Stem cells can create any kind of specific cell required by the body. It is difficult to replace human hair follicles as these are of combined origin from epithelial cells as well as mesenchymal cells. Stem cell experiments are successful in mice because the rodent hair follicles are of single cell origin.
If a stem cell is introduced into the body how will it know if it needs to repair the heart infarct or liver or damaged cartilage or paralyzed nerve or an athlete's muscle. Body has no confusion which ever tissue is undergoing repair secrets a specific signaling protein which invite the stem cells to the site for repair. The injected stem cell is guided to this tissue by the secreted signaling proteins.
Hair has lowest priority in the body there is no natural repair in the hair follicles and no signaling proteins to attract stem cells. The stem cells injected for hair follicle repair are redirected by the body be repair the smokers lung or liver instead of the being wasted on growing hair.
What are the stem cell offered in various clinics?
The presents remedies offered to encash the hype of stem cells are factors secreted by stem cells in the lab. These factors are injecting hoping to induce good growth from any other cells in the body. The injections are called stem cell extracts and are injected with the hope of improving hair growth, if at all.