Preparation and characterization of small-diameter decellularized scaffolds for vascular tissue engineering in an animal model.

BACKGROUND: The development of a suitable extracellular matrix (ECM) scaffold is the first step in vascular tissue engineering (VTE). Synthetic vascular grafts are available as an alternative to autologous vessels in large-diameter arteries (>8 mm) and medium-diameter arteries (6-8 mm). In small-diameter vessels (<6 mm), synthetic vascular grafts are of limited use due to poor patency rates. Compared with a vascular prosthesis, natural tissue ECM has valuable advantages. Despite considerable progress in recent years, identifying an optimal protocol to create a scaffold for use in small-diameter (<6 mm) fully natural tissue-engineered vascular grafts (TEVG), remains elusive. Although reports on different decellularization techniques have been numerous, combination of and comparison between these methods are scarce; therefore, we have compared five different decellularization protocols for making small-diameter (<6 mm) ECM scaffolds and evaluated their characteristics relative to those of fresh vascular controls. RESULTS: The protocols differed in the choice of enzymatic digestion solvent, the use of non-ionic detergent, the durations of the individual steps, and UV crosslinking. Due to their small diameter and ready availability, rabbit arteria carotis were used as the source of the ECM scaffolds. The scaffolds were subcutaneously implanted in rats and the results were evaluated using various microscopy and immunostaining techniques. CONCLUSIONS: Our findings showed that a 2 h digestion time with 1× EDTA, replacing non-ionic detergent with double-distilled water for rinsing and the application of UV crosslinking gave rise to an ECM scaffold with the highest biocompatibility, lowest cytotoxicity and best mechanical properties for use in vivo or in situ pre-clinical research in VTE in comparison.

As2 O3 combined with leflunomide prolongs heart xenograft survival via suppressing the response of Th1, Th2, and B cells in a rat model.

Xenotransplantation remits the severe shortage of human organs and tissues for transplantation, which is a problem that severely limits the application of transplantation to the treatment of human disease. However, severe immune rejection significantly limits the efficacy of xenotransplantation. In this study, we systematically investigated the immunosuppressive effect and mechanism of action of As2 O3 and leflunomide using a hamster-to-rat heart xenotransplantation model. We initially examined heart xenograft survival following As2 O3 and leflunomide treatment alone or combined treatment. We found that treatment with As2 O3 combined with leflunomide can significantly prolong the survival of heart xenograft by inhibiting Th1 and Th2 differentiation and reducing the production of IgG and IgM. Interestingly, As2 O3 and leflunomide showed low toxicity to the organs of the recipient. Taken together, these observations indicate that treatment with As2 O3 combined with leflunomide may be a promising immunosuppressive schedule for xenotransplantation.

Preparation and functional studies of hydroxyethyl chitosan nanoparticles loaded with anti-human death receptor 5 single-chain antibody.

OBJECTIVE: To prepare hydroxyethyl chitosan nanoparticles loaded with anti-human death receptor 5 single-chain antibody, and study their characteristics, functions, and mechanisms of action. MATERIALS AND METHODS: The anti-human death receptor 5 single-chain antibody was constructed and expressed. Protein-loaded hydroxyethyl chitosan nanoparticles were prepared, and their size, morphology, particle-size distribution and surface zeta potential were measured by scanning electron microscopy and laser particle-size analysis. Mouse H22 hepatocellular carcinoma cells were cultured, and growth inhibition was examined using the CellTiter-Blue cell-viability assay. Flow cytometry and Hoechst 33342 were employed to measure cell apoptosis. Kunming mice with H22 tumor models were treated with protein-loaded hydroxyethyl chitosan nanoparticles, and their body weight and tumor size were measured, while hematoxylin and eosin staining was used to detect antitumor effects in vivo and side effects from tumors. RESULTS: The protein-loaded hydroxyethyl chitosan nanoparticles had good stability; the zeta potential was -24.2±0.205, and the dispersion index was 0.203. The inhibition of the protein-loaded hydroxyethyl chitosan nanoparticles on H22 growth was both time- and dose-dependent. Increased expressions of active caspase 8, active caspase 3, and BAX were detected following treatment. The average weight gain, tumor weight, and mean tumor volume of the protein and protein-loaded hydroxyethyl chitosan nanoparticle groups were significantly different (P<0.05) compared with the phosphate-buffered saline group. CONCLUSION: The protein-loaded hydroxyethyl chitosan nanoparticles effectively suppressed tumor growth, indicating that nanotechnology has the potential for broad application in cancer therapy.