Penn scientists develop a new way to re-grow cartilage

April 26, 2011 By Brian M. Schleter, Penn Current

Every day the world over, runners hit the streets, pounding the pavement. Their knees are taking a pounding, too.

As runners well know, cartilage, the shock absorber within the joint, wears down over time and when an injury occurs, it is unable to heal itself. can cause small tears on the cartilage surface that never heal, and get worse with time. Trauma and are the primary culprits for sidelining jogging enthusiasts and weekend warriors alike.

When and rest no longer do the trick, it may be time for surgery. And while bone-grafting procedures have been used for decades, cartilage repair with new therapies is rapidly expanding. Minimally invasive and involves harvesting healthy cartilage from one site and transplanting the tissue to the defective area. Another approach involves growing new in a lab and re-injecting the cells to replace worn cartilage.

A group of Penn scientists working across disciplines—in this case engineering and medicine—has developed a novel way to allow patients to re-grow cartilage in their own bodies, using their own cells, directly in the site that has been damaged through injury or disease.

Penn Engineering Associate Professor Jason Burdick says the breakthrough represents a new way of thinking about tissue regeneration. The work could lead to new, more effective therapies that offer longer-lasting results.

Additionally, because the cells are taken directly from the patient, they don’t cause an immune response, unlike current grafting and repair technologies, so there is no risk the body will reject the implanted cells.

“We’re thinking about materials that can actually interact with the , whereas most people are thinking about inert materials that can provide only a framework” for new tissue to grow, Burdick says. “Our lab is interested in making new materials that can give us new functionality that is not currently available.”

A key first step to the growing pursuit of new biomaterial solutions begins with developing a fundamental understanding of the material properties of cells that make up cartilage. Since coming to Penn in 2005, Burdick and his team have looked at how the ingredients of cartilage change with time.

Working with Penn Associate Professor of Orthopaedic Surgery Robert Mauck in the McKay Orthopaedic Research Laboratory, they’ve studied the mechanical properties of these tissues, as well as the influence of mechanical loading on cells. Now, they are moving to the next phase: applying what they’ve discovered to translational therapies.

“A lot of our projects are based on a fundamental understanding of how cells interact with their surrounding microenvironment and using synthetic materials as a mimic for those interactions,” Burdick explains. “Being able to control the synthetic materials allows us  to probe questions about microenvironment chemistry, mechanical properties and other cues.”

Experiments in ovine models are being pursued  with adult stem cells, usually taken from bone marrow, and mixed with a hyaluronic acid hydrogel solution and injected into the troubled joint, where the stem cells are biologically instructed to regenerate into cartilage-forming cells. An ultraviolet light source is needed to form the material in the defect, but visible light works as well. The process is similar to how dentists fill tooth cavities.

Burdick cautions that it will likely be several years before the process is ready for clinical testing in humans.

Of one thing he is certain: As the active baby boomer generation ages, there will be great demand for new cartilage replacement therapies.

“One of the things that I really like about this field is that there are so many people with personal stories about how this could help,” he says. “I think many of us can appreciate the widespread application of such technology.”

Explore further: Stems cells might help repair joints

Related Stories

Stems cells might help repair joints

February 7, 2007

U.S. scientists have built a unique weaving machine that creates a three-dimensional fabric "scaffold" to repair joints with a patient's own stem cells.

Embryonic stem cells used to grow cartilage

September 6, 2007

Rice University biomedical engineers have developed a new technique for growing cartilage from human embryonic stem cells, a method that could be used to grow replacement cartilage for the surgical repair of knee, jaw, hip, ...

Growing Cartilage from Stem Cells

October 20, 2009

( -- Damaged knee joints might one day be repaired with cartilage grown from stem cells in a laboratory, based on research by Professor Kyriacos Athanasiou, chair of the UC Davis Department of Biomedical Engineering ...

Bone formation from embryonic stem cells

October 22, 2009

Jojanneke Jukes of the University of Twente, The Netherlands, has succeeded in growing bone tissue with the help of embryonic stem cells for the first time.

Recommended for you

How the finch changes its tune

August 3, 2015

Like top musicians, songbirds train from a young age to weed out errors and trim variability from their songs, ultimately becoming consistent and reliable performers. But as with human musicians, even the best are not machines. ...

Cow embryos reveal new type of chromosome chimera

May 27, 2016

I've often wondered what happens between the time an egg is fertilized and the time the ball of cells that it becomes nestles into the uterine lining. It's a period that we know very little about, a black box of developmental ...

Shaving time to test antidotes for nerve agents

February 29, 2016

Imagine you wanted to know how much energy it took to bike up a mountain, but couldn't finish the ride to the peak yourself. So, to get the total energy required, you and a team of friends strap energy meters to your bikes ...


Adjust slider to filter visible comments by rank

Display comments: newest first

5 / 5 (1) Apr 26, 2011
Great. My knee hurts so much when I use it because of a cartilage injury. It feels like my knee cap is going to come out. I hope this can help me not feel so OLD.....LOL
5 / 5 (1) Apr 27, 2011
Fingers crossed that it works, and fingers crossed that it isn't offered at a gouging price. After all, it isn't like people in pain won't pay almost any price to alleviate severe suffering.
not rated yet Apr 27, 2011
not rated yet Apr 27, 2011
I ran all the cushion off being addicted to cross country hills rain or shine. I need to get into this study. Find a way to get this process to Kaiser here in California. I am so sad because of my knee stiffness and pain. We will figure this out...
not rated yet Apr 27, 2011
Depends on what kind of cell structure they get. Autografts (regrown material from cartilage taken by biopsy) have already been tried. The problem is that such regrown cells don't exhibit the very ordered filament structure of knee cartilage:

- parallel fibers to the bone surface close to the bone
- orthogonal fibers in the intermediate layer
- parallel fibers where cartilage touches cartilage

If you grow an unstructured clump of cells then the biomechanical properties aren't the same and you'll again get problems at the autograft site after a relatively short time.
not rated yet Apr 28, 2011
This Penn State University research is funded by the evil socialist state.

We need to halt this funding and cut government spending.

Since we must keep a strong military at current levels, capable of fighting multiple wars on multiple fronts, to balance the budget all other functions of government must immediately be shut down.

This includes government funding for all medical research.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.