Scientists have developed a new method to gather samples of cerebrospinal fluid (CSF) — the liquid that circulates in the brain and spinal cord — in mice that allows them to analyze levels of a specific biomarker for Sanfilippo syndrome.
Sanfilippo syndrome, also known as mucoplysaccharydosis III (MPS III), is a lysosomal storage disorder (LSD) caused by mutations in the SGSH gene, which provides instructions for the production of an enzyme called sulfamidase. This enzyme is responsible for breaking down large sugar molecules called heparan sulfate.
MPSIIIA, one of the four subtypes of Sanfilippo syndrome, is the most prevalent and severe form of the disease.
“A mouse model of MPS IIIA, which faithfully recapitulates the human disease, has provided a platform for the testing of treatment strategies, including enzyme replacement therapy and gene therapy. In these preclinical studies, CSF collection could have provided a platform for measuring biomarkers for biochemical assessment of therapeutic efficacy that is translatable to human patients in which collection of brain tissue is not possible,” the investigators said.
Collecting pure samples of CSF from animals with sufficient volume to measure the levels of specific disease biomarkers has proven to be a challenge for researchers.
Now, a group of researchers from the University of Adelaide in Australia developed a method that allows them to gather pure CSF samples from the brains of adult mice to measure levels of a biomarker of MPSIIIA.
During the assay, animals are anesthetized and placed in a stereotactic device, used to perform minimally invasive brain surgery. A small needle is inserted into the brain’s lateral ventricles — cavities in the brain that are filled with CSF — and a micro-syringe pump is used to extract the samples.
With the new method, researchers were able to collect up to 10 μL of pure CSF that was clear and had the consistency of water.
Moreover, they found this small amount of fluid was sufficient to measure levels of heparan sulphate disaccharidea (a disease biomarker of MPSIIIA, HNS-UA) and allow them to distinguish healthy animals (levels lower than 5 pmol/mL) from MPSIIIA mice (average of 143 pmol/mL).
“Advantages of this method over the most commonly used … collection technique include increased CSF sample volume (10 μL) and reduced blood contamination. One drawback of CSF collection via the lateral ventricles was the time taken for collection,” the researchers said.
“In conclusion, we report an alternate method for the reliable collection of pure CSF samples from mice and show that a disease-specific biomarker can be quantified. By including CSF assessment in mouse studies that aim to elucidate neuropathological mechanisms and/or assess potential therapies, a translation into patients, from which only CSF can be collected, is possible,” they said.