42 research outputs found
Myoconductive and osteoinductive free-standing polysaccharide membranes
Free-standing (FS) membranes have increasing applications in the biomedical field as drug delivery systems for wound healing and tissue engineering. Here, we studied the potential of free-standing membranes made by the layer-by-layer assembly of chitosan and alginate to be used as a simple biomimetic system of the periosteum. The design of a periosteum-like membrane implies the elaboration of a thick membrane suitable for both muscle and bone formation. Our aim was to produce well-defined âŒ50 ÎŒm thick polysaccharide membranes that could be easily manipulated, were mechanically resistant, and would enable both myogenesis and osteogenesis in vitro and in vivo. The membranes were chemically crosslinked to improve their mechanical properties. Crosslinking chemistry was followed via Fourier transform infrared spectroscopy and the mechanical properties of the membranes were assessed using dynamic mechanical analysis. The loading and release of the potent osteoinductive growth factor bone morphogenetic protein 2 (BMP-2) inside and outside of the FS membrane was followed by fluorescence spectroscopy in a physiological buffer over 1 month. The myogenic and osteogenic potentials of the membranes in vitro were assessed using BMP-2-responsive skeletal myoblasts. Finally, their osteoinductive properties in vivo were studied in a preliminary experiment using a mouse ectopic model. Our results showed that the more crosslinked FS membranes enabled a more efficient myoblast differentiation in myotubes. In addition, we showed that a tunable amount of BMP-2 can be loaded into and subsequently released from the membranes, depending on the crosslinking degree and the initial BMP-2 concentration in solution. Only the more crosslinked membranes were found to be osteoinductive in vivo. These polysaccharide-based membranes have strong potential as a periosteum-mimetic scaffold for bone tissue regeneration.This work was financially supported by the Foundation for Science and Technology (FCT) through the scholarship SFRH/BPD/96797/2013, Fundo Social Europeu (FSE), and Programa Diferencial de Potencial Human (POPH) granted to Sofia G. Caridade. C.M. is indebted to the Association Francaise contre les Myopathies for financial support via a post-doctoral fellowship (AFM project 16673). J.A. acknowledges the Whitaker International Fellows and Scholars Program for support via a post-doctoral fellowship. This work was supported by the European Commission (FP7 program) via a European Research Council starting grant (BIOMIM, GA 259370 to C.P.) and by the AFM (grant Microtiss, 16530). We thank Isabelle Paintrand for her technical help with the confocal apparatus
Secondary structure of rhBMP-2 in a protective biopolymeric carrier material
Efficient delivery of growth factors is one of the great challenges of tissue engineering. Polyelectrolyte multilayer films (PEM) made of biopolymers have recently emerged as an interesting carrier for delivering recombinant human bone morphogenetic protein 2 (rhBMP-2 noted here BMP-2) to cells in a matrix-bound manner. We recently showed that PEM made of poly(l-lysine) and hyaluronan (PLL/HA) can retain high and tunable quantities of BMP-2 and can deliver it to cells to induce their differentiation in osteoblasts. Here, we investigate quantitatively by Fourier transform infrared spectroscopy (FTIR) the secondary structure of BMP-2 in solution as well as trapped in a biopolymeric thin film. We reveal that the major structural elements of BMP-2 in solution are intramolecular ÎČ-sheets and unordered structures as well as α-helices. Furthermore, we studied the secondary structure of rhBMP-2 trapped in hydrated films and in dry films since drying is an important step for future applications of these bioactive films onto orthopedic biomaterials. We demonstrate that the structural elements were preserved when BMP-2 was trapped in the biopolymeric film in hydrated conditions and, to a lesser extent, in dry state. Importantly, its bioactivity was maintained after drying of the film. Our results appear highly promising for future applications of these films as coatings of biomedical materials, to deliver bioactive proteins while preserving their bioactivity upon storage in dry state.This work was supported by the French Ministry of Research through an ANR-EmergenceBIO grant (ANR-09-EBIO-012-01), by the European Commission (FP7 program) via a European Research Council starting grant (BIOMIM, GA 259370), and by GRAVIT (081012_FIBIOS). C.P. is grafetul to IUF for financial support
Sleep-related improvements in motor learning following mental practice
International audienc
Osteoinductive coatings of implantable materials
National audienc
Tectonometamorphic evolution of the Atbashi high- P units (Kyrgyz CAOB, Tien Shan): Implications for the closure of the Turkestan Ocean and continental subduction-exhumation of the South Kazakh continental margin
The South Tien Shan (STS) belt results from the last collision event in the western Central Asian Orogenic Belt (CAOB). Understanding its formation is of prime importance in the general framework of the CAOB. The Atbashi Range preserves highâP (HP) rocks along the STS suture, but still, its global metamorphic evolution remains poorly constrained. Several HP units have been identified: (a) a HP tectonic mĂ©lange including boudins of mafic eclogites in a sedimentary matrix, (b) a large (>100 km long) highâP metasedimentary unit (HPMU) and (c) a lower blueschist facies accretionary prism. Raman Spectroscopy on carbonaceous material combined with phengite and chlorite multiequilibria and isochemical phase diagram modelling indicates that the HPMU recorded homogeneous PâT conditions of 23â25 kbar and 560â570°C along the whole unit. 40Ar/39Ar dating on phengite from the HPMU ranges between 328 and 319 Ma at regional scale. These ages are interpreted as (reâ) crystallization ages of phengite during Tmax conditions at a pressure range of 20â25 kbar. Thermobarometry on samples from the HP tectonic mĂ©lange provides similar metamorphic peak conditions. Thermobarometry on the blueschist to lower greenschist facies accretionary prism indicates that it underwent PâT conditions of 5â6 kbar and 290â340°C, highlighting a 17â20 kbar pressure gap between the HPMUâtectonic mĂ©lange units and the accretionary prism. Comparison with available geochronological data suggests a very short time span between the prograde path (340 Ma), HP metamorphic peak (330 Ma), the Tmax (328â319 Ma) and the final exhumation of the HPMU (303â295 Ma). Extrusion of the HPMU, accommodated by a basal thrust and an upper detachment, was driven by buoyant forces from 70â75 km up to 60 km depth, which directly followed continental subduction and detachment of the HPMU. At crustal depths, extrusion was controlled by collisional tectonics up to shallow levels. Lithological homogeneity of the HPMU and its continentalâderived character from the North Tien Shan suggest this unit corresponds to the hyperâextended continental margin of the Kazakh continent, subducted southward below the north continental active margin of the Tarim craton. Integration of the available geological data allows us to propose a general geodynamic scenario for Tien Shan during the Carboniferous with a combination of (a) Nâdipping subduction below the Kazakh margin of Middle Tien Shan until 390â340 Ma and (b) Sâdipping subduction of remaining Turkestan marginal basins between 340 and 320 Ma
Sleep: An Open-Source Python Software for Visualization, Analysis, and Staging of Sleep Data
International audienc
Cyclodextrin/Paclitaxel Complex in Biodegradable Capsules for Breast Cancer Treatment
A novel type of biocompatible hollow
capsules that combine severable
favorable features as a hydrophobic drug carrier, including hostâguest
complexation in the shell, the unique biological functions of hyaluronic
acid (HA), and transport properties of the multilayer shell, was designed
and prepared. These capsules were generated by layer-by-layer (LbL)
deposition of HA modified with ÎČ-cyclodextrin (CD) molecules
and polyÂ(l-lysine) (PLL) on calcium carbonate particles.
Simultaneously, paclitaxel (PTX) was loaded in the LbL wall via hostâguest
interaction. Under physiological conditions, the incorporated anticancer
drug was slowly released, and the capsules remained stable. Because
the PTX molecules are selectively complexed by CD in the shell, their
release can be triggered by the addition of competitive cyclodextrin
molecules in the external medium. By incubating the capsules with
breast cancer cells (MDA-MB-231), it was found that the cells bound
specifically to the capsules through the CD44 receptor of HA that
is overexpressed on their surface. Finally, when breast cancer cells
were incubated with the PTX-loaded capsules, their viability was found
to strongly decrease. All together, these results highlight the potential
for these HAâcyclodextrin-containing capsules in anticancer
therapy
Secondary Structure of rhBMPâ2 in a Protective Biopolymeric Carrier Material
Efficient delivery of growth factors is one of the great
challenges
of tissue engineering. Polyelectrolyte multilayer films (PEM) made
of biopolymers have recently emerged as an interesting carrier for
delivering recombinant human bone morphogenetic protein 2 (rhBMP-2
noted here BMP-2) to cells in a matrix-bound manner. We recently showed
that PEM made of polyÂ(l-lysine) and hyaluronan (PLL/HA) can
retain high and tunable quantities of BMP-2 and can deliver it to
cells to induce their differentiation in osteoblasts. Here, we investigate
quantitatively by Fourier transform infrared spectroscopy (FTIR) the
secondary structure of BMP-2 in solution as well as trapped in a biopolymeric
thin film. We reveal that the major structural elements of BMP-2 in
solution are intramolecular ÎČ-sheets and unordered structures
as well as α-helices. Furthermore, we studied the secondary
structure of rhBMP-2 trapped in hydrated films and in dry films since
drying is an important step for future applications of these bioactive
films onto orthopedic biomaterials. We demonstrate that the structural
elements were preserved when BMP-2 was trapped in the biopolymeric
film in hydrated conditions and, to a lesser extent, in dry state.
Importantly, its bioactivity was maintained after drying of the film.
Our results appear highly promising for future applications of these
films as coatings of biomedical materials, to deliver bioactive proteins
while preserving their bioactivity upon storage in dry state