Communication scientifique
Séance du 3 mars 2009

Le cordon ombilical, source de cellules souches totipotentes

MOTS-CLÉS : cellules souches mesenchymateuses applications cliniques. cordon ombilical
Umbilical cord mesenchymal stem cells (UC-MSC : biology, banking and clinical applications)
KEY-WORDS : clinical medicine. mesenchymal stem cells. umbilical cord

Zang Chao Han

Zang Chao HAN *

Human pluripotent mesenchymal stem cells (MSC) have the potential to generate cells of multiple lineages. MSC are present in virtually all postnatal tissues. Bone marrow MSC have been intensively investigated and used therapeutically. We have successfully isolated MSC from umbilical cord (UC) tissue. Their biological properties are very similar to those of BM-MSC. To explore the therapeutic potential of UC-MSC, we have established the first UC-MSC bank complying with Good Manufacturing Practices (GMP). A supporting system of QC and QA is applied to each step, including cord donor selection, collection, isolation, expansion, cryopreservation, thawing, biological characterization, and release of the final cell products.

UC samples with a median length of 25 cm were obtained from local maternity hospitals after normal deliveries. UC-MSC were isolated from whole umbilical cords as described elsewhere. Cells were plated at a density of 106/cm2 in uncoated culture flasks and maintained in humidified air with 5 % CO at 37C°. After 3 days 2 of culture the medium was replaced and non adherent cells were removed. The medium was then changed twice weekly. Once 70 %-80 % confluence had been reached, adherent cells were replated at a density of 104/cm2 in growth medium for expansion.

A total of 5400 umbilical cords were collected between May 2006 and December 2008. UC-MSC from 4428 (82 %) cords were finally stored, while 972 cords(18 %) were discarded because of microbial contamination or poor cell proliferation.

We investigated the transformation potential of UC-MSC after various culture periods in vitro . UC-MSC were isolated from 8 healthy donors and propagated in vitro until senescence or passage 20 (P20), and were then genetically characterized and tested for their telomerase activity and human telomerase reverse transcriptase transcript content at different passages. UC-MSC obtained at P3, P7 and P15 and P20 were stable in terms of plastic adherence, specific surface-antigen expression and multipotent differentiation potential. They showed no signs of senescence or chromosomal abnormalities. Approximately 1010 cells can be harvested at P7 from one umbilical cord, a number sufficient for several hundred clinical transplants.

Passage-7 UC-MSC were therefore used to manufacture final products for animal studies and clinical trials.

With respect to BM-MSC, UC-MSC show the full capacity for self-renewal, multilineage differentiation, genetic stability, hypo-immunogenicity, strong immune modulation, and hematopoiesis support. In animal models of graft-versus-host disease (GVHD), liver injury and stroke, UC-MSC transplantation significantly improves related functions. The therapeutic potential of UC-MSC was further investigated, with promising results, in patients with liver cirrhosis, autoimmune diseases, and GVHD after hematopoietic stem cell transplantation for leukemia.

Following the pioneering work of Gluckman, cord blood banks now operate in many countries, and cord-blood stem cells are one of the most commonly banked human tissues. Our data suggest that UC-MSC banking will open up interesting new possibilities for cell therapy and regenerative medicine.

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M. Jean-François STOLTZ

Quelle est la stabilité des lignées au cours des passages nécessaires pour obtenir des quantités de cellules suffisantes pour un traitement (phénotypes, télomères…) ?

Les MC-SMC sont télomérases négatives après au moins quatorze passages, ne sont pas toxiques (6,10 7 UC-MSC/ kg), ne sont pas allergisantes sur le cobaye, n’entrainent pas de tumorigénicité accrue sur MCF7 et K562 et surtout sont stables (vingt passages). Un cordon seul est suffisant pour une centaine d’injections.


<p>* Umbilical cord mesenchymal stem cells (UC-MSC): biology, banking and clinical application. Han ZC.National Engineering Research Center of Cell Products, Institute of Hematology, CAMS & PUMC, Tianjin, China.</p>

Bull. Acad. Natle Méd., 2009, 193, no 3, 545-547, séance du 3 mars 2009