Beyond nuclear transfer

Cloning technology can be divided into two areas: techniques for making transgenic cells or oocytes, and techniques for cloning those cells, i.e. turning transgenic cells into multiple identical developing embryos and live offspring.

Traditionally, microinjection of DNA into oocytes has been used to make transgenic livestock. However, nuclear transfer, which combines potentially transgenic cultured cells with enucleated oocytes to generate genetically identical embryos, is increasingly being used. Companies with nuclear transfer cloning technology include PPL Therapeutics plc (LSE:PTH, Roslin, U.K.), Pharming Holding N.V. (EASD:PHAR, Leiden, the Netherlands) with partner Infigen Inc. (DeForest, Wis.), and Genzyme Transgenics Corp. (GZTC, Framingham, Mass.) with partner Advanced Cell Technology Inc. (Worcester, Mass.)...