A light-emitting diode chip comprises a GaN-based, radiation-emitting epitaxial layer sequence, an active region, an n-doped layer and a p-doped layer. A porous core is positioned within the recess of the base, and has a core coolant inlet opening and a core coolant outlet opening that are arranged in corresponding relation with base coolant inlet opening and a base coolant outlet opening so as to be in fluid communication. , a mammal, in manner such that the encoded protein of the introduced expression cassette is persistently expressed at a high level in the target cell.