Table 1.
Colony-forming assay of fetal liver CD34+ cells and ‘1% mix’ CD34+ cells
| Total colonies | EGFP+ colonies | % EGFP+ colonies | |
|---|---|---|---|
| CD34 cells | |||
| VSVG | 4500 | 1525 | 34 |
| α-HLA | 4750 | 1200 | 25 |
| α-CD34 (My10) | 4375 | 400 | 9 |
| NoAb | 4625 | 0 | 0 |
| 1% CD34+ cells | |||
| VSVG | 50 | 6 | 12 |
| α-HLA | 48 | 5 | 10 |
| α-CD34 (My10) | 40 | 6 | 15 |
| NoAb | 35 | 0 | 0 |
5 × 104 of nonmix fetal liver CD34+ cells and a mixture of 1% fetal liver CD34+ cells with nonstimulated PBMCs were transduced overnight using VSV-G pseudotyped vectors or 2.2 targeting vectors followed by a low-pH treatment. Antibodies to HLA class I and CD34 (clone My10) were used in the 2.2 transductions. The number of CFU-G, CFU-M, CFU-GM, and CFU-GEMM colonies were scored under brightfield, and EGFP+ colonies were scored under fluorescence after 14 days of culture in a methycellulose medium supplemented with stem cell factor, GM-CSF, IL-3, and erythropoietin (Stem Cell Technologies). Compared to nonmix fetal liver CD34+ cells, the number of EGFP+ cells in the ‘1% mix’ fetal liver CD34+ cells were not significantly different from the expected efficiency (1%) in the α-CD34 (My10) group (p > 0.05). For the ‘1% mix’ cells, the group transduced by 2.2 with anti-CD34 (clone My10) achieved the highest number of EGFP+ colonies.