NEW INSIGHTS INTO FACIAL TRANSPLANTATION
In 2009, the first
face transplant was performed at Brigham and Women's Hospital (BWH), and lead
surgeon, Dr. Bohdan Pomahac has been pioneering the procedure since. However,
understanding the technical challenges, particularly around how the recipient
accepts or rejects the donated face, is just beginning. Following any
transplant, including facial transplant, T cells in the recipient mount an
immune response to the donated tissue, threatening rejection. This process is
successfully managed through immunosupression medication so that the recipient
is able to tolerate the transplanted face
Now, researchers at
BWH have made a discovery that provides new insight into the body's rejection
process. Researchers have demonstrated that immune cells, or T cells, involved
in the rejection process are significantly of donor origin. These findings are
published in Modern Pathology on January 17, 2014.
"The
conventional belief about face transplant was that rejection is directly
related to the recipient T cells attacking the donor T cells of the face, which
are perceived as foreign to the recipient's immune system," explained
Christine Lian, MD, a skin pathologist at BWH and lead author of this study.
"We now need to rethink this process. Based on our findings, it is clear
that the donor T cells, which are transferred as part of the new face, play a
significant role in the rejection process as well."
The researchers
examined 131 face transplant biopsy specimens from a total of five patients who
received a face transplant between 2009 and 2013 at BWH. The samples were
examined by conventional microscopy for categorizing the level of rejection and
guiding immunosuppressant therapy, and additional antibody based biomarkers
were also applied. The use of biomarkers allowed the researchers to
differentiate between the donor and recipient cells under the microscope.
Researchers found that during active rejection episodes, many to most of the
immune cells in the face specimens that were involved in the rejection were of
donor origin.
"The
participation of these donor immune cells in face transplant rejection
represents a paradigm shift in the understanding of the rejection
process," explained George F. Murphy, MD, director of Dermatopathology at
BWH and a senior author of this study. "One intriguing possibility that
now exists is that the transplanted faces are not simply passive targets
vulnerable to rejection, but carry along with them their own army of immune
cells that may defend the face against attacking recipient cells in order to
thwart the rejection process," says Murphy.
Researchers note
that more studies need to be done to better understand these complex immune
cell interactions, but these new findings will help to develop the best
diagnostic and therapeutic strategies that, for the first time, will consider
include immune cells from the donor as well as the recipient.
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