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by Keyword: Metabolism


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Pellegrini P, Hervera A, Varea O, Brewer MK, López-Soldado I, Guitart A, Aguilera M, Prats N, del Río JA, Guinovart JJ, Duran J, (2021). Lack of p62 Impairs Glycogen Aggregation and Exacerbates Pathology in a Mouse Model of Myoclonic Epilepsy of Lafora Molecular Neurobiology 59, 1214-1229

Lafora disease (LD) is a fatal childhood-onset dementia characterized by the extensive accumulation of glycogen aggregates—the so-called Lafora Bodies (LBs)—in several organs. The accumulation of LBs in the brain underlies the neurological phenotype of the disease. LBs are composed of abnormal glycogen and various associated proteins, including p62, an autophagy adaptor that participates in the aggregation and clearance of misfolded proteins. To study the role of p62 in the formation of LBs and its participation in the pathology of LD, we generated a mouse model of the disease (malinKO) lacking p62. Deletion of p62 prevented LB accumulation in skeletal muscle and cardiac tissue. In the brain, the absence of p62 altered LB morphology and increased susceptibility to epilepsy. These results demonstrate that p62 participates in the formation of LBs and suggest that the sequestration of abnormal glycogen into LBs is a protective mechanism through which it reduces the deleterious consequences of its accumulation in the brain. © 2021, The Author(s).

Keywords: accumulation, astrocytes, autophagy receptors, contributes, deficient mice, epilepsy, glycogen, lafora bodies, malin, metabolism, neurodegeneration, neuroinflammation, p62, polyglucosan bodies, temporal-lobe epilepsy, Epilepsy, Glycogen, Inclusion-body formation, Lafora bodies, Lafora disease, Malin, Neuroinflammation, P62


Prieto, Alejandro, Bernabeu, Manuel, Sánchez-Herrero, José Francisco, Pérez-Bosque, Anna, Miró, Lluïsa, Bäuerl, Christine, Collado, Carmen, Hüttener, Mário, Juárez, Antonio, (2021). Modulation of AggR levels reveals features of virulence regulation in enteroaggregative E. coli Commun Biol 4, 1295

Enteroaggregative Escherichia coli (EAEC) strains are one of the diarrheagenic pathotypes. EAEC strains harbor a virulence plasmid (pAA2) that encodes, among other virulence determinants, the aggR gene. The expression of the AggR protein leads to the expression of several virulence determinants in both plasmids and chromosomes. In this work, we describe a novel mechanism that influences AggR expression. Because of the absence of a Rho-independent terminator in the 3?UTR, aggR transcripts extend far beyond the aggR ORF. These transcripts are prone to PNPase-mediated degradation. Structural alterations in the 3?UTR result in increased aggR transcript stability, leading to increased AggR levels. We therefore investigated the effect of increased AggR levels on EAEC virulence. Upon finding the previously described AggR-dependent virulence factors, we detected novel AggR-regulated genes that may play relevant roles in EAEC virulence. Mutants exhibiting high AggR levels because of structural alterations in the aggR 3?UTR show increased mobility and increased pAA2 conjugation frequency. Furthermore, among the genes exhibiting increased fold change values, we could identify those of metabolic pathways that promote increased degradation of arginine, fatty acids and gamma-aminobutyric acid (GABA), respectively. In this paper, we discuss how the AggR-dependent increase in specific metabolic pathways activity may contribute to EAEC virulence.

Keywords: aggregative adherence, arginine metabolism, biofilm formation, escherichia-coli, gene-expression, messenger-rna, operon, persistent diarrhea, untranslated region, Fimbria-i expression


Schroeder, Barbara, Vander Steen, Travis, Espinoza, Ingrid, Venkatapoorna, Chandra MKurapaty, Hu, Zeng, Silva, Fernando Martín, Regan, Kevin, Cuyàs, Elisabet, Meng, XWei, Verdura, Sara, Arbusà, Aina, Schneider, Paula A., Flatten, Karen S., Kemble, George, Montero, Joan, Kaufmann, Scott H., Menendez, Javier A., Lupu, Ruth, (2021). Fatty acid synthase (FASN) regulates the mitochondrial priming of cancer cells Cell Death & Disease 12, 977

Inhibitors of the lipogenic enzyme fatty acid synthase (FASN) have attracted much attention in the last decade as potential targeted cancer therapies. However, little is known about the molecular determinants of cancer cell sensitivity to FASN inhibitors (FASNis), which is a major roadblock to their therapeutic application. Here, we find that pharmacological starvation of endogenously produced FAs is a previously unrecognized metabolic stress that heightens mitochondrial apoptotic priming and favors cell death induction by BH3 mimetic inhibitors. Evaluation of the death decision circuits controlled by the BCL-2 family of proteins revealed that FASN inhibition is accompanied by the upregulation of the pro-death BH3-only proteins BIM, PUMA, and NOXA. Cell death triggered by FASN inhibition, which causally involves a palmitate/NADPH-related redox imbalance, is markedly diminished by concurrent loss of BIM or PUMA, suggesting that FASN activity controls cancer cell survival by fine-tuning the BH3 only proteins-dependent mitochondrial threshold for apoptosis. FASN inhibition results in a heightened mitochondrial apoptosis priming, shifting cells toward a primed-for-death state “addicted” to the anti-apoptotic protein BCL-2. Accordingly, co-administration of a FASNi synergistically augments the apoptosis-inducing activity of the dual BCL-XL/BCL-2 inhibitor ABT-263 (navitoclax) and the BCL-2 specific BH3-mimetic ABT-199 (venetoclax). FASN inhibition, however, fails to sensitize breast cancer cells to MCL-1- and BCL-XL-selective inhibitors such as S63845 and A1331852. A human breast cancer xenograft model evidenced that oral administration of the only clinically available FASNi drastically sensitizes FASN-addicted breast tumors to ineffective single-agents navitoclax and venetoclax in vivo. In summary, a novel FASN-driven facet of the mitochondrial priming mechanistically links the redox-buffering mechanism of FASN activity to the intrinsic apoptotic threshold in breast cancer cells. Combining next-generation FASNis with BCL-2-specific BH3 mimetics that directly activate the apoptotic machinery might generate more potent and longer-lasting antitumor responses in a clinical setting.

Keywords: activation, apoptosis, bh3 mimetics, cytochrome-c, death, inhibition, metabolism, pathways, venetoclax, Bcl-2 family


Boschker, HTS, Cook, PLM, Polerecky, L, Eachambadi, RT, Lozano, H, Hidalgo-Martinez, S, Khalenkow, D, Spampinato, V, Claes, N, Kundu, P, Wang, D, Bals, S, Sand, KK, Cavezza, F, Hauffman, T, Bjerg, JT, Skirtach, AG, Kochan, K, McKee, M, Wood, B, Bedolla, D, Gianoncelli, A, Geerlings, NMJ, Van Gerven, N, Remaut, H, Geelhoed, JS, Millan-Solsona, R, Fumagalli, L, Nielsen, LP, Franquet, A, Manca, JV, Gomila, G, Meysman, FJR, (2021). Efficient long-range conduction in cable bacteria through nickel protein wires Nature Communications 12, 3996

Filamentous cable bacteria display long-range electron transport, generating electrical currents over centimeter distances through a highly ordered network of fibers embedded in their cell envelope. The conductivity of these periplasmic wires is exceptionally high for a biological material, but their chemical structure and underlying electron transport mechanism remain unresolved. Here, we combine high-resolution microscopy, spectroscopy, and chemical imaging on individual cable bacterium filaments to demonstrate that the periplasmic wires consist of a conductive protein core surrounded by an insulating protein shell layer. The core proteins contain a sulfur-ligated nickel cofactor, and conductivity decreases when nickel is oxidized or selectively removed. The involvement of nickel as the active metal in biological conduction is remarkable, and suggests a hitherto unknown form of electron transport that enables efficient conduction in centimeter-long protein structures. Filamentous cable bacteria conduct electrical currents over centimeter distances through fibers embedded in their cell envelope. Here, Boschker et al. show that the fibers consist of a conductive core containing nickel proteins that is surrounded by an insulating protein shell.

Keywords: Bacteria (microorganisms), Bacterial protein, Bacterial proteins, Bacterium, Chemistry, Deltaproteobacteria, Electric conductivity, Electricity, Electron, Electron transport, Metabolism, Microscopy, Nanowires, Nickel, Physiology, Protein, Resonance raman, Spectroscopy, Transport electrons


Andreu, I, Falcones, B, Hurst, S, Chahare, N, Quiroga, X, Le Roux, AL, Kechagia, Z, Beedle, AEM, Elosegui-Artola, A, Trepat, X, Farre, R, Betz, T, Almendros, I, Roca-Cusachs, P, (2021). The force loading rate drives cell mechanosensing through both reinforcement and cytoskeletal softening Nature Communications 12, 4229

Cell response to force regulates essential processes in health and disease. However, the fundamental mechanical variables that cells sense and respond to remain unclear. Here we show that the rate of force application (loading rate) drives mechanosensing, as predicted by a molecular clutch model. By applying dynamic force regimes to cells through substrate stretching, optical tweezers, and atomic force microscopy, we find that increasing loading rates trigger talin-dependent mechanosensing, leading to adhesion growth and reinforcement, and YAP nuclear localization. However, above a given threshold the actin cytoskeleton softens, decreasing loading rates and preventing reinforcement. By stretching rat lungs in vivo, we show that a similar phenomenon may occur. Our results show that cell sensing of external forces and of passive mechanical parameters (like tissue stiffness) can be understood through the same mechanisms, driven by the properties under force of the mechanosensing molecules involved. Cells sense mechanical forces from their environment, but the precise mechanical variable sensed by cells is unclear. Here, the authors show that cells can sense the rate of force application, known as the loading rate, with effects on YAP nuclear localization and cytoskeletal stiffness remodelling.

Keywords: Actin cytoskeleton, Actin filament, Actin-filament, Adhesion, Animal, Animals, Atomic force microscopy, Breathing, Cell, Cell adhesion, Cell culture, Cell nucleus, Cells, cultured, Cytoplasm, Extracellular-matrix, Fibroblast, Fibroblasts, Fibronectin, Frequency, Gene knockdown, Gene knockdown techniques, Genetics, Germfree animal, Integrin, Intracellular signaling peptides and proteins, Knockout mouse, Lung, Male, Mechanotransduction, Mechanotransduction, cellular, Metabolism, Mice, Mice, knockout, Microscopy, atomic force, Mouse, Optical tweezers, Paxillin, Physiology, Primary cell culture, Pxn protein, mouse, Rat, Rats, Rats, sprague-dawley, Respiration, Signal peptide, Softening, Specific pathogen-free organisms, Sprague dawley rat, Stress, Substrate, Substrate rigidity, Talin, Talin protein, mouse, Tln2 protein, mouse, Traction, Transmission, Ultrastructure, Yap1 protein, rat


Chacon DS, Torres TM, da Silva IB, de Araújo TF, Roque AdA, Pinheiro FASD, Selegato D, Pilon A, Reginaldo FPS, da Costa CT, Vilasboa J, Freire RT, Voigt EL, Zuanazzi JAS, Libonati R, Rodrigues JA, Santos FLM, Scortecci KC, Lopes NP, Ferreira LDS, dos Santos LV, Cavalheiro AJ, Fett-Neto AG, Giordani RB, (2021). Erythrina velutina Willd. alkaloids: Piecing biosynthesis together from transcriptome analysis and metabolite profiling of seeds and leaves Journal Of Advanced Research 34, 123-136

© 2021 Introduction: Natural products of pharmaceutical interest often do not reach the drug market due to the associated low yields and difficult extraction. Knowledge of biosynthetic pathways is a key element in the development of biotechnological strategies for plant specialized metabolite production. The scarce studies regarding non-model plants impair advances in this field. Erythrina spp. are mainly used as central nervous system depressants in folk medicine and are important sources of bioactive tetracyclic benzylisoquinoline alkaloids, which can act on several pathology-related biological targets. Objective: Herein the purpose is to employ combined transcriptome and metabolome analyses (seeds and leaves) of a non-model medicinal Fabaceae species grown in its unique arid natural habitat. The study tries to propose a putative biosynthetic pathway for the bioactive alkaloids by using an omic integrated approach. Methods: The Next Generation Sequencing-based transcriptome (de novo RNA sequencing) was carried out in a Illumina NextSeq 500 platform. Regarding the targeted metabolite profiling, Nuclear Magnetic Resonance and the High-Performance Liquid Chromatography coupled to a micrOTOF-QII, High Resolution Mass Spectrometer, were used. Results: This detailed macro and micromolecular approach applied to seeds and leaves of E. velutina revealed 42 alkaloids by metabolome tools. Based on the combined evidence, 24 gene candidates were put together in a putative pathway leading to the singular alkaloid diversity of this species. Conclusion: These results contribute by indicating potential biotechnological targets Erythrina alkaloids biosynthesis as well as to improve molecular databases with omic data from a non-model medicinal plant. Furthermore, they reveal an interesting chemical diversity in Erythrina velutina harvested in Caatinga. Last, but not least, this data may also contribute to tap Brazilian biodiversity in a rational and sustainable fashion, promoting adequate public policies for preservation and protection of sensitive areas within the Caatinga.

Keywords: benzylisoquinoline alkaloids, caatinga, codeinone reductase, expression, mass-spectrometry, molecular-cloning, morphine biosynthesis, natural-products, opium poppy, papaver-somniferum, plant-metabolism, targeted metabolite profile, transcriptome, Benzylisoquinoline alkaloids, Berberine bridge enzyme, Caatinga, Erythrina velutina, Targeted metabolite profile, Transcriptome


Marco-Rius I, Wright AJ, Hu De, Savic D, Miller JJ, Timm KN, Tyler D, Brindle KM, Comment A, (2021). Probing hepatic metabolism of [2-13C]dihydroxyacetone in vivo with 1H-decoupled hyperpolarized 13C-MR Magnetic Resonance Materials In Physics Biology And Medicine 34, 49-56

© 2020, The Author(s). Objectives: To enhance detection of the products of hyperpolarized [2-13C]dihydroxyacetone metabolism for assessment of three metabolic pathways in the liver in vivo. Hyperpolarized [2-13C]DHAc emerged as a promising substrate to follow gluconeogenesis, glycolysis and the glycerol pathways. However, the use of [2-13C]DHAc in vivo has not taken off because (i) the chemical shift range of [2-13C]DHAc and its metabolic products span over 144 ppm, and (ii) 1H decoupling is required to increase spectral resolution and sensitivity. While these issues are trivial for high-field vertical-bore NMR spectrometers, horizontal-bore small-animal MR scanners are seldom equipped for such experiments. Methods: Real-time hepatic metabolism of three fed mice was probed by 1H-decoupled 13C-MR following injection of hyperpolarized [2-13C]DHAc. The spectra of [2-13C]DHAc and its metabolic products were acquired in a 7 T small-animal MR scanner using three purpose-designed spectral-spatial radiofrequency pulses that excited a spatial bandwidth of 8 mm with varying spectral bandwidths and central frequencies (chemical shifts). Results: The metabolic products detected in vivo include glycerol 3-phosphate, glycerol, phosphoenolpyruvate, lactate, alanine, glyceraldehyde 3-phosphate and glucose 6-phosphate. The metabolite-to-substrate ratios were comparable to those reported previously in perfused liver. Discussion: Three metabolic pathways can be probed simultaneously in the mouse liver in vivo, in real time, using hyperpolarized DHAc.

Keywords: carbon-13 magnetic resonance spectroscopy, dynamic nuclear polarisation, gluconeogenesis, glycolysis, hyperpolarisation, liver, Carbon-13 magnetic resonance spectroscopy, Cycle, Dihydroxyacetone, Dynamic nuclear polarisation, Excitation, Fructose, Gluconeogenesis, Glucose, Glycolysis, Hyperpolarisation, Liver, Magnetic-resonance, Metabolism, Mri


Duran, Jordi, Brewer, M. Kathryn, Hervera, Arnau, Gruart, Agnès, del Rio, Jose Antonio, Delgado-García, José M., Guinovart, Joan J., (2020). Lack of astrocytic glycogen alters synaptic plasticity but not seizure susceptibility Molecular Neurobiology 57, 4657–4666

Brain glycogen is mainly stored in astrocytes. However, recent studies both in vitro and in vivo indicate that glycogen also plays important roles in neurons. By conditional deletion of glycogen synthase (GYS1), we previously developed a mouse model entirely devoid of glycogen in the central nervous system (GYS1Nestin-KO). These mice displayed altered electrophysiological properties in the hippocampus and increased susceptibility to kainate-induced seizures. To understand which of these functions are related to astrocytic glycogen, in the present study, we generated a mouse model in which glycogen synthesis is eliminated specifically in astrocytes (GYS1Gfap-KO). Electrophysiological recordings of awake behaving mice revealed alterations in input/output curves and impaired long-term potentiation, similar, but to a lesser extent, to those obtained with GYS1Nestin-KO mice. Surprisingly, GYS1Gfap-KO mice displayed no change in susceptibility to kainate-induced seizures as determined by fEPSP recordings and video monitoring. These results confirm the importance of astrocytic glycogen in synaptic plasticity.

Keywords: Astrocyte, Epilepsy, Glycogen, Long-term potentiation, Metabolism, Plasticity.


Garcia-Esparcia, P., Koneti, A., Rodríguez-Oroz, M. C., Gago, B., del Rio, J. A., Ferrer, Isidro, (2018). Mitochondrial activity in the frontal cortex area 8 and angular gyrus in Parkinson's disease and Parkinson's disease with dementia Brain Pathology 28, (1), 43-57

Altered mitochondrial function is characteristic in the substantia nigra in Parkinson's disease (PD). Information about mitochondria in other brain regions such as the cerebral cortex is conflicting mainly because most studies have not contemplated the possibility of variable involvement depending on the region, stage of disease progression and clinical symptoms such as the presence or absence of dementia. RT-qPCR of 18 nuclear mRNAs encoding subunits of mitochondrial complexes and 12 mRNAs encoding energy metabolism-related enzymes; western blotting of mitochondrial proteins; and analysis of enzymatic activities of complexes I, II, II, IV and V of the respiratory chain were assessed in frontal cortex area 8 and the angular gyrus of middle-aged individuals (MA), and those with incidental PD (iPD), long-lasting PD with parkinsonism without dementia (PD) and long-lasting PD with dementia (PDD). Up-regulation of several genes was found in frontal cortex area 8 in PD when compared with MA and in the angular gyrus in iPD when compared with MA. Marked down-regulation of genes encoding mitochondrial subunits and energy metabolism-related enzymes occurs in frontal cortex but only of genes coding for energy metabolism-related enzymes in the angular gyrus in PDD. Significant decrease in the protein expression levels of several mitochondrial subunits encoded by these genes occurs in frontal cortex area 8 and angular gyrus in PDD. Moreover, expression of MT-ND1 which is encoded by mitochondrial DNA is also reduced in PDD. Reduced enzymatic activity of complex III in frontal cortex area 8 and angular gyrus is observed in PD, but dramatic reduction in the activity of complexes I, II, II and IV in both regions characterizes PDD. Dementia in the context of PD is linked to region-specific deregulation of genomic genes encoding subunits of mitochondrial complexes and to marked reduction in the activity of mitochondrial complexes I, II, III and IV.

Keywords: Cerebral cortex, Dementia, Energy metabolism, Incidental PD, Mitochondria, Oxidative phosphorylation, Parkinson disease, PDD, Respiratory chain


Crespo, Anna, Pedraz, Lucas, Astola, Josep, Torrents, Eduard, (2016). Pseudomonas aeruginosa exhibits deficient biofilm formation in the absence of class II and III ribonucleotide reductases due to hindered anaerobic growth Frontiers in Microbiology 7, Article 688

Chronic lung infections by the ubiquitous and extremely adaptable opportunistic pathogen Pseudomonas aeruginosa correlate with the formation of a biofilm, where bacteria grow in association with an extracellular matrix and display a wide range of changes in gene expression and metabolism. This leads to increased resistance to physical stress and antibiotic therapies, while enhancing cell-to-cell communication. Oxygen diffusion through the complex biofilm structure generates an oxygen concentration gradient, leading to the appearance of anaerobic microenvironments. Ribonucleotide reductases (RNRs) are a family of highly sophisticated enzymes responsible for the synthesis of the deoxyribonucleotides, and they constitute the only de novo pathway for the formation of the building blocks needed for DNA synthesis and repair. P. aeruginosa is one of the few bacteria encoding all three known RNR classes (Ia, II, and III). Class Ia RNRs are oxygen dependent, class II are oxygen independent, and class III are oxygen sensitive. A tight control of RNR activity is essential for anaerobic growth and therefore for biofilm development. In this work we explored the role of the different RNR classes in biofilm formation under aerobic and anaerobic initial conditions and using static and continuous-flow biofilm models. We demonstrated the importance of class II and III RNR for proper cell division in biofilm development and maturation. We also determined that these classes are transcriptionally induced during biofilm formation and under anaerobic conditions. The molecular mechanism of their anaerobic regulation was also studied, finding that the Anr/Dnr system is responsible for class II RNR induction. These data can be integrated with previous knowledge about biofilms in a model where these structures are understood as a set of layers determined by oxygen concentration and contain cells with different RNR expression profiles, bringing us a step closer to the understanding of this complex growth pattern, essential for P. aeruginosa chronic infections.

Keywords: Pseudomonas aeruginosa, Ribonucleotide Reductases, Vitamin B 12, Anaerobic metabolism, Biofilm formation, DNA Synthesis, Oxygen diffusion, nrd genes.


Engel, E., Michiardi, A., Navarro, M., Lacroix, D., Planell, J. A., (2008). Nanotechnology in regenerative medicine: the materials side Trends in Biotechnology , 26, (1), 39-47

Regenerative medicine is an emerging multidisciplinary field that aims to restore, maintain or enhance tissues and hence organ functions. Regeneration of tissues can be achieved by the combination of living cells, which will provide biological functionality, and materials, which act as scaffolds to support cell proliferation. Mammalian cells behave in vivo in response to the biological signals they receive from the surrounding environment, which is structured by nanometre-scaled components. Therefore, materials used in repairing the human body have to reproduce the correct signals that guide the cells towards a desirable behaviour. Nanotechnology is not only an excellent tool to produce material structures that mimic the biological ones but also holds the promise of providing efficient delivery systems. The application of nanotechnology to regenerative medicine is a wide issue and this short review will only focus on aspects of nanotechnology relevant to biomaterials science. Specifically, the fabrication of materials, such as nanoparticles and scaffolds for tissue engineering, and the nanopatterning of surfaces aimed at eliciting specific biological responses from the host tissue will be addressed.

Keywords: Animals, Biocompatible Materials/ metabolism, Humans, Nanoparticles, Nanotechnology/ methods, Regenerative Medicine/ methods, Tissue Scaffolds


Engel, E., Del Valle, S., Aparicio, C., Altankov, G., Asin, L., Planell, J. A., Ginebra, M. P., (2008). Discerning the role of topography and ion exchange in cell response of bioactive tissue engineering scaffolds Tissue Engineering Part A , 14, (8), 1341-1351

Surface topography is known to have an influence on osteoblast activity. However, in the case of bioactive materials, topographical changes can affect also ion exchange properties. This makes the problem more complex, since it is often difficult to separate the strictly topographical effects from the effects of ionic fluctuations in the medium. The scope of this paper is to analyze the simultaneous effect of topography and topography-mediated ion exchange on the initial cellular behavior of osteoblastic-like cells cultured on bioactive tissue engineering substrates. Two apatitic substrates with identical chemical composition but different micro/nanostructural features were obtained by low-temperature setting of a calcium phosphate cement. MG63 osteoblastic-like cells were cultured either in direct contact with the substrates or with their extracts. A strong and permanent decrease of calcium concentration in the culture medium, dependent on substrate topography, was detected. A major effect of the substrate microstructure on cell proliferation was observed, explained in part by the topography-mediated ion exchange, but not specifically by the ionic Ca(2+) fluctuations. Cell differentiation was strongly enhanced when cells were cultured on the finer substrate. This effect was not explained by the chemical modification of the medium, but rather suggested a strictly topographical effect.

Keywords: Alkaline Phosphatase/metabolism, Bone Cements/pharmacology, Calcium/metabolism, Calcium Phosphates/pharmacology, Cell Adhesion/drug effects, Cell Differentiation/drug effects, Cell Proliferation/drug effects, Cell Shape/drug effects, Cells, Cultured, Culture Media, Durapatite/pharmacology, Humans, Interferometry, Ion Exchange, Materials Testing, Osteoblasts/ cytology/drug effects/enzymology/ultrastructure, Phosphorus/metabolism, Powders, Tissue Engineering, Tissue Scaffolds


Charles-Harris, M., Koch, M. A., Navarro, M., Lacroix, D., Engel, E., Planell, J. A., (2008). A PLA/calcium phosphate degradable composite material for bone tissue engineering: an in vitro study Journal of Materials Science-Materials in Medicine , 19, (4), 1503-1513

Biodegradable polymers reinforced with an inorganic phase such as calcium phosphate glasses may be a promising approach to fulfil the challenging requirements presented by 3D porous scaffolds for tissue engineering. Scaffolds' success depends mainly on their biological behaviour. This work is aimed to the in vitro study of polylactic acid (PLA)/CaP glass 3D porous constructs for bone regeneration. The scaffolds were elaborated using two different techniques, namely solvent-casting and phase-separation. The effect of scaffolds' micro and macrostructure on the biological response of these scaffolds was assayed. Cell proliferation, differentiation and morphology within the scaffolds were studied. Furthermore, polymer/glass scaffolds were seeded under dynamic conditions in a custom-made perfusion bioreactor. Results indicate that the final architecture of the solvent-cast or phase separated scaffolds have a significant effect on cells' behaviour. Solvent-cast scaffolds seem to be the best candidates for bone tissue engineering. Besides, dynamic seeding yielded a higher seeding efficiency in comparison with the static method.

Keywords: Biocompatible Materials/ chemistry, Bone and Bones/ metabolism, Calcium Phosphates/ chemistry, Cell Differentiation, Cell Proliferation, Humans, Lactic Acid/ chemistry, Microscopy, Confocal, Microscopy, Electron, Scanning, Osteoblasts/metabolism, Permeability, Polymers/ chemistry, Porosity, Solvents/chemistry, Tissue Engineering/ methods


Gustavsson, J., Altankov, G., Errachid, A., Samitier, J., Planell, J. A., Engel, E., (2008). Surface modifications of silicon nitride for cellular biosensor applications Journal of Materials Science-Materials in Medicine , 19, (4), 1839-1850

Thin films of silicon nitride (Si3N4) can be used in several kinds of micro-sized biosensors as a material to monitor fine environmental changes related to the process of bone formation in vitro. We found however that Si3N4 does not provide optimal conditions for osseointegration as osteoblast-like MG-63 cells tend to detach from the surface when cultured over confluence. Therefore Si3N4 was modified with self-assembled monolayers bearing functional end groups of primary amine (NH2) and carboxyl (COOH) respectively. Both these modifications enhanced the interaction with confluent cell layers and thus improve osseointegration over Si3N4. Furthermore it was observed that the NH2 functionality increased the adsorption of fibronectin (FN), promoted cell proliferation, but delayed the differentiation. We also studied the fate of pre-adsorbed and secreted FN from cells to learn more about the impact of above functionalities for the development of provisional extracellular matrix on materials interface. Taken together our data supports that Si3N4 has low tissue integration but good cellular biocompatibility and thus is appropriate in cellular biosensor applications such as the ion-sensitive field effect transistor (ISFET). COOH and NH2 chemistries generally improve the interfacial tissue interaction with the sensor and they are therefore suitable substrates for monitoring cellular growth or matrix deposition using electrical impedance spectroscopy.

Keywords: Adsorption, Amines/chemistry, Biocompatible Materials/ chemistry, Biosensing Techniques, Cell Differentiation, Cell Line, Cell Proliferation, Electric Impedance, Extracellular Matrix/metabolism, Fibronectins/chemistry, Humans, Materials Testing, Osteoblasts/ cytology, Silicon Compounds/ chemistry, Surface Properties