained drug release at the tumor site and reduce systemic side effects. A rapid prototyped macroporous polycaprolactone scaffold was embedded with a porous matrix composed of chitosan, nanoclay, and ß-tricalcium phosphate by freeze-drying. This composite scaffold was evaluated on its ability to deliver an anthracycline antibiotic and to promote formation of mineralized matrix in vitro. Scanning electronic microscopy, confocal imaging, and DNA quantification confirmed that immortalized human bone marrow-derived mesenchymal stem cells (hMSC-TERT) cultured in the scaffold showed high cell viability and growth, and good cell infiltration to the pores of the scaffold. Alkaline phosphatase activity and osteocalcin staining showed that the scaffold was osteoinductive. The drug-release kinetics was investigated by loading doxorubicin into the scaffold. The scaffolds comprising nanoclay released up to 45% of the drug for up to 2 months, while the scaffold without nanoclay released 95% of the drug within 4 days. Therefore, this scaffold can fulfill the requirements for both bone tissue engineering and local sustained release of an anticancer drug in vitro. These results suggest that the scaffold can be used clinically in reconstructive surgery after bone tumor resection. Moreover, by changing the composition and amount of individual components, the scaffold can find application in other tissue engineering areas that need local sustained release of drug.
Asunto(s)
Sistemas de Liberación de Medicamentos/instrumentación , Sistemas de Liberación de Medicamentos/métodos , Nanoestructuras/química , Ingeniería de Tejidos/instrumentación , Ingeniería de Tejidos/métodos , Andamios del Tejido , Fosfatasa Alcalina/química , Silicatos de Aluminio/química , Análisis de Varianza , Materiales Biocompatibles/química , Regeneración Ósea , Calcio/química , Fosfatos de Calcio/química , Línea Celular Transformada , Fenómenos Fisiológicos Celulares , Quitosano/química , Arcilla , Preparaciones de Acción Retardada , Histocitoquímica , Humanos , Células Madre Mesenquimatosas/citología , Osteogénesis , Poliésteres/químicaRESUMEN
PURPOSE: To be able to screen and identify potential candidate agents for noninvasive imaging of diseases involving angiogenesis, a standardized in vivo angiogenesis model is needed. Angiogenesis is a common feature of many pathological conditions and has become an important target for diagnosis and treatment, with many noninvasive imaging agents emerging. MATERIALS AND METHODS: Uniform scaffolds consisting of porous and flexible polycaprolactone were implanted subcutaneously in mice and studied after 1 to 6 weeks to describe the time course of angiogenesis. The model was characterized by histology and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). RESULTS: Microscopic examination revealed progressive ingrowth of new vessels from the periphery, leading to a fully vascularized scaffold within 6 weeks. Blood flow through the new vessels, assessed by DCE-MRI, revealed peripheral vascularization corresponding to 12.3% (SD 6.1%) of scaffold area at week 1 and a more uniform and complete distribution of vessels corresponding to 84.1% (SD 16.2%) of scaffold area at week 4. CONCLUSION: In agreement with microscopic examination, noninvasive DCE-MRI visualized progressive development of new vessels in a novel and standardized murine angiogenesis model, making this model suitable for screening angiogenesis-related drugs and contrast agents.
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Neovascularización Patológica/patología , Análisis de Varianza , Animales , Área Bajo la Curva , Medios de Contraste/farmacocinética , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Gadolinio DTPA/farmacocinética , Aumento de la Imagen/métodos , Ratones , Poliésteres , Porosidad , Andamios del TejidoRESUMEN
It is of high clinical relevance in bone tissue engineering that scaffolds promote a high seeding efficiency of cells capable of osteogenic differentiation, such as human bone marrow-derived mesenchymal stem cells (hMSCs). We evaluated the effects of a novel polycaprolactone (PCL) scaffold on hMSC seeding efficiency, proliferation, distribution and differentiation. Porous PCL meshes prepared by fused deposition modeling (FDM) were embedded in matrix of hyaluronic acid, methylated collagen and terpolymer via polyelectrolyte complex coacervation. Scaffolds were cultured statically and dynamically in osteogenic stimulation medium for up to 28 days. Compared to naked PCL scaffolds, embedded scaffolds provided a higher cell seeding efficiency (t-test, P<0.05), a more homogeneous cell distribution and more osteogenically differentiated cells, verified by a more pronounced gene expression of the bone markers alkaline phosphatase, osteocalcin, bone sialoprotein I and bone sialoprotein II. Dynamic culture resulted in higher amounts of DNA (day 14 and day 21) and calcium (day 21 and day 28), compared to static culture. Dynamic culture and the embedding synergistically enhanced the calcium deposition of hMSC on day 21 and day 28. This in vitro study provides evidence that hybrid scaffolds made from natural and synthetic polymers improve cellular seeding efficiency, proliferation, distribution and osteogenic differentiation.
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Huesos/fisiología , Matriz Extracelular/metabolismo , Ingeniería de Tejidos/métodos , Andamios del Tejido/química , Fosfatasa Alcalina/metabolismo , Biomarcadores/metabolismo , Huesos/efectos de los fármacos , Calcificación Fisiológica/efectos de los fármacos , Calcio/metabolismo , Núcleo Celular/efectos de los fármacos , Núcleo Celular/metabolismo , Supervivencia Celular/efectos de los fármacos , Condrogénesis/efectos de los fármacos , Condrogénesis/genética , ADN/metabolismo , Matriz Extracelular/efectos de los fármacos , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Células Madre Mesenquimatosas/citología , Células Madre Mesenquimatosas/efectos de los fármacos , Células Madre Mesenquimatosas/enzimología , Microscopía Confocal , Microscopía Electrónica de Rastreo , Osteogénesis/efectos de los fármacos , Osteogénesis/genética , Poliésteres/farmacología , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Coloración y Etiquetado , Telomerasa/metabolismoRESUMEN
The derivation of osteogenic cells from human embryonic stem cells (hESC) has been hampered by the absence of easy and reproducible protocols. hESC grown in feeder-free conditions, often show a sub population of fibroblast-like, stromal cells growing between the colonies. Thus, we examined the possibility that these cells represent a population of stromal (mesenchymal) stem cells (hESC-stromal). Two in house derived hES cell lines (Odense3 and KMEB3) as well as an externally derived cell line (Hues8) were transitioned to feeder-free conditions. A sub population of fibroblast-like cells established between the hESC colonies were isolated by selective adherence to hyaluronic acid-coated plates (100 µg/ml) and were characterized using a combination of FACS analysis and staining. The cells were CD44(+), CD29(+), CD73(+), CD166(+), CD146(+), and CD105(+); and, Oct4â», CD34â», CD45â» and CXCR4â». When cultured in osteogenic differentiation media, up regulation of osteoblastic lineage markers (DLX5, MSX2, RUNX2, SPARC, ALP, COL1a1, BGLAP, IBSP, DCN, LOX-L4) and production of in vitro mineralized matrix was detected. hESC-stromal cells loaded on a carrier and implanted either subcutaneously or in a critical size calvarial defect in immune deficient mice for 10 weeks, resulted in new bone formation and partial repair of the calvarial defect. In conclusion, hESC-stromal can be isolated from hESC cultures and represent a good source for obtaining cells with osteogenic differentiation potential suitable for regenerative medicine protocols.
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Células Madre Embrionarias/citología , Células del Estroma/citología , Adipocitos/citología , Diferenciación Celular/fisiología , Línea Celular , Condrocitos/citología , Células Madre Embrionarias/metabolismo , Citometría de Flujo , Humanos , Inmunohistoquímica , Osteoblastos/citología , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
The creation of complex tissues and organs is the ultimate goal in tissue engineering. Engineered morphogenesis necessitates spatially controlled development of multiple cell types within a scaffold implant. We present a novel method to achieve this by adhering nanoparticles containing different small-interfering RNAs (siRNAs) into nanostructured scaffolds. This allows spatial retention of the RNAs within nanopores until their cellular delivery. The released siRNAs were capable of gene silencing BCL2L2 and TRIB2, in mesenchymal stem cells (MSCs), enhancing osteogenic and adipogenic differentiation, respectively. This approach for enhancing a single type of differentiation is immediately applicable to all areas of tissue engineering. Different nanoparticles localized to spatially distinct locations within a single implant allowed two different tissue types to develop in controllable areas of an implant. As a consequence of this, we predict that complex tissues and organs can be engineered by the in situ development of multiple cell types guided by spatially restricted nanoparticles.
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Adipocitos/citología , Diferenciación Celular/genética , Células Madre Mesenquimatosas/citología , Nanoestructuras/química , Osteoblastos/citología , ARN Interferente Pequeño/genética , Andamios del Tejido , Adipocitos/metabolismo , Animales , Apoptosis , Proteínas Reguladoras de la Apoptosis/antagonistas & inhibidores , Proteínas Reguladoras de la Apoptosis/genética , Proteínas Reguladoras de la Apoptosis/metabolismo , Western Blotting , Proteínas Quinasas Dependientes de Calcio-Calmodulina , Proliferación Celular , Células Cultivadas , Condrogénesis , Proteína Quinasa Activada por ADN/fisiología , Proteínas de Unión al ADN/fisiología , Femenino , Citometría de Flujo , Silenciador del Gen , Proteínas Fluorescentes Verdes/genética , Humanos , Técnicas para Inmunoenzimas , Péptidos y Proteínas de Señalización Intracelular/antagonistas & inhibidores , Péptidos y Proteínas de Señalización Intracelular/genética , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Células Madre Mesenquimatosas/metabolismo , Ratones , Ratones Endogámicos NOD , Ratones SCID , Nanopartículas/ultraestructura , Nanoestructuras/ultraestructura , Proteínas Nucleares/fisiología , Osteoblastos/metabolismo , ARN Mensajero/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Ingeniería de TejidosRESUMEN
It is well established in the field of biomaterials that hydroxyapatite (HA) may provide interesting osteoconductive properties. In this study, we investigated the osseointegrational effect of a 50/50 vol % composite of HA nanoparticles and poly-D,L-lactic acid (PDLLA) coated on model titanium bone implants in an in vivo animal model. The aim is to evaluate how the addition of HA to PDLLA may improve the bone formation and initial fixation of the implant. Two titanium implants coated with the PDLLA/HA composite and pure PDLLA, respectively, were implanted bilaterally in proximal part of humeri with a 2-mm peri-implant gap in 10 sheep. After 12 weeks, the remains of the coatings were present on 20.3 and 19.8% of PDLLA/HA composite- and PDLLA-coated implants, respectively. It was observed that newly formed bone (39.3%) and fibrous tissue (58.3%) had replaced the PDLLA/HA composite, whereas pure PDLLA was replaced almost completely by fibrous tissue (96.2%). Consequently, the PDLLA/HA composite-coated implants were better fixated as confirmed by push-out tests. Using quantification of peri-implant tissue and implant fixation as parameters, the present findings, therefore, clearly reveal that the addition of nanoparticulate HA to a PDLLA coating on titanium implants increases osseointegration.
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Materiales Biocompatibles Revestidos , Durapatita , Ácido Láctico , Nanopartículas/química , Osteogénesis/fisiología , Polímeros , Prótesis e Implantes , Titanio/química , Animales , Huesos/anatomía & histología , Huesos/metabolismo , Huesos/cirugía , Materiales Biocompatibles Revestidos/química , Materiales Biocompatibles Revestidos/metabolismo , Durapatita/química , Durapatita/metabolismo , Humanos , Implantes Experimentales , Ácido Láctico/química , Ácido Láctico/metabolismo , Ensayo de Materiales , Microscopía de Fuerza Atómica , Microscopía Electrónica , Poliésteres , Polímeros/química , Polímeros/metabolismo , Ovinos , Propiedades de SuperficieRESUMEN
Risk assessment in patients with carotid atherosclerosis relies on the degree of luminal stenosis. Incorporating morphological information on plaque composition obtained noninvasively through the use of magnetic resonance imaging (MRI) could include other variables besides the degree of stenosis into carotid plaque risk assessment. Knowledge of the morphologic composition of the plaque allows determination of mechanic stresses exerted on the protective fibrous cap, which may be of importance in the assessment of plaque vulnerability. Based on image processing of transverse MRI scans, longitudinal 2D fluid-structure interaction (FSI) simulations of carotid atherosclerotic plaques were performed facilitating in-vivo estimation of longitudinal internal fibrous cap stresses. The FSI simulation combined finite element analysis (FEA) with computational fluid dynamics (CFD) simulations of blood-flow variables. Preliminary results from two symptomatic patients revealed longitudinal stress levels (max. 254.1 and 143.2 kPa) approaching established criteria for plaque rupture at known predilection sites of plaque rupture. Determination of longitudinal fibrous cap stresses may prove useful in assessing plaque vulnerability and improve risk stratification in patients with carotid atherosclerosis.