Fabrication of Biphasic Bone Scaffolds with Highly Connected Inner Porosity and Biomimetic Composition for Regeneration in Large, Load-Bearing Defects

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Author:
Hudock, Maria
Area of Honors:
Biomedical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Jian Yang, Thesis Supervisor
  • Jian Yang, Honors Advisor
  • Xiaojun Lance Lian, Faculty Reader
  • Cheng Dong, Faculty Reader
Keywords:
  • bone scaffold
  • osteoconductivity
  • freeze casting
  • BPLP-PSer
  • Pelodiscus sinensis collagen
  • large segmental defect
Abstract:
Regeneration of large bone defects, such as those originating from severe trauma, bone tumor excision, or debridement of infected implants, remains a challenge: as the size of scaffold required to bridge a defect increases, so does the difficulty of obtaining proper cell infiltration and nutrient and waste exchange throughout the structure. Further, increased porosity for permeability directly conflicts with the goal of increased mechanical strength if the scaffold is to be immediately load bearing. Therefore, for large defects in load-bearing members, an optimal bone tissue scaffold design will balance overall mechanical strength with facilitated access to areas least available to cells and diffusion. Toward this design goal, first, porous scaffolds with biomimetic composition were fabricated from citrate/phosphoserine-based photoluminescent biodegradable polymer (BPLP-PSer) and Pelodiscus sinensis collagen to determine the collagen’s effect on osteoconduction; it was shown that higher collagen content may promote deposition and mineralization of extracellular matrix, though it delays the expression of ALP. Then, biphasic scaffolds components were fabricated: a low-porosity outer phase of BPLP-PSer and hydroxyapatite (HA) for mechanical strength, and a highly porous inner phase created by directional freeze-casting of a BPLP-PSer/collagen/HA slurry. Mechanical strength of the outer phase and integrity and dye infiltration of the inner phase were evaluated; the results indicate directions for improving the mechanical integrity of both phases. The components developed here are steps toward building an optimal scaffold for full-length regeneration in large defects of load-bearing bone.