Finkenzeller Günter, Torio-Padron Nestor, Momeni Arash, Mehlhorn Alexander T, Stark G Björn
Department of Plastic and Hand Surgery, University of Freiburg Medical Center, Hugstetter Str. 55, D-79106 Freiburg, Germany.
Tissue Eng. 2007 Jul;13(7):1413-20. doi: 10.1089/ten.2006.0369.
Survival of ex vivo constructed tissues after transplantation is limited by insufficient oxygen and nutrient supply. Therefore, strategies aiming at the improvement of neovascularization of engineered tissues are a key issue. A method to enhance graft vascularization is to establish a primitive vascular plexus within the graft before transplantation by the use of cellular-based concepts. To explore the utility of endothelial progenitor cells (EPCs) for the ex vivo vascularization of tissue engineered grafts, we analyzed the in vitro angiogenic properties of this cell type in two different angiogenesis models: the 3-dimensional spheroid sprouting assay and the 2-dimensional matrigel assay. In both assays, EPCs were able to form tubelike structures, resembling early capillaries. This process was significantly enhanced by the addition of angiogenic growth factors. Direct comparison between EPCs and mature endothelial cells, represented by human umbilical vein endothelial cells (HUVECs), revealed that both cell types displayed an almost identical angiogenic potential. Other functional in vitro parameters such as angiogenic growth factor induced cell proliferation and cell survival were investigated as well, revealing a significantly decreased level of apoptosis of EPCs in relation to HUVECs under serum-deprived conditions. The observed survival advantage of EPCs along with the observation that EPCs perform very well in the above mentioned in vitro angiogenesis assays, make them an ideal autologous cell source for vascularization of ex vivo generated tissues. The attractiveness of this cell type for tissue engineering applications is strengthened further by the fact that these cells can be easily isolated from the peripheral blood of patients, thereby eliminating donor site morbidity.
移植后体外构建组织的存活受到氧气和营养供应不足的限制。因此，旨在改善工程组织新血管形成的策略是一个关键问题。一种增强移植物血管化的方法是在移植前通过基于细胞的概念在移植物内建立原始血管丛。为了探索内皮祖细胞（EPC）在组织工程移植物体外血管化中的效用，我们在两种不同的血管生成模型中分析了这种细胞类型的体外血管生成特性：三维球体发芽试验和二维基质胶试验。在这两种试验中，EPC都能够形成类似早期毛细血管的管状结构。添加血管生成生长因子可显著增强这一过程。以人脐静脉内皮细胞（HUVEC）为代表的EPC与成熟内皮细胞之间的直接比较表明，两种细胞类型显示出几乎相同的血管生成潜力。还研究了其他体外功能参数，如血管生成生长因子诱导的细胞增殖和细胞存活，结果显示在血清剥夺条件下，EPC的凋亡水平相对于HUVEC显著降低。EPC观察到的存活优势以及EPC在上述体外血管生成试验中表现良好的观察结果，使其成为体外生成组织血管化的理想自体细胞来源。这些细胞可以很容易地从患者外周血中分离出来，从而消除供体部位的发病率，这一事实进一步增强了这种细胞类型在组织工程应用中的吸引力。
