Eyestone W H, Campbell K H
PPL Therapeutics, Blacksburg, VA, USA.
J Reprod Fertil Suppl. 1999;54:489-97.
The reconstruction of mammalian embryos by transfer of a blastomere nucleus to an enucleated oocyte or zygote allows for the production of genetically identical individuals. This has advantages for research (that is, as biological controls) and commercial applications (that is, multiplication of genetically valuable livestock). However, the number of offspring that can be produced from a single embryo is limited both by the number of blastomeres (embryos at the 32-64-cell stage are the most widely used in farm animal species) and the limited efficiency of the nuclear transfer procedure. The ability to produce live offspring by nuclear transfer from cells that can be propagated and maintained in culture offers many advantages, including the production of many identical offspring over an extended period (since cultured cells can be frozen and stored indefinitely) and the ability to modify genetically or to select populations of cells of specific genotypes or phenotypes before embryo reconstruction. This objective has been achieved with the production of lambs using nuclei from cultured cells established from embryonic, fetal and adult material. In addition, lambs transgenic for human factor IX have been produced from fetal fibroblasts transfected and selected in culture.
通过将卵裂球细胞核转移到去核卵母细胞或受精卵中来重建哺乳动物胚胎，能够产生基因相同的个体。这对于研究（即作为生物学对照）和商业应用（即繁殖具有遗传价值的家畜）具有优势。然而，单个胚胎能够产生的后代数量受到卵裂球数量的限制（在农场动物物种中，32 - 64细胞阶段的胚胎使用最为广泛）以及核移植程序效率有限的制约。通过从能够在培养中繁殖和维持的细胞进行核移植来产生活体后代具有诸多优势，包括在较长时期内产生许多相同的后代（因为培养的细胞可以无限期冷冻保存），以及在胚胎重建之前能够对细胞进行基因改造或选择特定基因型或表型的细胞群体。利用从胚胎、胎儿和成年材料建立的培养细胞的细胞核生产羔羊，这一目标已经实现。此外，已经从在培养中进行转染和筛选的胎儿成纤维细胞中生产出了转人类因子IX基因的羔羊。
