There are so many examples for that in different areas, like biology experiment carried out in our lab recently.
Here's one link : https://www.creative-biogene.com/Services/Biosimilar-Cell-Line-Development.html
I don't know, maybe because of the way we see animals. Not as our equal parts
This study serves as a proof of concept that complete organs
can be grown from harvested stem cells and, when transplanted, achieve normal
function, the authors said, hopefully advancing the field from stem cell
transplantation for organ repair towards full organ replacement.
They produce a gas called ethylene.