>>139674411. One biochemical cascade in one cell is incredibly complex and use large macro molecules. We can't get those right yet.
2. Inside the cell gene expression occurs. Gene space, which is very large, much larger the organic chemistry, influences cell behavior not just division. Still we are at big cells. Some you can see with your eye. Cells that regenerate on their own and are resilient, like your skin. No gene therapies for liver or artery yet alone melanoma.
3. Neurons are tiny and condensed, barely bigger than DNA. Neurons have chemical and electrical synapses which exhibit quantum behavior. You can't just get the chemistry right which involving genes are very vast. Neurons do not regenerate on their own. Your best bet with anything neurological would be to use the recent advancements which reverse blood thinners in cases of stroke emergency trauma and try to curate to the patient. The neurons are not damaged here. A scab the size of a golf ball is messing them up and needs to dissolve. We can't even do that yet.
Another option is xenotransplant. Take one neuron from a hog, use you on an IV to modify it's genetics, and cath the neuron through your ear and the other on a very important muscle, like for swallowing, breathing, talking, or walking, and flood it all with spinal fluid. Probably impossible to do, and you have so many neurons you would die first before the treatment is over.
unmyelinated axons and brain matter are literal goo. The cells are microns with cpu transistor size delicate structures and there are billions of neurons. Operating on raw egg yolk and jelly, They use catheters and "only" stay within blood vessels. If there's trauma they just clean infection and patch it up as best as they can and off you go all chopped up.
