Abstract. Stem cells are known to differentiate in response toHowever, identification of these stem cell inducing molecules is non-trivial and rational approaches to discover drugs for achieving reproducible, targeted stem cell control remain elusive. Here, we demonstrate the design of supramolecular hydrogels that allow targeting of a range of stem cell phenotypes, providing a useful platform for discovery of differentiation inducing metabolites. These gels are simple in composition, containing a fibre forming aromatic peptide amphiphile, which is coassembled with a surfactant-like amphiphile that provides hydrophilic surface functionality to the fibres. The stiffness of the gels can be precisely tuned over the entire range that is typically associated with stem cell differentiation (0.1-40 kPa). 3We demonstrate that the gels can be used to direct stem cell differentiation without the need for induction media and they are therefore ideally suited to study stem cell behaviour -including as drug discovery platforms. To achieve this, we study the cell's usage of biological small molecules, metabolites, during differentiation and select bioactive metabolites that can target bone and cartilage formation specifically. This new use of designed supramolecular biomaterials can be envisaged to remove serendipity from discovery of metabolites associated with biological processes as drug candidates. Introduction.

Researchers develop a simple technique to enhance the activity of growth factors during tissue healing.

Insecticide resistance is a major problem for both medicine and agriculture and is frequently associated with overexpression of metabolic enzymes that catalyze the breakdown of pesticides, leading to broad-spectrum resistance. However, the insect tissues within which these metabolic enzymes normally reside remain unclear. Microarray analysis of nine adult tissues from Drosophila melanogaster reveals that cytochrome P-450s and glutathione-S-transferases show highly tissue-specific expression patterns; most were confined to one or more epithelial tissues, and half showed dominant expression in a single tissue. The particular detoxifying enzymes encountered by a xenobiotic thus depend critically on the route of administration. In particular, known insecticide metabolism genes are highly enriched in insect Malpighian (renal) tubules, implicating them in xenobiotic metabolism. The tubules thus display, with the fat body, roles analogous to the vertebrate liver and immune system, as well as its acknowledged renal function. To illustrate this, when levels of a single gene, Cyp6g1, were manipulated in just the Malpighian tubules of adult Drosophila, the survival of the whole insect after 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) challenge was altered, whereas corresponding manipulations in the nervous system or the fat body were without effect. This shows that, although detoxification enzymes are widely distributed, baseline protection against DDT resides primarily in the insect excretory system, corresponding to less than 0.1% of the mass of the organism.

It is emerging that nanotopographical information can be used to induce osteogenesis from mesenchymal stromal cells from the bone marrow, and it is hoped that this nanoscale bioactivity can be utilized to engineer next generation implants. However, the osteogenic mechanism of surfaces is currently poorly understood. In this report, we investigate mechanism and implicate bone morphogenic protein (BMP) in up-regulation of RUNX2 and show that RUNX2 and its regulatory miRNAs are BMP sensitive. Our data demonstrate that osteogenic nanotopography promotes colocalization of integrins and BMP2 receptors in order to enhance osteogenic activity and that vitronectin is important in this interface. This provides insight that topographical regulation of adhesion can have effects on signaling cascades outside of cytoskeletal signaling and that adhesions can have roles in augmenting BMP signaling.

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