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AAOS Now

Published 3/1/2003
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Annie Hayashi*

Fluorescent real-time imaging could transform sarcoma treatment

“Glowing proteins” allow investigators to visualize dynamics of cancer cells

“Real-time in vivo imaging of sarcoma cells has enabled us to visualize cell mobility, invasion, metastasis, and angiogenesis,” said Katsuhiro Hayashi, MD. “If this technology were applied to orthopaedic surgery, it would enable surgeons to visualize nerve or vessels with fluorescent protein and avoid injuring or damaging them.”

Dr. Hayashi and his colleagues presented their imaging technique and a video of how fluorescent proteins are used in real time as part of their scientific exhibit 70, “Innovative technology for real-time fluorescent sarcoma cell imaging.”

Red, green proteins provide roadmap
The discovery and development of green fluorescent protein (GFP) was heralded as “a guiding star for biochemistry.” First observed in jellyfish, the brightly glowing pro­tein has become an important tool for biochemistry. Important biologic processes that previously could not be seen are now illuminated by these brightly colored proteins.

Using GFP and red fluorescent protein (RFP), Dr. Hayashi and his colleagues labeled sarcoma cells that were then transplanted into the bone, soft tissue, spinal cord, or blood vessels of mice. They also placed GFP on the regulatory element of the stem cell marker nestin and injected it into transgenic mice.

“Nascent blood vessels expressed GFP in this model and tumor angiogenesis was imaged after transplantation of RFP sarcoma cells,” reported Dr. Hayashi.

Real-time imaging delivers critical information
“Fluorescent imaging readily distinguished the color-coded cell lines and their differential ability to survive at primary injection sites as well as metastasizing to the lung in mice,” Dr. Hayashi said.

The progression of metastasis was revealed through imaging of sarcoma cell trafficking—the intracellular transport of lipids and proteins.

“Rising internal tumor pressure increased the numbers of shed cells, fragments, and emboli within vessels,” he stated.

The investigators were also able to use GFP to visualize nascent blood vessels in growing bone and soft tissue tumors in mice and to quantify the density of nascent blood vessels in the tumors.

The eventual goal of this research, according to Dr. Hayashi, is to use it to visualize cancer cells in humans. Using GFP and RFP to label tumor cells in a spinal cord tumor, for example, would allow a surgeon to perform fluorescent-guided surgery.

“It would enable the surgeon to avoid damaging healthy tissue and to excise the tumor completely,” he concluded.

Co-presenters of this scientific exhibit include Hiroyuki Tsuchiya, MD; Norio Yamamoto, MD; Toshiharu Shirai, MD; Kensuke Yamauchi, MD; Hiroaki Kimura, MD; Akihiko Takeuchi, MD; Robert M. Hoffman, PhD; and Katsuro Tomita, MD. The authors do not report any conflicts.

*Annie Hayashi is the senior science writer for AAOS Now. She can be reached at hayashi@aaos.org Ms. Hayashi is not related to Dr. Katsuhiro Hayashi.