Objective To investigate the tissue remodeling and cell alignment of TDBM scaffolds seeded with rabbit tenocytes under the cycle dynamic tensile force or static tension-free culture in vitro. Methods TDBM were made by ourselves, and uniaxial cyclic tendon stretching device was designed and manufactured on our own. Primary tenocytes were isolated from the Achilles tendon of three-day-old New Zealand white rabbits and seeded into scaffolds, and were cultured collectively in DMEM in vitro. Samples were divided into two groups:dynamic tension-loaded group, and static tension-free group. Fresh natural tendons were used to be positive control. The experiment's time was six weeks. The scaffold-cell complexes were harvested at 3 and 7 days of culture for Inverted microscope and scanning electron micrograph (SEM) analysis. The morphological characters of the samples, including the general view, HE and Masson's dyeing, were observed at 2, 4 and 6 weeks. In addition, the gene expression of the I-type collagen and III-type collagen of the samples was detected by using Real time PCR at every week. Set fresh natural tendon as control. Results The inverted microscope and SEM showed that it was nice compatible condition between the tendon cells and TD-BM scaffold. In addition, the tendon of tension-loaded group revealed a structure of longitudinally aligned collagen fi bers and dense structure of collagen fibers arranged in orderly form a unique corrugated structure. Tenocytes layer located between the col-lagen fibers and aligned longitudinally along the force axis, with increased matrix deposition after the 3th week showed by RT-PCR. The cell/matrix ratio decreases. When cultured to 6 weeks, the tissue structure was very similar to that of fresh natural ten-don pattern. By contrast, HE and Masson's staining revealed the collagen fibro-tissue structure in tension-free groups with disorga-nized matrix structure and randomly distributed cells. Collagen fibers were gradually degraded with time. In tension-loaded group, Real-time PCR showed that gene expression of I-type collagen and III-type collagen gradually increase, but in tension-free group, the relative gene expression of I-type collagen and III-type collagen was highest at 3rd week, and from that time the relative expres-sion gradually decrease. Conclusion Under the dynamic stress, the TDBM scaffolds seeded with rabbit tenocytes can promote extra-cellular matrix biosynthesis and tendon structure remodeling, which is a promising method for tendon tissue engineering.

Enzymes play such a pivotal role in cellular metabolism that enzyme assays are important for bio-engineering, disease diagnoses and drug discovery. Among the reported methods, fluoremetry has attracted more and more attention due to its high sensitivity and possibility of continuous dynamic monitoring. The recent progresses and applications in enzyme assays using fluorescent probes were reviewed. Different methods were classified into direct fluorescence detection and indirect fluorescence detection according to their labeled substrates and detection mechanisms. Our writing purpose is to provide the readers with a flavor of the kinds of tools and strategies available in enzyme assays with fluorescent probes. Also, the research situation and prospects were disucssed
Animals ; Enzyme Assays ; methods ; trends ; Fluorescent Dyes ; Fluorometry ; methods ; Humans ; Microscopy, Fluorescence