The Holy Father said:
"Recognising human dignity as an inalienable right has its first foundation in that law - unwritten by the hand of man but inscribed by God the Creator in man's heart - which all juridical systems are called to recognise as inviolable, and all individuals to respect and promote. Without the basic principle of human dignity it would be difficult to find a wellspring for the rights of the person, and impossible to reach ethical judgements about those scientific advances which have a direct effect on human life".
"When we invoke respect for the dignity of the person, it is fundamental that such respect should be complete, total and unimpeded, ... recognising that we are always dealing with a human life"
Full text at Zenit.