Monday, June 5 | Arthritis
Foundation
What if injured joints could heal themselves before they
develop osteoarthritis (OA)? Dr. James Martin’s current 3-year
Arthritis Foundation-funded project, “Engineering Endogenous Cartilage Repair,”
is trying to do just that- find ways to help joints heal before developing OA.
Dr. Martin and his team use special goats that have defects
in areas of the thigh bones and cartilage, just above the knee. This closely
mimics knee injuries that are seen in humans. The defects are surgically
repaired with a hydrogel matrix that contains two important ingredients: repair
cell attractant and growth factor. The repair cell attractant causes repair
cells, called chondrogenic progenitor cells (CPCs), to migrate into the
hydrogel. CPCs naturally occur in the cartilage. The growth factor, which is
time-released over 10 days, causes the CPCs in the hydrogel to multiply
and repair the injury with new cartilage.
After surgery, the goats are sent to the University of Iowa to heal. Their activity is restricted for 30 days in pens. Then they are allowed to return to pasture, where they spend most of the duration of the study. The injuries are examined with MRI imaging at one and three months. At six months, tissue samples are examined and measurements are made to determine how much healing occurred.
After surgery, the goats are sent to the University of Iowa to heal. Their activity is restricted for 30 days in pens. Then they are allowed to return to pasture, where they spend most of the duration of the study. The injuries are examined with MRI imaging at one and three months. At six months, tissue samples are examined and measurements are made to determine how much healing occurred.
Dr. Martin and his team will begin analyzing the cartilage
repair data this summer. The location of the injury – weight bearing areas vs
non-weight bearing areas – will be an important part of the analyses. “We were
expecting that a weight bearing joint would not respond as well as a non-weight
bearing joint,” Dr. Martin explained. “However, cell culture experiments are
showing that the pressure in a weight bearing joint may be beneficial to the
healing process.”
OA is such a widespread and degenerative disease, affecting
more than 30 million Americans, which is one of the reasons why Dr. Martin is
studying it. He is particularly interested in post-traumatic OA (PTOA) because
you know when an injury occurs and how severe the injury is. The Department of
Defense (DOD) has expressed interest in his work to help treat veterans who are
susceptible to PTOA because of battle or service-related injuries. “This is
very exciting because it may offer a way for young people to avoid years of
pain and eventual joint replacement surgeries,” Dr. Martin explained.
Dr. Martin would like to continue his work with advanced OA.
“One of the problems with OA in older patients is that we don’t know when it
starts, so it develops over decades. While the project I am currently working
on should potentially work well in younger patients, it may work differently in
a more advanced case of OA. We may need a different approach to jump start the
CPCs that are present in an older injury. We may need additional ways to help
begin the healing process,” he said.
Dr. Martin recently published an article on a study that
laid some of the foundation for his current foundation-funded project. The
article, Enhanced phagocytic capacity endows chondrogenic progenitor cells with a
novel scavenger function within injured cartilage, looked at the
role of CPCs in the cartilage healing process. He was awarded a patent and
filed for a second patent on the technology related to his work with the
hydrogel matrix and methods used for cartilage repair.
Dr. Martin is an associate professor at the University of
Iowa. He works in the Department of Orthopedics and Rehabilitation, and the
Department of Pharmaceutical Sciences and Experimental Therapeutics at the
university. This is his first Arthritis Foundation funded project.
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