Casual cell surface remodeling using biocompatible lipid-poly(ethylene glycol)(n): development of stealth cells and monitoring of cell membrane behavior in serum-supplemented conditions.

Control of the cell surface allows modulation of the cell's biological response, producing practical applications and satisfying scientific interests. Consequently, to meet such goals and interests, diverse approaches were developed in cell surface engineering techniques. Poly(ethylene glycol) (PEG) intermediates were widely employed to modify proteins, enzymes, artificial surfaces, liposomes, and drugs for practical usage. PEGylation was also used for modification of cell surface properties. A method was recently developed for the rapid incorporation of proteins into mammalian cell membranes using lipid-PEG(n) derivatives under physiological conditions. This is a rapid and homogeneous method to incorporate lipid-PEG(n), which was used as a model to study the modification of cellular properties and cell-cell interactions. Because the stability of molecules incorporated into the cell surface shows the usefulness of the anchoring technique, it was also investigated whether potential factors such as time, the concentration of the incorporated lipid-PEG(n), and the type of medium affect this incorporation. At concentrations greater than 10 microM, when dual typed lipid-PEG(n) was incorporated into erythrocytes, antigenic recognition was dramatically attenuated, resulting in the successful development of stealth cells.

Lipoprotein lipase activator NO-1886 improves fatty liver caused by high-fat feeding in streptozotocin-induced diabetic rats.

NO-1886 is a lipoprotein lipase (LPL) activator. Administration of NO-1886 results in an increase in plasma high-density lipoprotein cholesterol (HDL-C) and a decrease in plasma triglyceride (TG) levels. The aim of this study was to ascertain whether NO-1886 improves fatty liver caused by high-fat feeding in streptozotocin (STZ)-induced diabetic rats. Administration of NO-1886 resulted in increased plasma HDL-C levels and decreased TG levels without affecting total cholesterol and glucose levels in the diabetic rats. NO-1886 dose-dependently decreased liver TG contents and cholesterol contents, resulting in improvement of fatty liver. NO-1886 also reduced plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) that accompany fatty liver. The liver cholesterol contents were inversely correlated with plasma HDL-C levels (r = -0.5862, P <.001) and were positively correlated with plasma TG levels (r = 0.4083, P <.003). The liver TG contents were inversely correlated with plasma HDL-C levels (r = -0.6195, P <.001) and were positively correlated with plasma TG levels (r = 0.5837, P <.001). There was no correlation between plasma cholesterol levels, and cholesterol and TG contents in liver. These results indicate that reducing plasma TG levels and elevating in HDL-C levels may result in improving fatty liver.