Disclosed are methods and compositions to genetically modify substantially intact cells having cosmetic function to enhance the cosmetic appearance in mammals so as to enhance and/or maintain a biochemical and/or physiological process that has a positive effect on cosmetic appearance. The methods and compositions may provide cosmetic benefits such as reduced skin sagging, increased skin thickness, reduced wrinkles, increased skin thickness and collagen content, increased skin tone and elasticity, increased skin hydration, and improved skin texture and color.