Characterization of tissue engineered cartilage products: Recent developments in advanced therapy

Legislative requirements for the quality of pharmacological agents underwent certain evolution when new type of therapies emerged. This relates to cell based medicines, such as tissue engineered cartilage products (TECP) which are increasingly developed as new modalities for widely prevalent orthopaedic disorders. Although quality measures for TECP are subject to the same general regulatory quality requirements, combination of cellular and scaffold substances requires definition of specific characteristics in vitro that are highly relevant to potency and efficacy of the newly designed medicinal product. One of the specific issues in designing cell based medicines is the fact that the biological activity of active substance, or cells, usually is altered after seeding them on a three-dimensional scaffold. Newly acquired features of the TECP are influenced by chemical, physical and mechanical characteristics of the scaffolds. A vast array of analytical methods has been employed to measure efficacy and potency of TECP in cartilage regeneration studies in vitro. Designing specific physical characteristics of scaffolds may become essential part influencing pharmacological activity of cell based medicinal products, and discern TECP from typical pharmacological products. As an example, increasingly growing popularity of three-dimensional printing that utilizes direct laser writing technique provides an opportunity to improve efficacy of the final TECP. This review is intended to provide brief summary of current approaches used to characterize cells and scaffolds in vitro before and after combination into TECP. Validating TECP as pharmacological agents with unique biological and physical characteristics may broaden their clinical application.