Fabrication and Characterization of Three-Dimensional Electrospun Scaffolds for Bone Tissue Engineering

Abstract

There are 600,000 bone-grafting procedures performed annually as a result of significant skeletal loss and bone deficiencies. This is an increasing worldwide medical issue as the average life expectancy increases 2–3 % annually. The current standards for bone treatment are autografts and allografts; both of which have drawbacks. Therefore, there is a need for alternative bone graft substitutes such as tissue-engineered grafts. Tissue engineering has emerged as a promising option for bone treatments by using biological or synthetic scaffolds to promote tissue regeneration. The advantages of this treatment include abundant supply and customizable features. The majority of scaffold fabrication techniques used in research focuses on mimicking the porous trabecular bone structure. A major characteristic of optimal scaffold integration and viability is vascularization, which is housed within the osteon canal of the cortical bone. Namely, there is a lack of tissue-engineered scaffolds for bone regeneration that mimic both trabecular and cortical bone structures. In this study, we combined two previously fabricated structures, sintered electrospun sheets and individual osteon-like scaffolds, to create scaffolds that mimic dual structural organization of the native bone with cortical and trabecular regions. Scaffolds were successfully mineralized in 10× simulated body fluid (SBF) up to 48 h with enhanced mineral distribution throughout the scaffolds. Mineralization for 24 h significantly increased mechanical properties of the scaffolds. In vitro studies performed over 28 days with mouse-pre-osteoblastic cells, MC3T3-E1s, proved that the mineralized scaffolds promoted cellular attachment, proliferation, and early stages of osteoblastic differentiation in comparison to the non-mineralized scaffolds. The implications of this study lead to the advancement of tissue-engineered mineralized trabecular and cortical bone scaffolds. The use of tissue-engineered scaffolds to harness a patients' own bone regenerative properties following traumatic bone loss has emerged as an alternative to current bone-grafting procedures. In this manuscript, the development and characterization process of a synthetic scaffold which mimics both the porous trabecular bone structure and dense cortical bone structure is discussed. Qualitative analysis confirmed the biomimetic porous structure necessary for nutrient transport and cellular infiltration and the cortical canal structure to house vascularization. Various mineralization techniques were investigated to determine the optimal mechanical properties. The scaffold also exhibited the ability to promote osteoblastic cellular attachment and proliferation. The mineral content deposited onto the scaffold led to an increase in osteoblastic behavior of the attached cells; suggesting early stages of osteogenesis. The results of this manuscript indicate the potential of utilizing a tissue-engineering scaffold as a promising treatment for bone tissue regeneration applications.