Other contributors have said "How does the body repair cells?" is the same question as "What is use to build and repair body cells?" If you believe that these are not asking the same thing and should be answered differently, click here
Proteins are used to build and repair body cells. That's why if you work out and are sore, if you eat protein you heal faster. It also helps you from getting sore in the first place.
Ummm... There are differnet cells that build the body. There are muscle cells that build muscle, skin cells that build skin, nerve cells that make up nerves, bone cells that make up bones, and blood...