Only dermis is vascularized. Nutrients reach epidermis by diffusing through the tissue from the blood vessels. Underneath dermis is hypodermis (superficial fascia), also called subcutaneous tissue which is composed of loose connective tissue (mostly areolar and adipose).
A collagen dressing is a type of wound dressing that is made with a form of collagen to aid in the body's healing processes. Collagen is a category of structural proteins that are naturally present in almost every part of the human body and are especially common in connective tissue.
Another common approach to smoothing wrinkles is collagen injections. Collagen is injected in the skin under the wrinkles in such a way that it pushes the groove of a wrinkle up making it less visible. This procedure does have some noticeable cosmetic effect but has a number of serious drawbacks.