In vivo monitoring of differentiation specific surface antigen expressing neural stem cells with thermosensitive hydrogel

Abstract

A stroke is caused by an obstruction within a blood vessel supplying blood to the brain. Although stroke remains a leading cause of disability and death, effective treatments for acute stroke are currently very limited. Recently, researchers have been studying the application of stem cells in the therapy of ischemic stroke. However, many issues related to stem cell therapy still need to be resolved, including the low cell viability, difficulty in the tracking of stem cell differentiation, and low cell engraftment after transplantation. To solve this problem, we created permissive niches for the transplanted cells through the use of a thermosensitive hydrogel as a promising approach for ischemic stroke therapy. A thermosensitive hydrogel has characteristics similar to those of the extracellular matrix, and has been recently used for tissue regeneration. In the present study, thermosensitive hydrogels were created with chitosan, collagen, and NaOH to mimic the extracellular microenvironment for tissue regeneration. We further provided various cytokines that are closely related to differentiation to support the survival and differentiation of neural stem cells. To resolve the problem in the tracking of stem cell differentiation, we used a neuron-specific promoter-based fluorescence reporter system with the synapsin I gene, which shows neuron-specific and developmentally regulated expression, along with red fluorescent protein (SYN-RFP) as an in vivo differentiation tracking system. RFP effectively reflected SYN expression during differentiation, indicating the ability of SYN-RFP reporter neural stem cells for the tracking of neurons. The proposed in vivo monitoring differentiation-specific SYN-RFP reporter system of neural stem cells and thermosensitive hydrogels are expected to contribute to the development of a new therapy for ischemic stroke.