Autologous bone grafts remain the gold standard for craniofacial reconstruction despite limitations of donor-site availability and morbidity. A myriad of commercial bone substitutes and allografts are available, yet no product has gained widespread use because of inferior clinical outcomes. The ideal bone substitute is both osteoconductive and osteoinductive. Craniofacial reconstruction often involves irregular three-dimensional defects, which may benefit from malleable or customizable substrates. “Hyperelastic Bone” is a three-dimensionally printed synthetic scaffold, composed of 90% by weight hydroxyapatite and 10% by weight poly(lactic-co-glycolic acid), with inherent bioactivity and porosity to allow for tissue integration. This study examines the capacity of Hyperelastic Bone for bone regeneration in a critical-size calvarial defect.
Eight-millimeter calvarial defects in adult male Sprague-Dawley rats were treated with three-dimensionally printed Hyperelastic Bone, three-dimensionally printed Fluffy–poly(lactic-co-glycolic acid) without hydroxyapatite, autologous bone (positive control), or left untreated (negative control). Animals were euthanized at 8 or 12 weeks postoperatively and specimens were analyzed for new bone formation by cone beam computed tomography, micro–computed tomography, and histology.
The mineralized bone volume–to–total tissue volume fractions for the Hyperelastic Bone cohort at 8 and 12 weeks were 74.2 percent and 64.5 percent of positive control bone volume/total tissue, respectively (p = 0.04). Fluffy–poly(lactic-co-glycolic acid) demonstrated little bone formation, similar to the negative control. Histologic analysis of Hyperelastic Bone scaffolds revealed fibrous tissue at 8 weeks, and new bone formation surrounding the scaffold struts by 12 weeks.
Findings from our study suggest that Hyperelastic Bone grafts are effective for bone regeneration, with significant potential for clinical translation.
Chicago and Evanston, Ill.
From Shriners Hospitals for Children-Chicago; The Craniofacial Center, Department of Surgery, Division of Plastic and Reconstructive Surgery, University of Illinois Health; and the Department of Materials Science and Engineering, the Simpson Querrey Institute for BioNanotechnology, the Department of Surgery, Division of Plastic and Reconstructive Surgery, the Department of Biomedical Engineering, and the Division of Organ Transplantation, Department of Surgery, Northwestern University.
Received for publication March 19, 2018; accepted October 9, 2018.
Disclosure:Patents pertaining to this work have been filed and are pending: (1) room-temperature synthesis and three-dimensional printing of bioactive elastic bone for tissue engineering applications (inventors: A.E.J. and R.N.S.), (2) ink compositions for three-dimensional printing and methods of forming objects using the ink compositions (inventors: A.E.J. and R.N.S.), and additive manufacturing of porous materials through creation and three-dimensional printing of salt containing liquid feedstock materials followed by multi-step leaching. The other authors declare that they have no competing interests. A.E.J. and R.N.S. are co-founders of and shareholders in Dimension Inx, LLC, which develops and manufactures new advanced manufacturing compatible materials and devices for medical and nonmedical applications. As of August of 2017, A.E.J. is currently full-time chief technology officer of Dimension Inx, and R.N.S. serves part time as chief science officer of Dimension Inx. A.E.J. and R.N.S. are inventors on patents that are licensed to Dimension Inx. Dimension Inx did not influence the conduct, description, or interpretation of the findings in this article.
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Ramille N. Shah, Ph.D., Department of Bioengineering, University of Illinois at Chicago, 851 South Morgan Street, 2nd floor, Chicago, Ill. 60607-7043, firstname.lastname@example.org