Erythrocytes, as carriers

R. Kravtzoff, C. Kopnra, M. Lagueim, nt aL Erythrocytes as carriers lor l-asparaglnase. Methodological and mouse in-vitro studies. A Pha/m. Pharmacol. 

R. Kravtzoff, L Desbois, C. Doinel, et al. Immunological response to 1-asparaginase loaded into red blood cells. The Uu of Reseated Erythrocytes as Carriers and... 

Millan CG, Marinero MLS, Castaneda AZ, et al. Drag, enzyme and peptide delivery using erythrocytes as carriers. J Control Release 2004 95 27-49. 

Erythrocyte Entrapment of Enzymes. Erythrocytes have been used as carriers for therapeutic enzymes in the treatment of inborn errors (249). Exogenous enzymes encapsulated in erythrocytes may be useful both for dehvery of a given enzyme to the site of its intended function and for the degradation of pathologically elevated, diffusible substances in the plasma. In the use of this approach, it is important to determine that the enzyme is completely internalized without adsorption to the erythrocyte membrane. Since exposed protein on the erythrocyte surface may ehcit an immune response following repeated sensitization with enzyme loaded erythrocytes, an immunologic assessment of each potential system in animal models is required prior to human trials (250). 

Erythrocyte Entrapment of Enzymes. Erythrocytes have been used as carriers for therapeutic enzymes in the treatment of inborn errors. Exogenous enzymes encapsulated in erythrocytes may be useful both for delivery of a given enzyme to Ihe she of its intended function and for file degradalinn of pathologically elevuied. diffusible substances in the plasma. 

Fratemale A, Casabianca A, Rossi L, et al. Inhibition of murine AIDS by combination of ACT and DDCTP-loaded erythrocytes. In Sprandel U, Way JL, eds. Erythrocytes as Drug Carriers in Medicine. New York Plenum Press, 1997 73-80. 

Cellular Carriers. Erythrocytes, leukocytes, platelets, islets, hepatocytes, and fibroblasts have all been suggested as potential carriers for drugs and biological substances. They can be used to provide slow release of entrapped drugs in the circulatory system, to deliver drugs to a specific site in the body, as cellular transplants to provide missing enzymes and hormones (in... 

Since erythrocytes, platelets, and leukocytes have received the greatest attention, the discussion that follows will be limited to these carriers. Fibroblasts [180] and hepatocytes [181] have been specifically used as viable sources to deliver missing enzymes in the management of enzyme-deficiency diseases, whereas islets are useful as a cellular transplant to produce insulin [182,183],... 

Antibodies have also been adsorbed or covalently linked to a variety of other carrier systems, such as liposomes [124], erythrocytes [226,227], and microcapsules and nanospheres, to selectively target them to a specific site in the body. 

Recently a colorimetric method for estimation of erythrocytic G-6-PDH was described (El). This procedure is based upon the interaction of phenazine methosulfate as electron carrier between NADPH2 formed in the reaction and dichloroindophenol, the rate of the reduction of the latter compound being followed at 620 mp. 

Major blood loss entails the danger of life-threatening circulatory failure, i.e., hypovolemic shock. The immediate threat results not so much from the loss of erythrocytes, i.e oxygen carriers, as from the reduction in volume of circulating blood. 

Samples are injected (1 pi) using the splitless mode, and helium is used as a carrier gas with an inlet pressure of 2.5 Bar (250 kPa). The temperature programme starts at 50°C and is maintained for 1.5 min, followed by an increase to 190°C at a rate of 30°C/min. After holding the temperature at this level for 5 min, the gradient continues at a rate of 8°C/min until a final level of 230°C. This will be sufficiently maintained to allow all high-boiling substances (cholesterol ) to be eluted. The total analysis time will be approximately 45 min. An example of a chromatogram of control erythrocytes is shown in Fig. 3.3.2. 

Out of this concept grew the cardinal idea of carrier mediated transport. Necessary for this was the development of a more coherent theoretical analysis built upon the general notion of facilitated diffusion. The major insight here came from Widdas who proposed in 1952 that carrier mediated transport would explain earlier data such as the transport of glucose across the sheep placenta, as well as his own observations on glucose entry into the erythrocyte. There were three assumptions made in developing this quantitative hypothesis ... 

The use of nanosilica particles as drug carriers raises questions concerning the nature of forces controlling the adsorption interaction of cells with Si02 nanoparticles.15 The average diameter of human erythrocytes is 7500 nm16 while typical dimensions of silica nanoparticles with specific area of 200 to 300 m2/g commonly used for water dispersions are from 20 to 10 nm, with dissipation of 4 to 17 nm (within a 90 per cent interval).2,8... 

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