Stem cells are thought to be under the influence of neighboring tissues in their environment; thus they can treat the organ which is in need of treatment. This effect may be due to some chemical substances or some signals emitted. This topic is not yet fully explored.
As a matter of fact, when stem cells encounter these substances or signals in laboratories, they turn into other cells. However, at this time, cancer may also occur with excessive cell reproduction. It is not yet known how the cancer formation can be suppressed while the stem cells in the human body are transforming normally.
Considering the question of how stem cells help healing in diseases, they may turn into other cells and lead to an improvement in the disease or emit some substances and signals that are able to heal the condition of the disease. We must be very careful and cautious about the use of stem cells for treatment in humans, until the answers to these questions are cleared.