Marta Sánchez CarbonellMasters Student
Molecular and Cellular Neurobiotechnology
+34 934 031 185
Staff member publications
Here we report on the development of a new type of hybrid fibrinogen-polylactic acid (FBG-PLA) nanofibres (NFs) with improved stiffness, combining the good mechanical properties of PLA with the excellent cell recognition properties of native FBG. We were particularly interested in the dorsal and ventral cell response to the nanofibres' organization (random or aligned), using human umbilical endothelial cells (HUVECs) as a model system. Upon ventral contact with random NFs, the cells developed a stellate-like morphology with multiple projections. The well-developed focal adhesion complexes suggested a successful cellular interaction. However, time-lapse analysis shows significantly lowered cell movements, resulting in the cells traversing a relatively short distance in multiple directions. Conversely, an elongated cell shape and significantly increased cell mobility were observed in aligned NFs. To follow the dorsal cell response, artificial wounds were created on confluent cell layers previously grown on glass slides and covered with either random or aligned NFs. Time-lapse analysis showed significantly faster wound coverage (within 12 h) of HUVECs on aligned samples vs. almost absent directional migration on random ones. However, nitric oxide (NO) release shows that endothelial cells possess lowered functionality on aligned NFs compared to random ones, where significantly higher NO production was found. Collectively, our studies show that randomly organized NFs could support the endothelization of implants while aligned NFs would rather direct cell locomotion for guided neovascularization.
Keywords: Electrospun nanofibers, Endothelial cells, Fibrinogen, Guided cellular behavior, Polylactic acid, Vascular tissue engineering
We present the estimation of a likelihood map for the location of the source of a chemical plume dispersed under atmospheric turbulence under uniform wind conditions. The main contribution of this work is to extend previous proposals based on Bayesian inference with binary detections to the use of concentration information while at the same time being robust against the presence of background chemical noise. For that, the algorithm builds a background model with robust statistics measurements to assess the posterior probability that a given chemical concentration reading comes from the background or from a source emitting at a distance with a specific release rate. In addition, our algorithm allows multiple mobile gas sensors to be used. Ten realistic simulations and ten real data experiments are used for evaluation purposes. For the simulations, we have supposed that sensors are mounted on cars which do not have among its main tasks navigating toward the source. To collect the real dataset, a special arena with induced wind is built, and an autonomous vehicle equipped with several sensors, including a photo ionization detector (PID) for sensing chemical concentration, is used. Simulation results show that our algorithm, provides a better estimation of the source location even for a low background level that benefits the performance of binary version. The improvement is clear for the synthetic data while for real data the estimation is only slightly better, probably because our exploration arena is not able to provide uniform wind conditions. Finally, an estimation of the computational cost of the algorithmic proposal is presented.
Keywords: Machine olfaction, Odor robots, Chemical sensors, Bayesian inference
Mimicking the complex intricacies of the extra cellular matrix including 3D configurations and aligned fibrous structures were traditionally perused for producing cartilage tissue from stem cells. This study shows that human adipose derived mesenchymal stem cells (hADMSCs) establishes significant chondrogenic differentiation and may generate quality cartilage when cultured on 2D and randomly oriented fibrinogen/poly-lactic acid nanofibers compared to 3D sandwich-like environments. The adhering cells show well-developed focal adhesion complexes and actin cytoskeleton arrangements confirming the proper cellular interaction with either random or aligned nanofibers. However, quantitative reverse transcription-polymerase chain reaction analysis for Collagen 2 and Collagen 10 genes expression confirms favorable chondrogenic response of hADMSCs on random nanofibers and shows substantially higher efficacy of their differentiation in 2D configuration versus 3D constructs. These findings introduce a new direction for cartilage tissue engineering through providing a simple platform for the routine generation of transplantable stem cells derived articular cartilage replacement that might improve joint function.
Keywords: Cartilage, Chondrogenic response, Collagen, FBG/PLA nanofibers, Mesenchymal stem cells
Abstract Vascular basement membrane remodeling involves assembly and degradation of its main constituents, type IV collagen (Col IV) and laminin, which is critical during development, angiogenesis, and tissue repair. Remodeling can also occur at cellâ€“biomaterials interface altering significantly the biocompatibility of implants. Here we describe the fate of adsorbed Col IV in contact with endothelial cells adhering on positively charged NH2 or hydrophobic CH3 substrata, both based on self-assembly monolayers (SAMs) and studied alone or mixed in different proportions. AFM studies revealed distinct pattern of adsorbed Col IV, varying from single molecular deposition on pure NH2 to network-like assembly on mixed SAMs, turning to big globular aggregates on bare CH3. Human umbilical endothelial cells (HUVECs) interact better with Col IV adsorbed as single molecules on NH2 surface and readily rearrange it in fibril-like pattern that coincide with secreted fibronectin fibrils. The cells show flattened morphology and well-developed focal adhesion complexes that are rich on phosphorylated FAK while expressing markedly low pericellular proteolytic activity. Conversely, on hydrophobic CH3 substrata HUVECs showed abrogated spreading and FAK phosphorylation, combined with less reorganization of the aggregated Col IV and significantly increased proteolytic activity. The later involves both MMP-2 and MMP-9, as measured by zymography and FITC-Col IV release. The mixed SAMs support intermediate remodeling activity. Taken together these results show that chemical functionalization combined with Col IV preadsorption provides a tool for guiding the endothelial cells behavior and pericellular proteolytic activity, events that strongly affect the fate of cardiovascular implants.
Keywords: Type IV collagen, Adsorption, Remodeling, Pericellular proteolysis, Reorganization, Substratum chemistry, CH3 and NH2 groups, Self-assembly monolayers
In this study, we propose a methodology to obtain a family of biomimetic substrates with a hierarchical rough topography at the micro and nanoscale that span the entire range of wettability, from the superhydrophobic to the superhydrophilic regime, through an Ar-plasma treatment at increasing durations. Moreover, we employ the same approach to produce a superhydrophobic-to- superhydrophilic surface gradient along centimetre-length scale distances within the same sample. We characterize the biological activity of these surfaces in terms of protein adsorption and cell response, using fibronectin, a major component of the extracellular matrix, and C2C12 cells, a myoblast cell line. Fibronectin conformation, assessed via binding of the monoclonal antibody HFN7.1, exhibits a non-monotonic dependence on surface wettability, with higher activity on hydrophilic substrates (WCA = 38.6 Â± 8.1Â°). On the other hand, the exposition of cell-binding epitopes is diminished on the surfaces with extreme wetting properties, the conformation being particularly altered on the superhydrophobic substrate. The assessment of cell response via the myogenic differentiation process reveals that a gradient surface promotes a different response with respect to cells cultured on discrete uniform samples: even though in both cases the same non-monotonic differentiation pattern is found, the differential response to the various wettabilities is enhanced along the gradient while the overall levels of differentiation are diminished. On a gradient surface cells are in fact exposed to a range of continuously changing stimuli that foster cell migration and detain the differentiation process.
Cells assemble fibronectin (FN) into fibrils in a process mediated by integrins. For this process to occur, it is known that the presence of other serum proteins is necessary. However, the individual effect of these proteins on FN fibrillogenesis has not been addressed so far. In this study, the effect of vitronectin (VN), an ECM adhesion protein, on material-driven FN fibrillogenesis and cell-mediated FN reorganization is investigated. Poly(ethyl acrylate), PEA, which has previously shown the ability to induce the organization of FN into well-developed physiological-like networks upon adsorption, was employed as a material substrate. FN adsorption, cell adhesion and cellular FN reorganization in the presence or absence of VN were studied. Both FN surface density, quantified via western blot, and its distribution on PEA surfaces, determined via atomic force microscopy, were altered when FN was adsorbed competitively with VN at certain compositions. Moreover, the presence of VN on the material surfaces enhanced cell-mediated FN reorganization and secretion, in comparison with the process which took place in the presence of serum proteins.
Plasma polymerization was used to produce novel nanometric coatings able to direct fibronectin adsorption and cell response. Using ethyl acrylate as a monomer, we obtain coatings whose chemical composition maintains some of the characteristic functionalities of the photo-initiated polymer, while the water contact angle increases monotonically with the duration of the plasma discharge. Enhanced surface mobility of the polymer chains due to a decrease of the thickness of the coating justifies this increase in wettability at lower treatment times. The coatings with higher surface mobility are shown to promote a more active conformation of the adsorbed protein, as proved by binding of the monoclonal antibodies HFN7.1 and mAb1937. Culture of MC3T3-E1 osteoblast-like cells onto the fibronectin-coated substrates further proves that the more mobile surfaces support better initial cell adhesion, even at low fibronectin surface density, as well as stronger cell-mediated fibronectin reorganization.