从募集优势卵泡开始提高胚胎质量

Improving quality of embryos from selective follicle recruitment

在体外受精一胚胎移植（IVF—ET）助孕周期中，通过给予外源性促性腺激素（Gn）进行控制性促排卵（COS）以获得多个卵泡的发育仍然是不可缺少的重要环节。卵泡刺激素（FSH）是促进卵泡生长发育的主要Gn。目前应用于临床的外源性FSH制剂依其原料来源的不同分为两大类：高纯度尿源性FSH（HP—FSH）和基因重组FSH（rFSH）。

Ovarian stimulation is an integral procedure in assisted reproduction treatment. It is achieved by the administration of exogenous gonadotropins to increase follicular recruitment and oocyte yield. At present, two follicle-stimulating hormone （FSH）products are commercially available for controlled ovarian Stimulation（COS） ：highly purified human-derived FSH（HP-FSH）and recombinant FSH （rFSH）. HP-FSH contains a higher proportion of acidic isoforms whereas rFSH contains a higher proportion of less-acidic isoforms. Less-acidic isoforms exhibit high bioactivity in vitro, but they have a faster clearance,and thus a shorter circulatory half-life than the acidic FSH isoforms. The slow clearance of the acidic isoforms results in more estrogenic follicles, follicular maturation and estradiol secretion. Fostimon,a new generation of HP-FSH product, contains more extensively glycosylated（acidic）FSH. Its improvements in specific activity, purity, degradation, and impurities have resulted in a high pregnancy rate similar to rFSH. The sequential treatment protocol with acidic and less-acidic FSH（Fostimon and rFSH） may mimic the physiologic cycle, whereas normal follicle development and ultimately normal oocyte function depend on an appropriate balance of sequential differentiation, and this balance is strongly influenced by FSH isoform distribution. Recently,it is reported that a sequential combined protocol using both acidic FSH and less-acidic FSH for controlled ovarian stimulation（COS）may improve oocytes maturity and embryo cleavage,and increase pregnancy and implantation rate compared with acidic FSH or less-acidic FSH alone. More attention should be paid to FSH isoform distribution of exogenous gonadotropins applied for COS.