I just want to point our that the title, "Italian doctors transplant kidney for spleen," remains misleading, to my eyes. This isn't as interesting as it sounds.

The patient had renal failure and needed a transplant. Due to vascular anatomy, it sounds like the lower abdomen was not an appropriate place for a new transplanted kidney.

The innovative technique was to sacrifice the spleen to create a space for the kidney, then to use the intact splenic vasculature to hook up to the transplanted kidney.

The spleen is a lymphoid organ that people can live without. Many people with sickle cell disease are "functionally" asplenic. It can be removed after injury. Etc. It's a highly vascular organ and has a robust supply via the splenic artery.

In no way does the kidney perform the function of the spleen.