Cellular Reprogramming Laboratory, Avenida del Autopista del Saler 16, 46013 Valencia, Spain.
Stem Cells. 2010 Mar 31;28(3):407-18. doi: 10.1002/stem.295.
Early development of mammalian embryos occurs in an environment of relative hypoxia. Nevertheless, human embryonic stem cells (hESC), which are derived from the inner cell mass of blastocyst, are routinely cultured under the same atmospheric conditions (21% O(2)) as somatic cells. We hypothesized that O(2) levels modulate gene expression and differentiation potential of hESC, and thus, we performed gene profiling of hESC maintained under normoxic or hypoxic (1% or 5% O(2)) conditions. Our analysis revealed that hypoxia downregulates expression of pluripotency markers in hESC but increases significantly the expression of genes associated with angio- and vasculogenesis including vascular endothelial growth factor and angiopoitein-like proteins. Consequently, we were able to efficiently differentiate hESC to functional endothelial cells (EC) by varying O(2) levels; after 24 hours at 5% O(2), more than 50% of cells were CD34+. Transplantation of resulting endothelial-like cells improved both systolic function and fractional shortening in a rodent model of myocardial infarction. Moreover, analysis of the infarcted zone revealed that transplanted EC reduced the area of fibrous scar tissue by 50%. Thus, use of hypoxic conditions to specify the endothelial lineage suggests a novel strategy for cellular therapies aimed at repair of damaged vasculature in pathologies such as cerebral ischemia and myocardial infarction.
哺乳动物胚胎的早期发育是在相对缺氧的环境中进行的。然而，人类胚胎干细胞（hESC）来源于囊胚的内细胞团，通常在与体细胞相同的大气条件（21% O(2)）下培养。我们假设 O(2)水平调节 hESC 的基因表达和分化潜能，因此，我们对在常氧或低氧（1%或 5% O(2))条件下培养的 hESC 进行了基因谱分析。我们的分析表明，低氧下调 hESC 中的多能性标记物的表达，但显著增加与血管生成和血管发生相关的基因的表达，包括血管内皮生长因子和血管生成素样蛋白。因此，我们能够通过改变 O(2)水平将 hESC 有效地分化为功能性内皮细胞（EC）；在 5% O(2)下培养 24 小时后，超过 50%的细胞为 CD34+。将得到的内皮样细胞移植后，可改善心肌梗死啮齿动物模型的收缩功能和缩短分数。此外，对梗死区的分析表明，移植的 EC 可使纤维瘢痕组织面积减少 50%。因此，利用低氧条件来指定内皮谱系为治疗脑缺血和心肌梗死等疾病中受损血管提供了一种新的细胞治疗策略。
