High mobility group box 1-immobilized nanofibrous scaffold enhances vascularization, osteogenesis and stem cell recruitment.

Most tissue engineered bone scaffolds are limited by insufficient vascularization. In this study, a high mobility group box 1 (HMGB1)-immobilized material for in situ tissue engineering was prepared to facilitate bone regeneration. The HMGB1-immobilized scaffold accelerated the adhesion and osteogenic differentiation of mesenchymal stem cells (MSCs) in vitro. Subcutaneous implantation and rat calvarial defect repair experiments proved that the HMGB1-immobilized scaffold induced vascularization and enhanced expression of osteocalcin in vivo. MSCs were recruited into the scaffold, which might due to the high expression of stromal cell-derived factor-1α. The bone repair efficiency of the HMGB1-immobilized scaffold was significantly superior to and faster than that of the poly-l-lactide/polycaprolactone nanofibrous scaffold. This research demonstrated the feasibility of using only one pro-inflammatory cytokine HMGB1 as a 'trigger' signal in bone tissue engineering to simultaneously realize multiple functions, including enhancing vascularization, inducing osteogenesis and recruiting stem cells. Consequently, the bone regeneration process was accelerated. The results are of great significance for preparing a new type of scaffold that can promote bone repair in multiple aspects by mimicking a natural manner.

The effect of silk gland sericin protein incorporation into electrospun polycaprolactone nanofibers on in vitro and in vivo characteristics.

The application of silk fibroin is a promising approach for designing biomaterials. However, silk sericin (SS) protein has not attracted much attention in the field of biomaterials as a natural biopolymer due to its immune responses, weak structural properties and high solubility. In this study, fifth instar silkworm (B. mori) middle gland extracted sericin protein and polycaprolactone (PCL) blends nanofibrous scaffolds were successfully fabricated via an emulsion electrospinning technique. PCL/SS nanofibrous scaffolds were characterized by combined techniques of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR). Water contact angle and tensile measurements indicated that the PCL/SS scaffolds exhibited improved mechanical properties, as well as more favorable wettability, than that obtained from PCL alone. We also analyzed the effect of SS content in blends on cell morphology and proliferation of human primary skin fibroblasts (FEK4 cells) within 1-5 days. The results showed that cell proliferation significantly increased in the appropriate ratio of PCL/SS blends while showing more elongated cellular morphology. The mRNA gene expression of transforming growth factor ß1 (TGF-ß1) and collagen I were up-regulated in PCL/SS scaffolds. Furthermore, in vivo experiments suggested that low fibrosis tissue formation and macrophages adhesion of the PCL/SS nanofibrous scaffolds reveal its potential as future biocompatible scaffolds for tissue engineering.

Matrix mechanics and fluid shear stress control stem cells fate in three dimensional microenvironment.

Stem cells have the ability to self-renew and to differentiate into multiple mature cell types during early life and growth. Stem cells adhesion, proliferation, migration and differentiation are affected by biochemical, mechanical and physical surface properties of the surrounding matrix in which stem cells reside and stem cells can sensitively feel and respond to the microenvironment of this matrix. More and more researches have proven that three dimensional (3D) culture can reduce the gap between cell culture and physiological environment where cells always live in vivo. This review summarized recent findings on the studies of matrix mechanics that control stem cells (primarily mesenchymal stem cells (MSCs)) fate in 3D environment, including matrix stiffness and extracellular matrix (ECM) stiffness. Considering the exchange of oxygen and nutrients in 3D culture, the effect of fluid shear stress (FSS) on fate decision of stem cells was also discussed in detail. Further, the difference of MSCs response to matrix stiffness between two dimensional (2D) and 3D conditions was compared. Finally, the mechanism of mechanotransduction of stem cells activated by matrix mechanics and FSS in 3D culture was briefly pointed out.

Permanent genetic resources added to molecular ecology resources database 1 April 2012 - 31 May 2012.

This article documents the addition of 123 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Brenthis ino, Cichla orinocensis, Cichla temensis, Epinephelus striatus, Gobio gobio, Liocarcinus depurator, Macrolophus pygmaeus, Monilinia vaccinii-corymbosi, Pelochelys cantorii, Philotrypesis josephi, Romanogobio vladykovi, Takydromus luyeanus and Takydromus viridipunctatus. These loci were cross-tested on the following species: Cichla intermedia, Cichla ocellaris, Cichla pinima, Epinephelus acanthistius, Gobio carpathicus, Gobio obtusirostris, Gobio sp. 1, Gobio volgensis, Macrolophus costalis, Macrolophus melanotoma, Macrolophus pygmaeus, Romanogobio albipinnatus, Romanogobio banaticus, Romanogobio belingi, Romanogobio kesslerii, Romanogobio parvus, Romanogobio pentatrichus, Romanogobio uranoscopus, Takydromus formosanus, Takydromus hsuehshanesis and Takydromus stejnegeri.