Pope Benedict said on Thursday that embryonic stem cell research, artificial insemination and the prospect of human cloning had "shattered" human dignity.
In an address to members of the Vatican department on doctrinal matters, Benedict said the Church had a duty to defend the "great values at stake" in the field of bioethics.
He said this included total respect for the human being as a person "from conception until natural death," and respect for the natural transmission of life through sexual intercourse.
Practices like freezing embryos, suppression of embryos in multiple pregnancies, embryonic stem cell research, the prospect of human cloning and artificial insemination outside the body had "shattered the barriers meant to protect human dignity", he said.
"When human beings in the weakest and most defenseless state of their existence are selected, abandoned, killed or used as pure 'biological material,' how can one deny that they are being treated not as 'someone' but as 'something,'" he said.
Such practices "questioned the very concept of the dignity of man," he said in the speech to the department known as the Congregation for the Doctrine of the Faith.