Krum J M, Rosenstein J M
Department of Anatomy, George Washington University Medical Center, Washington, D.C. 20037.
J Comp Neurol. 1988 May 15;271(3):331-45. doi: 10.1002/cne.902710304.
Vascular integration between transplanted fetal CNS tissues and host brain is essential for long-term transplant survival. This study compares the time course and mechanism of vascularization in allografts of fetal cerebral cortex inserted either into the fourth ventricle or directly into the parietal cortex or hippocampus of perinatal rats. Recipient animals were administered 3H-thymidine after various postoperative time periods. The tissues were processed for light microscopic autoradiography to determine the temporal pattern of endothelial proliferation at the graft sites. Correlative electron microscopy depicted the morphological changes in transplant vasculature. Some recipients were prelabelled with 3H-thymidine prior to transplantation to determine if host vessels invaded the grafts; conversely, some donor tissues were prelabelled in utero to ascertain if the intrinsic vascular anlagen survived. Intraventricular transplants contained patent vessels, probably originating from the host pia mater, as early as 24 hours postoperative. Intraparenchymal transplants had patent vessels by 72 hours and a more complete network by 5 days. Prelabelling experiments and ultrastructural observations demonstrated that adjacent host pial vessels became incorporated into the perimeter of the intraventricular transplants and later grew centrally into the grafts. Intraparenchymal transplants also contained host vessels that exhibited a similar growth pattern. Intrinsic graft vessels remained viable and continued their development, and presumably anastomosed with the ingrowing host vasculature. Temporal labelling studies revealed that both vessel populations attained their highest proliferative rates within 72 hours after transplantation. This study demonstrates that the vasculature which develops within both intraventricular and intraparenchymal fetal CNS transplants is chimeric, consisting of intrinsic fetal vasculature and proliferating host vessels. The mechanism of transplant vascularization may be significant with regard to astrocytic, immunological, or blood-brain-barrier characteristics at these transplantation sites.
移植的胎儿中枢神经系统组织与宿主脑之间的血管整合对于移植组织的长期存活至关重要。本研究比较了将胎儿大脑皮质同种异体移植到围产期大鼠的第四脑室或直接移植到顶叶皮质或海马体后血管化的时间进程和机制。在术后不同时间段给受体动物注射³H-胸腺嘧啶核苷。对组织进行光镜放射自显影处理，以确定移植部位内皮细胞增殖的时间模式。相关的电子显微镜观察描绘了移植血管的形态变化。一些受体在移植前用³H-胸腺嘧啶核苷进行预标记，以确定宿主血管是否侵入移植组织；相反，一些供体组织在子宫内进行预标记，以确定固有血管原基是否存活。脑室内移植早在术后24小时就含有可能源自宿主软脑膜的开放血管。脑实质内移植在72小时时有开放血管，5天时形成更完整的网络。预标记实验和超微结构观察表明，相邻的宿主软脑膜血管融入脑室内移植组织的周边，随后向中央生长进入移植组织。脑实质内移植也含有呈现类似生长模式的宿主血管。移植组织的固有血管保持存活并继续发育，推测与长入的宿主血管系统吻合。时间标记研究表明，两种血管群体在移植后72小时内达到最高增殖率。本研究表明，在脑室内和脑实质内胎儿中枢神经系统移植中发育的血管系统是嵌合的，由胎儿固有血管和增殖的宿主血管组成。移植血管化的机制可能与这些移植部位的星形细胞、免疫或血脑屏障特性有关。
