63 research outputs found
Multiscale three-dimensional scaffolds for soft tissue engineering via multimodal electrospinning
A novel (scalable) electrospinning process was developed to fabricate bio-inspired multiscale three-dimensional scaffolds endowed with a controlled multimodal distribution of fiber diameters and geared towards soft tissue engineering. The resulting materials finely mingle nano- and microscale fibers together, rather than simply juxtaposing them, as is commonly found in the literature. A detailed proof of concept study was conducted on a simpler bimodal poly(ε-caprolactone) (PCL) scaffold with modes of fiber distribution at 600 nm and 3.3 μm. Three conventional unimodal scaffolds with mean diameters of 300 nm and 2.6 and 5.2 μm, respectively, were used as controls to evaluate the new materials. Characterization of the microstructure (i.e. porosity, fiber distribution and pore structure) and mechanical properties (i.e. stiffness, strength and failure mode) indicated that the multimodal scaffold had superior mechanical properties (Young's modulus ∼40 MPa and strength ∼1 MPa) in comparison with the controls, despite the large porosity (∼90% on average). A biological assessment was conducted with bone marrow stromal cell type (mesenchymal stem cells, mTERT-MSCs). While the new material compared favorably with the controls with respect to cell viability (on the outer surface), it outperformed them in terms of cell colonization within the scaffold. The latter result, which could neither be practically achieved in the controls nor expected based on current models of pore size distribution, demonstrated the greater openness of the pore structure of the bimodal material, which remarkably did not come at the expense of its mechanical properties. Furthermore, nanofibers were seen to form a nanoweb bridging across neighboring microfibers, which boosted cell motility and survival. Lastly, standard adipogenic and osteogenic differentiation tests served to demonstrate that the new scaffold did not hinder the multilineage potential of stem cells. © 2009 Acta Materialia Inc
Interfacing Sca-1pos Mesenchymal Stem Cells with Biocompatible Scaffolds with Different Chemical Composition and Geometry
An immortalized murine mesenchymal stem cell line (mTERT-MSC) enriched for Linneg/Sca-1pos fraction has been obtained through the transfection of MSC with murine TERT and single-cell isolation. Such cell line maintained the typical MSC self-renewal capacity and continuously expressed MSC phenotype. Moreover, mTERT-MSC retained the functional features of freshly isolated MSC in culture without evidence of senescence or spontaneous differentiation events. Thus, mTERT-MSC have been cultured onto PLA films, 30 and 100 μm PLA microbeads, and onto unpressed and pressed HYAFF-11 scaffolds. While the cells adhered preserving their morphology on PLA films, clusters of mTERT-MSC were detected on PLA beads and unpressed fibrous scaffolds. Finally, mTERT-MSC were not able to colonize the inner layers of pressed HYAFF-11. Nevertheless, such cell line displayed the ability to preserve Sca-1 expression and to retain multilineage potential when appropriately stimulated on all the scaffolds tested
Contribution of cryopreservation to the cumulative live birth rate: a large multicentric cycle-based data analysis from the Italian National Registry
Magic-factor 1, a partial agonist of Met, induces muscle hypertrophy by protecting myogenic progenitors from apoptosis.
Hepatocyte Growth Factor (HGF) is a pleiotropic cytokine of mesenchymal origin that mediates a characteristic array of biological activities including cell proliferation, survival, motility and morphogenesis. Its high affinity receptor, the tyrosine kinase Met, is expressed by a wide range of tissues and can be activated by either paracrine or autocrine stimulation. Adult myogenic precursor cells, the so called satellite cells, express both HGF and Met. Following muscle injury, autocrine HGF-Met stimulation plays a key role in promoting activation and early division of satellite cells, but is shut off in a second phase to allow myogenic differentiation. In culture, HGF stimulation promotes proliferation of muscle precursors thereby inhibiting their differentiation
MB III Rampart & Cyclopean Wall of Tell es-Sultan/Jericho
I sistemi di fortificazione a terrapieno ( rampart ) che si diffondono nel Levante meridionale nel corso del Bronzo Medio II e III, costruiti generalmente sfruttando declivi preesistenti, proteggendo i tell dagli effetti dell’erosione, erano usualmente costituiti da due elementi fondamentali: muri di contenimento e terrazzamento; gettate di terra e pietrisco che ricoprivano tali muri. Il terrapieno di Tell es-Sultan/antica Gerico fu eretto durante il Bronzo Medio III (1650-1550 a.C.) ed è costituito da un muro di contenimento di pietra, detto Ciclopico in virtù della tec-
nica costruttiva, che cingeva il tell ai suoi piedi, e da uno spesso strato di gettate sovrapposte di terra e pietrisco
Endoscopic follow up after curative resection for colorectal carcinoma ― 5 years of a prospective study
Impianti di trattamento di acque reflue urbane di potenzialità >10.000 A.E. in provincia di Treviso. Aspetti amministrativi e gestionali
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