AAV viral vectors containing the AAV9 capsid were generated using the methods described previously by Challis et al. Briefly, 293FT cells were grown to ~90% confluency in Corning hyperflasks and co-transfected with 129 µg pHELPER, 238 µg pAAV 2/9n rep-cap plasmid and 64.6 µg equimolar mixtures of pAAV-U6-shRNA-CMV-tdTomato or pAAV.hSyn-HI-eGFP-MEN1 using the PEIpro transfection reagent (Polyplus). AAVs were precipitated from media harvested after 3 days and 5 days using 40%PEG/2.5 M NaCl and the pooled cells were harvested after 5 days in buffer containing 500 mM NaCl, 40 mM Tris Base and 10 mM MgCl2. The lysate was incubated with 100 U/mL salt-active nucleases at 37 °C for 1 h and then centrifuged at 2000× g for 15 min. AAV was purified from the resulting lysate using an iodixanol step gradient containing 15, 25, 40 and 60% iodixanol in optiseal tubes followed by centrifugation at 350,000× g using a Type 70 Ti ultracentrifuge rotor. Following centrifugation, the AAVs were harvested from the 40% layer using a 10 cc syringe and 16-gauge needle, diluted in 1XPBS containing 0.001% pluronic F68 and filtered using a 0.2 um syringe filter. The AAVs were concentrated and buffer-exchanged by 5 rounds of centrifugation using Amicon Ultra-15 100 kDa molecular weight cut off centrifugal filter units. The titer was determined using the qPCR Adeno-Associated Virus Titration kit and the purity was verified by SDS-PAGE and total protein staining using instant blue reagent.