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Animal studies play a vital role in validating the concept, feasibility, safety, performance and efficacy of biomaterials products during their bench-to-clinic translation. This article aims to share regulatory considerations for animal studies of biomaterial products. After briefly emphasizing the importance of animal studies, issues of animal studies during biomaterial products' translation are discussed. Animal studies with unclear purposes, flawed design and poor reporting quality could significantly reduce the translation efficiency and create regulatory challenges. Regulatory perspectives on the purpose, principle, quality and regulatory science of animal studies are also presented. Animal studies should have clear purposes, follow principles of 3R+DQ (replacement, reduction, refinement, design and quality) and execute under an efficiently operating quality management system. With the advancement of regulatory science, National Medical Products Administration of China has been developing a series of standards and guidance documents on animal studies of medical devices. Case studies of making decisions on whether to conduct animal studies are provided in the end with drug-eluting stents as examples. In summary, animal studies of biomaterial products should pay close attention to the rationale, design and quality in order to achieve their purposes., Competing Interests: None., (© 2021 The Authors.)

Ti alloys with lattice structures are garnering more and more attention in the field of bone repair or regeneration due to their superior structural, mechanical, and biological properties. In this study, six types of composite lattice structures with different strut radius that consist of simple cubic (structure A), body-centered cubic (structure B), and edge-centered cubic (structure C) unit cells are designed. The designed structures are firstly simulated and analysed by the finite element (FE) method. Commercially pure Ti (CP-Ti) lattice structures with optimized unit cells and strut radius are then fabricated by selective laser melting (SLM), and the dimensions, microtopography, and mechanical properties are characterised. The results show that among the six types of composite lattice structures, combined BA, CA, and CB structures exhibit smaller maximum von-Mises stress, indicating that these structures have higher strength. Based on the fitting curves of stress/specific surface area versus strut radius, the optimized strut radius of BA, CA, and CB structures is 0.28, 0.23, and 0.30 mm respectively. Their corresponding compressive yield strength and compressive modulus are 42.28, 30.11, and 176.96 MPa, and 4.13, 2.16, and 7.84 GPa, respectively. The CP-Ti with CB unit structure presents a similar strength and compressive modulus to the cortical bone, which makes it a potential candidate for subchondral bone restorations., Competing Interests: The authors declare that they have no known competing for financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2020 [The Author/The Authors].)