For those with serious hair loss, you might want to consider Matristem ACell + PRP treatment.
ACell is, to put it very simply, a stem cell activator. Originally designed to minimize (and in some cases) prevent surgical scarring, hair restoration surgeons discovered that sites where they removed hair, when treated with ACell, not only had minimal scarring but often had new hair growth.
This has expanded now to a full set of treatments without hair transplants in many cases, that restores hair to much denser quantities than existed previously.
In my own case, I am a type 6 hair loss candidate (yes, horribly horribly bad!) and am hoping that I can generate enough new hair on top to then make transplants worthwhile, which right now they are not.
In Google (or Bing or your favorite search engine) search for Matristem ACell hair restoration to find more articles about the technique.