Hybrid Protein-Glycosaminoglycan Hydrogels Promote Chondrogenic Stem Cell Differentiation

[EN] Gelatin-hyaluronic acid (Gel-HA) hybrid hydrogels have been proposed as matrices for tissue engineering because of their ability to mimic the architecture of the extracellular matrix. Our aim was to explore whether tyramine conjugates of Gel and HA, producing injectable hydrogels, are able to induce a particular phenotype of encapsulated human mesenchymal stem cells without the need for growth factors. While pure Gel allowed good cell adhesion without remarkable differentiation and pure HA triggered chondrogenic differentiation without cell spreading, the hybrids, especially those rich in HA, promoted chondrogenic differentiation as well as cell proliferation and adhesion. Secretion of chondrogenic markers such as aggrecan, SOX-9, collagen type II, and glycosaminoglycans was observed, whereas osteogenic, myogenic, and adipogenic markers (RUNX2, sarcomeric myosin, and lipoproteinlipase, respectively) were not present after 2 weeks in the growth medium. The most promising matrix for chondrogenesis seems to be a mixture containing 70% HA and 30% Gel as it is the material with the best mechanical properties from all compositions tested here, and at the same time, it provides an environment suitable for balanced cell adhesion and chondrogenic differentiation. Thus, it represents a system that has a high potential to be used as the injectable material for cartilage regeneration therapies.The authors are grateful for the financial support received from the Spanish Ministry through the MAT2016-76039-C4-1-R project (including the FEDER financial support), the BES-2011-046144, and the EEBB-I-14-08725 grants. The CIBER-BBN initiative is funded by the VI National R&D&I Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program. CIBER actions are financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund. M.S.-S. acknowledges the European Research Council (ERC-HealInSynergy 306990) and the UK Engineering and Physical Sciences Research Council (EPSRC-EP/P001114/1)Moulisova, V.; Poveda-Reyes, S.; Sanmartin-Masia, E.; Quintanilla-Sierra, L.; Ferrer, G.; Salmerón Sánchez, M. (2017). Hybrid Protein-Glycosaminoglycan Hydrogels Promote Chondrogenic Stem Cell Differentiation. ACS Omega. 2(11):7609-7620. https://doi.org/10.1021/acsomega.7b01303S7609762021

Simultaneous boron ion-channel/growth factor receptor activation for enhanced vascularization

[EN] Boron ion is essential in metabolism and its concentration is regulated by ion-channel NaBC1. NaBC1 mutations cause corneal dystrophies such as Harboyan syndrome. Here we propose a 3D molecular model for NaBC1 and show that simultaneous stimulation of NaBC1 and vascular growth factor receptors (VEGFR) promote angiogenesis in vitro and in vivo with ultra-low concentrations of VEGF. We show Human Umbilical Vein Endothelial Cells (HUVEC) organization into tubular structures indicative of vascularization potential. Enhanced cell sprouting was found only in the presence of VEGF and boron, effect abrogated after blocking NaBC1. We demonstrate that stimulated NaBC1 promotes angiogenesis via PI3k-independent pathways and that ¿5ß1/¿vß3-integrin binding is not essential to enhanced HUVEC organization. We describe a novel vascularization mechanism that involves the crosstalk and colocalization between NaBC1/VEGFR receptors. This has important translational consequences: just by administering boron, taking advantage of endogenous VEGF, in vivo vascularization is shown in a chorioallantoic membrane assay.P.R. acknowledges support from the Ministerio de Economia, Industria y Competitividad, Gobierno de Espana (MINECO) (MAT2015-69315-C3-1-R), and European Regional Development Fund (FEDER). CIBER-BBN is an initiative funded by the VI National R&D&I Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions and financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund. M. S. S. acknowledges support from the European Research Council (ERC-HealInSynergy 306990) and the UK Engineering and Physical Sciences Research Council (EPSRC-EP/P001114/1). The authors are very grateful to Productos Florida farm for kindly providing chick embryos for CAM assay.Rico Tortosa, PM.; Rodrigo Navarro, A.; La Peña Del Rivero, MD.; Moulisova, V.; Costell, M.; Salmerón Sánchez, M. (2018). Simultaneous boron ion-channel/growth factor receptor activation for enhanced vascularization. Advanced Biosystems. 3(1):1-12. https://doi.org/10.1002/adbi.201800220S11231Yancopoulos, G. D., Davis, S., Gale, N. W., Rudge, J. S., Wiegand, S. J., & Holash, J. (2000). Vascular-specific growth factors and blood vessel formation. Nature, 407(6801), 242-248. doi:10.1038/35025215Carmeliet, P. (2005). Angiogenesis in life, disease and medicine. Nature, 438(7070), 932-936. doi:10.1038/nature04478Moulisová, V., Gonzalez-García, C., Cantini, M., Rodrigo-Navarro, A., Weaver, J., Costell, M., … Salmerón-Sánchez, M. (2017). Engineered microenvironments for synergistic VEGF – Integrin signalling during vascularization. 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Engineered coatings for titanium implants to present ultralow doses of BMP-7

The ongoing research to improve the clinical outcome of titanium implants has resulted in the implemetation of multiple approches to deliver osteogenic growth factors accelerating and sustaining osseointegration. Here we show the presentation of human bone morphogenetic protein 7 (BMP-7) adsorbed to titanium discs coated with poly(ethyl acrylate) (PEA). We have previously shown that PEA promotes fibronectin organization into nanonetworks exposing integrin- and growth-factor-binding domains, allowing a synergistic interaction at the integrin/growth factor receptor level. Here, titanium discs were coated with PEA and fibronectin and then decorated with ng/mL doses of BMP-7. Human mesenchymal stem cells were used to investigate cellular responses on these functionalized microenvironments. Cell adhesion, proliferation, and mineralization, as well as osteogenic markers expression (osteopontin and osteocalcin) revealed the ability of the system to be more potent in osteodifferentiation of the mesenchymal cells than combinations of titanium and BMP-7 in absence of PEA coatings. This work represents a novel strategy to improve the biological activity of titanium implants with BMP-7

Simultaneous boron ion-channel/growth factor receptor activation for enhanced vascularization

Boron ion is essential in metabolism and its concentration is regulated by ion-channel NaBC1. NaBC1 mutations cause corneal dystrophies such as Harboyan syndrome. Here we propose a 3D molecular model for NaBC1 and show that simultaneous stimulation of NaBC1 and vascular growth factor receptors (VEGFR) promote angiogenesis in vitro and in vivo with ultra-low concentrations of VEGF. We show Human Umbilical Vein Endothelial Cells (HUVEC) organization into tubular structures indicative of vascularization potential. Enhanced cell sprouting was found only in the presence of VEGF and boron, effect abrogated after blocking NaBC1. We demonstrate that stimulated NaBC1 promotes angiogenesis via Akt-independent pathways and that α5β1/αvβ3-integrin binding is not essential to enhanced HUVEC organization. We describe a novel vascularization mechanism that involves the crosstalk and colocalization between NaBC1/VEGFR receptors. This has important translational consequences: just by administering boron, taking advantage of endogenous VEGF, in vivo vascularization is shown in a chorioallantoic membrane assay

3D gelatin-chitosan hybrid hydrogels combined with human platelet lysate highly support human mesenchymal stem cell proliferation and osteogenic differentiation

Bone marrow and adipose tissue human mesenchymal stem cells were seeded in highly performing 3D gelatin–chitosan hybrid hydrogels of varying chitosan content in the presence of human platelet lysate and evaluated for their proliferation and osteogenic differentiation. Both bone marrow and adipose tissue human mesenchymal stem cells in gelatin–chitosan hybrid hydrogel 1 (chitosan content 8.1%) or gelatin–chitosan hybrid hydrogel 2 (chitosan 14.9%) showed high levels of viability (80%–90%), and their proliferation and osteogenic differentiation was significantly higher with human platelet lysate compared to fetal bovine serum, particularly in gelatin–chitosan hybrid hydrogel 1. Mineralization was detected early, after 21 days of culture, when human platelet lysate was used in the presence of osteogenic stimuli. Proteomic characterization of human platelet lysate highlighted 59 proteins mainly involved in functions related to cell adhesion, cellular repairing mechanisms, and regulation of cell differentiation. In conclusion, the combination of our gelatin–chitosan hybrid hydrogels with hPL represents a promising strategy for bone regenerative medicine using human mesenchymal stem cells

Replacement of cyclosporin A from its binding to hepatocyte plasma membrane by silymarin flavonoids

Interactions between cyclosporin A and three silymarin flavonoids (silybin, silydianin, and silychristin) were studied on the rat hepatocyte plasma membrane using the replacement of [3H]cyclosporin A by silymarin flavonoids. It was found that flavonoids significantly replaced CsA from its binding to the rat hepatocyte plasma membrane. It seems that these two types of compounds are competitors at the same binding site of the plasma membrane receptor

Behavior of keys in random databases

We consider random databases formed by a sequence of random vectors (tuples) with common discrete distribution P=#left brace#p(k)#right brace#. A key is a collection of columns (attributes) which identifies a tuple in a database. A minimal key does not contain any key subset. Many database theory and application problems (e.g., data search optimization, database design) are substantially defined by the complexity of a database, i.e., the size of key, functional dependency, and minimal key systems. Moreover, the average behavior of these characteristics is crucial for certain problems. Based on the Renyi entropy, h_p=-log_2(#SIGMA#_kp(k)"2), and the Poisson approximation (Stein-Chen) technique, we establish an approximation for the probability that a given set of attributes A is a key (minimal key) or there is a functional dependencey between two sets of attributes as a part of the average complexity evaluation. Asymptotics for parameters (e.g., the entropy, the length) of most likely minimal key candidates are also derived. The length of the shortest keys in A have different interpretations in computer science (e.g., the height of digital trees for a certain model). We establish that this value can be approximated by the linear transformation of the Gumbel (double exponential) random variable with a given accuracy. Thus, the Monte-Carlo approach is feasible for an investigation. Several numerical examples and simulation results are presented. (orig.)Available from TIB Hannover: RR 8073(1997,12) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Brandschutzverbesserung bei Schienenfahrzeugen Verzoegerung und Begrenzung der Brandausbreitung durch raumabschliessende Systeme. Schlussbericht (Zusammenfassung)

Available from TIB Hannover: D.Dt.F. QN1(1,27) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman