Find and Replace using RegEx

Can anyone help?

I have a script to find a regex of information, my question is :-

can I replace the items matched with with another regex?

such as ... $item -replace $regex , $regex2

or

with an array, so I can replace each unique match with a different item from an array.

so ... Item1,Item2,Item3

becomes ... somethinga,another4,whatever8a1

Regards

Kev

kittuk