A method to stimulate joint regeneration following injury in mice using a combination of growth factors is reported in Nature Communications this week.

Mammals have poor regenerative capabilities, and in response to an amputation or traumatic injury, scar tissue normally forms at the site of the wound. Previous research has shown that treatment of digit amputation wounds in mice with a growth factor, called bone morphogenetic protein (BMP) 2, promotes elongation of the stump bone. However, the joint and additional skeletal elements were not regenerated.

Ken Muneoka and colleagues report that in mice, treatment with another factor called BMP9 stimulates the formation of joint structures comprising a synovial cavity and a skeletal element lined with articular cartilage. However, the authors found that the process also requires cells to express the Prg4 gene to initiate the formation of the cavity. In addition, they show that sequential treatment of the wound with BMP2 and BMP9 leads to formation of bone and joint cells.

The authors argue that the results provide evidence that cells in a mammalian amputation wound retain the capacity and information for joint regeneration.