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Nearly Forgotten 80-Year-Old Tissue Allograft Method for Transplanting Fly Tissue Resurrected, Enables Resurgent Study of Tissue Regeneration and Tumor Growth in Drosophila

A study conducted by ICREA (Catalan Institution for Research and Advanced Studies) researcher Dr. Cayetano González, at the Institute for Research in Biomedicine (IRB Barcelona), and published online on September 10, 2015 in Nature Protocols describes a virtually forgotten technique used in the fly Drosophila melanogaster dating back 80 years. This method allows the transplantation of tissue from larvae to adult flies, thus allowing research into tumor growth and other biological processes of biomedical interest, such as tissue regeneration. The article is titled “Studying Tumor Growth in Drosophila Using the Tissue Allograft Method.” In 2002, Dr. González, head of the Cell Division lab at IRB Barcelona, faced a major technical problem with respect to research into tumor growth in Drosophila, namely the limitless growth of malignant tumours, which kill the fly. The solution seemed straightforward—tumor transplants, a common technique used in cancer research in mammals, including humans, which involves the transplantation of the tumor mass to mice. With over a century of research into the fly, it was hoped that the many tools available for this model would include one for tissue transplants. “And this was indeed the case, but the articles devoted to methodologies were few and incomplete and therefore reproducing the technique in the lab was very complicated,” explains Professor González. Developed in 1935, the technique was used extensively in the following decades and then fell into disuse and practically disappeared towards the end of the last century. “In 2002, only a small number of researchers worldwide were aware of the existence of the technique,” he says. Professor János Szabad, from the University of Szeged, in Hungary, was one of the few who continued to use the method and he invited Dr. González to visit his lab to learn about it. Since then, Dr. González has used this approach in his research into cancer models in flies, and his lab has trained scientists from centres in Europe, the US, India and Australia about its implementation.

The technique consists of dissecting a tissue of interest and loading it into a fine, purpose-built glass needle for later injection into an adult fly. “It is in fact simple. But there are many small details, from the building of the needle to the care of the implanted flies, that seem easy when learnt from an expert but in practice are very difficult to reproduce without previous training,” states Professor González.

The article, written by Dr. Fabrizio Rossi, a postdoctoral fellow at IRB Barcelona, and Dr. González, describes the materials, equipment, and methods required to implement the procedure rapidly and efficiently and provides links to videos that show each step of the process. “Now any Drosophila lab anywhere in the world can use this powerful method,” says Dr. González.

The authors note that their “protocol describes a method to allograft Drosophila larval tissue into adult fly hosts that can be used to assay the tumorigenic potential of mutant tissues. The tissue of interest is dissected, loaded into a fine glass needle and implanted into a host. Upon implantation, nontransformed tissues do not overgrow beyond their normal size, but malignant tumors grow without limit, are invasive, and kill the host. By using this method, Drosophila malignant tumors can be transplanted repeatedly, for years, and therefore they can be aged beyond the short life span of flies.”

“Because several hosts can be implanted using different pieces from a single tumor, the method also allows the tumor mass to be increased to facilitate further studies that may require large amounts of tissue (i.e., genomics, proteomics, and so on)."

“This method also provides an operational definition of hyperplastic, benign, and malignant growth. The injection procedure itself requires only ~1 d. Tumor development can then be monitored until the death of the implanted hosts."

[Press release] [Nature Protocols article]