A review on recent advances in polymeric microneedle loading cells: Design strategies, fabrication technologies, transdermal application and challenges

Microneedle systems (MNs) loading living cells are a powerful platform to treat various previously incurable diseases in the era of precision medicine. Herein, an overview of recent advances in MN-based strategies for cell delivery is summarized, including material selection, design of morphological structures, and processing methods. We also systematically outlined the law of microstructural design relative to the structure-effective/function relationship in transdermal delivery or precision medicine and the design principles of cell microneedle (CMN). Furthermore, the representative works of precision treatments focusing on inflammatory skin diseases were tracked and discussed using CMN. Indeed, it highlights a practical path to solving the dilemma of cell therapy and raising the hope of precision medicine. However, there are still some challenges in developing CMN since they need multi-dimensional comprehensive properties, including mechanical properties, cell viability preservation, release, therapeutic effect, etc. The manuscript could provide insights into developing an innovative fit-to-purpose vehicle in cell therapy for interested researchers.