Study Focuses on Mammal Model of Bladder Regenration

Focusing on the regenerative process that enables rats to re-grow their bladder within eight weeks, the new study carried by the researchers at Wake Forest Baptist Medical Center's Institute for Regenerative Medicine report, characterize this unique model of bladder regeneration with the goal of applying what they learn to human patients.

The ability to re-grow damaged limbs is common in starfish, zebrafish and salamanders. But hardly anything is known about the regenerative capabilities of mammals.

"A better understanding of the regenerative process at the molecular and cellular level is a key to more rapid progress in applying regenerative medicine to help patients," said George Christ, Ph.D., senior researcher and professor of regenerative medicine at Wake Forest Baptist.

Prior to this christ's team had conducted a study on rats that showed  that when about 75 percent of the animals' bladders were removed, they were able to regenerate a complete functional bladder within eight weeks. 

"There is very little data on the mechanisms involved in organ regeneration in mammals," said Christ. "To our knowledge, bladder regeneration holds a unique position there is no other mammalian organ capable of this type of regeneration."

"The ability of the liver to grow in size when lobes are removed is sometimes referred to as regeneration, but this is a misnomer," said co-author Bryon Petersen, Ph.D., who was a professor of regenerative medicine at Wake Forest Baptist during the period the research occurred. "Instead, through a proliferation of cells, the remaining tissue grows to compensate for the lost size. In contrast, the hallmark of true regeneration is following nature's "pattern" to exactly duplicate size, form and function."

"If we can understand the bladder's regenerative process, the hope is that we can prompt the regeneration of other organs and tissues where structure is important from the intestine and spinal cord to the heart," said Petersen.

Through the current study the researchers have projected that animal's bodies respond to injury by increasing the rate at which certain cells divided and grew. The first notable response was observed in the urothelium the layer of tissue that lines the bladder.

They also noticed that as the bladder lining waned the activity continued either in the fibrous band that separates the bladder lining from the bladder muscles and in the bladder muscle itself.

"The researchers have several theories about how the process works," said Christ. "One possibility is that cells in the bladder lining transition and become a type of stem cell that can proliferate throughout the bladder. Other theories are that cells in the bladder lining signal other cells to replicate and that injury prompts stem cells to arrive through the blood stream to repair the bladder damage."

The researchers later will work to identify the exact regenerative process and will expand the work into mice.

The details of the study was carried in the PLOS ONE a peer reviewed online publication.