Freeze-dried gene-treated implants effective in repairing injured tendons

January 13th, 2008 - 1:29 pm ICT by admin  

London, Jan 13 (ANI): A research team from University of Rochester Medical Center is developing freeze-dried implants loaded with gene therapy solution that can help repair injured and difficult-to-treat tendons in patients with orthopaedic injury.

The researchers said that the new technique of using the so-called allografts inserted with therapeutic genes offers orthopaedic surgeons a better approach in treating common sports injuries such as anterior cruciate ligaments and rotator cuffs.

The study was conducted in a mouse model designed to resemble hard-to-repair flexor tendons in human hands.

Tendons are elastic cords that anchor muscle to bone and enable flexing muscle to move limbs. In many standard repair attempts, surgeons implant an autograft, a piece of tendon from elsewhere in the same patient. Along with requiring patients to sacrifice tendon, the problem with live autografts is that both the graft and the graft site know they have been injured.

That signals immune cells and chemicals to rush into the graft site, seeking to fight infection. Unfortunately, those same processes cause inflammation and scarring, which in turn cause implanted tendon to stick to the joint. To work properly, the tendon must be free to glide across the joint. Tendon adhesions, a longstanding post-surgical problem, cause pain and permanently limit range of motion.

The latest technique uses donated, freeze dried implants, known as allografts, loaded with a gene therapy solution, which directed the recipient’s cells to accept the graft and remodel it into living tissue.

The mice experiments showed that the use of allografts loaded with gene therapy solution led to significantly fewer adhesions.

At 28 days after surgery, the mice who received these implants had recovered nearly 65 percent of the normal range of motion.

On the contrary, animals given an allograft loaded with a non-therapeutic gene had recovered only 35 percent of the normal range.

“Tendon is very durable. It could conceivably be freeze-dried, thawed and then freeze-dried again without damaging it. It could be left on shelves at tissue banks indefinitely and then shipped long distances, BBC quoted Dr Regis O’Keefe, who also worked on the study, as saying.

“To get it ready for surgery, you would thaw it in a solution containing growth factors, cut it to size on the spot and implant it.

“While we acknowledge that this work is in mice, that there are differences between species and that more work needs to be done, we believe these results promise practical yet dramatic improvements in reconstructive surgery, he added.

Dr Steve Bollen, president of the British Orthopaedic Sports Trauma Association, said allografts were used in the UK, but only for intricate reconstruction and revision cases, and not accompanied by gene therapy.

“Gene therapy is a field which is going to take off in a serious way over the next five to 10 years. It holds great promise for being to able to manipulate tissue to become more like that of the host, but it is still very early days, Bollen said.

The study is published in Molecular Therapy. (ANI)

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