3R-Project 25-92

Organotypic cultures: A model for pharmacological analysis in the central nervous system

Muller D.
Pharmacologie CMU, Centre Médical Universitaire, Genève

Duration: 3 years End of the Project: 1995

Background and Aim
The major aim of the project was to determine whether organotypic slice cultures could be used as a model for pharmacological studies and analyses in the central nervous system. Two possible applications were proposed to be tested: one concerned mechanisms of neurite sprouting and synapse regeneration, one of the most important property used by the brain for functional recovery in case of neuronal death; the second application concerned mechanisms of excitotoxicity, a phenomenon which is implicated in many neuropathological conditions.
These characteristics were planned to be studied using immunohistochemical and electrophysiological techniques and via the development of an electrode array for chronic recordings of electrical activity.

Method and Results
The experiments that have been carried out have lead to the main conclusion that organotypic slice cultures represent a valid and interesting model for pharmacological studies in the central nervous system. In particular, we have provided evidence that this in vitro preparation can be successfully used for studies of the mechanisms of sprouting and synaptogenesis.
We have shown that producing a lesion in these cultures even several weeks after explantations is followed by a recovery period of about 1-2 weeks during which a scar is formed by glial cells, a sprouting reaction takes place which can be visualised using immunohistochemical techniques, new fibres grow and cross the lesioned area and new synapses are formed on the opposite side of the lesion (Stoppini et al., 1993). This process of lesion-induced recovery, as it is under in vivo conditions, becomes much less effective in older cultures. In recent experiments, we found that this is at least partly due to extrinsic factors which inhibit sprouting and regeneration, since recovery was markedly improved when older cultures were allowed to regenerate into younger tissue (manuscript in preparation; Stoppini et al., 1996).
Impact on testing procedures: This study and the validation of the model of interface-type of organotypic cultures has already had some impact on testing procedures since numerous research laboratories as well as a Japanese company (Shionogi LTD) has adapted this system for the analysis of pharmacological agents and the testing of compounds in the domain of excitatory receptors and ischemia.

References
1. Neuroscience 57, 985-994.
2. Neuroscience, 61, 441-445.