The present invention relates to gene and cell therapy using a cell fusion technology and more particularly, cells overexpressing hemagglutinin neuraminidase (HN) and fusion (F) proteins have effects of enhancing cell fusion with other cells, restoring cell damage through the cell fusion with damaged cells, and transferring a normal gene. Therefore, when a vector including genes encoding the HN and F proteins of the present invention or a cell transformed with the vector is clinically applied to neurodegenerative diseases, muscular diseases, and the like, an effect of reducing the damage of damaged cells through cell fusion can be expected.