Item cells known also as the primary undifferentiated cells remain exciting for their ability to create specific tissues that can 'grow organs'. It is argued that potentially, they can radically change the disease cure mechanism in the world. Found both at the embryonic as well as at the adult stage, the ability to transform into different tissues is maximum in the embryonic stem cell lines. The controversy then begins with the extractions of stem cell lines involving destruction of human embryos.
Critics argue that human life is incepted at the time of fertilisation and stem cell research can't take place without destroying 'life'. It is also reasoned that such a research can also lead to instrumentalisation of human lives. The contrarian's argument, however, vouchsafes for embryonic research given its potentiality in curing diseases like cancer. It is argued that embryos that get created but not used in in-vitro fertility centres (which either get destroyed or stored indefinitely) can be used for the research. In US alone, about 400,000 such embryos are known to exist.
Given significant ethical, social, moral and political concerns sufficient regulation is required for the research, but banning the research most certainly doesn't make sense.