Background: The blood brain barrier (BBB) is an impediment to the development of large and highly charged molecules as therapeutics for diseases and injuries of the central nervous system (CNS). Antisense oligonucleotides (ASOs) are large (6000-8000MW) and highly charged and therefore do not cross the BBB. A method of circumventing the blood brain barrier to test ASOs, and other non-BBB penetrant molecules, as CNS therapeutics is the direct administration of these molecules to the CNS tissue or cerebral spinal fluid.
New method: We developed a rapid, simple and robust method for the intrathecal catheterization of rats to test putatively therapeutic antisense oligonucleotides. This method utilizes 23-gauge needles, simply constructed ½in. long 19-gauge guide cannulas and 8cm long plastic PE-10 sized catheters.
Comparison with existing methods: Unlike the cisterna magna approach, this method uses a lumbar approach for intrathecal catheterization with the catheter residing entirely in the cauda equina space minimizing spinal cord compression. Readily available materials and only a few specialized pieces of equipment, which are easily manufactured, are used for this intrathecal catheterization method.
Conclusions: This method is easy to learn and has been taught to multiple in house surgeons, collaborators and contract laboratories. Greater than 90% catheterization success is routinely achieved with this method and as many as 100 catheters can be placed and test substance administered in one 6-h period. This method has allowed the pre-clinical testing of hundreds of ASOs as therapeutics for CNS indications.
Keywords: Antisense oligonucleotide; Catheter; Cerebral spinal fluid; Drug delivery; Intrathecal; Rat; Subarachnoid space; Thecal sack.
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