Search

Highlights • Specific glucose consumption rate based on the local glucose concentration. • Image analysis tecnique for scaffold morphology characterization and cell counting. • Modeling of the cell growth heterogeneity in a perfusion dynamic bioreactor. • A method to evaluate the local cell distribution, based on scaffold pore size. Abstract Motivation It has been widely demonstrated that perfusion bioreactors improve in vitro cell culture on three-dimensional (3D) matrices. Goal We aimed to determine the local cell distribution, based on the pore diameter, within a 3D scaffold during cell growth in a perfusion bioreactor. Materials and methods Scaffolds under perfusion were collected at 0, 4, and 7 days of culture; scaffold morphology and cell distribution within the construct were evaluated by imaging analysis. A mathematical model representing the cell growth heterogeneity in 3D perfusion bioreactor was developed; a specific rate equation for glucose was experimentally determined. Model accuracy was assessed comparing the cell proliferation predictions with experimental data. Results Cell proliferation was successfully determined by coupling cell imaging with an ad hoc algorithm. The total number of cells in the scaffold, the number of cells for a single cross section, and the local cell distribution based on the scaffold pore size, were determined. Good agreement between computations and experiments was observed. Conclusions A new methodology was developed to determine the cell heterogeneity within a 3D scaffold under perfusion. The proposed approach provides a helpful tool for 3D dynamic cell culture optimization for biological studies and tissue engineering applications. [ABSTRACT FROM AUTHOR]

Abstract: The mass transport through biocompatible and biodegradable polymeric 3D porous scaffolds may be depleted by non-porous impermeable internal walls. As consequence the concentration of metabolites and growth factors within the scaffold may be heterogeneous leading to different cell fate depending on spatial cell location, and in some cases it may compromise cell survival. In this work, we fabricated polymeric scaffolds with micro- and nano-scale porosity by developing a new technique that couples two conventional scaffold production methods: solvent casting-salt leaching and gas antisolvent precipitation. 10–15w/w solutions of a hyaluronic benzyl esters (HYAFF11) and poly-(lactic acid) (PLA) were used to fill packed beds of 0.177–0.425mm NaCl crystals. The polymer precipitation in micro and nano-porous structures between the salt crystals was induced by high-pressure gas, then its flushing extracted the residual solvent. The salt was removed by water-wash. Morphological analysis by scanning electron microscopy showed a uniform porosity (~70%) and a high interconnectivity between porous. The polymeric walls were porous themselves counting for 30% of the total porosity. This wall porosity did not lead to a remarkable change in compressive modulus, deformation, and rupture pressure. Scaffold biocompatibility was tested with murine muscle cell line C2C12 for 4 and 7days. Viability analysis and histology showed that micro- and nano-porous scaffolds are biocompatible and suitable for 3D cell culture promoting cell adhesion on the polymeric wall and allowing their proliferation in layers. Micro- and nano-scale porosities enhance cell migration and growth in the inner part of the scaffold. [Copyright &y& Elsevier]

The success of skeletal muscle reconstruction depends on finding the most effective, clinically suitable strategy to engineer myogenic cells and biocompatible scaffolds. Satellite cells (SCs), freshly isolated or transplanted within their niche, are presently considered the best source for muscle regeneration. Here, we designed and developed the delivery of either SCs or muscle progenitor cells (MPCs) via an in situ photo-cross-linkable hyaluronan-based hydrogel, hyaluronic acid-photoinitiator (HA-PI) complex. Partially ablated tibialis anterior (TA) of C57BL/6J mice engrafted with freshly isolated satellite cells embedded in hydrogel showed a major improvement in muscle structure and number of new myofibers, compared to muscles receiving hydrogel MPCs or hydrogel alone. Notably, SCs embedded in HA-PI also promoted functional recovery, as assessed by contractile force measurements. Tissue reconstruction was associated with the formation of both neural and vascular networks and the reconstitution of a functional SC niche. This innovative approach could overcome previous limitations in skeletal muscle tissue engineering. [ABSTRACT FROM AUTHOR]

Our goal was to develop a computational model describing the spatiotemporal evolution of cell heterogeneity within a three-dimensional porous scaffold during cell growth in a perfusion bioreactor. The scaffold was assumed formed by an ensemble of independent parallel cylindrical channels with a defined diameter distribution. The total flow rate partitioning in each channel depends on the effective diameter, which is reduced by the cell growth on the channel wall. The mass balance for one metabolite and the cell volume balance were solved. For each channel diameter, the model simulation provide the spatiotemporal evolution of velocity, shear stress, metabolite concentration, and cell volume growth. In particular, all of these outcomes can be analyzed as a function of channel diameter providing an evaluation of cell property heterogeneity. The model describes that the cell growth can be substantially different in each channel diameter. For instance, in the small diameter channel, cell growth is limited by metabolite mass transport, whereas in the larger diameter channel, shear stress inhibits cell growth. This mathematical model could be an important tool for a priori estimation of the time variation of the cell volume fraction and its degree of heterogeneity as a function of operational parameters and scaffold pore size distribution. [ABSTRACT FROM AUTHOR]

The nucleus Locus Coeruleus (LC) is placed in the upper part of the pons, is mainly formed by medium-sized neurons containing neuromelanin and it is part of the so-called isodendritic core of the brain stem reticular formation. LC is the main source of noradrenaline in the brain. In humans, each one of two symmetrical LC nuclei is formed by up to 60.000 neurons, which send axons profusely branching and innervating the entire cerebral and cerebellar cortices. Noradrenaline is released through "bouton en passage" by LC axons, and thus it modulates the activity of several cortical areas. In particular, LC modulates sleep/wake cycle, different cognitive functions (such as attention, alerting and novelty orienting and memory consolidation) and electroencephalogram activity. It also plays an important role in neural plasticity and neuroprotection. Several post-mortem studies showed a significant LC cell loss in Parkinson's Disease (PD) and in cases of severe Alzheimer's Disease (AD) dementia, in post-mortem studies. Recent histological data suggest a very early involvement of LC in the pathogenesis of AD. In particular accumulation of phospho-tau deposits in the axons of LC neurons may precede their occurrence in limbic regions in Mild Cognitive Impairment (MCI, which is the prodromal phase of Dementia) or even in pre-MCI stages. Experimental data show that LC impairment may accelerate beta amyloid plaques deposition and neuroinflammation. Recently, specific 1,5 and 3,0 Tesla Magnetic Resonance Imaging (MRI) protocols and postprocessing analysis have been developed in order to detect neuromelanin-containing LC neurons in vivo in controls and in PD patients, as well as in dementia. In this presentation, we report the state of the art of the neuroanatomical features of LC in models of degenerative diseases, as well as more recent evidence in humans. These data disclose a novel scenario for LC, stemming from in vivo neuroanatomy to neurobiology of neurodegenerative diseases. [ABSTRACT FROM AUTHOR]

The mammalian Target of Rapamycin (mTOR) is a molecular complex equipped with kinase activity which controls cell viability being key in the PI3K/PTEN/Akt pathway. mTOR acts by integrating a number of environmental stimuli to regulate cell growth, proliferation, autophagy, and protein synthesis. These effects are based on the modulation of different metabolic pathways. Upregulation of mTOR associates with various pathological conditions, such as obesity, neurodegeneration, and brain tumors. This is the case of high-grade gliomas with a high propensity to proliferation and tissue invasion. Glioblastoma Multiforme (GBM) is a WHO grade IV malignant, aggressive, and lethal glioma. To date, a few treatments are available although the outcome of GBM patients remains poor. Experimental and pathological findings suggest that mTOR upregulation plays a major role in determining an aggressive phenotype, thus determining relapse and chemoresistance. Among several activities, mTOR-induced autophagy suppression is key in GBM malignancy. In this article, we discuss recent evidence about mTOR signaling and its role in normal brain development and pathological conditions, with a special emphasis on its role in GBM. [ABSTRACT FROM AUTHOR]

Nonsteroidal anti-inflammatory drugs, besides exerting detrimental effects on the upper digestive tract, can also damage the small and large intestine. Although the underlying mechanisms remain unclear, there is evidence that enteric bacteria play a pivotal role. The present study examined the enteroprotective effects of a delayed-release formulation of rifaximin-EIR (R-EIR, 50 mg/kg BID, i.g.), a poorly absorbed antibiotic with a broad spectrum of antibacterial activity, in a rat model of enteropathy induced by indomethacin (IND, 1.5 mg/kg BID for 14 days) administration. R-EIR was administered starting 7 days before or in concomitance with IND administration. At the end of treatments, blood samples were collected to evaluate hemoglobin (Hb) concentration (as an index of digestive bleeding). Small intestine was processed for: (1) histological assessment of intestinal damage (percentage length of lesions over the total length examined); (2) assay of tissue myeloperoxidase (MPO) and TNF levels, as markers of inflammation; (3) assay of tissue malondialdehyde (MDA) and protein carbonyl concentrations, as an index of lipid and protein peroxidation, respectively; (4) evaluation of the major bacterial phyla. IND significantly decreased Hb levels, this effect being significantly blunted by R-EIR. IND also induced the occurrence of lesions in the jejunum and ileum. In both intestinal regions, R-EIR significantly reduced the percentage of lesions, as compared with rats receiving IND alone. Either the markers of inflammation and tissue peroxidation were significantly increased in jejunum and ileum from IND-treated rats. However, in rats treated with R-EIR, these parameters were not significantly different from those observed in controls. R-EIR was also able to counterbalance the increase in Proteobacteria and Firmicutes abundance induced by INDO. To summarize, R-EIR treatment significantly prevents IND-induced intestinal damage, this enteroprotective effect being associated with a decrease in tissue inflammation, oxidative stress and digestive bleeding as well as reversal of NSAID-induced alterations in bacterial population. [ABSTRACT FROM AUTHOR]

In the present paper, we analyze the cell number within lamina X at the end stage of disease in a G93A mouse model of ALS; the effects induced by lithium; the stem-cell like phenotype of lamina X cells during ALS; the differentiation of these cells towards either a glial or neuronal phenotype. In summary we found that G93A mouse model of ALS produces an increase in lamina X cells which is further augmented by lithium administration. In the absence of lithium these nestin positive stem-like cells preferentially differentiate into glia (GFAP positive), while in the presence of lithium these cells differentiate towards a neuron like phenotype (βIII-tubulin, NeuN, and calbindin-D28K positive). These effects of lithium are observed concomitantly with attenuation in disease progression and are reminiscent of neurogenetic effects induced by lithiumin the subependymal ventricular zone of the hippocampus. [ABSTRACT FROM AUTHOR]