autologous (your) blood injected into the acne scars is not a standard treatment. If you're discussing the injection of blood as a means to improve the outcome of scar revision by increasing collagen underneath the scar and helping to lift it up, then there might be a possible contribution that blood has. This had been done with an old treatment called Fibrel which involved utilizing one's own blood components to help collagen production underneath scars. If however, you are discussing poor healing from actual laser resurfacing, your blood does have many components that help in the wound healing process, but be wary of this non-standard treatment. Blood is an excellent nutruient for bacteria and hematomas, or collections of blood underneath the skin after surgery, can get infected.
Web reference: http://www.thenyac.com/acne-scars/index.html