Storing multiple selection as an array…

When using FF for user registration, multiple selections stored in the DB as a string.
Is there a way to convert it to an array, which would make it editable on the front end…

EXAMPLE

Currently, selection ONE, TWO, THREE as user_meta_field is stored as ONE, TWO, THREE

What would be really useful is to store it as:

a:3:{i:0;s:3:”ONE”;i:1;s:3:”TWO”;i:2;s:5:”THREE”;}

Thanks in advance!