I missed that; ctrl-f tendon doesn't find it, but ctrl-f cartilage turns it up. Thanks for bringing it up.

When you hit a certain age "oh my aching joints" is far more relevant to your interests than "brains might survive motorcycle crash", though the brain stuff is admittedly cooler.

Stem cells may not necessary for soft tissue; if you could inject some time-release hormones or steroids or whatnot you might get improved results vis-a-vis what's out there now.