Heparin Competition Assay in HEK293T and HuH-7 Cells

HuH-7 cells were kindly provided by Dr Jerome Laurence (The University of Sydney). HEK293T cells were obtained from ATCC (Cat#CRL-3216). All cells were tested for mycoplasma and were mycoplasma-free. Cells were cultured as described previously^{23 (link)} with no modifications. Specifically, HEK293 cells were cultured in Dulbecco’s Modified Eagle’s Medium (DMEM) supplemented with 10% fetal bovine serum (FBS), 1% penicillin/streptomycin (P/S), and incubated in humidified 37 °C incubator with 5% CO2. HuH-7 cells were cultured under the same conditions, with the addition of 1% non-essential amino acids (NEA) in the medium. For the heparin competition assay (Supplementary Fig. 1), cells were seeded at 10⁵ per well into 24-well plates at day 0 and transduced at the indicated vector genome/cell. When indicated, heparin sodium salt (Sigma, H3149-50KU, lot no. SLBW2119) or Clexane was supplemented at 50 μg/mL or at 200 μg/mL. After 72 h, the cells were harvested using TrypLE express and analyzed for GFP using BD LSRFortessa cell analyzer. The data were analyzed using FlowJo 7.6.1.