Crystallization behaviour of nanostructured hybrid SiO2-TiO2 gel glasses to nanocomposites.

The crystallization behaviour of hybrid SiO2-TiO2 nanocomposites derived from titanosiloxanes by sol-gel method has been investigated depending on the type of siloxane precursor and the pirolysis temperature. The resulting hybrid titanosiloxanes, crosslinked with trimethylsilil isocyanate (nitrogen-modified) or methyltrietoxisilane (carbon-modified), were pirolyzed in an inert atmosphere in the temperature range between 600 to 1100 degrees C in order to form C-(N)-Si-O-TiO2 nanocomposites. By means of XRD, FTIR, 29Si NMR, SEM, TEM and AFM investigations have been established that the transformation of the nanostructured SiO2-TiO2 hybrid materials into nanocomposites as well as the crystalline size depend on the titanium content and the type of cross-linking agents used in the synthesizes.

Hemangioblasts from human embryonic stem cells generate multilayered blood vessels with functional smooth muscle cells.

Background: The formation and regeneration of functional vasculatures require both endothelial cells (ECs) and vascular smooth muscle cells (SMCs). Identification and isolation of progenitors with potential for both EC and SMC lineage differentiation from an inexhaustible source, such as human embryonic stem (hES) or induced pluripotent stem cells, will be desirable for cell replacement therapy.

Method: Recently, we have developed a serum-free and animal feeder-free differentiation system to generate blast cells (BCs) from hESCs.

Robust generation of hemangioblastic progenitors from human embryonic stem cells.

Background: Human embryonic stem cells (hESCs) are a potentially inexhaustible source of cells for replacement therapy. However, successful preclinical and clinical progress requires efficient and controlled differentiation towards the specific differentiated cell fate.

Methods: We previously developed a strategy to generate blast cells (BCs) from hESCs that were capable of differentiating into vascular structures as well as into all hematopoietic cell lineages.

Recombinant HoxB4 fusion proteins enhance hematopoietic differentiation of human embryonic stem cells.

Enforced expression of the HoxB4 gene promotes expansion of hematopoietic stem cells (HSCs) and enhances hematopoietic development of both murine and human embryonic stem (ES) cells. HoxB4- expanded HSCs have also been shown to retain their normal potential for differentiation and longterm self-renewal in vivo without the development of leukemia, suggesting that manipulation of HoxB4 expression might represent an effective way to expand functional HSCs for use in transplantation medicine. However, the genetic modification of cells poses clinical concerns, including a potentially increased risk of tumor genicity.

Members of the Toc159 import receptor family represent distinct pathways for protein targeting to plastids.

Plastids represent a diverse group of organelles that perform essential metabolic and signaling functions within all plant cells. The differentiation of specific plastid types relies on the import of selective sets of proteins from among the approximately 2500 nucleus-encoded plastid proteins. The Toc159 family of GTPases mediates the initial targeting of proteins to plastids.