Animal Experiments Show That Some Vertebrate Organs Can Regenerate "From Scratch"

Xinhua News Agency recently reported that a latest study has found that vertebrates can completely "regenerate from scratch" a complex lymphoid organ—the thymus—without any residual tissue. The study was completed by the team of Maximina H. Yun, senior researcher at the Capital Medical Sciences Innovation Center in China, together with the team of Rene Maehr, professor at the University of Massachusetts Medical School in the United States.

The study demonstrates the thymus-regenerating ability of the Mexican axolotl, which is famous for its "limb regeneration," broadening the recognized boundaries of organ-regeneration capacity and holding profound value for translational medicine.

Previously, research in animal regenerative medicine had focused mainly on limited tissues such as skin and bone. Regenerative medicine mainly exploits the dedifferentiation capacity of cells: under certain conditions, already differentiated cells are converted back into dedifferentiated cells, becoming pluripotent stem cells that regenerate new individuals or new tissues. Regenerative medicine can be used to solve certain human disease problems.

This new study used the Mexican axolotl as a model to complete a series of experiments. Through precise and complete total thymectomy, continuous high-resolution time-lapse imaging, and functional verification, the team confirmed the complete process of thymus regeneration. After 35 days, the axolotl had grown a brand-new thymus identical to the original organ in morphology, cell types, and function. The study found that the key to initiating thymus regeneration comes from two signaling pathways: bone morphogenetic protein (BMP) and a less-understood "regeneration initiator"—midkine.

The researchers say that if a safe way can be found to activate similar signaling pathways in the human body, it may be possible to help people with damaged thymuses reactivate or enhance their thymic function. This could bring benefit to children who have undergone thymic surgery, patients with specific immunodeficiencies, and the elderly with declining immunity.