Considering all the polluted blood out there now, I have a question for anyone who knows.

I came across someone who said that blood transfusions are sort of a con. He said if you need blood for some reason, they can do it without putting someone else's blood into you. They just need to put liquid into you with electrolytes, and your body will make blood from that, and it will be only your own blood.

Anybody know about this?