You can't run SATA express on a standard sata SSD. Just like boosted said, they are two different interfaces.
However, you can get M.2 SSD adapters that will put twin m.2 SSDs in a raid 0 and you can attach them to sata express. However plugging two of them into the PCIE slots is better.
SATA express in my opinion is already dead. Nobody has made SATA express SSDs, and other connection types like PCI express and the other one that the intel 750 SSDs use are far better.