MSE Seminar: David Dean, The Osteo Engineering Laboratory Research Program

This seminar, optional for our graduate students, will be held in Room 184 Watts Hall

Abstract

Regenerative medicine seeks to restore lost function. The Osteo Engineering Laboratory’s research uses patient-specific Computer Aided Design (CAD) and 3D printing technologies to produce patient-matched devices for musculoskeletal reconstructive surgical therapies. Our CAD software analyzes both shape and mechanical function to design devices ranging from resorbable, bone tissue engineered implants to graft and traumatic fracture skeletal fixation devices. Our bone tissue engineering research includes surface functionalization using bioactive molecules that modulate mesenchymal stem cell (i.e., bone progenitor cell) seeding, culture, and differentiation. Our skeletal fixation devices deviate from standard of care (i.e., Ti-6Al-4V) devices in either of two ways: (1) 3D printing NiTi in order to accomplish stiffness matching, shape memory, and/or superelasticity, or (2) Mg-1.2Zn-0.5Ca-0.5Mn resorbable skeletal fixation devices. Stiffness matched or resorbing fixation hardware attempts to remove the significant risk of stress shielding (bone resorption) and stress concentration (device failure) associated with Ti-6Al-4V medical devices.

Materials and Methods: (1) Implant CAD: Beginning with my dissertation research, our lab has produced average bone surface images, i.e., bone templates, from human 3D CT-scans. Those averaged images have been used to design cranial implants that have been received by patients since the mid-1990’s. Our template fitting method focuses on surface curvature as an image mapping/matching strategy. (2) Polymers: Our lab uses photo-crosslinking to 3D print, i.e., solid cure, a liquid polymer, poly(propylene fumarate) (PPF), to form resorbable, tissue engineering scaffolds for bone regeneration. We seed these scaffolds with bone progenitor cells which produce bone extracellular matrix. Currently we have a 4.0 cm mandibular segmental defect model with the goal of producing enough bone to secure a dental implant. (3) Stiffness-Matched Skeletal Fixation: We use powderbed fusion technologies to 3D print metallic skeletal fixation. Most current metallic medical devices contain alpha alloys of titanium. However, beta alloys are being explored because their shape memory and superelasticity properties allow stiffness matching of off-the-shelf or patient-matched devices that may reduce stress shielding and/or stress concentrations. Our lab, in collaboration with other labs, uses 3D printing of NiTi to stiffness-match skeletal fixation hardware to the site where it will be used. (3) Resorbable Skeletal Fixation: The field of resorbable metals is beginning to have an impact in the clinic in the areas of bone screws, vascular sealants, and cardiovascular stents. Our lab has developed an Mg alloy, Mg-1.2Zn-0.5Ca-0.5Mn, that can be sufficiently strengthened to be used in highly loaded parts of the skeleton, while simultaneously maintaining the ability to resorb during a clinically relevant timeframe.

Results and Discussion: Our CAD software analyzes patient-specific shape and material property control of function. Our bone tissue engineering research utilizes 3D printed, ECM-coated, poly(propylene fumarate) (PPF) scaffolds. Our study of skeletal fixation devices using stiffness-matched NiTi or a resorbable Mg alloy may eventually lead to using both materials in composite devices.

Bio

David Dean received the Ph.D. degree from the City University of New York in 1993. Following a two year post-doctoral appointment in the Institute for Reconstructive Plastic Surgery at New York University he joined the faculty of the School of Medicine at Case Western Reserve University (CWRU) in Cleveland, Ohio. In 2013 his primary appointment transferred from the Department of Neurological Surgery at CWRU to The Ohio State University where he is currently an Associate Professor in the Department of Plastic Surgery and a member of the Center for Regenerative Medicine and Cell-Based Therapies and the Institute for Materials Research. His research has led to the development of computer aided design software for the additive manufacture (3D printing) of patient-specific (custom) inert and tissue engineered bone implants and surgical instrumentation. His research program currently includes custom polymeric, tissue engineered, bone implants as well as stiffness-matched (NiTi) and resorbable (Mg alloy) skeletal fixation.