1 Campus of Hematology F. and P. Cutino, Villa Sofia-Cervello Hospital, Palermo, Italy.
2 Section of Histology and Embryology, Department of Experimental Biomedicine and Clinical Neurosciences, University of Palermo, Palermo, Italy.
Cell Transplant. 2018 Jan;27(1):117-129. doi: 10.1177/0963689717737089.
Wharton's jelly mesenchymal stromal cells (WJ-MSCs) have been recently exploited as a feeder layer in coculture systems to expand umbilical cord blood-hematopoietic stem/progenitor cells (UCB-HSPCs). Here, we investigated the role of WJ-MSCs in supporting ex vivo UCB-HSPC expansion either when cultured in direct contact (DC) with WJ-MSCs or separated by a transwell system or in the presence of WJ-MSC-conditioned medium. We found, in short-term culture, a greater degree of expansion of UCB-CD34 cells in a DC system (15.7 ± 4.1-fold increase) with respect to the other conditions. Moreover, in DC, we evidenced two different CD34 cell populations (one floating and one adherent to WJ-MSCs) with different phenotypic and functional characteristics. Both multipotent CD34/CD38 and lineage-committed CD34/CD38 hematopoietic progenitors were expanded in a DC system. The former were significantly more represented in the adherent cell fraction than in the floating one (18.7 ± 11.2% vs. 9.7 ± 7.9% over the total CD34 cells). Short-term colony forming unit (CFU) assays showed that HSPCs adherent to the stromal layer were able to generate a higher frequency of immature colonies (CFU-granulocyte/macrophage and burst-forming unit erythroid/large colonies) with respect to the floating cells. In the attempt to identify molecules that may play a role in supporting the observed ex vivo HSPC growth, we performed secretome analyses. We found a number of proteins involved in the HSPC homing, self-renewal, and differentiation in all tested conditions. It is important to note that a set of sixteen proteins, which are only in part reported to be expressed in any hematopoietic niche, were exclusively found in the DC system secretome. In conclusion, WJ-MSCs allowed a significant ex vivo expansion of multipotent as well as committed HSPCs. This may be relevant for future clinical applications.
沃顿氏胶间充质基质细胞（WJ-MSCs）最近被用作共培养系统中的饲养层，以扩增脐带血造血干/祖细胞（UCB-HSPCs）。在这里，我们研究了 WJ-MSCs 在支持 UCB-HSPC 体外扩增中的作用，无论是在与 WJ-MSCs 直接接触（DC）培养时，还是在通过 Transwell 系统分离培养时，或是在存在 WJ-MSC 条件培养基时。我们发现，在短期培养中，与其他条件相比，UCB-CD34 细胞在 DC 系统中（15.7±4.1 倍增加）的扩增程度更高。此外，在 DC 中，我们证明了两种不同的 CD34 细胞群体（一种漂浮，一种粘附于 WJ-MSCs），具有不同的表型和功能特征。多能性 CD34/CD38 和谱系定向性 CD34/CD38 造血祖细胞均在 DC 系统中扩增。前者在贴壁细胞部分中的比例明显高于漂浮细胞部分（18.7±11.2%相对于总 CD34 细胞的 9.7±7.9%）。短期集落形成单位（CFU）测定显示，与悬浮细胞相比，粘附于基质层的 HSPC 能够产生更高频率的未成熟集落（CFU-粒细胞/巨噬细胞和爆式形成单位红细胞/大集落）。为了鉴定可能在支持观察到的 HSPC 体外生长中起作用的分子，我们进行了分泌组分析。我们发现了在所有测试条件下参与 HSPC 归巢、自我更新和分化的多种蛋白质。重要的是要注意，一组 16 种蛋白质，仅部分报告在任何造血龛位中表达，仅在 DC 系统分泌组中发现。总之，WJ-MSCs 允许多能性和定向性 HSPCs 的显著体外扩增。这可能与未来的临床应用有关。
