In vivo bioprinting: Broadening the therapeutic horizon for tissue injuries

Tissue injury is a collective term for various disorders associated with organs and tissues induced by extrinsic or intrinsic factors, which significantly concerns human health. In vivo bioprinting, an emerging tissue engineering approach, allows for the direct deposition of bioink into the defect sites inside the patient's body, effectively addressing the challenges associated with the fabrication and implantation of irregularly shaped scaffolds and enabling the rapid on-site management of tissue injuries. This strategy complements operative therapy as well as pharmacotherapy, and broadens the therapeutic horizon for tissue injuries. The implementation of in vivo bioprinting requires targeted investigations in printing modalities, bioinks, and devices to accommodate the unique intracorporal microenvironment, as well as effective integrations with intraoperative procedures to facilitate its clinical application. In this review, we summarize the developments of in vivo bioprinting from three perspectives: modalities and bioinks, devices, and clinical integrations, and further discuss the current challenges and potential improvements in the future. [Display omitted] •In vivo bioprinting introduces the concept of additive manufacturing into the clinical settings for tissue injury treatment.•The distinctive intracorporal environment imposes unique requirements for the modalities and bioink of in vivo bioprinting.•Handheld and multi-axis bioprinting devices are well-established, and minimally invasive devices are emerging approaches.•Integration of bioprinting with the clinical procedures are required in pre, during and post bioprinting stages.•The migration of artificial intelligence, and robotics from industry to bioprinting is a trend for clinical applications.