B. Holmes, K. Bulusu, M. Plesniak, L.G. Zhang
Nanochon LLC, George Washington University,
Keywords: 3D printing, nanomaterials, orthopedics, tissue engineering, stem cells
Summary:In recent years, 3D printing has become a popular and widely investigated method for the fabrication of large bone implants. 3D printed bone constructs, devices and treatments hold great potential to repair traumatic and chronic injuries, restore tissue shape and function and return those afflicted with diseases and traumatic injury to large portions of bone (such as craniofacial and maxillofacial trauma) to normal, and even fully functional lives. One of the most pressing reasons is that large and highly functioning areas of damaged bone, so called “critical defects,” require an interconnected and effective vascular network. A dramatic example of such an injury would be someone who had severe damage to their skull and face, resulting from a car accident. Solving this challenge is critical, as bone relies on an adequate network of blood vessels to transport waste, nutrients in and out of the tissue. Bone tissue engineering has a specific need to solve this critical issue. Here we have combined nanomaterials and 3D printing for a highly innovative complex 3D printed scaffold with both nano and micro features for both bone and vascular growth. Key innovations of this project include the design and fabrication of a fully interconnected 3D fluid perfusable microchannel network, within a microstructured bone forming matrix (Figure 1). Also in this study we designed and achieved a unique integration of nanocrystalline hydroxyapatite (nHA) into our 3D printed scaffolds using a post fabrication process. We incorporated hydrodynamic measurement of unsteady pressure and flow rates. These measurements facilitate a preliminary understanding of the causal effects of predesigned structure-induced flow perturbations and the efficacy of such structures. Our motivation to study arterial blood flow in context of predesigned vascular structures is due to the essential role of blood supply for the growth of large critical-sized bone tissue. We therefore, modeled the hydrodynamic experiments under similar flow conditions in an exclusive arterial flow loop, recreating those salient cardiovascular flow characteristics (Figure 2). Ultimately, we believe that vascular flow properties and pulsatility may have a greater role to play toward fast, in situ delivery of blood, nutrients, progenitors and growth factors through our predesigned vascular structures. Cellular study was also conducted to prove scaffolds’ effectiveness in enhancing cell growth and tissue formation, and physical characterization was performed to show desirable, bone like characteristics (Figure 3).