Final Report Summary - SCINSCEF (Repair Spinal Cord Injury by Controlling Migration of Neural Stem Cells - multidiciplinary approaches of electric stimulation and nanotechnology)
Millions of people worldwide suffer from spinal cord injury (SCI), with devastating consequences and costs. Various treatments have been proposed clinically to treat spinal cord injury with little satisfaction due to the limited self-regeneration capacity of the neurons. Neural stem cell transplantation is a promising treatment with great potential in treating SCI, however the mechanisms regulating the grafted stem cells is unclear. We propose in the project to use electric stimulation to promote neural regeneration, and to explore the mechanisms underpinning such event.
Neural stem cells require delicate surrounding environment to support their adhesion and migration, and growth factors (for example epidermal growth factor or EGF, and fibroblast growth factor or FGF) to maintain the stem cell functions. This project used interdisciplinary approaches to combine neural stem cells transplantation with electric stimulation and engineered nanomaterials, to optimize a novel stem cell replacement therapy. We rationally designed hydrogel nanofibers which could be functionalised to bind essential peptides for neuronal behaviours onto the nanomaterials, to provide a favourable stem cells niche for the transplantation study. We have demonstrated the roles of certain genes (for example PI3 Kinase) in the regulation of neural stem cell migration in spinal cord injury model.
We established the organotypic spinal cord injury model to study the cellular behaviours of the grafted neural stem cells, and showed that physiological electric stimulation could precisely regulate the directed migration of transplanted neural stem cells within the spinal cord tissue in 3D environment. We further investigated the interactions between electric signals and the chemical guidance cues, and demonstrated that EGF and bFGF are both required in the electrotactic regulation of neural stem cells, and the combination of EGF/bFGF and electric signals could synergistically elevate the directed cell migration response of neural stem cells.
One of the major problems to evaluate the effect of stem cells replacement therapy in treating spinal cord injury, is how to identify the behaviours of the transplanted stem cells post transplantation. Conventional method of cell tracking is restricted to time-point data collection post operation, however this means inevitable sacrifice of large numbers of experimental animals, impossible to record the cellular response and functional recovery post transplantation in an accurate / comparable way on the same animals, and more importantly impossible to translate into human trails in the future. Superparamagnetic nanoparticle based MRI scanning has been studied in the past to be able to track the transplanted cells non-invasively in a real-time fashion, however the commonly used nanoparticle contrasting agent (iron oxide, etc) can be toxic to stem cells, especially at high concentration. We rationally designed a novel CoPt nanoparticle in this project, which showed more superior MRI contrasting efficiency, with hollow structure to reduce the cell toxicity. We proved the safety and efficiency of the nanoparticle in maintaining neural stem cells functions and neuronal differentiation capacity in both culture dish and 3D organotypic spinal cord culture model.
We also investigated the role of ion channels in the regulation of electric field triggered cell recruitment in the injury repair, and proved that potassium channel Kv1.2 is one of the key regulators in such control. We further proved that cell adhesion molecule integrin is essential in the of electrotactic response, regulated by kindlin-1 gene.
We proved that microglia / macrophage also plays an important role in the regulation of neuronal behaviours as a crosstalk manner, which suggests that immune modulation in central nervous system is pivotal in a successful clinical treatment and should be looked into in greater details in the near future.
Neural stem cells require delicate surrounding environment to support their adhesion and migration, and growth factors (for example epidermal growth factor or EGF, and fibroblast growth factor or FGF) to maintain the stem cell functions. This project used interdisciplinary approaches to combine neural stem cells transplantation with electric stimulation and engineered nanomaterials, to optimize a novel stem cell replacement therapy. We rationally designed hydrogel nanofibers which could be functionalised to bind essential peptides for neuronal behaviours onto the nanomaterials, to provide a favourable stem cells niche for the transplantation study. We have demonstrated the roles of certain genes (for example PI3 Kinase) in the regulation of neural stem cell migration in spinal cord injury model.
We established the organotypic spinal cord injury model to study the cellular behaviours of the grafted neural stem cells, and showed that physiological electric stimulation could precisely regulate the directed migration of transplanted neural stem cells within the spinal cord tissue in 3D environment. We further investigated the interactions between electric signals and the chemical guidance cues, and demonstrated that EGF and bFGF are both required in the electrotactic regulation of neural stem cells, and the combination of EGF/bFGF and electric signals could synergistically elevate the directed cell migration response of neural stem cells.
One of the major problems to evaluate the effect of stem cells replacement therapy in treating spinal cord injury, is how to identify the behaviours of the transplanted stem cells post transplantation. Conventional method of cell tracking is restricted to time-point data collection post operation, however this means inevitable sacrifice of large numbers of experimental animals, impossible to record the cellular response and functional recovery post transplantation in an accurate / comparable way on the same animals, and more importantly impossible to translate into human trails in the future. Superparamagnetic nanoparticle based MRI scanning has been studied in the past to be able to track the transplanted cells non-invasively in a real-time fashion, however the commonly used nanoparticle contrasting agent (iron oxide, etc) can be toxic to stem cells, especially at high concentration. We rationally designed a novel CoPt nanoparticle in this project, which showed more superior MRI contrasting efficiency, with hollow structure to reduce the cell toxicity. We proved the safety and efficiency of the nanoparticle in maintaining neural stem cells functions and neuronal differentiation capacity in both culture dish and 3D organotypic spinal cord culture model.
We also investigated the role of ion channels in the regulation of electric field triggered cell recruitment in the injury repair, and proved that potassium channel Kv1.2 is one of the key regulators in such control. We further proved that cell adhesion molecule integrin is essential in the of electrotactic response, regulated by kindlin-1 gene.
We proved that microglia / macrophage also plays an important role in the regulation of neuronal behaviours as a crosstalk manner, which suggests that immune modulation in central nervous system is pivotal in a successful clinical treatment and should be looked into in greater details in the near future.