Modulation of Cultured Neural Networks Using Neurotrophin Release

Polyacrylamide and poly(ethylene glycol) diacrylate hydrogels were synthesized and characterized for use as drug release and substrates for neuron cell culture. Protein release kinetics was determined by incorporating bovine serum albumin (BSA) into hydrogels during polymerization. To determine if hydrogel incorporation and release affect bioactivity, alkaline phosphatase was incorporated into hydrogels and a released enzyme activity determined using the fluorescence-based ELF-97 assay. Hydrogels were then used to deliver a brain-derived neurotrophic factor (BDNF) from hydrogels polymerized over planar microelectrode arrays (MEAs). Primary hippocampal neurons were cultured on both control and neurotrophin-containing hydrogel-coated MEAs. The effect of released BDNF on neurite length and process arborization was investigated using automated image analysis. An increased spontaneous activity as a response to the released BDNF was recorded from the neurons cultured on the top of hydrogel layers. These results demonstrate that proteins of biological interest can be incorporated into hydrogels to modulate development and function of cultured neural networks. These results also set the stage for development of hydrogel-coated neural prosthetic devices for local delivery of various biologically active molecules.This work was supported by the International Collaboration Program, Nano Bioelectronics and Systems Engineering Research Center/Korea Science and Engineering Foundation (R11-2000-075-00002-0), by the Nanobiotechnology Center (NBTC), an STC Program of the National Science Foundation under agreement no. ECS-9876771, the National Institutes of Health under agreement no. R01-NS044287 (WS) and by the National Institute of Biomedical Imaging and Bioengineering under agreement no. R21EB007782 (MRH). The computational image analysiswas supported by the Center for Subsurface Sensing and Imaging Systems (NSF EEC- 9986821). The authors acknowledge use of the Wadsworth Center Advanced Light Microscopy & Image Analysis Core Facility. They would also like to thank Shirley Madewell and Adriana Verschoor for critical review of the manuscript