Ex Vivo Expansion of Hematopoietic Stem- and Progenitor Cells from Cord Blood in Coculture with Mesenchymal Stroma Cells from Amnion, Chorion, Wharton's Jelly, Amniotic Fluid, Cord Blood, and Bone Marrow

In most cases, the amount of hematopoietic stem and progenitor cells (HSPCs) in a single cord blood (CB) unit is not sufficient for allogenic transplantation of adults. Therefore, two CB units are usually required. The ex vivo expansion of HSPCs from CB in coculture with mesenchymal stroma cells (MSCs) might be an alternative. It was investigated, whether bone marrow-derived MSCs, which have to be obtained in an invasive procedure, introduce a further donor and increases the risk of transmissible infectious diseases for the patient can be replaced by MSCs from amnion, chorion, Wharton's jelly, amniotic fluid, and CB, which can be isolated from placental tissue which is readily available when CB is sampled. In a two-step ex vivo coculture mononuclear cells from cryopreserved CB were cultured with different MSC-feederlayers in a medium supplemented with cytokines (stem cell factor, thrombopoietin [TPO], and granulocyte colony-stimulating factor). Expansion rates were analyzed as well, by long-term culture-initiating cell (LTC-IC) and colony-forming unit (CFU) assays, as by measuring CD34(+)- and CD45(+)-cells. Due to the comparably low number of 5x10(2) to 1x10(4) CD34(+)-cells per cm(2) MSC-monolayer, we observed comparably high expansion rates from 80 to 391,000 for CFU, 70 to 313,000 for CD34(+)-, and 200 to 352,000 for CD45(+)-cells. Expansion of LTC-IC was partly observed. Compared to the literature, we found a better expansion rate of CD34(+)-cells with MSCs from all different sources. This is probably due to the comparably low number of 5x10(2) to 1x10 CD34(+)-cells per cm(2) MSC-monolayer we used. Comparably, high expansion rates were observed from 80 to 391,000 for CFUs, 70 to 313,000 for CD34(+)-, and 200 to 352,000 for CD45(+)-cells. However, the expansion of CD34(+)-cells was significantly more effective with MSCs from bone marrow compared to MSCs from amnion, chorion, and Wharton's jelly. The comparison of MSCs from bone marrow with MSCs from CB and amniotic fluid showed no significant difference. We conclude that MSCs from placental tissues might be useful in the expansion of HSPCs, at least if low numbers of CD34(+)-cells per cm(2) MSC-monolayer and a high TPO concentration are implemented in the expansion culture.