Laboratory grown bladders successfully transplanted

Doctors have successfully grown new urinary bladders from patient’s own cells and transplanted them.

“Tissue rejection” is a difficult problem in organ transplantation. Not only is the availability of organs for transplantation (very) limited, the vast majority of those organs are unsuitable for any one patient. The simplistic notion of “blood group” for organ transplantation seen in some television shows and popular movies (e.g., Muggers) has distorted the public mind on the difficulty of finding a match.

The human immune system is remarkably good at detecting “foreign” substances and “tissue rejection” occurs when the host immune system attacks the “donor” tissue or organ. This detection is mediated by the “major histocompatibility complexes” – a set of molecules which are on the surface of cells. A close match between the donor and host lowers the risk of a rejection reaction. A perfect match would be extremely rare, except in the case of a transplant from an identical twin – or self-transplantation (e.g., in the case of skin grafts).

Usually, a slight mismatch in the MHC must be tolerated and powerful anti-rejection drugs used indefinitely. Even so, the risk of tissue rejection is ever present, potentially leading to organ failure within hours to years after the transplantation. The anti-rejection drugs work by suppressing the immune system, significantly increasing the risk of serious infections and cancer.

The inherent problem of organ transplantation with “allografts” is the driving force behind stem cell and tissue regeneration research. The best transplant tissue or organ to use, after all, is an “autograft”.

It was revealed earlier this month that researchers have grown complete urinary bladders from the patient’s own cells and transplanted them into seven young patients with spina bifida. Apparently, these have been working well – for an average of four years in the patients.

Due to a disruption in the spinal cord in spina bifida, the bladder often lacks the usual control and coordination. High pressures inside the bladder lead to recurrent urinary tract infections and kidney damage. This is an important cause of illness and death in people with spina bifida.

The transplanted bladders do not function as in people without the condition as that would involve neuronal regeneration as well. Nevertheless, by increasing the capacity of the bladder, they reduce the risk of high pressures, infection and incontinence. The “neo-bladders” represent a tremendous advance in the field of tissue engineering.

From: The Sydney Morning Herald

Bladders grown from patients' own cells (excerpt)
By Rick Weiss
April 5, 2006

...RESEARCHERS have grown complete urinary bladders in a laboratory and transplanted them into patients, improving their health and achieving the first cultivation of working replacements for failing solid human organs...

...The organs have remained free of the many complications that bedevil the conventional practice of surgically constructing bladders from other tissues.

Researchers said they hope some day to offer patients more than a dozen other homegrown organs, including blood vessels, partial kidneys and perhaps even hearts...

...Experts applauded the work as a coming-of-age for the long-struggling field of tissue engineering and as a possible way to bypass some of the controversy over embryonic stem cells.

Because the replacement bladders were made from patients' own cells, they did not stimulate an immune-system reaction...