A new medical technology can be used clinically only if it is effective and safe  In 1998, American scientists successfully made human embryonic stem cells grow and proliferate in vitro  if this stem cell technology is combined with cloning technology, the necessary tissue cells can be cultured from patients' somatic cells to replace patients' damaged cells  to treat a variety of difficult diseases, this is the so-called therapeutic cloning
Because therapeutic cloning involves the destruction of early human embryos, it has aroused strong opposition from the Roman Church and the governments of the United States, France, Germany and other countries
 But now therapeutic cloning is still a long way from clinical use