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双胞胎的脐带血储存

09.12.2017

 

双胞胎的脐带血储存

 
双胞胎照片来自Cryo-Cell公司

近几十年来,在美国的双胞胎数量增加了很多。相比于历史基线来看,目前额外多了一百多万对双胞胎1。从上世纪八十年代开始,生育时间的推迟和辅助生殖的流行都使得双胞胎出生率从2%增加到了3%以上1-3

多数的双胞胎是异卵双生,也就是说母亲的两个卵子分别受精。两个孩子来自同一个卵子的同卵双生双胞胎出生率一直没变,大约是每285个孕妇中会出现一例。也就是说,曾经大约一半的双胞胎是同卵双生,而现在只有三分之一的是同卵双生4

从遗传角度来考虑,异卵双生双胞胎和一般兄弟姐妹的情况是类似的,他们只是同时出生而已。异卵双生双胞胎和其他兄弟姐妹都有25%的可能性抗原配型相符5。这也就是说有四分之一的可能性兄弟姐妹间能有完全匹配的血型来进行脐带血干细胞移植,或者其他需要HLA匹配的干细胞治疗。

当两个婴儿同在一个子宫中时,两个孩子体型都会略小一些。从上世纪六十年代开始,在美国的足月婴儿平均体重是7斤2两(8磅)。小于5斤(5.5磅)的婴儿属于低出生体重儿6。但是过去十年的研究调整了人们对双胞胎的医学看法。单胞胎一般会在母亲体内待满39至40周,但是研究显示为了避免生长限制,双胞胎最好在37周左右出生7,8。37周的双胞胎平均体重在5斤(5.5磅)左右9

此外,双胞胎体重较小同时使得他们的胎盘更小,脐带血量更少。不少双胞胎的家长会对存脐带血有担忧10,11。一方面,他们会担心自己的孩子会跟不少早产儿和低体重儿一样碰到学习障碍12(虽然现在通过脐带血移植已经可以治疗13-15),另一方面,他们担心收集的脐带血量不够来进行移植操作。

Cryo-Cell血库进行了目前唯一的多胎孕妇脐带血收集调查。因为每100个孕妇中3例是双胞胎,他们收集了最近的10,000例单胞胎和300例多胞胎案例进行了分析。不出人意外的是,多胞胎收集到的脐带血量中位数相对要少10%。而好消息是,较脐带血储存的最低量,从多胞胎中收集的脐带血包含近4倍多的有核细胞(TNC)和近8倍多的CD34阳性细胞。

Cryo-Cell的报道表明,按照目前的用量指导15, 从多胞胎中收集的脐带血有足够的干细胞来治疗婴幼儿脑瘫以及其他婴幼儿中会有的症状。

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