Fertility in the Klinefelter syndrome by testicular stem cell transplantation - an experimantal approach in the XXY mice

人类男性不育最常见的遗传原因是Klinefelter综合征（KS, 47，XXY），导致睾丸功能衰竭、生殖细胞丧失和不同程度的雄激素缺乏，并伴有促性腺激素的变化。虽然KS是众所周知的，但尚不清楚导致SCO综合征的生殖细胞损失是由于生殖细胞系的缺陷，睾丸环境的干扰，还是两者的结合。许多Klinefelter患者来我们研究所治疗不孕症。任何可能的治疗方法来克服这种不孕症需要从实验工作的发现。拟议的项目旨在阐明在Klinefelter患者中获得生育能力的治疗方法的先决条件，例如通过使用自体干细胞。由于在这个阶段，这种工作不能在患者身上进行，因此产生和使用合适的动物模型是必不可少的。携带多余的x染色体（核型41，XXY）的小鼠模仿患者的情况，通过繁殖带有自发突变y染色体的动物而产生。我们建立了B6Ei菌株的小鼠菌落。Lt-Y获得41只（XXY）雄性小鼠，并通过荧光原位杂交（FISH）分别测定活体动物的不同核型。我们将展示是否睾丸环境和垂体-性腺轴在男性携带多余的x染色体能够支持发育正常，二倍体精原干细胞使用我们完善的方法生殖细胞移植和移植睾丸组织。我们将描述男性内分泌学和睾丸功能的基本方面，特别是睾丸间质细胞的功能和成熟。由于一些Klinefelter患者产生少量精子来源于表面上正常的二倍体精原细胞，睾丸环境应该能够支持精子发生。然而，这是否在每个患者中都是可能的，或者取决于嵌合的程度，目前还不清楚。染色体异常率高的睾丸精子会增加流产率。因此，在提供任何临床移植方法之前，必须解决睾丸环境紊乱和非整倍体风险增加的问题。这个问题将在小鼠模型中解决，通过检查生殖细胞移植后产生的精子，并进行ICSI，然后对胚胎进行染色体分析。

The most common genetic cause of human male infertility is the Klinefelter syndrome (KS, 47,XXY) resulting in testicular failure, loss of germ cells and variable degrees of androgen deficiency paralleled by changes in gonadotropins. Although the KS is well known, it is not clear whether the loss of germ cells resulting in a Sertoli-cell-only (SCO) syndrome is due to a defect of the germ cell line, a disturbance of the testicular environment, or a combination of both. Many Klinefelter patients attend our Institute for infertility. Any possible therapeutic approaches to overcome this infertility requires findings from experimental work. The proposed project seeks to elucidate those prerequisites for therapeutic approaches to gain fertility in Klinefelter patients, e.g. by making use of autologous stem cells. Since at this stage such work cannot be performed in the patients themselves, the generation and use of an appropriate animal model is indespensable. Mice bearing a supernumerary X-chromosome (karyotype 41, XXY) mimicking the conditions found in patients have been generated by breeding animals with a spontaneously mutated Y-chromosome. We established a mouse colony of the strain B6Ei.Lt-Y to obtain 41 (XXY) male mice and determined the distinct karyotype of the living animals individually by fluorescence in situ hybridisation (FISH). We will show whether the testicular environment and the pituitary-gonadal axis in males bearing a supernumerary X-chromosome are able to support development of normal, diploid spermatogonial stem cells using our well-established methods of germ cell transplantation and grafting of testicular tissue. We will characterize aspects essential for male endocrinology and testicular function as in particular the Leydig cell function and maturation. Since some Klinefelter patients produce a small amount of sperm deriving from apparently normal diploid spermatogonia, the testicular environment should be able to support spermatogenesis. However, whether this would be possible in every patient or depends on the degree of mosaicism has not been clarified. Testicular sperm with a high rate of chromosomal abnormalities increase the abortion rate. Thus questions of disturbed testicular environment and an increased risk of aneuploidy have to be solved before any clinical transplantation approach can be offered. This problem will be addressed in the mouse model by examining sperm produced after germ cell transplantation and by performing ICSI followed by chromosomal analysis of embryos.