Human life starts from one single stem cell in a fertilized egg. Stem cell is unique in that it has the capability of both proliferating itself and differentiating to a new and different cell type. There is much research ongoing to take advantage of the unique characteristics of stem cell in the field of medicine. Regenerative medicine is a new approach to the treatment of degenerative diseases, hardly curable by currently available medications, by the power of stem cell.
There are sub-categories of stem cells, including embryonic-, adult-, and induced pluripotent stem cell. Adult- or mesenchymal stem cell (MSC) is of special interest in regenerative medicine as 1) it can be obtained without ethical issue (as opposed to embryonic stem cell) and 2) the safety is confirmed in many non-clinical and clinical studies (as opposed to induced pluripotent stem cell). All seven stem cell drugs approved so far in the world are based on MSC. MSC secrets a variety of cell to cell signaling molecules, in the process of proliferation and differentiation, which include growth factors, cytokines and chemokines. Physiological functions of such molecules play a key role in the therapeutic efficacy of stem cell drugs. A collection of such molecules secreted by stem cell is called ‘Stem Cell Conditioned Media’, and the physiological functions of the stem cell conditioned media are collectively called ‘Paracrine Effect’. The paracrine effect includes activation of indigenous stem cells which is noteworthy especially in the application of the stem cell conditioned media to skincare.