Optimizing the Mineralization of a Silk-Constructed Tendon Enthesis Scaffold
Restricted (Penn State Only)
- Author:
- Tse, Claire
- Area of Honors:
- Biomedical Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Justin Lee Brown, Thesis Supervisor
Justin Lee Brown, Thesis Honors Advisor
Spencer Szczesny, Faculty Reader - Keywords:
- Mineralization
Simulated Body Fluid
Silk
Silk Fibroin
Bone
Calcium
Biomaterial
Polymer
Tendon Enthesis
Enthesis
Scaffold - Abstract:
- At any given time one of the 100 enthesis junctions within the human body could become inflamed, ruptured, or diseased. Rotator cuff injuries are an example of a tendon-bone interface or enthesis injury caused by degeneration and old age. Currently, the most frequently used method for repair is through surgical reconstruction, however, this is accompanied by low restoration of previous tissue structure and high chances of re-injury. Thus, a new approach to repairing enthesis injuries has emerged. Through the creation and transplantation of organizational structures (scaffolds) that mimic the native environment and surface in order to promote patient stem cell differentiation into corresponding tendon and bone cells within the enthesis junction, previous failures in enthesis repair can be addressed. In this research, we focused on recreating the mineralization gradient observed in native enthesis tissues using silk-fibroin (SF) biomaterial. This was done by characterization of mineralization through Alizarin Red S (ARS) staining, scanning electron microscope (SEM), and energy dispersive x-ray spectroscopy (EDS) of various conditions, including varying concentrations of calcium chloride (CaCl2) and simulated body fluid (SBF), durations of submersion in SBF, and presence or absence of a preloading step. Fluorescent staining of human mesenchymal stem cells was conducted to observe mineralized scaffold effects on cell viability. Addition of CaCl2 to SF polymers prior to electrospinning produced nanometer to micrometer fiber diameters on a single surface and CaCl2 was seen incorporated into the polymer on electrospun coverslip samples. The addition of a preloading step for seed crystal formation before mineralization proved crucial for mineral formation. The best mineralization conditions are preloading before mineralization, a 1% CaCl2 addition to 10% silk-fibroin polymers, 4x simulated body fluid concentrations, and mineralization durations between 1 and 3 days.