Encapsulated living choroid plexus cells: potential long-term treatments for central nervous system disease and trauma.

In neurodegenerative disease and in acute brain injury, there is often local up-regulation of neurotrophin production close to the site of the lesion. Treatment by direct injection of neurotrophins and growth factors close to these lesion sites has repeatedly been demonstrated to improve recovery. It has therefore been proposed that transplanting viable neurotrophin-producing cells close to the trauma lesion, or site of degenerative disease, might provide a novel means for continuous delivery of these molecules directly to the site of injury or to a degenerative region. The aim of this paper is to summarize recent published information and present new experimental data that indicate that long-lasting therapeutic implants of choroid plexus (CP) neuroepithelium may be used to treat brain disease. CP produces and secretes numerous biologically active neurotrophic factors (NT). New gene microarray and proteomics data presented here indicate that many other anti-oxidant, anti-toxin and neuronal support proteins are also produced and secreted by CP cells. In the healthy brain, these circulate in the cerebrospinal fluid through the brain and spinal cord, maintaining neuronal networks and associated cells. Recent publications describe how transplanted CP cells and tissue, either free or in an immunoprotected encapsulated form, can effectively deliver therapeutic molecules when placed near the lesion or site of degenerative disease in animal models. Using simple techniques, CP neuroepithelial cell clusters in suspension culture were very durable, remaining viable for 6 months or more in vitro. The cell culture conditions had little effect on the wide range and activity of genes expressed and proteins secreted. Recently, completed experiments show that implanting CP within alginate-poly-ornithine capsules effectively protected these xenogeneic cells from the host immune system and allowed their survival for 6 months or more in the brains of rats, causing no adverse effects. Previously reported evidence demonstrated that CP cells support the survival and differentiation of neuronal cells in vitro and effectively treat acute brain injury and disease in rodents and non-human primates in vivo. The accumulated preclinical data together with the long-term survival of implanted encapsulated cells in vivo provide a sound base for the investigation of these treatments for chronic inherited and established neurodegenerative conditions.

Ionotropic alginate beads for controlled intestinal protein delivery: effect of chitosan and barium counter-ions on entrapment and release.

Alginate beads containing the model protein haemoglobin (Hb) were prepared by coagulation with various counter-ions to improve the controlled release of the protein. The effect of Ba(2+) and Ca(2+) ions and of the polycationic polysaccharide chitosan was investigated. Coagulation with Ba(2+), Ca(2+) and/or chitosan showed differences in the swelling index of the beads, in the encapsulation efficiency of Hb entrapment and in the release of the entrapped protein. Chitosan in the coagulation fluid markedly enhanced the encapsulation efficiency of the Hb. Release studies were conducted in simulated gastric fluid (SGF pH approximately or equal to 1.2) and subsequently in simulated intestinal fluid (SIF ) at 37 degrees C. Beads were stable in the gastric fluid but released their protein upon transfer to intestinal fluid. The release coincides with the burst and disintegration of beads. Rate of protein release from the beads was affected by the Ba(2+) and chitosan concentration in coagulation fluid.