Figure 4.

Split-Intein CBE-Mediated Base Editing Reduces Mutant SOD1 Reactive Inclusions in the Spinal Cord and Protects Motor Neurons and Neuromuscular Junctions

(A) Representative immunofluorescence staining of end-stage spinal cord sections from G93A-SOD1 mice injected with 8 × 10¹⁰ particles each of dual AAV encoding the hSOD1- or mRosa26-targeting N- and C-terminal split-intein CBEs. Scale bars, 15 μm. (B) Quantitation of area occupied by SOD1 reactive inclusions in the anterior horn (left) and white matter (right) of spinal cord sections from end-stage treated (hSOD1) or untreated (mRosa26) G93A-SOD1 mice (n = 5). (C and D) Mean number of (C) ChAT⁺ motor neurons (MNs) per lumbar spinal cord hemisection and (D) fully denervated neuromuscular junctions (NMJs) from tibialis anterior muscle sections from end-stage treated or untreated G93A-SOD1 mice (C, n = 7; D, n = 7). (E) Representative immunofluorescence staining of spinal cord sections from end-stage G93A-SOD1 animals showing expression of the split-intein CBE. Scale bars, 30 μm, anterior horn; 50 μm, white matter. (F) Plot showing the mean frequency change of the target cytosine in the SOD1 gene in the cervical spinal cord from G93A-SOD1 mice. hSOD1 (n = 4); mRosa26 (n = 5). Values indicate means and error bars indicate SD. *p < 0.05; (B–D and F) one-tailed unpaired t test.