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PEGDA was photopolymerized to form hydrogels under different UV light irradiation times. In order to investigate the degradation rate in vitro, the various PEGDA hydrogels were incubated in PBS solution at 37 degrees C in shaking water bath system. The physical-chemical properties such as pH values, dimension, mass and volume change, compressive strength and Young's modulus were measured. MALDI-MS and SEM were employed to evaluate the PBS solutions and corroded hydrogels after a designed period of time till 8 weeks. The results indicate that the PEGDA formed hydrogels can be tailored with prompted properties specifically for various cell-based tissue engineering needs.

Quantum dots (QDs) are semiconductor nanocrystals that serve as promising alternatives to organic dyes for cell labeling. Because of their unique spectral, physical and chemical properties, QDs are useful for concurrently monitoring several intercellular and intracellular interactions in live normal cells and cancer cells over periods ranging from less than a second to over several days (several divisions of cells) [1]. Here, peptide CGGGRGD is immobilized on CdSe-ZnS QDs coated with carboxyl groups by cross linking with amine groups. These conjugates are directed by the peptide to bind with selected integrins on the membrane of human Mesenchymal stem cells. Upon overnight incubation with optimal concentration, QDs effectively labeled all the cells. Here, we report long-term labeling of human bone-marrowderived mesenchymal stem cells (hMSCs) with RGDconjugated quantum dots (QDs) during self replication and differentiation into osteogenic cell lineages.

The present study was designed to explore an ex vivo culturing protocol for fibroblastic differentiation of human mesenchymal stem cells (hMSCs) using connective tissue growth factor (CTGF). Fibroblastic differentiation from stem cells is of widespread significance in the engineering of virtually all tissues including tendons, ligaments, periodontal ligament, cranial sutures and as interstitial filler of all organs. The treatment with 100 ng/ml of recombinant human CTGF and 50 mug/ml ascorbic acids on monolayer cultured hMSCs showed significant increases in type I collagen and tenascin-C (Tn-C) contents by 2 and 4 wks. In addition, CTGF-treated hMSCs failed to show osteogenic or chondrogenic differentiation. The present data show that CTGF is an effective induction factor for fibroblastic differentiation of hMSCs. These findings have implications for engineering fibrous tissue by providing the initial evidence of a reproducible protocol for fibroblastic differentiation of hMSCs.