Blood Cell-Based Drug Delivery Systems: From Biological and Mechanical Design to Clinical Applications.

Conventional drug delivery systems often suffer from problems such as limited targeting specificity, short half-lives, poor biocompatibility, and systemic toxicity, which significantly limit their therapeutic efficacy against major diseases like cancer. Blood cells, as native components of the human circulatory system, offer distinct advantages including low immunogenicity, long circulation times, remarkable mechanical flexibility, and innate ability to home to disease sites. These attributes make blood cells a promising platform for next-generation targeted drug carriers. In this review, we examine the biological and mechanical properties of red blood cells, white blood cells, platelets, and cell-derived membrane vesicles. We highlight recent advances in how these cells are engineered and loaded with drugs, and their application in tumor-targeted therapy, while also considering their potential in other diseases. We also discuss current technical challenges and outline future directions for clinical translation, offering a practical perspective on advancing blood cell-based delivery technologies.