Synthetic Windpipe Seeded With Stem Cells Successfully Transplanted in Tracheal Cancer Patient

in technology, medicine, biology

A synthetic windpipe, seeded with patient's own stem cells, was successfully transplanted in a patient with tracheal cancer by physicians in Sweden. According to the hospital, the transplanted patient was recovering without the use of immunosuppressive drugs.

The windpipe implanted was made using nanocomposite materials developed by Scientists at the University College London (UCL).  Together with Professor Paolo Macchiarini at Karolinska, Professor Alexander Seifalian at UCL designed and developed the trachea scaffold using a novel nanocomposite polymer.

The operation was performed on June 9th 2011 at Karolinska University Hospital in Huddinge, Stockholm, by professor Paolo Macchiarini, of Karolinska University Hospital and Karolinska Institutet, and colleagues. The patient was discharged on July 8, 2011.

windpipe transplant with stem cells

The windpipe after the stem cells have been incorporated, just before transplantation. Image Credit: University College, Londonre 

The UCL and Karolinska scientists designed and built the nanocomposite tracheal scaffold and Harvard Bioscience (Boston, USA) produced a specifically designed bioreactor used to seed the scaffold with the patient’s own stem cells.

Stem cells are progenitor cells that have the remarkable potential to develop into many different cell types in the body. In many tissues they are involved in the repair and renewal of existing differentiated cells. Because of their potential to differentiate into different cell types, scientists have been able to make remarkable strides in biomedical research by directing its differentiation to replace injured or genetically defective cells.

In this case, the patient has been suffering from late stage tracheal cancer. Despite maximum treatment with radiation therapy, the tumor had reached approximately 6 cm in length and was extending to the main bronchus. It was progressing and almost completely blocked the trachea.  Since no suitable donor windpipe was available, the transplantation of the synthetic tissue engineered trachea was performed as the last possible option for the patient. The patient was referred by Professor Tomas Gudbjartsson of Landspitali University Hospital (Reykjavik, Iceland) who was also part of the surgical team.

As well as being used for tissue scaffolds, the nano composite materials used in the windpipe have other potential uses such as coronary stents and grafts. A nanocomposite is a material containing some components that are less than 100 nanometers (nm) in size. To give a sense of scale, a human hair is about 60,000 nanometers in thickness. A polymer is a repeating chain of small, identical molecules (called monomers) which are linked  together.

The development of a full size ‘y-shaped’ trachea scaffold was accomplished using a CT (computerized tomography) scan of the patient as a guide, to create the exact shape and dimension needed. A mould was then made using the nanocomposite material. Patient's cells were incorporated into this polymer scaffold and the full biological trachea was grown in a bioreactor - a device designed for the procedure by Harvard Bioscience which provides the correct environment for the tissue to grow. This process was employed to make sure that the trachea very effectively simulates natural tissue and has the same properties as a ‘real’ trachea.

When transplantation is done using tissues from another human donor, the graft is called an allograft. When the donor tissue is from a different species, such as pig, the graft is called a xenograft. In this case the donor cells were derived from the recipient patient and therefore the graft is an autograft. An autograft seldom undergoes rejection and therefore, it does not need immunosuppressive drugs to sustain the graft.

Professor Seifalian said: “What makes this procedure different is it’s the first time that a wholly tissue engineered synthetic windpipe has been made and successfully transplanted, making it an important milestone for regenerative medicine. We expect there to be many more exciting applications for the novel polymers we have developed.”

Transplantations of tissue engineered windpipes with synthetic scaffolds in combination with the patient s own stem cells as a standard procedure, means that patients will not have to wait for a suitable donor organ. This would be a substantial benefit for patients since they could benefit from earlier surgery and have a greater chance of cure. In addition to treating adult patients; tissue engineered synthetic trachea transplants would, not least, be of great value for children, since the availability of donor tracheas is much lower than for adult patients.

This is indeed a leap the translational use of nanomaterials and stem cells, however to translate this further into more complex organs scientists will have to make more progress in tissue engineering and directed stem cell differentiation.

Link to Karolinska Institutet
Link to University College London

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