Exosome-based bioinks for 3D bioprinting applications in tissue engineering and regenerative medicine

Bioprinting is an emerging technology for tissue engineering and regenerative medicine. Despite its fast, accurate manufacture for tissues and organs in vitro, bioprinting has been seriously limited for biofabrication because of the restricted approaches to reproducing the extracellular matrix (ECM) with sufficient bioactivities for bioprinted cells. Exosomes are natural biological particles with proteins, lipids, or genetic materials. They have distinct properties and unique biological functions to manipulate cellular behaviors and cell fates, showing great potential to support cells for bioprinting. Here, we reviewed the recent progresses of exosome-advanced bioprinting for tissue engineering and regenerative medicine. Firstly, we offer an overview of the basics of exosomes and the current representative applications of exosomes in bone tissue engineering, immunological regulations, angiogenesis, and neural regenerations. Then, a brief introduction about the bioinks and the currently developed bioprinting methods is provided. We further give an in-depth review of the biomedical applications of bioprinting with exosomes, majorly in bone engineering, vascular engineering, therapy of neuron injury, and skin regeneration. We also conclude with an outlook on the challenges of the unmet needs of bioprinting cells with correspondent ECM environments through bioprinting with exosomes.