Research progress in liver tissue engineering.

Liver transplantation is the definitive treatment for patients with end-stage liver diseases (ESLD). However, it is hampered by shortage of liver donor. Liver tissue engineering, aiming at fabricating new livers in vitro, provides a potential resolution for donor shortage. Three elements need to be considered in liver tissue engineering: seeding cell resources, scaffolds and bioreactors. Studies have shown potential cell sources as hepatocytes, hepatic cell line, mesenchymal stem cells and others. They need scaffolds with perfect biocompatiblity, suitable micro-structure and appropriate degradation rate, which are essential charateristics for cell attachment, proliferation and secretion in forming extracellular matrix. The most promising scaffolds in research include decellularized whole liver, collagens and biocompatible plastic. The development and function of cells in scaffold need a microenvironment which can provide them with oxygen, nutrition, growth factors, et al. Bioreactor is expected to fulfill these requirements by mimicking the living condition in vivo. Although there is great progress in these three domains, a large gap stays still between their researches and applications. Herein, we summarized the recent development in these three major fields which are indispensable in liver tissue engineering.

Bone marrow mesenchymal stem cells suppress metastatic tumor development in mouse by modulating immune system.

INTRODUCTION: Bone marrow mesenchymal stem cells (BMSCs) have been studied extensively because of their potential use in clinical therapy, regenerative medicine, and tissue engineering. However, their application in tumor therapy remains yet in preclinical stage because of the distinct results from different researches and vagueness of their functional mechanism. In this study, the influence of BMSCs on tumor growth was observed and the potential mechanism was investigated. METHOD: Two animal models, H22 ascitogenous hepatoma in BALb/c mouse and B16-F10 pulmonary metastatic melanoma in C57 mouse, were adopted in experience in vivo and treated with BMSCs by intravenous injection. The percentage of Gr-1+CD11b+ myeloid-derived suppressor cells (MDSCs) and IFN-γ+ T cells were observed in peripheral blood (PB) and bone marrow (BM) by Flow Cytometry. BMSCs were co-cultured in vitro with tumor cells and MDSCs in a tumor conditioned medium separately in order to illustrate the mechanism. RESULTS: Our results demonstrated that BMSCs treatment caused a delayed tumor growth and a prolonged survival in both tumor models, the homing fraction of BMSCs in BM was 2% - 5% in 24-72 hours after transfusion and the percentage of Gr-1+CD11b+ MDSCs was downregulated in peripheral blood and BM. Meanwhile, IFN-γ+ T lymphocytes in PB increased. In vitro co-culture showed that BMSCs inhibited the induction and proliferation of MDSCs in tumor conditioned medium, whereas they didn't affect the proliferation of B16-F10 and H22 cells by in vitro co-culture. Both in vivo and in vitro results showed that BMSCs have a systemic suppressive effect on MDSCs. CONCLUSION: Our data suggest that BMSCs has suppressive effect on tumor and is feasible to be applied in cancer treatment. BMSCs inhibiting MDSCs induction and proliferation is likely one of the mechanism.

An approach to preparing decellularized whole liver organ scaffold in rat.

OBJECTIVES: In present study, we plan to produce a decellularization protocol from rat liver to generate a three-dimensional whole organ scaffold. METHODS: A combination of 1% SDS and 1% tritonX-100 were used orderly to decellularize rat livers. After about 6 h of interactive antegrade/retrograde perfusion, a decellularized whole translucent liver scaffold with integrated blood vessel networks was generated. The decellularized livers are charactered by light microscopy, scanning electron microscopy, and biochemical analysis (DNA quantification) for preservation of the three-dimension of extracellular matrix architecture. RESULTS: The decellularization protocol was verified by observation of the whole translucent liver organ with intact vascular trees under macroscopy, in conjunction with the hematoxylin-eosin staining that showed no cells or nuclear material remained. Additionally, the Masson's stain indicted that the extracellular proteins were well kept and scanning electron microscopy (SEM) revealed a preserved decellularized matrix architecture. Compared to normal livers, DNA in the decellularized livers was quantified less than 10% at the same mass. CONCLUSIONS: The current method of decellularization protocol was feasible, simple and quick, and was verified by an absence of residual cells. The decellularized extracellular matrix had preserved integrate vascular network and a three-dimensional architecture.

[Study of density functional theory (DFT) for Raman spectra of CH3OLi and CH3CH2OLi].

Molecular configurations of CH3 OLi and CH3 CH2 OLi were structured based on the previous study that lithium atom and oxygen atom are directly joined by O-Li bond in alkoxy lithium (ROLi). Neither experimental nor theoretical Raman spectra of CH3 OLi and CH3 CH2 OLi have been reported up to now. In the present paper, DFT method at the B3LYP/ 6-31G(d,p) level was used to optimize molecular configurations of CH3 OLi and CH3 CH2 OLi, obtaining each corresponding equilibrium configuration. Vibration frequencies and Raman spectra of these two molecules were calculated based on equilibrium configuration. The vibration frequencies of obtained calculated results were analyzed by normal coordinate analysis. Besides, the Raman vibration modes of CH3 OLi and CH3 CH2 OLi were assigned according to potential energy distribution of each vibration frequency, which will provide theoretical basis for experimental workers to analyze the components of solid electrolyte interface film (SEI film) of lithium ion battery.

[Investigation on optical limiting performance in solution of cobalt porphyrin].

The nonlinear optical effects of cobalt porphyrin have been investigated with three CW laser lines of 457.9, 488 and 514.5 nm, respectively. Three curves with peak followed by valley using the single beam z-scan technique were obtained. According to M Sheik-bahae's theory the sample has a negative nonlinear refractive index, that is, there is a thermal self-defocusing effect. Three curves of transmittance show a decrease with the increase in the incident laser power, which means that the sample has reverse saturated absorption property under the three laser wavelengths. It's well known that both thermal self-defocusing effect and reverse saturated absorption can lead to optical limiting. It was found that cobalt porphyrin has the optical limiting effect under those wavelengths, and that the critical value of optical limiting decreases with the decrease in laser wavelength. Furthermore, the effect of optical limiting is very good and the critical value is very low, so it's a new optical limiting material with a great potential application value. For that, it is possible to use the co-operation of both effects from cobalt porphyrin to produce a new kind of optical limiting device.