Hey forum how would I go about in order to compute this indefinite integral,

$\displaystyle \int \, (x^2 +1)^2 \, \text{d}x \ ?$

I can't seem to eliminate all $\displaystyle x$-variables using $\displaystyle u = x^2 + 1$. I know I can simply compute it by expanding the integrand but I want to do it using substitution in particular.