Computer-Aided Bone Graft Process Devised with Stem Cells

(Audrey, Flickr)

18 July 2018. A tissue engineering team developed a process that includes computer-assisted design for personalized grafts derived from a patient’s own stem cells, to repair bone defects caused by trauma or disease. Researchers from New York Stem Cell Foundation Research Institute describe the process in today’s issue of the journal Scientific Reports.

The New York institute group led by tissue engineering and regenerative medicine researcher Giuseppe de Peppo is seeking better treatment options for individuals suffering broken or diseased bones needing repair, including children whose bones are still growing. The institute cites data showing 1 million people per year suffer fractures from bone diseases, particularly older individuals with bones growing weaker, as well as trauma caused by auto accidents, domestic violence, and military service.

Options for repairing bones are often limited to grafts grown from donated bone banks, or transfers of bone pieces from other parts of the patient’s body, but the authors say these options are far from ideal. Bone bank donations run risks of immune rejection, and while transfers of bone segments from other parts of the body can overcome immune rejection, they may not match up with the defective bone or do not grow the connective tissue and blood vessels for supporting bone growth.

The process developed by de Peppo and colleagues called Segmental Additive Tissue Engineering begins with a digital reconstruction of the broken bone, derived from microcomputed tomography scans, and visualized in three-dimensional computer-assisted design software. From that model, the affected part of the bone is divided into segments, with the dimensions of each model segment serving as specifications for a 3-D printed decellularized cow bone scaffold.

The scaffolds have channels to allow for fluid flow, and are seeded with pluripotent stem and progenitor cells. The seeded scaffolds are then cultured in a bioreactor to regrow bone tissue, allowing for the segments to be reassembled into a repaired bone. The process allows for adhesives or connectors to hold the new bone segments in place while the assembled pieces fuse together into a mechanically stable bone.

The researchers demonstrated the process and concept with a femur — upper leg bone — from a rabbit, and seeded the repair scaffolds with human pluripotent stem cells. The authors say new bone segments to repair the bone were grown in the lab in about 5 weeks. While the engineered bones produced with these techniques are individualized, the Segmental Additive Tissue Engineering process itself is standardized and can be supplemented with advanced manufacturing techniques, such as rapid prototyping. While most of the process uses off-the-shelf materials and software, the researchers needed to build their own bioreactor for this task.

The following video from New York Stem Cell Foundation Research Institute tells more about the Segmental Additive Tissue Engineering process.

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