Even when highly enriched fetal liver Mac-1+Lineage-Sca-1+ HSCs were tested, most HSC activity was in the CD144+ (VE-cadherin+) fraction at E13.5, but both CD144+ and CD144- fractions had HSC activity by E16.5
Fetal liver Mac-1+Lin-Sca-1+ cells . | Mice that engrafted (%) . | Long-term multilineage reconstituted (%) . | Transient multilineage reconstituted (%) . | Oligopotent reconstituted (%) . | Frequency of HSCs . |
|---|---|---|---|---|---|
| E13.5 CD144- | 5 of 8 (63) | 1 of 8 (13) | 2 of 8 (25) | 2 of 8 (25) | 1 in 38 |
| E13.5 CD144+ | 9 of 11 (82) | 5 of 11 (45) | 3 of 11 (27) | 1 of 11 (9) | 1 in 8.8 |
| E16.5 CD144- | 13 of 15 (87) | 10 of 15 (67) | 2 of 15 (13) | 1 of 15 (7) | 1 in 5.1 |
| E16.5 CD144+ | 5 of 6 (83) | 4 of 6 (67) | 0 of 6 (0) | 1 of 6 (17) | 1 in 5.1 |
Fetal liver Mac-1+Lin-Sca-1+ cells . | Mice that engrafted (%) . | Long-term multilineage reconstituted (%) . | Transient multilineage reconstituted (%) . | Oligopotent reconstituted (%) . | Frequency of HSCs . |
|---|---|---|---|---|---|
| E13.5 CD144- | 5 of 8 (63) | 1 of 8 (13) | 2 of 8 (25) | 2 of 8 (25) | 1 in 38 |
| E13.5 CD144+ | 9 of 11 (82) | 5 of 11 (45) | 3 of 11 (27) | 1 of 11 (9) | 1 in 8.8 |
| E16.5 CD144- | 13 of 15 (87) | 10 of 15 (67) | 2 of 15 (13) | 1 of 15 (7) | 1 in 5.1 |
| E16.5 CD144+ | 5 of 6 (83) | 4 of 6 (67) | 0 of 6 (0) | 1 of 6 (17) | 1 in 5.1 |
Five CD45.2+CD144-Mac-1+Lineage-Sca-1+ cells or CD144+Mac-1+Lineage-Sca-1+ cells from the E13.5 or E16.5 fetal liver were injected along with 200 000 CD45.1+ cells into lethally irradiated CD45.1+ mice. To be considered reconstituted, donor-type cells of a particular lineage had to represent greater than 0.3% of cells. Mice were considered long-term multilineage reconstituted when donor-derived myeloid, B, and T cells were observed in the blood for at least 6 months after reconstitution. Mice were considered transiently multilineage reconstituted if donor-derived myeloid, B, and T cells were observed in the blood, but donor-type myeloid cells could no longer be detected by 16 weeks. Oligopotent reconstitution was characterized by transient donor reconstitution of 1 or 2 lineages. The frequency of HSCs was calculated by Poisson limit-dilution statistics18,21 based on the frequency of mice that became long-term multilineage reconstituted.