Importantly, regeneration of heart tissue in the mice was achieved without the use of drugs, transferred cells or tissues, such as stem cells, or any other intervention. The observed healing is a native capacity of this particular strain of mice.
"In these adult mice, cells in the region of an injury to the heart tissue were replaced over time by new cells that were indistinguishable from neighboring healthy heart cells," says Ellen Heber-Katz, Ph.D., a professor at The Wistar Institute and senior author on the study. "After two months, the damaged heart tissue looked normal and functioned well."
The degree of tissue renewal seen in the MRL mice is strikingly atypical of mammalian heart tissue. Similar injuries to the heart tissue of control mice, for example, showed that only 1 to 3 percent of the heart cells in the region of the injury were capable of dividing. In the MRL mice, however, up to 20 percent of the heart cells divided in response to injury.
The only species known to demonstrate similar capacities for regeneration are non-mammalian species - certain reptiles and amphibians - able to replace limbs and other body parts.
"In more than 15 years of investigations involving muscle tissue, I'd never seen anything like this," says John M. Leferovich, first author on the study. "The observation was quite stunning."
The current study follows on observations of the remarkable regenerative powers of the MRL mice first published by Heber-Katz and her coworkers in 1998. At that time, they not
Contact: Franklin Hoke
The Wistar Institute