GSM1846973: Live_PLRC [US-1457351-11]; Homo sapiens; RNA-Seq
Cortical pieces were divided into one half for sectioning and the other half for cell isolation. The half for sectioning was fixed in 4% PFA in PBS overnight at 4oC, then cryoprotected in 30% sucrose in PBS for 48-72 h, rinsed briefly with PBS and embedded and frozen in OCT. The other half (approx. 0.25 - 0.5 mL volume) was minced into small pieces with #5 forceps (Fine Science Tools, Foster City CA) in Ca2+- and Mg2+-free HBSS (14175-095, Life Technologies, Chicago IL, Chicago IL). Minced pieces were treated with 2 mL trypsin solution for 20 min at 37 oC ( Ca2+- and Mg2+-free HBSS, 10 mM HEPES, 0.5 mM EDTA, 0.25 mg/ml bovine pancreatic trypsin (EMD Millipore, Billerica MA), 10 μg/mL DNase I (Roche, Basel, Switzerland), pH 7.6). Digestion was quenched with 6 mL of ice-cold quenching buffer (440 ml Leibovitz L-15 medium, 50 ml water, 5 mL 1M HEPES pH 7.3–7.4, 5 ml 100x Pen-Strep, 20 ml 77.7 mM EDTA pH 8.0 [prepared from Na2H2EDTA], 1g bovine serum albumin [A7030, Sigma, St. Louis MO]) containing 100 μg/mL trypsin inhibitor (T6522, Sigma) and 10 μg/mL DNase I (Roche). Samples were then pelleted (220xg, 4 min, 4°C), resuspended with 1 mL of quenching buffer and triturated on ice with a P1000 pipette set to 1 mL, using 25 gentle cycles up and down without forming bubbles. The cell suspension was then diluted to 30-40 mL in quenching buffer, filtered through a 45 micron cell filter, pelleted (220xg, 10 min, 4°C), resuspended in 5 mL Staining Medium, and counted on a hemocytometer (typically ~30-50 million live cells isolated per cortical piece at ~50% viability). Library construction was carried out as previously reported by Smart-Seq2 and Nextera XT DNA prep kit.