Development of an Ipsc Progenitor Loaded Biomimetic Scaffold for Spinal Cord Repair Applications
Creators: name: O' Connor, Cian
Publisher: name: Royal College of Surgeons in Ireland
Year: 2024
Subjects: classificationCode: 300199
subject: Agricultural biotechnology not elsewhere classified
classificationCode: 310199
subject: Biochemistry and cell biology not elsewhere classified
classificationCode: 320999
subject: Neurosciences not elsewhere classified
classificationCode: 320606
subject: Regenerative medicine (incl. stem cells)

description: Following spinal cord injury, a complex scar forms around the resultant lesion cavity, creating an unsupportive environment and preventing axonal regrowth through the injury site, attenuating the recovery of sensorimotor control. Despite the ongoing development of cell replacement therapies recovery remains a challenge due to the lack of a supportive environment for transplanted cells and reduced cell viability following implantation. Biomaterial scaffolds that match the physicochemical properties of the native cord and bridge the lesion cavity with a supportive environment while simultaneously delivering trophic progenitor cells to support axonal regrowth may have the potential to overcome these challenges. Therefore, the objective of this thesis was to develop a biomimetic scaffold capable of supporting neurons, astrocytes, and trophic induced pluripotent stem cell (iPSC) progenitors and to determine the effectiveness of the scaffold platform for spinal cord repair applications.
Chapter 2 aimed to develop a biomimetic scaffold and validate its design for spinal cord applications. Soft (0.9 Pa) hyaluronic acid scaffolds with similar mechanical properties to the native spinal cord (&lt; 1 kPa), functionalized with the identified composition of cord native extracellular matrix proteins, collagen-IV and fibronectin, facilitated immunomodulation of astrocytes towards a neurotrophic phenotype and promoted neurite growth from neurons throughout the scaffold. The findings within this chapter thus demonstrated the successful development of a novel, ‘off-the-shelf’ biomimetic scaffold and showed that the interaction of scaffold stiffness and matrix composition plays an essential role in mediating astrocytic and neuronal responses.
In Chapter 3, the potential of utilising the biomimetic scaffolds developed in Chapter 2 to support trophic iPSC progenitor cells as a therapeutic cell delivery platform was assessed. Scaffold stiffness and matrix composition synergistically affected iPSC progenitor behaviour where soft, collagen-IV &amp; fibronectin functionalized scaffolds enhanced progenitor cell viability, morphology and infiltration, the release of brain-derived neurotrophic factor and functional capacity to uptake glutamate. These findings demonstrated that these soft biomimetic scaffolds can be used as an effective platform to support trophic iPSC progenitors and that optimizing scaffold properties has significant implications for the behaviour and viability of cells seeded in scaffolds.
As the application of the iPSC-seeded scaffolds to effectively be utilized for spinal cord repair applications remained to be explored, Chapter 4 aimed to determine if the cell-seeded scaffolds platforms could successfully be employed to promote the regrowth of neural tissue. Soft, collagen-IV &amp; fibronectin functionalized scaffolds significantly enhanced the neurotrophic potential of the scaffold-seeded progenitor cells to promote spinal cord neurite outgrowth in vitro without eliciting negative glia-trophic responses in healthy and injured astrocytes. Finally, softer scaffolds promoted cellular infiltration, increased astrocyte process numbers and axonal extension towards iPSC progenitors from aged neural tissue explants that have a reduced intrinsic capacity to regrow.
Collectively, the research presented in this thesis describes the development and utilization of a biomimetic scaffold platform and demonstrates that biomimetically inspired scaffolds can enhance the growth of cord resident neurons and astrocytes and promote the neurotrophic potential of implanted progenitor cells to enhance neurite growth to act as a novel platform for spinal cord injury repair applications.