Encapsulated insulin-producing

Moreover, insulin-loaded PLA nanoparticles with high yields of encapsulation were produced by Elvassore and coworkers [61]. In this work, a homogeneous solution of protein and polymer is sprayed through a nozzle in a high-pressure vessel. In order to achieve nanoencapsulation, mixtures of dichloromethane (DCM) and dimethylsulfoxide (DMSO) were used to ensure the solubility of both the polymer and the protein. In Figure 9.9-3 a SEM image of the fine-particle powders produced is presented. 

Poly(L-lactide) (PLA)-encapsulated insulin has been produced using PCA (95). The PLA was dissolved in methylene chloride and added to a solution of insulin in acidified DMSO or acidified methanol. This solution was sprayed into a CO2 antisolvent continuum at 37°C and 8.4 MPa. Ninety percent of the microparticles produced were <5 pm. Greater encapsulation efficiencies were obtained using methanol (up to 99% encapsulation) relative to DMSO (49 % encapsulation) (132). The tap density of the powders was 0.1-0.2 g/cm. When injected in mice, the processed insulin produced no burst effect and suppressed blood glucose levels for more than 48 h. 

Wang N, Adams G, Buttery L, Falcone FH, Stolnik S. Alginate encapsulation technology supports embryonic stem cells differentiation into insulin-producing cells. J Biotechnol 2009 144 304-312. 

Insulin (molecular weight 7000) has been formulated in controlled release microbeads and pellets (135,136). A solvent evaporation micro-encapsulation procedure was used to produce microspheres with up to 20% by weight insulin. Solvent-casting techniques were used to prepare pellets. The investigations demonstrated that the PLA... 

An alternate approach has been to encapsulate living beta cells into microcapsules. These microcapsules can then produce insulin on demand, but are protected from the body s immune system by the polymeric membrane. These experimental microcapsules are usually... 

Chronic Diseases. Xenotransplantation has the potential to treat many chronic diseases that cause cell death. For example, in diabetes, pancreatic cells that produce insuhn are destroyed. Encapsulation is being tested as a means of introducing porcine islet cells (pancreatic cell structures from pigs) into human patients with diabetes. The encapsulated porcine cells help these patients produce the insulin that they would otherwise have to inject into themselves. 

Figure 21.5. Human pre-adipocyte (derived fromfresh human bone marrow) culture inside mineralized chitosan-coated alginate cap>sules (n=12). A) A single whole capsule containing 450,000 pre-adipocytes at 24 hours. Pre-adipocyte cells are metabolically very active and exapnd in numbers rapidly after encapsulation. B) Embedded pre-adipocytes produce rounded colonies containing dense oil droplet formations in complete (+single insulin dose) media at day 21. C) Oil droplets stained with oil red-O to indicate presence of fat inside observed droplets at day 12. D) Oil-droplet formation from same population of cells grown in 2D mono-layer culture at day 21.

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