In Spanish, Isela is a Latin American variant of Icela, a nickname for Maricela. In Spain, Icela is pronounced ee-THEL-a, and Isela is ee-SEL-a, but in Latin America they are both pronounced ee-SEL-a, which explains the spelling change. Maricela can be written as Marisela in Latin America because of this.
Edit: Just remembered Maricela and Icela can also be written Marizela and Izela (albeit rarely) in Latin America, with the same pronunciation.
This message was edited by the author on February 5, 2010 at 2:41:05 AM