There are actually several companies producing and manufacturing Type I collagen that is used regularly in commercial medical devices. They don't sell gels, but you can easily make a collagen gel from the micronized Type I collagen they do sell. Off the top of my head, I'd suggest Kensey Nash (http://www.kenseynash.com/kensey-nash-technologies/collagen-technology) and Collagen Matrix Inc. (http://www.collagenmatrix.com/).