Effects of intranasal neural stem cells transplantation on olfactory epithelium regeneration in an anosmia-induced mouse model.

This study aims to investigate the efficacy of intranasally transplanted neural stem cells (NSCs) in anosmia-induced mice. Twenty-four male mice were included in the study. A food-finding test (FFT) was performed beforehand to confirm that all mice had normal olfactory functions. The mice were then randomly divided into two groups (Groups 1 and 2) and anosmia was induced by 3-methylindole (3-MI). In the first week following the 3-MI injection (week 1), mice in Group 1 received intranasal saline, while mice in Group 2 received intranasal NSCs. The NSCs were prepared from green fluorescent protein (GFP)-transgenic mice. Olfactory function was evaluated through weekly FFTs. One week after NSC or saline administration (week 2), half of the mice in each group were randomly selected and sacrificed for histological examination. The remaining mice were sacrificed for histological examination in week 4. At week 4, the olfactory epithelium of all mice was also examined by polymerase chain reaction (PCR) to detect GFP + cells. The NSC group showed significantly shorter FFT times compared to the saline group. Epithelial damage scores, indicating greater injury, were higher in the saline group, whereas the NSC group exhibited greater epithelial thickness. Immunohistochemical analysis revealed a significantly higher number of olfactory marker protein-expressing cells in the NSC group. GFP + cells were observed in olfactory bulb (OB) and olfactory epithelium (OE) in the NSC group. PCR confirmed the presence of the GFP gene in the OE of NSC-transplanted mice. Intranasal NSCs promoted functional recovery and GFP + cell integration, supporting further research into their therapeutic potential for olfactory dysfunction.