Investigation on the mechanisms for biocompatibility of chitosan using agarose/chitosan blended hydrogels as a model / 国际生物医学工程杂志

ObjectiveTo investigate the possible mechanisms for biocompatibility of chitosan material using agarose/chitosan blended hydrogels as a model.Methods A series of agarose/chitosan blended hydrogels with different chitosan content were prepared by the blending method.The chemical groups of the blended hydrogels were analyzed by the Fourier transform infrared (FTIR) spectroscopy.The blending compatibility between the agarose and chitosan was evaluated with the fluorescein-4-isothiocyanate (FITC) staining method.The charge of the blended hydrogels was determined by the zeta potential measurement.The adsorption of total fetal bovine serum (FBS) proteins and bovine serum albumin (BSA) on the blended hydrogels was measured by the bicinchoninic acid (BCA) method.The adsorption of fibronectin (FN) on the blended hydrogels was measured with ELISA.Cell culture experiment adopted human microvascular endothelial cell line (HMEC-1) as the model.The cytocompatibility was studied by evaluating adhesion,proliferation,and morphology of the cells on the blended hydrogels.Results Characteristic chemical groups of chitosan could be detected in the agarose/chitosan blended hydrogels.The chitosan had a good blending compatibility with the agarose.The amino groups of chitosan were uniformly distributed in the blended hydrogels.The blended hydrogels were strongly positively charged at acidic pH (pH 3.0),however,the zeta potentials of all the hydrogels were reduced to nearly 0 mV at neutral pH (pH 7.4).There were no significant differences in the adsorption of total FBS proteins and BSA between the blended hydrogel groups.However,the adsorption of FN on the hydrogels significantly increased with the increase of chitosan content.Cell culture experiment indicated that the cytocompatibihty of the blended hydrogels was significantly improved with the increase of chitosan content.The HMECs exhibited higher levels of adhesion,spreading,and proliferation on the hydrogels with higher chitosan content.ConclusionResults in this study indicated that the chitosan component preferentially adsorbed FN compared to the other serum proteins,leading to adhesion and spreading of the cells on the blended hydrogels.In contrast to prevailing views,it was found in the present study that the biocompatibility of chitosan did not relate to its positive charge.

Suppression of GSK3β by ERK mediates lipopolysaccharide induced cell migration in macrophage through β-catenin signaling

We investigate the role of β-catenin signaling in the response of macrophage to lipopolysaccharide (LPS) using RAW264.7 cells. LPS rapidly stimulated cytosolic β-catenin accumulation. β-catenin-mediated transcription was showed to be required for LPS induced gene expression and cell migration. Mechanically, ERK activation-primed GSK3β inactivation by Akt was demonstrated to mediate the LPS induced β-catenin accumulation. Overall, our findings suggest that suppression of GSK3β by ERK stimulates β-catenin signaling therefore contributes to LPS induced cell migration in macrophage activation.

Adipose derived mesenchymal stem cell transplantation for Alzheimer's disease / 中国组织工程研究

Alzheimer's disease is an irreversible neurodegenerative disease characterized by progressive neuronal loss. To date, there has been no effective medicine or therapy for neurodegenerative disease. With development of stem cell technique and theory, neural stem cell transplantation has been found to be prospective in Alzheimer's disease treatment. However, it was challenged by the deficiency of autologous neural stem cell, which can bypass immunological barrier. Compared with neural stem cells, mesenchymal stem cells exhibit extensive resources, such as liver, bone marrow and adipose, and multiple differentiations into bone, muscle or adipose. Considering the easy access, the minor trauma to the patients, and the neuron differentiation potential of adipose derived mesenchymal stem cells (A-MSC), we hypothesize that A-MSC graft is a potential and innovative strategy for the treatment of Alzheimer's disease.

Mechanisms for biocompatibility of chitosan: A new viewpoint / 中国组织工程研究

OBJECTIVE:In recent years, chitosan has been widely used as tissue engineering scaffolds. In this paper we reviewed the research progress in chitosan biocompatibility and gave a hypothesison possible mechanism of interactions between cells and chitosan. A model system to test this hypothesis was also discussed. DATA SOURCES: Literatures about chitosan biocompatibility were retrieved with computer in Medline, Pubmed and Elsevier from January 1998 to December 2006 with the key words of."chitosan, biocompatibility, surface charge, cell adhesion" in English.STUDY SELECTION: Literatures about chitosan biocompatibility and interactions between chitosan and cells, especially the influence of chitosan charges on cell attachment, were included, whereas repeated experiments were excluded.DATA EXTRACTION: Totally 374 literatures were collected. Among which, 30 were admitted and reviewed.DATA SYNTHESIS: Many mammalian cells can adhere, spread and proliferate on chitosan materials. It is widely accepted that the biocompatibility of chitosan is due to the electrostatic attractive force between positively charged amino groups on chitosan chains and negatively charged cell membranes. However, the pKa value of chitosan amino groups is 6.2-6.8 and the positive charge of chitosan chains is largely decreased under physiological condition as a result of amino groups unprotonation. Thus whether the chitosan's biocompatibility is due to its positive charge remains doubtful and needs further study.CONCLUSION: Based on prior studies, we hypothesize that the positive charge of amino groups on chitosan chains might not be the major factor in biocompatibility of chitosan material. Agarose/chitosan blending hydrogels is supposed to be an appropriate model system to test this hypothesis.