C. Almici et al., CLONOGENIC CAPACITY AND EX-VIVO EXPANSION POTENTIAL OF UMBILICAL-CORDBLOOD PROGENITOR CELLS ARE NOT IMPAIRED BY CRYOPRESERVATION, Bone marrow transplantation, 19(11), 1997, pp. 1079-1084
Umbilical cord blood (UCB) progenitor cells have been demonstrated to
possess significant advantages over bone marrow (BM), in terms of prol
iferative capacity and immunologic reactivity. Therefore, UCB has been
recently considered an attractive potential alternative to BM as a so
urce of hematopoietic progenitor cells for clinical applications. Sinc
e several programs throughout the world are currently evaluating the f
easibility of large-scale UCB banking for unrelated transplants, it wa
s the aim of this study to evaluate whether cryopreservation procedure
s might heavily impair the clonogenic capacity, the feasibility of CD3
4(+) selection and the ex vivo expansion potential of UCB progenitor c
ells. UCB samples were collected and cryopreserved as unseparated (n =
21) or mononuclear (MNC) cells (n = 15) within 12 h from delivery, an
d evaluated for viability, immunophenotype, cell and progenitor number
s after a minimum stay in liquid nitrogen of 6 months (range 6-14 mont
hs). Viability was always > 97% and no statistically significant diffe
rence was detected by flow cytometric analysis. Clonogenic recovery fr
om unseparated cells was 80-87% for HPP-CFC, CFU-GEMM, BFU-E and CFU-G
M, and from MNC cells ranged from 82 to 91% for LTC-IC, CFU-GEMM,, BFU
-E and CFU-GM. CD34(+) selection (n = 8) was performed on fresh and cr
yopreserved MNC cells using the MiniMACS immunomagnetic separation dev
ice, showing no difference in yield (68 +/- 7% vs 57 +/- 4%, P less th
an or equal to 0.4) or in purity (89 +/- 2% vs 81 +/- 6%, less than or
equal to 0.4), for fresh in comparison to cryopreserved MNC cells. Af
ter 14 days of liquid culture in the presence of different combination
s of SCP, IL-3, IL-6 and G-CSF no statistically significant difference
was detected in CFC fold-expansion for fresh or cryopreserved MNC cel
ls and for CD34(+) cells, either selected and cultured from fresh or c
ryopreserved MNC cells. In conclusion we can state that UCB is a poten
tial source of primitive progenitor cells that can be cryopreserved un
manipulated or after physical separation without major losses in clono
genic capacity and immunophenotypic composition. Moreover, CD34(+) sel
ection from cryopreserved MNC cells is feasible and ex vivo expansion
is not impaired. These results have important implications in the larg
e scale UCB banking, in view of the potential applications of ex vivo
expanded hematopoietic progenitor cells for the engraftment of adult p
atients.