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Title:Differential human mesenchymal stem cell responses across multi-compartment scaffolds for tendon-bone regeneration
Author(s):Mozdzen, Laura
Advisor(s):Harley, Brendan A.
Department / Program:Chemical & Biomolecular Engr
Discipline:Chemical Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Tendon Bone Junction Regeneration
Collagen-glycosaminoglycan(GAG) Scaffold
Tissue Engineering
Spatially Selective Cues
Abstract:The TBJ is a unique anatomical zone which transmits high tensile loads from aligned, fibrous tendon to stiff bone. Injuries to the rotator cuff account for 4.5 million physician visits per year and an annual 250,000 surgeries in the United States alone. However, current surgical techniques do not provide regeneration at the tendon bone junction (TBJ) and the re-failure rate is extremely high (>90%). This thesis explores approaches to develop a porous collagen-glycosaminoglycan (CG) biomaterial containing overlapping patterns of structural and biomolecular properties to promote TBJ regeneration. Notably, we describe a scaffold containing a gradient interfacial zone between mineralized and non-mineralized CG scaffold compartments. Fabricated via lyophilization, we explore use of diffusion-based approaches to form the gradient interface. We also describe an approach to create an interdigitated interface, and showed composite elastic modulus and failure load increased with increasing interdigitation. Next, we examined cellular response after tensile strain across two multi-compartment scaffold variants, one containing only a mineral gradient (layered) and the other incorporating microstructural alignment characteristic of the native osteotendinous interface (osteotendinous). We found that layered scaffolds induce very little change in nuclear elongation (aspect ratio) or nuclear orientation of human mesenchymal stem cells, while the osteotendinous scaffolds induces an increase in nuclear aspect ratio and alignment with strain. Most notably, cell nuclei and actin fibers were more aligned and aspect ratio was increased at 0% strain in the non-mineralized compartment of the osteotendinous scaffold. This suggests that pore architecture alone was responsible for the cellular response. Finally, we demonstrated orthogonal approaches to both define the elastic modulus and patterned biomolecules (PDGF-BB for proliferation; BMP-2 for osteogenesis) on CG membranes. Using this approach to explore how biomolecular and biophysical cues may work synergistically to direct MSC fate, we saw an increase in proliferation with covalently-bound PDGF-BB, while BMP-2 did not impact proliferation. In the PDGF-BB patterned membranes, we saw that osteogenesis was positively correlated with stiffness but inversely correlated with proliferation. In the BMP-2 patterned scaffolds, osteogenesis was positively correlated stiffness and adipogenesis was inversely correlated with stiffness. These results suggest that mechanical and biomolecular cues play an integral role in cellular response. These platforms each contain the ability to spatially manipulate biomolecular and biophysical cues to elicit cellular response, and will eventually be integrated into a single construct to provide basic cues to enhance TBJ healing and regeneration after injury.
Issue Date:2014-05-30
Rights Information:Copyright 2014 Laura Mozdzen
Date Available in IDEALS:2014-05-30
Date Deposited:2014-05

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