Idea:
When an admin creates an article he can set the "made by user" to any user name. In this case the selected user can edit the article afterwards. Now that article is restricted to the admin only. This could be easy if an admin wants to help a user. He could login as that user, but in this way he can keep logging in as admin and still create content meant for a specific user.
Sometimes users need some help and will ask the admin. In this way he can do so more easy.