Department of Medical Sciences, University of Milan, Endocrine Unit-Padiglione Granelli, Istituto di Ricovero e Cura a Carattere Scientifico Ca' Granda, Via Francesco Sforza, 35, 20122 Milan, Italy.
J Clin Endocrinol Metab. 2012 May;97(5):1452-61. doi: 10.1210/jc.2011-3160. Epub 2012 Mar 7.
The term "microchimerism" indicates the coexistence, in the same organism, of genetically distinct populations of cells derived from two different individuals. The passage of cells from the fetus to the mother is called fetal cell microchimerism, whereas that occurring from the mother to the fetus is named maternal cell microchimerism. Microchimeric cells can persist in blood and tissues for decades.
A literature search through the U.S. National Library of Medicine was used to identify and review studies on maternal and fetal microchimerism, focusing on endocrine diseases.
According to the majority of reports, fetal cell microchimerism seems to have a detrimental role in autoimmune diseases and a positive effect on tumor burden in most human cancers studied. In autoimmune thyroid diseases, fetal microchimeric cells (fmcs) have been found to be significantly more represented within the thyroid gland of women with Hashimoto's thyroiditis and Graves' disease compared to those without thyroid autoimmunity, suggesting a pathogenic role. In thyroid cancer tissues, fmcs have been found to be present at higher levels than in contralateral normal tissues and have been shown to differentiate into epithelial and hematopoietic cells. Microchimeric cells with hematopoietic differentiation could have a role in destroying the tumor, whereas epithelial cells are believed to participate in the repairing processes. At the peripheral level, circulating fmcs were less frequently detected in patients with thyroid cancer than in healthy individuals, consistent with data obtained for breast cancer and other solid and hematological malignancies, indicating a protective role against cancer development. Finally, type 1 diabetes has been mostly related to maternal cell microchimerism. Indeed, the levels of circulating maternal cells were higher in type 1 diabetes patients than in controls. At the pancreas level, female β-cells were identified and hypothesized to be targets of autoimmunity or to regenerate diseased tissues.
“微嵌合体”一词表示在同一生物体中存在来自两个不同个体的遗传上不同的细胞群体。细胞从胎儿转移到母亲的过程称为胎儿细胞微嵌合体，而从母亲转移到胎儿的过程则称为母体细胞微嵌合体。微嵌合细胞可以在血液和组织中持续存在数十年。
通过美国国家医学图书馆进行文献检索，以确定和审查有关母体和胎儿微嵌合体的研究，重点关注内分泌疾病。
根据大多数报告，胎儿细胞微嵌合体在自身免疫性疾病中似乎具有有害作用，而在大多数研究的人类癌症中对肿瘤负担具有积极影响。在自身免疫性甲状腺疾病中，与无甲状腺自身免疫的女性相比，桥本甲状腺炎和格雷夫斯病女性的甲状腺中发现胎儿微嵌合细胞（fmcs）的比例明显更高，提示其具有致病性。在甲状腺癌组织中，发现 fmcs 的水平高于对侧正常组织，并且已显示其分化为上皮细胞和造血细胞。具有造血分化的微嵌合细胞可能在破坏肿瘤中发挥作用，而上皮细胞则被认为参与修复过程。在周围水平，甲状腺癌患者的循环 fmcs 比健康个体更不频繁地检测到，这与乳腺癌和其他实体瘤和血液恶性肿瘤的数据一致，表明其对癌症发展具有保护作用。最后，1 型糖尿病主要与母体细胞微嵌合体有关。实际上，1 型糖尿病患者的循环母体细胞水平高于对照组。在胰腺水平，鉴定出女性β细胞，并假设其是自身免疫的靶标或再生病变组织。
