Microfluidic Platforms for Exosome Engineering: Scalable Therapeutics for Cancer Immunotherapy and Infectious Diseases.

Extracellular vesicles (EVs), particularly small EVs or exosomes, are promising cell-free therapeutics with superior biocompatibility and intrinsic targeting for synthetic nanoparticles. However, conventional bulk preparation methods suffer from low yield, poor reproducibility, and structural instability. Microfluidic technologies resolve these issues by enabling precise, automated, and low-shear fluidic manipulation. This mini-review highlights recent advances in microfluidic-engineered exosomes for cancer immunotherapy and infectious diseases. We evaluate critical microfluidic strategies for isolation, surface engineering, and cargo loading, contrasting platforms like ExoArc, acoustofluidics, cellular nanoporation, and electroporation. Particular emphasis is placed on complex modalities, including immune cell-derived exosomes (IEX), neo-antigen presentation, chimeric antigen receptor (CAR)-derived exosomes, and targeted siRNA delivery networks. Crucially, we analyze the technological disconnect between analytical microfluidic scales and massive therapeutic manufacturing volumes, addressing how physical forces risk damaging conformationally sensitive surface proteins (e.g., CAR scFv). Finally, we outline future perspectives, including high-throughput 3D-multiplexed networks, stimulus-responsive scarless elution, and integrated "sample-to-therapy" circuits. Guided by the MISEV2023 guidelines, this review frames the path toward standardized, clinical-scale engineering of multi-functional, cell-free immunotherapies.