Functionality and degradation of 3D-printed polymeric scaffolds for mandibular reconstruction and vascularized bone tissue repair

K.V. Bulusu, B. Holmes, P. Paulson, L.G. Zhang, M.W. Plesniak
The George Washington University,
United States

Keywords: 3D printing, nanomaterials and biomedical applications, polymer diffusivity

Summary:

One of the greatest challenges in field of maxillofacial and craniofacial reconstruction is to quickly and adequately induce a vascular network within any large sections of repaired bone tissue. In this study we are addressing that challenge through an experimental framework that encompasses three aspects of polymeric scaffold design and fate for mandibular repair and reconstruction. First, 3D printed scaffolds were fabricated using Fused Deposition Modeling (FDM). Conventional mandibular repair involves using living graft bone taken from the fibula, along with skin and bone, to create new complex tissue in and around the jaw. However, this technique presents a host of complications (i.e. infection, donor site morbidity, cosmetic issues, inadequate vascularization). A 3D printing approach allows for the construction of intricate, porous and micro-vascularized scaffolds that support bone and vascular growth. Second, the functionality of polymeric scaffolds with nanostructured porosity and conjugated with osteogenic facilitators was investigated for nanoscale texturization (using SEM) and osteoinduction potential (using confocal microscopy). Castro et al., in a recently published study showed that a novel biomaterial and a calcium-based nanomaterial could effectively and rapidly facilitate the growth of new bone, using mesenchymal stem cells. Follow up studies (by Nanochon LLC, in partnership with Children’s National Medical Center, Washington DC) demonstrated that this approach could yield vascularized bone in vitro and in vivo. Successes such as these are promising for the field, but lack predictability, reliability and scalability. Thus, in the third phase the diffusivity and fate of ultra-fast degrading (polyvinyl alcohol-based) scaffolds were studied in a specialized experiment used for arterial hemodynamic investigations. It is necessary to tune scaffold degradation to ensure hierarchical and time dependent tissue growth. Accordingly, the transport and degradation mechanisms in polyvinyl alcohol-based (PVA) 3D-printed scaffolds of varying porosity were investigated using catheterized-pressure measurements under blood-like flow conditions. The quantification of polymer interactions is essential to tuning the degradation of such scaffolds within the body, to release tissue forming agents and providing hierarchical and time dependent support for osteogenesis. The ultimate goal of our research is to create prefabricated and synthetic graft implants, designed for patient-specific requirements, with predictable and tunable degradation characteristics, to restore damaged bone.