RESUMEN
Inflammation is considered a mechanistic driver of Alzheimer's disease, thought to increase tau phosphorylation, the first step to the formation of neurofibrillary tangles (NFTs). To further understand how inflammation impacts the development of tau pathology, we used (hTau) mice, which express all six, non-mutated, human tau isoforms, but with an altered ratio of tau isoforms favoring 3R tau due to the concomitant loss of murine tau (mTau) that is predominantly 4R. Such an imbalance pattern has been related to susceptibility to NFTs formation, but whether or not this also affects susceptibility to systemic inflammation and related changes in tau phosphorylation is not known. To reduce the predominance of 3R tau by increasing 4R tau availability, we bred hTau mice on a heterozygous mTau background and compared the impact of systemic inflammation induced by lipopolysaccharide (LPS) in hTau mice hetero- or homozygous mTau knockout. Three-month-old male wild-type (Wt), mTau+/-, mTau-/-, hTau/mTau+/-, and hTau/mTau-/- mice were administered 100, 250, or 330 µg/kg of LPS or its vehicle phosphate buffer saline (PBS) [intravenously (i.v.), n = 8-9/group]. Sickness behavior, reflected by behavioral suppression in the spontaneous alternation task, hippocampal tau phosphorylation, measured by western immunoblotting, and circulating cytokine levels were quantified 4 h after LPS administration. The persistence of the LPS effects (250 µg/kg) on these measures, and food burrowing behavior, was assessed at 24 h post-inoculation in Wt, mTau+/-, and hTau/mTau+/- mice (n = 9-10/group). In the absence of immune stimulation, increasing 4R tau levels in hTau/mTau+/- exacerbated pS202 and pS396/404 tau phosphorylation, without altering total tau levels or worsening early behavioral perturbations characteristic of hTau/mTau-/- mice. We also show for the first time that modulating 4R tau levels in hTau mice affects the response to systemic inflammation. Behavior was suppressed in all genotypes 4 h following LPS administration, but hTau/mTau+/- exhibited more severe sickness behavior at the 100 µg/kg dose and a milder behavioral and cytokine response than hTau/mTau-/- mice at the 330 µg/kg dose. All LPS doses decreased tau phosphorylation at both epitopes in hTau/mTau+/- mice, but pS202 levels were selectively reduced at the 100 µg/kg dose in hTau/mTau-/- mice. Behavioral suppression and decreased tau phosphorylation persisted at 24 h following LPS administration in hTau/mTau+/- mice.
Asunto(s)
Hipocampo/metabolismo , Inflamación/complicaciones , Tauopatías/etiología , Proteínas tau/metabolismo , Animales , Citocinas/biosíntesis , Lipopolisacáridos/toxicidad , Masculino , Ratones , Ratones Endogámicos C57BL , Fosforilación , Isoformas de Proteínas/análisis , Proteínas tau/análisisRESUMEN
Treatment of esophageal disease can necessitate resection and reconstruction of the esophagus. Current reconstruction approaches are limited to utilization of an autologous conduit such as stomach, small bowel, or colon. A tissue engineered construct providing an alternative for esophageal replacement in circumferential, full thickness resection would have significant clinical applications. In the current study, we demonstrate that regeneration of esophageal tissue is feasible and reproducible in a large animal model using synthetic polyurethane electro-spun grafts seeded with autologous adipose-derived mesenchymal stem cells (aMSCs) and a disposable bioreactor. The scaffolds were not incorporated into the regrown esophageal tissue and were retrieved endoscopically. Animals underwent adipose tissue biopsy to harvest and expand autologous aMSCs for seeding on electro-spun polyurethane conduits in a bioreactor. Anesthetized pigs underwent full thickness circumferential resection of the mid-lower thoracic esophagus followed by implantation of the cell seeded scaffold. Results from these animals showed gradual structural regrowth of endogenous esophageal tissue, including squamous esophageal mucosa, submucosa, and smooth muscle layers with blood vessel formation. Scaffolds carrying autologous adipose-derived mesenchymal stem cells may provide an alternative to the use of a gastro-intestinal conduit for some patients following resection of the esophagus.
Asunto(s)
Células Inmovilizadas , Enfermedades del Esófago , Esófago , Trasplante de Células Madre Mesenquimatosas/métodos , Células Madre Mesenquimatosas/metabolismo , Regeneración , Andamios del Tejido/química , Animales , Autoinjertos , Células Inmovilizadas/metabolismo , Células Inmovilizadas/trasplante , Modelos Animales de Enfermedad , Enfermedades del Esófago/metabolismo , Enfermedades del Esófago/patología , Enfermedades del Esófago/cirugía , Esófago/fisiología , Esófago/cirugía , Porcinos , Ingeniería de TejidosRESUMEN
NAD metabolism and the NAD biosynthetic enzymes nicotinamide nucleotide adenylyltransferases (NMNATs) are thought to play a key neuroprotective role in tauopathies, including Alzheimer's disease. Here, we investigated whether modulating the expression of the NMNAT nuclear isoform NMNAT1, which is important for neuronal maintenance, influences the development of behavioral and neuropathological abnormalities in htau mice, which express non-mutant human tau isoforms and represent a model of tauopathy relevant to Alzheimer's disease. Prior to the development of cognitive symptoms, htau mice exhibit tau hyperphosphorylation associated with a selective deficit in food burrowing, a behavior reminiscent to activities of daily living which are impaired early in Alzheimer's disease. We crossed htau mice with Nmnat1 transgenic and knockout mice and tested the resulting offspring until the age of 6 months. We show that overexpression of NMNAT1 ameliorates the early deficit in food burrowing characteristic of htau mice. At 6 months of age, htau mice did not show neurodegenerative changes in both the cortex and hippocampus, and these were not induced by downregulating NMNAT1 levels. Modulating NMNAT1 levels produced a corresponding effect on NMNAT enzymatic activity but did not alter NAD levels in htau mice. Although changes in local NAD levels and subsequent modulation of NAD-dependent enzymes cannot be ruled out, this suggests that the effects seen on behavior may be due to changes in tau phosphorylation. Our results suggest that increasing NMNAT1 levels can slow the progression of symptoms and neuropathological features of tauopathy, but the underlying mechanisms remain to be established.
Asunto(s)
Conducta Animal/fisiología , Memoria/fisiología , Nicotinamida-Nucleótido Adenililtransferasa/genética , Tauopatías/patología , Actividades Cotidianas , Animales , Modelos Animales de Enfermedad , Ratones Noqueados , Neuronas/metabolismo , Proteínas tau/metabolismoRESUMEN
Malignant oesophageal pathology typically requires resection of a portion of oesophagus. The aim of this study was to investigate attachment and growth of swine oesophageal mucosal cells on electrospun synthetic nanofibre matrices of varying chemistries and to determine whether a mucosal-seeded graft, in a swine animal model, could induce regeneration. Swine mucosal oesophageal cells were isolated and seeded them onto five different matrix materials. Matrix samples were cultured for up to 14 days, after which matrices were analysed for cell attachment. Attachment varied for each of the matrix materials tested, with the most rigid showing the lowest levels of attachment. Importantly, sections of these matrices illustrated that multiple layers of mucosal cells formed, mimicking endogenous oesophageal structure. A tdTomato reporter line (mucosaltdt cells) was created to enable cell tracking. As polyurethane matrix was found optimal through in vitro testing, a graft was prepared using mucosaltdt cells, along with an unseeded control, and implanted into swine for determination of oesophageal regeneration. Mucosal seeded polyurethane grafts initiated full thickness regeneration of the oesophagus, including epithelial, submucosal, and skeletal muscle layers which were highly vascularized. Interestingly, an unseeded graft showed similar regeneration, indicating that the role of cells in the process of oesophageal regeneration is still unclear. The electrospun polyurethane matrix does appear suitable for multilayered cellular attachment and growth of oesophageal mucosal cells, and implantation of polyurethane grafts initiated full thickness regeneration of the oesophagus, indicating potential for oesophageal reconstruction in humans. Copyright © 2016 John Wiley & Sons, Ltd.
Asunto(s)
Esófago/fisiología , Membrana Mucosa/trasplante , Poliuretanos/farmacología , Regeneración/efectos de los fármacos , Animales , Esófago/efectos de los fármacos , Esófago/trasplante , Matriz Extracelular/metabolismo , Genes Reporteros , Membrana Mucosa/citología , Membrana Mucosa/efectos de los fármacos , PorcinosRESUMEN
RATIONALE: Cardiomyocytes (CMs) differentiated from human pluripotent stem cells (PSCs) are increasingly being used for cardiovascular research, including disease modeling, and hold promise for clinical applications. Current cardiac differentiation protocols exhibit variable success across different PSC lines and are primarily based on the application of growth factors. However, extracellular matrix is also fundamentally involved in cardiac development from the earliest morphogenetic events, such as gastrulation. OBJECTIVE: We sought to develop a more effective protocol for cardiac differentiation of human PSCs by using extracellular matrix in combination with growth factors known to promote cardiogenesis. METHODS AND RESULTS: PSCs were cultured as monolayers on Matrigel, an extracellular matrix preparation, and subsequently overlayed with Matrigel. The matrix sandwich promoted an epithelial-to-mesenchymal transition as in gastrulation with the generation of N-cadherin-positive mesenchymal cells. Combining the matrix sandwich with sequential application of growth factors (Activin A, bone morphogenetic protein 4, and basic fibroblast growth factor) generated CMs with high purity (up to 98%) and yield (up to 11 CMs/input PSC) from multiple PSC lines. The resulting CMs progressively matured over 30 days in culture based on myofilament expression pattern and mitotic activity. Action potentials typical of embryonic nodal, atrial, and ventricular CMs were observed, and monolayers of electrically coupled CMs modeled cardiac tissue and basic arrhythmia mechanisms. CONCLUSIONS: Dynamic extracellular matrix application promoted epithelial-mesenchymal transition of human PSCs and complemented growth factor signaling to enable robust cardiac differentiation.
Asunto(s)
Técnicas de Cultivo de Célula/métodos , Diferenciación Celular/fisiología , Colágeno , Matriz Extracelular/fisiología , Laminina , Miocitos Cardíacos/citología , Células Madre Pluripotentes/citología , Proteoglicanos , Activinas/farmacología , Proteína Morfogenética Ósea 4/farmacología , Diferenciación Celular/efectos de los fármacos , Línea Celular , Células Cultivadas , Combinación de Medicamentos , Transición Epitelial-Mesenquimal/efectos de los fármacos , Transición Epitelial-Mesenquimal/fisiología , Factor 2 de Crecimiento de Fibroblastos/farmacología , Humanos , Péptidos y Proteínas de Señalización Intercelular/farmacología , Miocitos Cardíacos/efectos de los fármacos , Células Madre Pluripotentes/efectos de los fármacos , Transducción de Señal/efectos de los fármacos , Transducción de Señal/fisiologíaRESUMEN
A major factor limiting the engraftment of transplanted stem cells after myocardial infarction is the low rate of retention in the infarcted site. Our long-term objective is to improve engraftment by enabling stem cells to recognize and bind infarcted tissue. To this end, we proposed to modify the surface of embryonic stem cells (ESCs) with the C2A domain of synaptotagmin I; this allows the engineered stem cells to bind to dead and dying cardiac cells by recognizing phosphatidylserine (PS). The latter is a molecular marker for apoptotic and necrotic cells. The C2A domain of synaptotagmin I, which binds PS with high affinity and specificity, was attached to the surface of mouse ESCs using the biotin-avidin coupling mechanism. Binding of C2A-ESCs to dead and dying cardiomyocytes was tested in vitro. After the surface modification, cellular physiology was examined for viability, pluripotency, and differentiation potential. C2A covalently attached to the ESC surface at an average of about 1 million C2A molecules per cell under mild conjugation reaction conditions. C2A-ESCs avidly bound to dying, but not viable, cardiomyocytes in culture. The normal physiology of C2A-modified ESCs was maintained. The binding of C2A-ESCs to moribund cardiomyocytes demonstrates that the retention of transplanted cells may be improved by conferring these cells with the ability to bind infarcted tissue. Once established, this novel approach may be applicable to other types of transplanted therapeutic cells.
Asunto(s)
Células Madre Embrionarias/trasplante , Infarto del Miocardio/terapia , Animales , Supervivencia Celular , Células Cultivadas , Ratones , Miocitos Cardíacos/citología , Miocitos Cardíacos/metabolismo , Unión Proteica , Ratas , Propiedades de Superficie , Sinaptotagmina I/química , Sinaptotagmina I/metabolismoRESUMEN
Highly enriched, pure populations of pluripotent mouse embryonic stem (mES) cells are a prerequisite to downstream experimental manipulations. However, the existing preplating method does not allow complete removal of co-cultured mouse embryonic fibroblast (MEF) feeder cells. The primary objective of the current investigation was to develop and validate a rapid, single-step separation technique for the complete removal of MEF feeder cells from mES cells. A discontinuous density gradient was prepared using Histopaque 1119 at incremental percentages from the top to bottom of a test tube (20, 40, 60, and 100% in culture medium). A suspension of mES cells and MEF feeder cells was layered on top of the gradient. After centrifugation at 400 x g, ES cells and MEF feeder cells were segregated discretely in separate layers at the 40/20% and 100/60% density interfaces, respectively. The mES cells were enriched to a purity of greater than 99% with a recovery rate of greater than 90%. The separation did not alter the viability or the differentiation potential of mES cells. This study validates a simple technique that enables the preparation of highly enriched mES cells that are essentially free of contaminating MEF feeder cells. The discontinuous density gradient separation method is inexpensive, efficient, rapid, and reproducible. The method can be readily scaled-up to accommodate large batch preparations, enabling a broad range of processing needs. Overall, this simple technique significantly expedites the recovery and enrichment of mES cells from MEFs.
Asunto(s)
Separación Celular/métodos , Células Madre Embrionarias/citología , Fibroblastos/citología , Células Madre Pluripotentes/citología , Animales , Recuento de Células , Diferenciación Celular , Supervivencia Celular , Células Cultivadas , Técnicas de Cocultivo , Células Madre Embrionarias/fisiología , Ratones , Células Madre Pluripotentes/fisiología , Factores de TiempoRESUMEN
We tested the idea that T-box factors direct serum response factor (SRF) gene activity early in development. Analysis of SRF-LacZ "knock-in" mice showed highly restricted expression in early embryonic cardiac and skeletal muscle mesoderm and neuroectoderm. Examination of the SRF gene for regulatory regions by linking the promoter and 5'-flanking sequences, up to 5.5 kb, failed to target LacZ transgene activity to the heart and the tail pre-somitic mesenchyme. However, linkage of a minimal SRF promoter with the SRF 3'-untranslated region (UTR), inundated with multimeric T-box binding sites (TBEs), restored robust reporter gene activity to embryonic heart and tail. Finer dissection of the 3'-UTR to a small cluster of TBEs also stimulated transgene activity in the cardiac forming region and the tail, however, when the TBEs contained within these DNA sequences were mutated, preventing Tbx binding, transgene activity was lost. Tbx2, Tbx5, and the cardiac-enriched MYST family histone acetyltransferase TIP60, were observed to be mutual interactive cofactors through the TIP60 zinc finger and the T-box of the Tbx factors. In SRF-null ES cells, TIP60, Tbx2, and Tbx5 were sufficient to stimulate co-transfected SRF reporter activity, however this activity required the presence of the SRF 3'-UTR. SRF gene transactivation was blocked by two distinct TIP60 mutants, in which either the histone acetyltransferase domain was inactivated or the Zn finger-protein binding domain was excised. Our study supports the idea that SRF embryonic cardiac gene expression is dependent upon the SRF 3'-UTR enhancer, Tbx2, Tbx5, and TIP60 histone acetyltransferase activity.