1, stem cells generally refer to bone marrow stem cells, which are primitive cells with self-replication and multi-directional differentiation potential, and are divided into embryonic stem cells and adult stem cells. Stem cells can be transformed into various cells in the blood system, including white blood cells, red blood cells and platelets. They are widely used in clinic, and can be used in hematology to treat malignant hematological diseases, including leukemia and lymphoma, and also in plastic surgery.

2. Lizards and salamanders may lose their tails when threatened, but it is impressive that in about 60 days, through the process of stem cell reuse, these reptiles exert their whole cellular mechanism to recover themselves.

This worm found in fresh water has the ability of infinite regeneration from stem cells, which is why scientists call it a "theoretically immortal creature".

When a serious heart attack occurs in mammals, millions of cells die and cannot recover, thus weakening and damaging some organs. But this will not happen to zebrafish. No matter how many cells are lost, zebrafish can get the heart back to work.