Single-cell gene expression profiling was performed utilizing the Fluidigm Biomark dynamic array according to the manufacturer’s protocol18,26. Briefly, single cells growing on culture dishes after 5 or 6 weeks of transduction were collected by aspiration into patch electrodes and ejected into 2× cells direct buffer (Invitrogen), flash frozen and kept at −80°C until further processing. Thawed cells were subject to target-specific reverse-transcription and 18 cycles of PCR pre-amplification with a mix of primers specific to the target genes (STA). STA products were then processed for real-time PCR analysis on Biomark 48:48 Dynamic Array integrated fluidic circuits (Fluidigm). To ensure the specificity of the amplification, titrations of total human brain RNA were included in each experiment, and only primers that demonstrated a linear amplification were analyzed. Furthermore, melting curves of the PCR products were compared between the single cells and the control RNA to ensure the specificity of the PCR products.
