DEAE - dextran

Cationic samples can be adsorbed on the resin by electrostatic interaction. If the polymer is strongly cationic, a fairly high salt concentration is required to prevent ionic interactions. Figure 4.18 demonstrates the effect of increasing sodium nitrate concentration on peak shapes for a cationic polymer, DEAE-dextran. A mobile phase of 0.5 M acetic acid with 0.3 M Na2S04 can also be used. 

Cationic hydrophilic Glycol chitosan, DEAE-dextran, poly(ethyleneimine), poly(trimethylaminoethyl methacrylate) iodide salt 0.5 M acetic acid with 0.3 M NaiSO, or 0.8 M NaNO.,... 

FIGURE 19.6 Effect of ionic strength on elution of cationic polymer, DEAE-dextran, from TosoHaas... 

Classical gene transfer methods still in use today are diethylamino ethyl (DEAE)-dextran and calcium phosphate precipitation, electroporation, and microinjection. Introduced in 1965, DEAE-dextran transfection is one of the oldest gene transfer techniques [2]. It is based on the interaction of positive charges on the DEAE-dextran molecule with the negatively charged backbone of nucleic acids. The DNA-DEAE-dextran complexes appear to adsorb onto cell surfaces and be taken up by endocytosis. 

The calcium phosphate method was first used in 1973 to introduce adenovirus DNA into mammalian cells [3]. DNA-Calcium-phosphate complexes are formed by mixing DNA in a phosphate buffer with calcium chloride. These complexes adhere to the cell membrane and enter the cytoplasm by endocytosis. Disadvantages of DEAE-dextran and calcium phosphate transfection are a certain level of cytotoxicity, a complicated transfection procedure, and the fact that not all cell types can be transfected using these methods. 

Transfection is the process of introducing DNA or RNA into eukaryotic ceils. The use of transfection is to study the role and regulation of proteins or to understand the mechanisms of a pathway. Transfection can be transient for rapid analysis or stable , mostly for induction of expression. There are various methods of transfection which include electroporation, viral vectors, DEAE-Dextran, calcium phosphate or Lipofectamine. The choice of transfection depends on the cell type used. The most desirable technique is the one which gives high efficiency of nucleic acid transfection with less interference to the cells physiology and high reproducibility. 

DEAE-dextran (diethylamino-ethyl-dextran (Mw - 2000000) Active in vivo against NJA leukemia, JBI ascites, plasmocytoma in mice, and Yoshida ascites in rats 62... 

Lifetime of the glycerol-3-phosphate membrane extended up to 1 month by storage in the working buffer containing 1% DEAE-dextran and 5% lactitol. More than 350 samples can be assayed. 

Maitani, Y., Y. Machida, and T. Nagai. 1989. Influence of molecular weight and charge on nasal absorption of dextran and DEAE-dextran in rabbits. Int J Pharm 49 23. 

Holter W, Fordis CM, Howard BH (1989) Efficient gene transfer by sequential treatment of mammalian cells with DEAE-dextran and deoxyribonucleic acid. Exp Cell Res 184(2) 546-551... 

Mack KD, Wei R, Elbagarri A et al (1998) A novel method for DEAE-dextran mediated transfection of adherent primary cultured human macrophages. J Immunol Methods 211 79-86... 

A. Manosroi, and K. H. Bauer, The entrapment of a human insulin-DEAE-dextran complex in different compound liposomes, Drug Dev. Ind. Pharm. 75 2531-2546 (1989). 

---