Your Own Rib can Help Reconstruct Your Jawbone: Here’s How

Natural bone made inside the patient by attaching a 3D printed scaffold to patient’s rib can be successfully used as an implant to replace damaged jaw bone in craniofacial reconstruction surgery.

Highlights:

Natural and strong bone implants to improve outcomes in craniofacial reconstruction surgery can be grown within the patient by attaching a 3D printed scaffold to the patient’s own rib
Craniofacial injuries are common in battlefield injuries and reconstruction of damaged bone is a complex and long drawn out process
Current methods of obtaining new bone for implant involve harvesting bone grafts from patient’s hip, leg or shoulder and growing new bone by the addition of external growth factors which requires regulatory approvals and is more complicated

Natural and strong bone implants can be made within the patient to treat craniofacial injuries by attaching a 3D printed scaffold to the patient’s own rib. Stem cells and blood vessels from the patient’s rib will grow into and around scaffold material and replace it with a new natural bone to suit the patient’s needs.

The study was conducted by scientists at Rice, the University of Texas Health Science Center at Houston (UTHealth) and Baylor College of Medicine led the study, and the results appear in the Proceedings of the National Academy of Sciences.

The study was led by bioengineer Antonios Mikos, one of the pioneers in the field of tissue engineering and has culminated in success following a decade-long program sponsored by the Armed Forces Institute of Regenerative Medicine.

The aim of the research was to improve craniofacial surgical reconstruction by using the body’s own natural healing powers

"A major innovation of this work is leveraging a 3D-printed bioreactor to form bone grown in another part of the body while we prime the defect to accept the newly generated tissue," said Mikos, the Louis Calder Professor of Bioengineering and Chemical and Biomolecular Engineering at Rice and a member of the National Academy of Engineering and National Academy of Medicine.

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‘Current bone reconstruction techniques use bone graft tissues taken from different sites in the patient, and adding external growth factors and cell cultures to grow the bone. The process is complicated, and requires approvals and regulations. Developing bone implants on the patient’s rib using 3D scaffold overcomes this drawback. More importantly, multiple bone implants can be grown simultaneously using the patient’s multiple ribs.’
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How This Study Is Superior To Previous Research

Previous research demonstrated a technique to produce bone grafts from real bone implanted into the chest cavity.
In contrast, the current study showed that viable bone grafts could be created from artificial bone substitute materials to create the 3D printed scaffold and a spacer (see below) both namely made of synthetic material termed PMMA (polymethyl methacrylate) or bone cement.
The spacer mold is placed at the site of craniofacial injury and promotes healing and prevents scar tissue from filling the defect at the site of injury, while the bone implant was being made on the patient’s rib

Mark Wong, a professor, chair and program director of the Department of Oral and Maxillofacial Surgery with the School of Dentistry at UTHealth, and co-author said: "The significant advantage of this approach is that you do not need to harvest a patient's own bone to make a bone graft, but that other non-autogenous sources can be used."

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Creating Natural Bone Implant Using Patient’s Rib

To test their theory, the study team used sheep as the animal model in which a rectangular defect was created in its jaw bone.

The team excised enough bone from the animal’s rib so that the periosteum was exposed. This periosteum would serve as the source of stem cells and blood vessels to seed the attached 3D printed scaffold
Crushed rib bone or synthetic calcium phosphate materials were used to 3D print the biocompatible scaffold.
The scaffold, with the rib side open to create a strong attachment point, stayed in place for nine weeks after which the new natural bone was removed and placed in the craniofacial defect replacing the spacer
In the animal models studied, the new bone wove seamlessly into the bony defect in the jaw and soft tissue grew around this and covered the defect

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Why Were Ribs Chosen and Why Was PMMA Chosen as Scaffold and Spacer Material?

Ribs are a rich source of stem cells
Since it is made within the patient, it will match the patient’s tissue
Also, since it is natural bone and does not involve any external factors, elaborate permissions and approvals are avoided
Multiple bone implants can be made simultaneously using patient’s multiple ribs

Also, PMMA (polymethyl methacrylate) was chosen as the material for the 3D printed scaffold and spacer because in World War II, when PMMA was used as a windshield for fighter planes, it was noted that shards embedded within injured pilots did not cause any tissue inflammation or damage and was therefore considered a harmless and biocompatible material.

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Rice University researchers are incorporating a unique way to deliver time-released antibiotics to ward off infection while a patient heals.

Summary

Natural bone implant made in the patient’s own body by attaching a biocompatible 3D printed scaffold to the patient’s rib can be used to improve outcomes in craniofacial reconstruction surgery.

Reference:

Biomaterials-aided mandibular reconstruction using in vivo bioreactors - (https://www.pnas.org/content/early/2019/03/12/1819246116)

Source-Medindia