Printing New Bones: From Print-and-Implant Devices to Bioprinted Bone Organ Precursors

• Published in: Trends in molecular medicine 2021-07, Vol.27 (7), p.700-711
• Main Authors: Freeman, Fiona E., Burdis, Ross, Kelly, Daniel J.
• Format: Article
• Language: English
• Subjects: Animals; bioprinting; Bioprinting - instrumentation; bone and bones; Bone and Bones - cytology; Bone Regeneration; Humans; Printing, Three-Dimensional - instrumentation; tissue engineering; Tissue Engineering - methods; Tissue Scaffolds - chemistry; Wound Healing
• ISSN: 1471-4914; 1471-499X
• DOI: 10.1016/j.molmed.2021.05.001

Regenerating large bone defects remains a significant clinical challenge, motivating increased interest in additive manufacturing and 3D bioprinting to engineer superior bone graft substitutes. 3D bioprinting enables different biomaterials, cell types, and growth factors to be combined to develop patient-specific implants capable of directing functional bone regeneration. Current approaches to bioprinting such implants fall into one of two categories, each with their own advantages and limitations. First are those that can be 3D bioprinted and then directly implanted into the body and second those that require further in vitro culture after bioprinting to engineer more mature tissues prior to implantation. This review covers the key concepts, challenges, and applications of both strategies to regenerate damaged and diseased bone. 3D bioprinting strategies generally fall under two categories, herein defined as either print-and-implant approaches or those that require further in vitro maturation post-printing to create engineered tissues.By combining ceramics and synthetic polymers, researchers are able to generate osteoinductive implants with mechanical properties compatible with implantation into load-bearing environments.Using 3D bioprinting to deliver growth factors in a spatiotemporal manner that mimics the natural healing cascade can significantly enhance bone regeneration.Endothelialised 3D printed channels have been shown to anastomose with host vasculature following implantation.Bioprinted avascular cartilage templates can induce endochondral bone formation in vivo.3D bioprinting of scaffold-free tissues has emerged as potential new strategy for the engineering of functional tissues.