Cutting-Edge Science Holds Promise for Treating Sports Injuries
Feb. 18, 2000 (Atlanta) -- Growth factors, substances naturally produced by
the body that promote the growth of specific tissues, may be the wave of the
future for treating musculoskeletal injuries, according to a report in the
February issue of The Physician and Sportsmedicine. But doctors say that
more studies are needed before gene therapy and tissue engineering are used in
Because ligaments, tendons, and cartilage have a limited blood supply,
injuries to these tissues are often slow to heal. For this reason, the use of
growth factors in generating cells and tissue is an active area of research.
The authors say that both gene therapy and tissue engineering hold great
promise in treating slow-healing injuries, severe fractures, and arthritis.
"Gene therapy delivers corrected genetic material to cells and tissues
through vectors, or carrier cells," says Johnny Huard, PhD, associate
director of the Pittsburgh Tissue Engineering Initiative and assistant
professor of orthopaedic surgery, molecular genetics, and biochemistry at the
University of Pittsburgh. "And viruses make ideal vectors because of their
ability to invade cells." Huard tells WebMD that illness-causing viral
genes must first be replaced with growth factors.
"Once the corrected genetic material is delivered to the injured area,
it serves as a template for cellular production of growth hormones in muscle,
ligament, or bone," says Huard. "But there's a potential for
overproduction and mutation of these transferred genes. That's why it's only
used to treat cancer, muscular dystrophy, and cystic fibrosis." Huard says
that regulatory enhancements in gene therapy will allow for use in combination
with tissue engineering.
"Tissue engineering involves using biological substitutes to reconstruct
musculoskeletal tissue. And recently, genetic modifications have been combined
with these substitutes to optimize the healing process," says Huard.
"In large injuries or when blood supply is inadequate, genetically
engineered tissue acts as scaffolding for rebuilding injured cartilage."
Huard tells WebMD that tendons from cows have been used to rebuild human knee
tissue, and other research in this area is underway.
"This summer, we're beginning the second phase of a gene therapy trial
for rheumatoid arthritis in conjunction with Harvard," says Paul Robbins,
PhD, a professor of molecular genetics and biochemistry at the University of
Pittsburgh. "And similar studies are getting underway at the University of
Michigan and in the Netherlands." But Robbins tells WebMD that gene
research has already shown that joint spaces are an effective route of
"Local gene therapy for rheumatoid arthritis involves injecting the
joint with genetically modified cells. These cells then line the joint and
reproduce therapeutic genes," says Robbins. "With this ex vivo [outside
the body] approach, the cells are genetically modified in the laboratory. But
in the future, it may be possible for a viral vector to safely modify cells
within the joint itself. And with this simple and inexpensive in vivo [inside
the body] approach, gene therapy may one day become routine treatment."
- A report on the treatment of musculoskeletal injuries says that gene
therapy and tissue engineering are the wave of the future.
- Gene therapy delivers corrected genetic material into the cell, acting as a
template for the cellular production of growth hormones in the muscle,
ligament, or bone.
- Tissue engineering involves using biological substitutes to reconstruct
tissue by providing scaffolding-like structure for rebuilding injured