Torben Moos
Department of Health Science and Technology, Biomedicine, Aalborg University, Fredrik Bajers Vej 3B, 9000 Aalborg, Denmark

Abstract:

The blood-brain barrier (BBB) formed by brain capillary endothelial cells protects the brain against potentially harmful substances present in the circulation, but also restricts exogenous substances such as pharmacologically acting drugs from entering the brain. These notions are contradicted by the fact that in several neurological and psychiatric diseases, neurons up regulate receptors in their membrane which could allow for soluble growth factors in the extracellular fluid to nourish such receptors if they could pass the BBB. A novel and rather unchallenged approach to allow proteins to enter the brain is gene therapy based on delivery of genetic material into brain capillary endothelial cells. In theory in vivo transfection will allow protein secretion from brain capillary endothelial cells and further into the brain and would denote a new paradigm for therapy to transport proteins across the BBB. The aim of this study was to investigate the possibility to use brain capillary endothelial cells as small factories for recombinant protein production. Non-viral gene carriers were prepared from pullulan, an organic polysaccharide, and spermine, a naturally occurring polyamine that were additionally conjugated with plasmid DNA. We were able to transiently transfect rat brain endothelial cells (RBE4s) and human brain microvascular endothelial cells (HBMECs). Transfection of HBMECs with pullulan-spermine conjugated with cDNA encoding human growth hormone 1 (hGH1), lead to secretion of hGH1 into the growth medium. It was furthermore possible to conjugate an anti-rat transferrin receptor antibody (OX-26) with the pullulan-spermine complex creating a carrier complex for targeted drug-delivery.