In a promising science-fiction-meets-real-world juxtaposition, regenerative medicine researchers at the University of Texas (UT) Southwestern Medical Center have discovered that the mammalian newborn heart can heal itself completely. Researchers there, working with mice, found that a portion of the heart removed during the first week after birth grew back wholly and correctly – as if nothing had happened.
"This shows that postnatal mammals can [regenerate their hearts]," said Stephen Badylak, DVM, PhD, MD, deputy director of the McGowan Institute for Regenerative Medicine, professor in the Department of Surgery at the University of Pittsburgh, and director of the Center for Pre-Clinical Tissue Engineering within the McGowan Institute, who was not involved in the research. "That's very important."
Previous research has demonstrated that the lower organisms, like some fish and amphibians, that can regrow fins and tails, can also regrow portions of their hearts after injury.
"It's been known for a long time that fetuses in different species can regenerate a lot of different body structures, but by the time they're born, they lose that regeneration process," said Dr. Badylak.
The UT researchers found that within 3 weeks of removing 15 percent of the newborn mouse heart, the heart was able to completely grow back the lost tissue, and as a result looked and functioned just like a normal heart. The researchers believe that uninjured beating heart cells, called cardiomyocytes, are a major source of the new cells. They stop beating long enough to divide and provide the heart with fresh cardiomyocytes.
"A majority of the cells that contributed to regeneration were existing heart cells, not stem cells. That's huge," said Dr. Badylak. "That suggests that cells have been pulled out of the cell site. They've differentiated, [then] divide and form new cells."
"Now the question is maybe we can control this ability to regenerate at a site of interest," Dr. Badylak added. "If that's possible, then the therapeutic potential is huge."
Illustration: Microsoft clipart.
Abstract (Transient Regenerative Potential of the Neonatal Mouse Heart. Hesham A. Sadek, et al. Science; 25 February 2011: Vol. 331, No. 6020, pp. 1078-1080)