Abstract: The present disclosure provides extruded or spun, semi-permeable, porous hollow fibres, comprising covalent ester, thioester and/or amide crosslinked polypeptides as well as processes for their production. The hollow fibres may be produced from protein, protein extracts, and/or protein isolates derived from plants, animals, bacteria, algae, archaea, and/or fungi, and in certain embodiments are intended to be suitable for human and/or animal ingestion. In some embodiments, the hollow fibres may be designed to be used in the production of cartridges that are compatible with existing and/or novel bioreactor platforms, for harbouring cell cultures in cultured meat production.