A group of American researchers led by Michael Levin, a biologist at the Allen Research Center at Tufts University, invented a device with which they were able to grow new limbs in an experimental frog.
Many species of fish, amphibians, and also lower organisms have the ability to regenerate. Now there is hope of awakening this ability in mammals.
The scientists 3D printed a tiny silicon device that they filled with the hormone progesterone and silk protein to hydrate the wound. Progesterone is a sex hormone, the main function of which is to prepare the female body for childbirth. It also controls the electrical mechanisms of cells, enhances immunity, and is involved in the repair of body tissues. Silk protein is a protein found in silk fibers known for its healing properties. It can be found in various cosmetic products.
As a test material, scientists have chosen smooth clawed frogs (Xenopus Iaevis) for their weak ability to regenerate. In place of the lost limb in this species of amphibians, a small cartilaginous process is usually formed.
The frogs participating in the experiment were divided into several groups - two experimental and one control. The hind limbs were removed. Subjects from the first group were injected with miniature silicon devices filled with silk protein and progesterone into wounds at the sites of amputation; the second group received devices without progesterone. The third group of experimental subjects was left untreated for the purity of the experiment. The devices were removed two days later.
After that, the process of tissue repair was monitored for nine months. The published study reports that the first group of branches has limbs that look like frog legs without feet. Slightly smaller limbs grew in the second group. Finally, the control group developed a very small process at the site of amputation. It turned out that the regrown limbs of the first group are fully functional and help animals to swim.
Gene analysis showed an increase in oxidative reactions, increased production of serotonin and leukocytes. At the same time, the immune responses responsible for the formation of scar tissue decreased. From this, scientists concluded that progesterone alters the body's response to injury. It turns off the process of scarring of wounds, and turns on the process of regeneration.
The functions of progesterone have not yet been adequately researched. A member of Michael Levin's research team, Celia Herrera-Rincon, reports that a mechanism for the involvement of progesterone in the brain has recently been discovered.
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Michael Levine spoke about the beginning of another series of experiments using new combinations of biological materials. The first results have already been obtained, allowing us to hope that it will soon be possible to restore full-fledged limbs in the experimental subjects.
The key to creating living tissue lies in the combination of hormones - the tools with which the body develops an embryo. Scientists hope that, with the help of the technology they have created, it will soon be possible to regenerate the tissues of the human body.