There were currently two huge, conflicting forces inside the body of the Queen of Blades. The first was the power from the Protoss' Keystone. This power originated from the mighty Xel'naga race and represented the supreme power of purification. It could erase all the mutations in a biological gene and restore it to the original state.
In fact, the Keystone was actually just a very common medical device for the Xel'naga race in their prime. It's real name was the Concave Lens Filter, and it was somewhat similar to the X-ray machine or CT scan machine in the real world.
The reason the Xel'naga created the Terrans, Protoss and Zerg was to carry out various experiments on these experimental races in an effort to create the perfect life-form. Based on the various experimental data and results obtained from them, the Xel'naga would, in the end, decide on an optimal plan to apply to their own race, so as to extend their maximum life span.