Engineering Ice Microneedles Loaded with Cells and Microorganisms for Disease Treatment

Cell- and microorganisms-based therapeutics are promising strategies for treating various diseases, yet their clinical translation faces some obstacles such as poor patient compliance and instability. Microneedles (MNs) have gained much attention due to their characteristics of minimally invasive nature, high efficiency, and good compliance. However, traditional MNs face limitations in delivering living cells and microorganisms. Ice MNs, fabricated under low-temperature conditions, represent innovative delivery platforms that helps maintain the activity of cells and microorganisms. This review aimed to explore recent progress in delivering living cells and microorganisms using ice MNs. In this review, the preparation methods, materials, and advantages of ice MNs are first summarized. Then, the application of conventional MNs and ice MNs in the field of biomedicine is reviewed. In this section, the application of conventional MNs in the delivery of living microorganisms and cells is first described. We further discuss the application of ice MNs in tumors, inflammatory diseases, bacterial infections, vaccine delivery, and hair regeneration in detail. Finally, the challenges and prospects of ice MNs are outlined. It is expected that the integration of ice MNs with living cells and microorganisms holds great promise for significant breakthroughs in future clinical applications.