Having previously regenerated bone in mice using the BMP2 protein, scientists then added BMP9:
When using the combination on mice with amputated toes, over 60 percent of the stump bones formed a layer of cartilage within three days. Without the proteins, the amputated toes would’ve healed over as normal.
That cartilage is a key part of joints, and shows definite progress in limb regeneration. Even in animals who can naturally regrow lost limbs, it’s rare to see joint as well as bone growth.
“These studies provide evidence that treatment of growth factors can be used to engineer a regeneration response from a non-regenerating amputation wound,” explain the researchers in their paper.
The results of the study showed that the regeneration process was most advanced when BMP2 was applied first, with BMP9 added a week after – in this case it led to the growth of more complete joint structures, even with some connections to the bone.
Sounds like a potential cure for arthritis. Maybe people who have all the cartilage worn off on a joint can regrow it with these proteins.