Transduction efficiency in Sca-1⁺ mouse BM cells after lentiviral magselectofection. Sca-1⁺ cells were enriched over LS columns first. Subsequently, up to 2 × 10⁶ Sca-1⁺ cells were magselectofected within an MS column modified with SO-Mag2/LV-PGKeGFP complexes at different MNP-to-VP ratios, but a fixed MOI of 3. (A) Positively selected cells were analyzed by FACS. Cell purity on passage of a cell isolate through a first unmodified LS column followed by passage through second lentiviral magnetic vector-modified columns at constant virus dose with increasing Fe/VP ratios. Cell separation efficiency is only impaired at very high magnetic particle-to-virus ratios. (B) Quantification of mouse BFU-E colonies at day 14 after magselectofection. Total BM, Lin⁻Sca-1⁺ (first round selection), and second round selection with increasing ratios of Fe per LVP (0-20 fg Fe/LVP) are shown. (C) Quantification of mouse CFU-GM colonies at day 14 after magselectofection. Total BM, Lin⁻Sca-1⁺ (first round selection), and second round selection with increasing ratios of Fe per LVP (0–20 fg Fe/LVP) are shown. (D) Reconstitution of T cells in blood of Il2rg^−/− mice (N = 4-8) transplanted with 30 000 overnight cultured or magselectofected wild-type Lin⁻Sca-1⁺ cells. (E) Reconstitution of B cells in blood of Il2rg^−/− mice (N = 4-8) transplanted with 30 000 overnight cultured or magselectofected wild-type Lin-Sca-1⁺ cells. (F) GFP percentage in peripheral blood of Il2rg^−/− mice (N = 4) transplanted with magselectofected wild-type Lin⁻Sca1⁺ cells. Long-term GFP expression was detected in erythrocytes, T cells (CD3⁺CD4⁺ and CD3⁺CD8⁺), B cells (B220⁺IgD⁺), and myeloid cells (CD11b⁺Gr-1⁺).