[Growth properties of hematopoietic stem/progenitor cells in the second or third trimester and term fetal cord blood].

OBJECTIVE

To investigate the growth properties of hematopoietic progenitor/stem cells in umbilical cord blood (CB) of second trimester, third trimester, and term fetuses.

METHODS

Blood was collected by umbilical cord puncture in 27 just delivered fetuses, including 16 term babies and 11 preterm fetuses. Mononuclear cells were isolated. CD34(+) cells were enriched and isolated using the MACS. The frequencies of CD34(+), CD34(+) CD38(-) and CD34(+) HLA-DR(+) cells were determined by fluorescence-activated cell sorting. The proliferative and self-renewal capacity and expansion response to varying concentrations of defined growth factors were determined by short or long-term liquid culture and methylcellulose self-solid culture.

RESULTS

The frequency of CD34(+) and CD34(+) CD38(-) cells in CB and the frequency of CD34(+) CD38(-), CD34(+) HLA-DR(+) cells among CB CD34(+) cells were significantly higher in preterm CB than in term CB (3.14% and 0.76% vs 0.78% and 0.18%; and 9.8% and 20.4% vs 3.9% And 14.6%; P < 0.001). The number of colony forming units (CFUs) in preterm CB was higher and was correlated with the content of CD34(+) cells (r = 0.83). The number of long-term culture initiating cells (LTC-IC) in preterm CB was about 3 times as much as in term CB (5.7 +/- 1.2/10(5) cells vs 1.7 +/- 0.8/10(5) cells, P < 0.05), Progenitors from preterm CB could be expanded in short-term liquid cultures supplemented with hematopoietic growth factors as efficiently as progenitors from term CB, the peaks of expansion in terms of CFU, CD34(+) cells and CD34(+) CD38(-) cells were all at day 7, in particular under the condition of combining the early-acting and late-acting growth factors together (SCF + FL + TPO + IL-3 + IL-6).

CONCLUSION

The frequency of hematoietic stem/progenitor cell in umbilical cord blood of preterm fetus (especially of mid-term fetus) is significantly higher than in CB of term babies. The hematoietic stem/progenitor cells in umbilical cord blood of preterm fetus have greater colony forming capacity, are sensitive to growth factors, effectively expand and proliferate in vitro, and are preferable target cells for gene therapy.