Pardanaud L, Dieterlen-Lièvre F
Institut d'Embryologie cellulaire et moléculaire du CNRS, Nogent-sur-Marne, France.
J Soc Biol. 1999;193(2):171-9.
The hypothesis that the endothelial and hemopoietic lineages have a common ontogenic origin is currently being revived. We have shown previously by means of quail/chick transplantations that two subsets of the mesoderm give rise to endothelial precursors: a dorsal one, the somite, produces pure angioblasts (angiopoietic potential), while a ventral one, the splanchnopleural mesoderm, gives rise to progenitors with a dual endothelial and hemopoietic potential (hemangiopoietic potential). To investigate the cellular and molecular controls of the angiopoietic/hemangiopoietic potential, we devised an in vivo assay based on the polarized homing of hemopoietic cell precursors to the floor of the aorta detectable in the quail/chick model. In the present work, quail mesoderm was grafted, after various pretreatments, onto the splanchnopleure of a chick host; the homing pattern and nature of graft-derived cells were analyzed thereafter using the QH1 monoclonal antibody which recognizes both quail endothelial and hemopoietic lineages. We report that transient contact with endoderm or ectoderm could change the behavior of cells derived from treated mesoderm, and that the effect of these germ layers could be mimicked by treatment with several growth factors VEGF, bFGF, TGF beta 1, EGF and TGF alpha, known to be involved in endothelial commitment and proliferation, and/or hemopoietic processes. The endoderm induced a hemangiopoietic potential in the associated mesoderm. Indeed, the association of paraxial or somatopleural mesoderm with endoderm promoted the "ventral homing" and the production of hemopoietic cells from mesoderm not normally endowed with this potential. The hemangiopoietic induction by endoderm could be mimicked by VEGF, bFGF and TGF beta 1. In contrast, a contact with ectoderm or EGF/TGF alpha treatments totally abrogated the hemangiopoietic capacity of the splanchnopleural mesoderm which produced pure angioblasts with no "ventral homing" behavior. We postulate that two gradients, one positive and one negative, modulate the angiopoietic/hemangiopoietic potential of the mesoderm.
内皮细胞谱系和造血细胞谱系具有共同的个体发生起源这一假说目前正在复兴。我们之前通过鹌鹑/鸡移植实验表明，中胚层的两个亚群产生内皮前体细胞：一个位于背侧的体节，产生纯成血管细胞（血管生成潜能），而位于腹侧的脏壁中胚层产生具有内皮和造血双重潜能（造血血管生成潜能）的祖细胞。为了研究血管生成/造血血管生成潜能的细胞和分子调控机制，我们设计了一种基于造血细胞前体向主动脉底部极化归巢的体内检测方法，这种归巢现象在鹌鹑/鸡模型中可以检测到。在本研究中，将经过各种预处理的鹌鹑中胚层移植到鸡宿主的脏壁上；然后使用识别鹌鹑内皮细胞和造血细胞谱系的QH1单克隆抗体分析移植来源细胞的归巢模式和性质。我们报告，与内胚层或外胚层的短暂接触可以改变经处理的中胚层来源细胞的行为，并且这些胚层的作用可以通过用几种已知参与内皮细胞定向分化和增殖以及/或造血过程的生长因子VEGF、bFGF、TGFβ1、EGF和TGFα处理来模拟。内胚层在相关中胚层中诱导了造血血管生成潜能。实际上，轴旁或体壁中胚层与内胚层的联合促进了“腹侧归巢”，并使通常不具备这种潜能的中胚层产生造血细胞。内胚层的造血血管生成诱导作用可以被VEGF、bFGF和TGFβ1模拟。相反，与外胚层接触或EGF/TGFα处理完全消除了脏壁中胚层的造血血管生成能力，该中胚层产生的是没有“腹侧归巢”行为的纯成血管细胞。我们推测，存在一个正梯度和一个负梯度调节中胚层的血管生成/造血血管生成潜能。
