Huang Z, Miao X, Patarroyo M, Nilsson G P, Pernow J, Li N
Clinical Pharmacology Unit, Department of Medicine-Solna, Karolinska Institutet, Stockholm, Sweden.
Department of Dental Medicine, Department of Medicine-Solna, Karolinska Institutet, Stockholm, Sweden.
J Thromb Haemost. 2016 Mar;14(3):606-18. doi: 10.1111/jth.13248. Epub 2016 Feb 11.
ESSENTIALS: Platelet releasates (PRs) enhance endothelial colony forming cell (ECFC) angiogenesis. The impact of platelet membrane components on ECFC angiogenesis was studied by a tube formation assay. Platelets enhanced ECFC angiogenesis more potently than PR, via tetraspanin CD151 and integrin α6β1. Optimal enhancement of ECFC angiogenesis by platelets requires both membrane proteins and PR.
Platelets promote angiogenesis of endothelial colony forming cells (ECFCs), with the underlying mechanisms not being fully understood.
To investigate if platelets regulate the angiogenic property of ECFCs via mechanisms beyond platelet-released angiogenic regulators.
Endothelial colony forming cells were generated by ECFC-directed cell culture of peripheral blood mononuclear cells. Capillary-like tube formation of ECFCs was assessed using a Matrigel assay. Platelets promoted ECFC tube formation in both basic and complete ECFC medium. Importantly, the ECFC angiogenic responses induced by platelets were stronger than those induced by platelet releasates. Thus, the branching points of ECFC tube formation (30.5 ± 9.0/field, ECFC alone) were increased by platelet releasates (58.2 ± 8.3/field) and even more profoundly by platelets (95.5 ± 17.6/field), indicating that platelet membrane components also promoted ECFC tube formation. The latter was further supported by evidence that fixed platelets did enhance ECFC tube formation. Subsequent experiments revealed that the promotion was dependent on platelet-surface glycoproteins, as removal of sialic acid from platelet glycoproteins by neuraminidase abolished the enhancement. Furthermore, platelet-expressed, but not ECFC-expressed, CD151 was important for the enhancement, as pretreatment of platelets, but not ECFCs, with a CD151-blocking antibody attenuated the effect. Integrin α6β1 on both ECFCs and platelets also participated in platelet-promoted tube formation, as integrin α6 or β1 blockade of either cell type markedly or totally inhibited the phenomenon. Moreover, platelets exerted the enhancement via the Src-PI3K signaling pathway of ECFCs.
Platelet-enhanced ECFC angiogenesis requires platelet tetraspanin CD151 and α6β1 integrin, as well as ECFC α6β1 integrin and Src-PI3K signaling.
要点：血小板释放物（PRs）可增强内皮祖细胞（ECFC）的血管生成。通过管形成试验研究了血小板膜成分对ECFC血管生成的影响。血小板通过四跨膜蛋白CD151和整合素α6β1比PR更有效地增强ECFC血管生成。血小板对ECFC血管生成的最佳增强需要膜蛋白和PR两者。
血小板促进内皮祖细胞（ECFCs）的血管生成，但其潜在机制尚未完全了解。
研究血小板是否通过血小板释放的血管生成调节因子以外的机制调节ECFC的血管生成特性。
通过外周血单个核细胞的ECFC定向细胞培养生成内皮祖细胞。使用基质胶试验评估ECFC的毛细血管样管形成。血小板在基础和完全ECFC培养基中均促进ECFC管形成。重要的是，血小板诱导的ECFC血管生成反应比血小板释放物诱导的更强。因此，ECFC管形成的分支点（单独ECFC为30.5±9.0/视野）被血小板释放物增加（58.2±8.3/视野），被血小板更显著地增加（95.5±17.6/视野），表明血小板膜成分也促进ECFC管形成。固定血小板确实增强ECFC管形成的证据进一步支持了后者。随后的实验表明，这种促进作用依赖于血小板表面糖蛋白，因为用神经氨酸酶从血小板糖蛋白中去除唾液酸消除了这种增强作用。此外，血小板表达而非ECFC表达的CD151对这种增强作用很重要，因为用CD151阻断抗体预处理血小板而非ECFC可减弱这种作用。ECFC和血小板上的整合素α6β1也参与了血小板促进的管形成，因为对任何一种细胞类型的整合素α6或β1进行阻断都显著或完全抑制了该现象。此外，血小板通过ECFC的Src-PI3K信号通路发挥增强作用。
血小板增强的ECFC血管生成需要血小板四跨膜蛋白CD151和α6β1整合素，以及ECFC的α6β1整合素和Src-PI3K信号通路。
