Careful and detailed documentation concerning the characteristics of the starting materials (e.g. history of the cell line derivation and cell banking) and manufacturing process steps (e.g. procurement of tissue or cells and manipulation) must be maintained. The cellular part of every cell-based medicinal product must be characterized in terms of identity, purity, potency, viability and suitability for the intended use. The non-cellular constituents must be also characterized with regards to their intended function in the final product. For example, scaffolds or membranes that are used to support the cells must be identified and characterized in terms of porosity, density, microscopic structure and particular size. The same requirement for characterization applies for biologically active molecules, such as growth factors or cytokines.