Browsing by Author "Wang, Lisheng"

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    The Effect of The Notch Signalling Pathway Inhibition on The Osteogenic Differentiation of Pluripotent Stem Cells
    (2022-04) Helmi, Summer Ahmed Mahmoud; Rancourt, Derrick Emile; Jamniczky, Heather; Kurrasch, Deborah; Wang, Lisheng; Cobb, John
    Critical size bone defects are a common problem in orthopedics; a critical-size bone defect is a defect larger than 1.5 times the diameter of the injured bone. The most common causes of critical size bone defects are trauma, tumor excision, and infection. The treatment options for critical-size bone defects are very challenging, primarily with underlying chronic conditions like osteoporosis and diabetes. Bone is a dynamic and highly specialized connective tissue due to its unique regeneration capability. However, if the bone defect is large, it would require grafting to heal properly as this defect will not heal by itself if left untreated. Induced Pluripotent stem cell-based cell therapies for bone regeneration involve reprogramming a patient’s cells into iPSC and re-directing them to differentiate into the osteoblast lineage, then culturing them onto a scaffolding system that provides structural and functional support to the differentiated cells. Appropriate scaffolds and the careful use of bioactive molecules to enhance the differentiation outcome are vital components for successful iPSC-based tissue engineering. These combinations considerably impact bone cell-material interactions that guide bone regeneration and improve bone healing and regeneration processes. The Notch signalling pathway is highly conserved in cell fate determination throughout the animal kingdom and plays a role in the terminal differentiation in various tissues. The Notch signalling pathway was proven to enhance self-renewal and inhibit differentiation of bone progenitors. In the first part of this thesis, we explored the effect of inhibiting the Notch signalling pathway on mouse pluripotent stem cells. The results showed that inhibiting the Notch signalling pathway enhanced the differentiation of mouse pluripotent stem cells to osteoblasts. Moving forward, in the second part of the thesis, we explored if inhibiting the Notch signalling pathway in human pluripotent stem cells will have a similar advancement in the differentiation to bone cells. The results showed significant improvement in the osteogenic differentiation outcome compared to control cultures. In the third part, we tested the effect of Notch inhibition on the osteogenic differentiation of human induced pluripotent stem cells in vivo in an ectopic bone formation model. Collagen scaffolds mixed with DAPT Notch inhibitor guided and enhanced the osteogenic differentiation of human iPSC to tumor-free bone tissue. This approach can significantly accelerate the bone generation and healing of critical-size bone defects in normal patients and patients with underlying debilitating conditions.