Hughes S, Chang-Ling T
Department of Anatomy and Histology, Institute for Biomedical Research, University of Sydney, Australia.
Microcirculation. 2000 Oct;7(5):317-33.
To examine the roles of apoptosis, macrophages, and endothelial cell migration in vascular remodeling during development of the central nervous system.
The terminal deoxynucleotide transferase-mediated dUTP nick end labeling (TUNEL) technique was combined with Griffonia simplicifolia isolectin B4 histochemistry to detect apoptotic endothelial cells in retinal whole-mount preparations derived from rats at various stages of postnatal development as well as from rat pups exposed to hyperoxia. Macrophages were detected by immunohistochemistry with the monoclonal antibody ED1, and proliferating endothelial cells were identified by incorporation of bromodeoxyuridine.
Only small numbers of TUNEL-positive endothelial cells were detected during normal development of the retinal vasculature, with the apoptotic cell density in the inner plexus peaking during the first postnatal week and decreasing markedly during the second week, at a time when vessel retraction was widespread. Neither apoptotic endothelial cells nor macrophages were apparent at sites of initiation of vessel retraction. TUNEL-positive endothelial cells were observed in vessels destined to remain. Hyperoxia induced excessive vessel withdrawal, resulting in the generation of isolated vascular segments containing apoptotic endothelial cells. A topographical analysis showed low numbers of proliferating endothelial cells at sites of angiogenesis whereas vascular proliferation was increased in the adjacent inner plexus.
Endothelial cell apoptosis and macrophages do not initiate vessel retraction, but rather contribute to the removal of redundant cells throughout the vasculature. We suggest that vessel retraction is mediated by endothelial cell migration and that endothelial cells derived from retracting vascular segments are redeployed in the formation of new vessels. Only when retraction results in compromised circulation and redeployment is not possible, does endothelial cell apoptosis occur.
研究细胞凋亡、巨噬细胞和内皮细胞迁移在中枢神经系统发育过程中血管重塑中的作用。
将末端脱氧核苷酸转移酶介导的dUTP缺口末端标记（TUNEL）技术与简叶豆凝集素B4组织化学相结合，以检测出生后不同发育阶段大鼠以及暴露于高氧环境的幼鼠视网膜整装标本中的凋亡内皮细胞。通过用单克隆抗体ED1进行免疫组织化学检测巨噬细胞，并用溴脱氧尿苷掺入法鉴定增殖的内皮细胞。
在视网膜血管正常发育过程中仅检测到少量TUNEL阳性内皮细胞，内丛中的凋亡细胞密度在出生后第一周达到峰值，并在第二周显著下降，此时血管退缩广泛发生。在血管退缩起始部位未见凋亡内皮细胞和巨噬细胞。在注定要保留的血管中观察到TUNEL阳性内皮细胞。高氧诱导过度的血管退缩，导致产生含有凋亡内皮细胞的孤立血管段。地形分析显示，血管生成部位增殖的内皮细胞数量较少，而相邻内丛中的血管增殖增加。
内皮细胞凋亡和巨噬细胞不会引发血管退缩，而是有助于清除整个脉管系统中的多余细胞。我们认为血管退缩是由内皮细胞迁移介导的，并且来自退缩血管段的内皮细胞在新血管形成中被重新利用。只有当退缩导致循环受损且无法重新部署时，才会发生内皮细胞凋亡。
