Fabrication and Characterization of 3D Printed Scaffold based on PLA/TCP for Bone Tissue Engineering

Abstract

Medical advances have led to a welcome increase in life expectancy. However, accompanying longevity introduces new challenges: increases in age-related diseases and associated reductions in quality of life. The loss of skeletal tissue that can accompany trauma, injury, disease or advancing years can result in significant morbidity and significant socio-economic cost and emphasise the need for new, more reliable skeletal regeneration strategies. To address the unmet need for bone augmentation, tissue engineering and regenerative medicine have come to the fore in recent years with new approaches for de novo skeletal tissue formation. Typically, these approaches seek to harness stem cells, innovative scaffolds and biological factors that promise enhanced and more reliable bone formation strategies to improve the quality of life for many. Synthetic bone substitutes provide an alternative to the limited resources of autografts and the problems which arise when using allogenic and xenogenic grafts. The successful implantation of a biomaterial into bone is determined by the intimate interaction between the implant and the host tissue at the implant/tissue interface. The process of bone cell ingrowth is highly influenced by surface properties and the architecture of the scaffold. A bone graft material should therefore possess sufficient porosity and permeability to allow integration within the native tissue and vascular invasion, and it must satisfy the transport demands for oxygen and nutrients. Porous bone scaffolds can be made by a variety of methods. Chemical/gas foaming, solvent casting, particle/salt leaching, freeze drying, thermally induced phase separation, and foam-gel are some of those that have been used extensively. However, the production of a scaffold with complicated and irregular geometry can be limited by conventional scaffold fabrication techniques. Also, pore size, shape, and its interconnectivity cannot be fully controlled in these approaches. Therefore, recent research efforts have focused on the fabrication of a scaffold with complicated and interconnected pore structure, including several computer-designed scaffold fabrication techniques. In this study, to provide bone grafts of synthetic calcium phosphates (CaP) and PLA(Poly lactic acid), three-dimensional (3D) printing have been used to realize 3D bone-like structures. These technologies allow the design and fabrication of complex scaffold geometries with a fully interconnected pore network. The objective of this research was to carry out an in vitro and in vivo study of the biological performance of 3D printed PLA/β-TCP composite material, to estimate the scope of their potential applications in bone surgery. Samples with increasing β-TCP(0-70% w/w) contents were processed by 3D plotting system. The chemical composition and surface properties of 3D printed PLA/β-TCP were characterized by FT-IR, TGA and SEM. In vitro studies were also done to evaluate the biomineralization activity and the cytotoxic profile of the scaffolds. The in vivo study was carried out using of composite materials composed composite materials containing 50 or 70% β-TCP and pure β-TCP, respectively. This study showed that adding increasing percentages of β-TCP to a lactic acid polymer matrix stimulated the proliferation of mouse osteoblast cells and synthesis of the extracellular bone matrix in a dose-dependent manner. In vivo results indicate that, the composite materials containing 70% β-TCP demonstrated a higher performance in terms of osteogenesis.