Texas A&M Researchers Prove Mammalian Joint Regeneration Possible
Posted February 07, 2019
Research by Texas A&M College of Veterinary Medicine &
Biomedical Sciences (CVM) professor Ken Muneoka and his colleagues
has opened the doors to the future possibility of regenerating
joints in mammals.
study, “BMP9 stimulates joint regeneration at digit amputation
wounds in mice,” published Feb. 5 in Nature Communications, expands
on previous research conducted by his laboratory showing that the
treatment of digit amputation wounds in mice with a growth factor,
called bone morphogenetic protein BMP-2, promotes elongation of the
In that study, however, the joint and additional skeletal
elements were not regenerated.
Now, Muneoka’s team has devised a method to stimulate joint
regeneration following injury in mice using a combination of growth
That growth factor, BMP-9, stimulates the formation of joint
structures comprising a synovial cavity and a skeletal element
lined with articular cartilage, while the sequential treatment of
the wound with BMP-2 and BMP-9 leads to the formation of bone and
The authors found that the process also requires cells to
express the Prg4 gene to initiate the formation of
the synovial cavity.
Unlike amphibians and reptiles, mammals have poor regenerative
capabilities, and in response to an amputation or traumatic injury,
scar tissue normally forms at the site of the wound.
The authors argue that the results provide evidence that cells
in a mammalian amputation wound retain the capacity and information
for joint regeneration.
“We have been working on this project for nine years, and there
are really two different levels that we can talk about with the
study,” Muneoka said. “The first is really a basic science issue;
it’s the question of why some animals regenerate and some can't.
For example, salamanders regenerate wonderfully, but mammals, for
reasons we don't understand, don't regenerate it all.
"There's this basic idea that regeneration is really an ancient
property that evolved very early and then disappeared in some
animals and has been regained in some animals,” he said. “There's
good evidence that there is selective pressure to gain or lose
“The other level, which is more clinically relevant, is that
joints and joint tissues don't regenerate, nor does articular
cartilage, which forms at the ends of your bones and buffers the
stress that we experience on a day-to-day basis. Joint injuries,
sports injuries, or diseases like osteoarthritis, are really
debilitating; I think they are the biggest cause of disability in
the world,” he continued. “The question of how you can replace
articular cartilage is in the backdrop of what we've been working
on, which is what we're able to regenerate in this process. It
really demonstrates that these cells have the ability to replace
themselves and we just haven't figured out how to do that.”
Larry Suva, head of the CVM’s Department of Veterinary
Physiology & Pharmacology (VTPP), said that what’s truly
incredible about Muneoka’s work is its transformative nature,
bringing to mind the Nelson Mandela quote “It always seems
impossible until it’s done.”
“Until this information comes out, the field, the world,
basically thinks mammals can't regenerate a joint. Dr. Muneoka’s
work suggests that it is possible—you can regenerate portions of a
joint in an animal and recapitulate that structure,” Suva said.
“That has a whole variety of translational potentials that may be
far down the road, but the road didn't exist until somebody did the
impossible and showed that you could run.
“Dr. Muneoka's a scientist's scientist and he's progressing
through this project to understand how each of those tissues can be
regenerated,” Suva said. “It might be a long time—after all of our
lifetimes—before someone actually regrows an amputee's or a war
victim's limb, but nobody was even thinking about it (before)
because we couldn't get past regenerating a joint."
Muneoka said he is thankful for the support he has received at
the CVM and in the VTPP department.
“It's terrific to have the level of support, both financial and
moral support that we're doing the right thing, that I have at the
CVM,” he said. “That support was a big factor in my coming to Texas
The next step in the study, he says, will be exploring the
engineering of an articular cartilage.
The paper is available online at https://www.nature.com/articles/s41467-018-08278-4.
For more information about the Texas
A&M College of Veterinary Medicine & Biomedical Sciences,
please visit our website at vetmed.tamu.edu or join us on Facebook, Instagram, and Twitter.
Contact Information: Megan Palsa, Executive Director of
Communications, Media & Public Relations, Texas A&M College
of Veterinary Medicine & Biomedical Science; email@example.com;
979-862-4216; 979-421-3121 (cell)
↑ Back to Top
« Back to Press Releases