Yaoting Yu

Culture of hepatocytes on fructose-modified chitosan scaffolds

Fructose was conjugated onto the inner surface of highly porous chitosan scaffold prepared by lyophilization. The modified scaffold with average pore size 50-200 microm was used to cultivate rat hepatocytes harvested by portal vein collagenase perfusion. The results indicated that while chitosan sponge alone supported cell attachment and growth, the scaffold modified with fructose accommodated a much larger number of hepatocytes due to the specific interaction between seeded hepatocytes and fructose moieties conjugated onto the surface of the scaffold. Hepatocytes exhibited a round cellular morphology with many microvilli evident on the surface of the cells, indicating healthy cells. Metabolic activities in terms of albumin secretion and urea synthesis were evaluated. It was found that hepatocytes cultured within fructose-modified scaffold resulted in much higher activities than within unmodified chitosan sponge. Scanning electron microscopy results showed that fructose-modified porous scaffold promoted the formation of cellular aggregates.

A novel amphiphilic adsorbent for the removal of low-density lipoprotein

Dextran adsorbent with amphiphilic ligands for adsorption of low-density lipoprotein (LDL) was prepared by the following procedures. Cholesterol group was linked to Dextran G 75 by reacting with cholesterol N-(6-isocyanatohexyl) carbamate in the presence of pyridine in DMSO at 80. In order to introduce the hydrophilic moiety, it was then reacted with chlorosulfonic acid in formamide which introduced the sulfonic group. Adsorption capacity of the adsorbent was studied which showed the removal of LDL-cholesterol (LDL-C), total cholesterol (TC) and TG to be 1.916, 2.132 and 1.349 mg/ml, respectively without significantly affecting total protein levels in the plasma. Moreover, the adsorbent has a better selectivity in removing LDL-C, TC, TG compared to dextran which has only hydrophobic or hydrophilic ligand.

In vitro, in vivo studies of a new amphiphilic adsorbent for the removal of low-density lipoprotein.

A new amphiphilic adsorbent for the removal of low-density lipoprotein (LDL) was prepared according to the literature (Artif. Cells Blood Subs., Immob. Biotechnol. 30 (4) (2002) 285). The effects of sulfonation and grafting time of cholesterol on the swelling property of adsorbent were studied. When sulfonation and grafting time of cholesterol was 3 and 5 h, respectively, the amphiphilic adsorbent had a high adsorption capacity for LDL without significantly adsorbing high-density lipoprotein. The adsorption capacity of the adsorbent for the removal of LDL, total cholesterol (TC) and TG was 1.916, 2.132, 1.349 mg/ml, respectively. Hyperlipidemia rabbits were developed by feeding with fodder containing high content of cholesterol or yolk, which was then perfused with an optimal amount of amphiphilic adsorbent. After 2 h hemoperfusion, the LDL levels decreased from 3.619+/-0.354 to 0.724+/-0.07 mmol/l, which showed that the adsorbent could effectively remove LDL without side effect.

Immobilization of cholesterol oxidase on cellulose acetate membrane for free cholesterol biosensor development.

This article describes the immobilization of cholesterol oxidase on a cellulose acetate (CA) membrane activated by Sodium periodate, ethylenediamine, and glutaraldehyde etc. The properties of the immobilized enzyme membrane were investigated. The factors affecting the activity of immobilized enzyme such as the concentration of glutaraldehyde, the concentration of enzyme used during immobilization, temperature, pH, and immobilizing time etc. were also studied. The immobilized COD membrane has been used to construct fibre-optic fluorescent biosensor.

New Method for Preparing More Stable Microcapsules for the Entrapment of Genetically Engineered Cells

In this paper, we studied a new preparation method of microcapsules for entrapment of genetically engineered cells. Polyvinyl alcohol microcapsules having well defined shape, high mechanical strength, good biochemical and permeability properties were prepared by using low temperature physical crosslinking method. Comparing with currently used alginate-polylysine-alginate microcapsules, polyvinyl alcohol microcapsules have much higher mechanical strength. The low temperature physical crosslinking procedure of polyvinyl alcohol is nontoxic to the genetically engineered E. coli DH5α cell, which attained high activity in decomposing and metabolizing urea in vitro studies.

Extracorporeal Whole Blood Immunoadsorption of Autoimmune Myasthenia Gravis by Cellulose Tryptophan Adsorbent

Whole blood immunoadsorption (WBIA) system, using an adsorbent to remove pathogenic antibodies of myasthenia gravis (MG), was studied. Cellulose-tryptophan adsorbent was synthesized and its adsorption capacity of binding with acetylcholine receptor in the plasma of MG patient was evaluated. Experimental autoimmune myasthenia gravis (EAMG) rabbits were induced by Ta183–200 peptide. The rabbits underwent extracorporeal whole blood adsorption for 2 h. Results showed no significant damages on blood cells and no changes in the concentration of electrolytes. Total protein decreased by 12.0% (P < 0.05), and globulin protein decreased 23.9 ± 5.6% (P < 0.05). The mean overall removal of antibodies against Ta183–200 was 41.12%. The percentage of decrement of compound muscle action potential in 3, 5, 10 Hz of EAMG rabbits all dropped down after the treatment. In conclusion, the adsorbent is biocompatible, was safe for whole blood immunoadsorption, and can remove antibodies in an MG patient effectively. Whole blood immunoadsorption improved clinical manifestation and neuromuscular function of the EAMG rabbits.

In vitro study of a novel low-density lipoprotein adsorbent

Hypercholesterolemia has been identified as a major risk in the development of premature atherosclerosis and in its clinical sequelae is similar to coronary artery disease and myocardial infarction. It is generally agreed that low-density lipoprotein (LDL) cholesterol levels above 130 mg/dl are associated with a very high incidence of coronary heart disease (1). Recently scientists found that drastic reductions of LDL by diet, exercise, and drugs can stop the progression of coronary stenoses or even induce regression of atherosclerotic lesions (2). However, a sufficient reduction of LDL-cholesterol can not be attained by conservative treatment alone in many instances, such as familiar hypercholesterolemia, and further extracorporeal LDL removal by plasmaphe-

Preparation of chitosan/amino multiwalled carbon nanotubes nanocomposite beads for bilirubin adsorption in hemoperfusion

Chitosan-carbon nanotube composite beads combines the advantages of chitosan in forming a stable biocompatible framework and carbon nanotube that provide nanometer effects (high strength and high specific surface area etc.). In this study, chitosan/amino multiwalled carbon nanotubes (CS/AMWCNT) composite beads was prepared by phase-inversion method, in which CS and AMWCNT was crosslinked by ethylene glycol diglycidyl ether (EGDE). The CS/AMWCNT nanocomposite beads produced has been characterized by BET, SEM, TGA, and Raman spectroscopy which exhibited enhanced thermal stability due to the incorporation of AMWCNT. Mechanical test results showed that mechanical strength of the CS/AMWCNT composite beads was significantly enhanced when comparing to unmodified chitosan beads, the breakage percentage decreased from 34.1% to 0.67%. The adsorption capacity for bilirubin was measured in PBS and BSA solutions, and the CS/AMWCNT composite beads with 5 wt% AMWCNT showed much higher adsorption capacity (12.7 mg/g in PBS and 7.6 mg/g in BSA) to bilirubin than chitosan beads (8.5 mg/g in PBS and 4.2 mg/g in BSA). Our nanocomposite beads with excellent hemocompatibility has a high potential application in blood purification as an efficient adsorbent for bilirubin.

Effect of PEG spacer on cellulose adsorbent for the removal of low density lipoprotein-cholesterol.

Carboxyl modified PEG spacer was synthesized and linked covalently to cellulose beads. L-lysine ligand was coupled to the spacer and its selective affinity for low-density lipoprotein-cholesterol (LDL-C) was determined. It was found that the adsorption capacity and the efficiency of the ligand for adsorption of LDL-C was increased when PEG spacer was used. Experimental results showed that with the chain length of PEG spacers increased from 1000 Da to 6000 Da, the average adsorption capacity of LDL-C was enhanced from 0.242 mg/ml to 0.903 mg/ml. Above results indicate that PEG spacers are conducible to the selective removal of LDL-C from human plasma. In addition, LDL-C adsorbent with PEG spacers has a low adsorption capacity for high-density lipoprotein (HDL-C).

A Novel Immunoadsorbent for Rheumatoid Arthritis Therapy—Preparation and Efficacy Evaluation

Aim To develop a novel immunoadsorbent for rheumatoid arthritis (RA) therapy. Methods: A RA immunoadsorbent was developed by binding heat-aggregated human IgG(HAHIgG) to porous agar gel beads. Its adsorption capacity for rheumatoid factors (RFs), storage stability and blood compatibility were evaluated. Results: The coupling yield of HAHIgG on the carrier was 6.0mg/g wet gel. Saturation adsorption capacity of the adsorbent for IgMRF, IgGRF and IgARF were 3400, 2240 and 2400 IU/g, respectively. The adsorbent can be stored at 4°C for three months without significant variance in its activity. Its fine permeability and hemocompatibility were demonstrated by extracorporeal hemoperfusion on rabbits. Conclusion: HAHIgG/agar gel is a safe and effective immunoadsorbent for RA therapy, its potential clinical use is promising in the future.