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TO BUSINESS AND MEDICAL EDITORS:
BioTransplant and Massachusetts General Hospital Announce
Vital Link between Blood Cells and Transplantation Tolerance
CHARLESTOWN, Mass., May 15 /PRNewswire/ --
BioTransplant Incorporated (NASDAQ:BTRN) and the Massachusetts General
Hospital (MGH) today reported the detection of multilineage microchimerism in
animals that had successfully accepted donor kidneys following transplantation
of hematopoietic stem cells. The study reinforces the correlation between
mixed chimerism and the induction of transplantation tolerance. These results
will be presented today at the American Society for Transplantation (AST)
Annual Meeting in Chicago by scientists from BioTransplant and the laboratory
of David H. Sachs, M.D., Director of the Transplantation Biology Research
Center at the Massachusetts General Hospital and Chairman of BioTransplant's
Scientific Advisory Board.
In the studies, miniature swine received a prototype of BioTransplant's
AlloMune(TM) System and a 30 to 60 day course of cyclosporin as conditioning
for a high-dose peripheral blood stem cell (PBSC) transplant from
haploidentical donors. Blood cells originate from such stem cells, which
subsequently differentiate into lymphoid, myeloid and erythroid lineages.
These cells are transplanted in order to induce "mixed chimerism," the
condition of a blended immune system between donor and recipient, so that the
animal accepts donor cells as "self" while preserving its own immune cells as
well. In separate studies, BioTransplant has demonstrated the cancer fighting
applications of mixed chimerism. While the chimeric state keeps donor cells
from attacking the recipient's healthy tissues, cancerous cells are not
protected from the immune response.
Examination of the peripheral blood showed that the majority of these PBSC
recipients exhibited long-term (greater than 100 days) chimerism in the
lymphoid lineage only. To determine whether the pigs possessed precursor cells
from the donor animal, which are capable of evolving into multiple types of
blood cells, bone marrow samples were taken. Using the highly sensitive "PCR"
(polymerase chain reaction) assay, the cells were examined for evidence of
donor DNA.
Seven long-term recipients of hematopoietic stem cells were analyzed. Six
of the seven demonstrated myeloid progenitor cells. Significantly, all six
animals with multilineage chimerism detected by PCR accepted donor-matched
kidney transplants without the need for further immunosuppression. The one
recipient showing no evidence of multilineage chimerism rejected two renal
allografts in succession.
The correlation between multilineage mixed chimerism and survival of the
renal graft without the deleterious and costly effects of long-term
immunosuppression may have significant implications for the treatment of blood
cancers and the future of solid organ transplantation. Approaches to augment
the level and type of chimerism in these animals are currently under
investigation.
For several years, MGH and BioTransplant have been developing strategies
for the induction of donor-specific tolerance through hematopoietic stem cell
transplantation which allows successful organ allografting without the need
for chronic immunosuppressive therapy. The procedure in this study follows a
mild conditioning regimen that uses no irradiation and does not require
life-long immunosuppressive therapy.
A separate report between BioTransplant and MGH for end-stage renal
disease and multiple myeloma, was also presented at the AST Annual Meeting.
The study continued to show success in a double transplant procedure that
freed two patients from the need for whole body irradiation to treat cancer.
No rejection episodes have occurred, and both patients have continued normal
kidney function without progression of myeloma for over 2.5 years and 6 months
respectively, in the absence of chronic immunosuppressive drugs. The procedure
also eliminates the need for life-long immunosuppressive drugs to prevent
donor graft rejection.
Elliot Lebowitz, Ph.D., BioTransplant's President and C.E.O. said, "Our
AlloMune(TM) System for Cancer utilizes a number of advanced approaches
designed to facilitate the acceptance of donor cells and tissue by the human
immune system. We will continue to develop this technology, which is designed
to enable long-term acceptance of transplanted cells, tissues and organs by
re-educating the patient's immune system to recognize donor tissue as self."
The Massachusetts General Hospital, established in 1811, is the original
and largest teaching hospital of the Harvard Medical School and conducts the
largest hospital-based research program in the United States. The MGH has
major research centers in transplantation biology, the neurosciences,
cardiovascular research, cancer, AIDS, cutaneous biology and photomedicine.
Along with the Brigham and Women's Hospital, the MGH is a founding member of
Partner's HealthCare System, Inc. an integrated health care delivery system
comprising the two academic medical centers, specialty and community
hospitals, a network of physician groups and non-acute and home health
services.
BioTransplant Incorporated utilizes its proprietary technologies to
re-educate the body's immune responses to allow tolerance of foreign cells,
tissues and organs. Based on this technology, the Company is developing a
portfolio of products for application in a range of medical conditions,
including organ and tissue transplantation, and treatment of cancer and
autoimmune diseases, for which current therapies are inadequate.
BioTransplant's products under development are intended to induce long-term
functional transplantation tolerance in humans, increase the therapeutic
benefit of bone marrow transplants, and reduce or eliminate the need for
lifelong immunosuppressive therapy. This release and additional information on
BioTransplant is available on the Web at biotransplant.com. |
