Andrade Pedro Z, de Soure António M, Dos Santos Francisco, Paiva Artur, Cabral Joaquim M S, da Silva Cláudia L
Department of Bioengineering and Institute for Biotechnology and Bioengineering (IBB), Instituto Superior Técnico, Technical University of Lisbon, Portugal.
Histocompatibility Centre of Coimbra, Portugal.
J Tissue Eng Regen Med. 2015 Oct;9(10):1172-81. doi: 10.1002/term.1731. Epub 2013 Apr 17.
Physiologically low O(2) tensions are believed to regulate haematopoietic stem cell (HSC) functions in the bone marrow (BM; 0-5%). In turn, placenta and umbilical cord are characterized by slightly higher physiological O(2) tensions (3-10%). We hypothesized that O(2) concentrations within this range may be exploited to augment the ex vivo expansion/maintenance of HSCs from umbilical cord (placental) blood (UCB). The expansion of UCB CD34(+) -enriched cells was studied in co-culture with BM mesenchymal stem/stromal cells (MSCs) under 2%, 5%, 10% and 21% O(2). 2% O(2) resulted in a significantly lower CD34(+) cell expansion (25-fold vs 60-, 64- and 92-fold at day 10 for 5%, 21%, 10% O(2), respectively). In turn, 10% O(2) promoted the highest CD34(+) CD90(+) cell expansion, reaching 22 ± 5.4- vs 5.6 ± 2.4- and 5.7 ± 2.0-fold for 2%, 5% and 21% O(2), respectively, after 14 days. Similar differentiation patterns were observed under different O(2) tensions, being primarily shifted towards the neutrophil lineage. Cell division kinetics revealed a higher proliferative status of cells cultured under 10% and 21% vs 2% O(2). Expectedly, higher specific glucose consumption and lactate production rates were determined at 2% O(2) when compared to higher O(2) concentrations (5-21%). Overall, these results suggest that physiological oxygen tensions, in particular 10% O(2), can maximize the ex vivo expansion of UCB stem/progenitor cells in co-culture with BM MSCs. Importantly, these studies highlight the importance of exploiting knowledge of the intricate microenvironment of the haematopoietic niche towards the definition of efficient and controlled ex vivo culture systems capable of generating large HSCs numbers for clinical applications.
生理低氧张力被认为可调节骨髓中造血干细胞（HSC）的功能（骨髓中氧张力为0 - 5%）。相反，胎盘和脐带的生理氧张力略高（3 - 10%）。我们推测，这个范围内的氧浓度可用于增强脐带（胎盘）血（UCB）中HSC的体外扩增/维持。在2%、5%、10%和21%氧浓度下，研究了UCB中富集的CD34⁺细胞与骨髓间充质干/基质细胞（MSC）共培养时的扩增情况。2%氧浓度导致CD34⁺细胞扩增显著降低（第10天时，2%氧浓度下扩增25倍，而5%、21%、10%氧浓度下分别为60倍、64倍和92倍）。相反，14天后，10%氧浓度促进了最高的CD34⁺CD90⁺细胞扩增，2%、5%和21%氧浓度下分别达到22±5.4倍、5.6±2.4倍和5.7±2.0倍。在不同氧张力下观察到类似的分化模式，主要向中性粒细胞谱系转变。细胞分裂动力学显示，与2%氧浓度相比，10%和21%氧浓度下培养的细胞增殖状态更高。与较高氧浓度（5 - 21%）相比，2%氧浓度下特定葡萄糖消耗率和乳酸产生率更高是预期的。总体而言，这些结果表明，生理氧张力，特别是10%氧浓度，可在与骨髓MSC共培养时使UCB干/祖细胞的体外扩增最大化。重要的是，这些研究突出了利用造血微环境复杂知识来定义高效且可控的体外培养系统的重要性，该系统能够产生大量用于临床应用的HSC。
