*2.1.4 Replaced region*

Skin substitutes can be categorised based on their ability to replace the epidermal, dermal or composite (epidermal and dermal) layers of skin. Epidermal replacement should, in theory, be sufficient for reconstruction of burn wounds and other wound with intact dermal elements. However, deeper dermal and full thickness injuries ultimately require epidermal and dermal reconstruction in order to achieve robust wound healing while minimising scar formation and loss of function. Replication of basement membrane and dermal-epidermal junction are one of several scientific challenges that has yet to be overcome by advanced skin substitute design (discussed in further detail in Section 2.5), in order to attain stable skin coverage for deep tissue injuries [19, 20].
