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Research / Discovery

Enhancing safety of donated tissues

January 21, 2009

Through a research partnership with AlloSource, Animal Cancer Center researchers are helping to make tissue transplants safer while advancing the science of allograft transplantation for all species.

Advancing medical science

The Colorado State University Animal Cancer Center, or ACC, has long been a leader in the field of limb-sparing surgery, where donor bone is used to replace diseased bone in canine patients with osteosarcoma (bone cancer).

Through a research partnership with AlloSource, ACC researchers are helping to make similar tissue transplants safer while advancing the science of allograft transplantation for all species.

An allograft is cells, tissues, or organs that are transplanted from one person to another (or one dog to another at the ACC). The types of allografts routinely used in human patients include skin, corneal, heart and heart valves, liver, kidney, bone and cartilage, demineralized bone matrix, ligaments and tendons.

(Photo: Assistant Professor Stewart Ryan)

Donor tissues save lives

The tissues come from deceased donors and are used to enhance or save other people’s lives, from using skin grafts for burn victims to using donor bone to save the arm of a teenager, from repairing the knee of a young athlete to restoring vision when eyes are failing.

Stewart Ryan,  an assistant professor in the Department of Clinical Sciences and member of the ACC team, has developed an excellent partnership with AlloSource that has led to numerous research projects including, most recently, a study to identify potential risk factors for bacterial contamination of donor allografts, another study focusing on the translocation of bacteria following death, and a third study looking at the development of an anti-adhesion membrane for spinal surgery.

Transplanting cartilage and bone

In a statistical risk factor study, Ryan works with Paul Morley, an assistant
professor in the Department of Clinical Sciences and epidemiologist with the Animal Population Health Institute at CSU. They are identifying potential risk factors for allograft contamination of donor tissues used in joint restoration. These types of cartilage transplant procedures are being used with increasing frequency in the treatment of individuals with disabling cartilage injury or disease.

“Recently, osteochondral allograft procedures have become increasingly popular
in the orthopaedic community,” said Ryan. “In an osteochondral allograft, where we are transplanting cartilage and bone, we can’t irradiate or sterilize the tissue as we can do with other allografts because these processes adversely affect the biomechanical properties of cartilage and the viability of the chondrocytes, so the risk of disease transmission is always a potential concern. 

Hope to reduce rejection because of bacterial contamination

“Rigorous bacteriological testing of allograft tissues at recovery and during processing is performed to decrease this risk. Too many osteochondral allografts are rejected for transplantation because of bacterial contamination which is a poor use of the gift of donation, as well as time, financial and human resources. With this study, we hope to ensure a positive outcome for patients, as well as identify factors that will lead to better use of resources while increasing the number of allografts available for transplantation in recipients.”

In another related study, researchers are investigating the phenomenon of bacterial translocation after death and how highly infectious bacteria move through the body. Using a rodent model, bacterial solutions are tagged with a marker, fluorescently labeling the bacteria.

Refining models for decontamination procedures

Following death, the bacteria are followed through the body using a special imaging camera at multiple time points. Ryan noted, for example, in humans a highly infectious bacteria can migrate from the respiratory or gastrointestinal tract to regions where these bacteria are not normally found, compromising suitability of those tissues for transplantation. Tissue collection and cooling are important factors in bacterial translocation.

“Other studies have shown that if someone dies of a chronic disease, the risk of bacterial translocation is higher,” said Ryan. “If they die of trauma and there is damage to the organs that may cause an increased risk due to shaking and impact on the internal organs. Right now, we are not able to track bacteria as well as we would like, but we are working on refining the model for application as a means to trial novel decontamination procedures.”

The original story was published on page 26 of the College of Veterinary Medicine and Biomedical Sciences Insight newsletter, Fall 2008.