Treatment of intervertebral disc degeneration

A method for preventing or retarding degeneration of intervertebral disc at an intervertebral disc defect site of a mammal comprising:

• a) inserting a gene encoding a protein having intervertebral disc regenerating function into a first mammalian cell to provide a transduced first mammalian cell;
• and
• b) transplanting a mixture of the transduced first mammalian cell of a) and an unmodified second mammalian cell into the intervertebral disc defect site of the mammal,
• wherein the first mammalian cell is human embryonic kidney cells or epithelial cells, and wherein the second mammalian cell is connective tissue cells.