Progress report from the research team
In December, we reported the successful establishment of the different types of mouse cortical neurons from mouse brain tissue. This process has been further refined and optimised over the last quarter, with the identity of morphologically differentiated neurons confirmed using immunostaining tests for several neuron-specific proteins.
The breeding program is proceeding well, allowing new cultures of mouse brain tissue to be established each week since the start of the year. With the six-week differentiation period, this means that differentiated neurons are now coming online and available for analysis on a weekly basis since mid-February.
These neurons are now being investigated using automated image analysis methods to quantify the expression of acetylated alpha-tubulin and for the intracellular distribution of peroxisomes and mitochondria.
Fan has also been investigating the expression of certain proteins in the brains of the adult mice with different genotypes – normal, heterozygous and homozygous for the SPG4 mutation. He has quantified the same proteins investigated in the SPAST patient-derived olfactory stem cells – SPG4 (SPAST), SPG3A, STMN, and acetylated-alpha tubulin.
Once these baseline quantifications of HSP mouse neurons have been completed, the next step will be drug testing on them.
Following on from the December report of the successful establishment of induced pluripotent HSP stem cells (iPSCs) from an HSPer with a SPAST (SPG4) mutation, the first batch of cells have now been successfully differentiated into corticospinal neurons.
This batch has been used as quality control to confirm the identity of the neurons and to confirm that neurons could be generated both from the HSPer and from 2 unaffected people. The neurons passed the quality control tests. This is a major milestone.
The process to differentiate neurons in iPSC cultures takes 8 weeks. Regular batches of iPSC cultures have been established with the goal of providing ongoing availability of differentiated neurons for analysis. These neurons derived from human tissue will undergo almost identical analysis to the mouse neurons as described in the Mouse project report.