胎儿细胞进入孕妇血循环的实验研究

目的 从胎盘组织中寻找胎儿细胞穿越胎盘屏障，进入孕妇外周血的实验室证据，为利用孕妇外周血进行无创性产前基因诊断提供实验依据。方法 分娩胎盘组织22份(男婴的12份，女婴的10份)，平行切片，分2组：一组HE染色，光镜观察绒毛中胎儿细胞的分布；另一组用Dig-碱性磷酸酶标记SRY区域(Sex determlining region)基因扩增片断制成探针，通过原位杂交鉴定胎盘绒毛内，特别是绒毛间隙胎儿细胞的存在。阳性对照由男性外周血有核细胞涂片经原位杂交提供。结果 HE染色光镜观察：22例胎盘组织切片可见胎儿细胞有穿越绒毛毛细血管内皮和滋养层基膜的现象。胎盘组织原位杂交结果显示：分娩男婴的12份胎盘切片的绒毛毛细血管腔内、绒毛滋养层基膜边缘，以及绒毛间隙，可见阳性信号；分娩女婴的10份胎盘切片均无阳性信号出现；阳性对照涂片杂交后可见清晰阳性信号。结论 胎盘组织切片常规HE染色观察胎儿细胞分布，结合原位杂交技术鉴定绒毛内、绒毛间隙细胞的性质，可以初步反映胎儿微量遗传物质穿越胎盘进入母亲血液循环的过程。

Experimental study of the fetal cells crossing the placenta into the maternal circulation

Objective To investigate the proof of fetal cells passing through the placental barrier into the maternal peripheral blood to provide laboratory data for the non invasive prenatal gene diagnosis of genetic diseases. Methods A total of 22 samples of placental tissues delivered(male fetus: 12, female fetus: 11) were divided into two groups for parallel section. HE staining was used to find the distribution of fetal cells in chorionic villi. In situ hybridization (ISH) technique with SRY DNA probes was used to identify the existence of fetal cells in placental villi, particularly in intervillous space. Results Light microscope examination revealed that there were fetal cells that passed through the capillary endothelium of villi and trophoblast basement membrane in the placental tissue sections of the 22 samples. ISH with SRY DNA probe also revealed that there were positive signals in the capillary of villi, at the edge of trophoblast basement membrane and in intervillous space in the placental tissue sections of the 12 placentas, but no signals were found in 10 female placentas. Conclusion This study demonstrates that the distribution of the fetal cells in the chorionic villi and intervillous space could be identified. The detection of fetal DNA in maternal circulation is one of the candidate approaches for non invasive prenatal gene diagnosis.