Nuclear transfer in human medicine and animal breeding.

Cloning has a number of potential applications in human medicine and animal breeding, but the efficiency of production of developmentally competent embryos and healthy animal offspring needs to be improved. The primary deficiency appears to be incomplete or abnormal nuclear reprogramming after nuclear transfer, and it is hypothesized that epigenetic regulators of transcription cannot always be converted to the embryonic pattern and this leads to implantation failure, gestational abnormalities and poor health of offspring. Research needs to be focused on this aspect of development for nuclear transfer embryos. However, there is a gradual demand for commercial application for cloning in animal production, transgenesis and animal biopharmaceuticals, particularly in milk. These applications will expand in the near future. There is little application of nuclear transfer in human medicine at present, but important applications may be demonstrated for prevention of the inheritance of mitochondrial mutations, prevention of age-related aneuploidis in women, artificial gametes for sterile individuals or couples and for therapeutic cloning to enable cell and gene therapies.