05/24/2022
By Xinchen Wu

The Francis College of Engineering, Biomedical Engineering and Biotechnology Program, invites you to attend a doctoral dissertation defense by Xinchen Wu on “Development of 3D Scaffolds Using Unconventional Mineralized Biomaterials for Bone Tissue Engineering.”

Candidate Name: Xinchen Wu
Defense Date: Tuesday, June, 7, 2022
Time: 1 - 4 p.m.
Location: Southwick 240, North Campus

Committee:

  • Advisor Gulden Camci-Unal, Ph.D., Department of Chemical Engineering, University of Massachusetts Lowell
  • Thomas A. Wilson, Ph.D., Department of Biomedical and Nutritional Sciences, University of Massachusetts Lowell
  • Dongming Xie, Ph.D., Department of Chemical Engineering, University of Massachusetts Lowell
  • Boce Zhang, Ph.D., Department of Food Science and Human Nutrition, University of Florida

Brief Abstract:

Mineralized biomaterials have been demonstrated to enhance bone regeneration compared to their non-mineralized analogs. As non-mineralized scaffolds do not perform as well as mineralized scaffolds in terms of their mechanical and surface properties, osteoconductivity and osteoinductivity, mineralization strategies are promising methods in the development of functional biomimetic bone scaffolds. In particular, the mineralization of three-dimensional (3D) scaffolds has become a promising approach for guided bone regeneration. In this thesis, we studied approaches used for mineralizing tissue engineering constructs. The resulting scaffolds provide growing tissues with minerals chemically similar to the inorganic component of natural bone, carbonated apatite, Ca5(PO4,CO3)3(OH)). Sequential mineralization enables integration of minerals within the 3D structure scaffolds. Sequentially mineralized scaffolds were fabricated to regenerate critical size cranial defects in vivo. The minerals in the scaffolds were confirmed to be hydroxyapatite, which is the major mineral component of natural bone. In vitro experiments were performed to test the physical properties and osteoinductivity of the scaffolds. The subcutaneous implantation of these mineralized scaffolds in vivo demonstrated that the scaffolds were biocompatible and biodegradable. The critical size cranial defects in a rat model exhibited nearly complete bone regeneration when the mineralized scaffolds were implanted in the defect sites. Due to the superior biophysical properties of calcium carbonate over the other calcium-based minerals, incorporation of chicken eggshell microparticles (ESP) into protein-based hydrogels can possibly enhance osteogenic differentiation and bone regeneration. We fabricated ESP reinforced gelatin-based hydrogels to obtain mechanically stable and biologically active 3D constructs that can differentiate pre-mature cells into osteoblasts. Pre-osteoblasts were encapsulated within the ESP-reinforced hydrogels to study their differentiation and evaluate mineral deposition by these cells. The ESP-reinforced gels were then subcutaneously implanted in a rat model to determine their biocompatibility and degradation behaviors. The composite hydrogels have shown outstanding tunability in physical and biological properties holding substantial promise for engineering mineralized tissues. Subsequently, in vivo studies were performed to implant eggshell microparticle-reinforced composite hydrogel scaffolds into critical sized cranial defects in Sprague Dawley (SD) rats for up to 12 weeks to study bone regeneration. The eggshell microparticle-reinforced scaffolds also supported significantly higher bone formation, remodeling, and vascularization over 6 and 12 weeks as confirmed by immunohistochemistry analysis. Collectively, our results indicated that eggshell microparticle-reinforced scaffolds facilitated significant bone regeneration in critical sized cranial defects.