Department of Cardiothoracic Surgery, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany.
Int J Cardiol. 2010 Mar 4;139(2):134-41. doi: 10.1016/j.ijcard.2008.10.009. Epub 2008 Nov 12.
Progenitor cells contribute to repair of ischemia-associated disturbances of microcirculations, but detailed mechanisms of paracrine angiogenic activation of endothelium by progenitor cells are unclear. The present study was designed to test whether progenitor cells maintain their activation pattern of cytokine secretion and capillary-like endothelial sprout attraction under conditions of hypoxia induced angiogenic activation.
CD34 progenitor cells were kept separated together with spheroids of human umbilical vein endothelial cells (HUVEC) sharing a common medium supernatant to generate a paracrine diffusion gradient from CD34 cells to the endothelial cell spheroids. The expression of 27 cytokines was analyzed in the supernatant. The length and the direction of the capillary like sprouts were analyzed under 20% and 1% oxygen concentration.
Co-culture with CD34 cells increased sprout length of HUVEC spheroids by 18%, while reduction of oxygen concentration from 20% to 1% increased sprout length by 52%. Analysis of the direction of the sprout growth revealed a directed growth toward CD34 cells under normoxic as well as under hypoxic conditions. Paracrine induction of cytokine secretion by co-culture was similar in normoxia and in hypoxia with IL-8 (60-80-fold induction) >IL-6 and MIP-1beta (10-20-fold) >MIP-1alpha and MCP-1 (3-10-fold).
These data indicate that CD34 cell induced paracrine activation of cytokine secretion pattern and attraction of endothelial sprouting are well maintained under conditions of hypoxia induced endothelial cell sprout growth. This is a prerequisite for paracrine effectiveness of trapped progenitor cells in hypoperfused and hypooxygenated tissue areas.
祖细胞有助于修复与缺血相关的微循环紊乱，但祖细胞通过旁分泌激活内皮细胞的血管生成的详细机制尚不清楚。本研究旨在测试祖细胞在缺氧诱导的血管生成激活条件下是否保持其细胞因子分泌的激活模式和对毛细血管样内皮芽的吸引。
将 CD34 祖细胞与共享共同培养基上清液的人脐静脉内皮细胞（HUVEC）球体分开培养，以产生从 CD34 细胞到内皮细胞球体的旁分泌扩散梯度。分析上清液中 27 种细胞因子的表达。在 20%和 1%氧气浓度下分析毛细血管样芽的长度和方向。
与 CD34 细胞共培养可使 HUVEC 球体的芽长度增加 18%，而将氧气浓度从 20%降低至 1%可使芽长度增加 52%。对芽生长方向的分析表明，在常氧和低氧条件下，芽都向 CD34 细胞定向生长。旁分泌诱导共培养的细胞因子分泌在常氧和低氧条件下相似，IL-8（60-80 倍诱导）>IL-6 和 MIP-1beta（10-20 倍）>MIP-1alpha 和 MCP-1（3-10 倍）。
这些数据表明，CD34 细胞诱导的旁分泌细胞因子分泌模式激活和内皮芽吸引在缺氧诱导的内皮细胞芽生长条件下得到很好的维持。这是被困在低灌注和低氧组织区域的祖细胞旁分泌有效性的前提。
