By defining the properties of stem cells that regenerate complex body parts, scientists are learning how injury causes these stem cells to regenerate the missing part instead of just forming scar tissue.
Future research may make it possible to apply this knowledge in new kinds of medical treatments. Pluripotent stem cells How similar are the pluripotent stem cells of the planarian to mammalian embryonic stem cells or induced pluripotent stem cells? By studying the planarian, maybe we will gain insight into how to control human embryonic stem cells to replace parts of our own bodies.
Tissue stem cells Salamanders and frogs use tissue stem cells that may be much like our own, so why can they regenerate a whole limb whereas we form scars? Ongoing research indicates that regenerative animals keep a kind of map inside their adult tissues, telling cells where they are and what they should be.
Parts of this map may have been lost in mammals, or perhaps our stem cells have lost the ability to read the map.
Researchers hope to find out what exactly is missing or blocked in mammals, and whether such information can be restored to direct stem cells to take part in regeneration for medical applications. Differentiated cells Can we make adult, differentiated cells like heart muscle cells start dividing again, as in the zebrafish? It will be important to find out why mammalian heart cells lose this ability, and if it can be restored.
The Reddien lab and their research on planarian regeneration. This factsheet was created by Elly Tanaka. Planarian image by Peter Reddien. Salamander image in right-hand panel by Orizatriz. Remaining salamander images and all diagrams by Elly Tanaka.
Regeneration: what does it mean and how does it work? Factsheets General Stem Cell Knowledge. What do we know? Some human organs, e. What are researchers investigating? What are the challenges?
NIGMS-funded scientists are focused on understanding the basic features of regeneration. For example, researchers are looking closely at where the cells involved in regenerated tissue originate.
State-of-the-art imaging tools let them watch tissue regeneration in living animals, and genetic techniques allow them to systematically identify the genes involved in regeneration. Many scientists are working to better understand the unique properties of stem cells and their role in regeneration. Others are looking for chemical compounds that could be used as medicines to stimulate regeneration.
Knowledge gained from these basic biomedical studies will provide a foundation for future clinical applications.
NIGMS is a part of the National Institutes of Health that supports basic research to increase our understanding of biological processes and lay the foundation for advances in disease diagnosis, treatment, and prevention.
Toggle navigation Toggle Search. It looks like your browser does not have JavaScript enabled. Please turn on JavaScript and try again. Fold1 Content. What are regeneration and regenerative medicine? What organisms can regenerate?
More complex animals such as mammals have limited regenerative capacities. These include: Forming thick scars in tissues and skin to promote the healing of injured or amputated body parts. Regrowing hair and skin. So birth defects, traumatic injury, aging, degenerative disease, cancer. Levin was born in Moscow in As a child, he spent hours looking at bugs and electrical parts. A cybernetic system, such as a thermostat, controls itself using feedback: a thermometer detects a change in room temperature, and then turns on the heat or cooling system until the desired temperature has been reached.
It seemed reasonable to think that the developing body itself was cybernetic: its many parts used inner feedback mechanisms to align around shared goals. In , when he was nine, they took advantage of a visa program for Soviet Jews and moved the family to Lynn, Massachusetts, spending three months on the way as refugees in Italy.
He brought home old equipment, including a computer with a black-and-white monitor that ran only Fortran, an early programming language. When Levin told his parents that he wanted to play Pac-Man, his father said that he could do it only if he programmed his own version. He tested whether bean plants could navigate mazes as they grew, and investigated their responses to magnetic fields. Becker, an orthopedic surgeon, described the experiments he had carried out on salamanders and other animals, exploring the role that electricity played in their development and in their ability to regenerate limbs.
Salamanders can regenerate their severed limbs and tails; if you remove a leg and graft on a tail, the tail morphs into a leg. In the twentieth century, the reality of bioelectricity began to come into focus. In , it was discovered that larval salamanders regenerate faster when electricity courses through their aquarium water; in the following decades, researchers measured distinct bioelectrical patterns associated with development and wound healing.
Eventually, biologists came to understand that electricity is integral to cellular life. Some ion channels open or close in response to the voltage outside, leading the cell to change its behavior in response to electrical signals and thereby creating a feedback loop. Cells employ the bioelectric system as a kind of intercellular internet; they use it to build intricate and expansive communication networks that control the transcription of genes, the contraction of muscles, and the release of hormones.
Many drugs target ion channels, using them to treat arrhythmia, epilepsy, and chronic pain. When Levin arrived for college at Tufts, in , he decided to major in computer science, so that he could work on artificial intelligence. Levin had been calling researchers and reading everything he could on the topic of bioelectricity.
He showed his reading list to Susan Ernst, a biologist at Tufts; she was impressed, but told him that she had no room in her lab for more undergraduates. The next day, she changed her mind. She called Levin, and they decided that he would apply electromagnetic fields to sea-urchin embryos. As an undergraduate, even as he ran a small backup-software company with his father, Levin was the primary author of two papers published with Ernst. When he earned a Ph.
The containers were casserole dishes filled with floating specks. Some contained worms with strange heads—spiky, tubular, hat-shaped—while one held the famous two-headed worms. Most of the inhabitants of worm world were descendants of the same parent. Instead, responding to their environment, the cells negotiate and feel their way toward a final form. A fertilized egg divides, and divides again, creating a hollow ball of cells called a blastula; genes instruct these cells to release chemicals, and other cells, reacting to those chemical concentrations, decide to migrate elsewhere or to develop into specific types of tissue.
Other influences—oxygen, nutrients, hormones, sometimes toxins—further shape gestation. But there is no map or instruction set for an organ inside a cell. Mathematicians and computer scientists, versed in the language of self-organizing systems—crystals, traffic, storms—have turned out to possess useful conceptual tools for understanding development.
Thousands of frog embryos are transferred there twice a week, so that researchers can analyze their developmental decisions. In the spots where they placed this paint-by-numbers pattern, some of the embryos developed extra eyes.
In time, their nervous systems began building optic nerves to connect the new eyes to the brain by way of the spinal cord. Not all patterns are as simple to interpret or create as the electric face; prompting the regeneration of a missing ear or hand, Levin said, may require detecting and mastering bioelectric patterns that are abstract and hard to decipher.
They left the cuff on for twenty-four hours, then observed for about a year. But the frogs in the experiment grew paddle-like limbs. About nine months later, little toes started to emerge. Levin thinks that, eventually, the same kind of cuff could be used on humans; you might wear one for a few months, long enough to persuade your body to restart its growth. Levin was wary of showing me any mouse experiments.
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