Abstract: The present disclosure provides a bioreactor for extracting cell-derived products from cultured cells, the bioreactor comprising a container, an inlet for inputting cell culture medium into the container, an outlet for outputting cell culture medium comprising cell-derived products from the container, the container comprising, or being connected to, a compartment comprising nanostructured cellulose configured to receive cells, said compartment comprising a first separating surface separating the nanostructured cellulose from the outlet and allowing cell culture medium comprising cell-derived products to pass through the first separating surface. The present disclosure also provides a method for separating cell-derived products from cultured cells and a nanostructured cellulose product.