Adult Hair Follicles an Alternative to Embryonic Stem Cells
By Yao Fei Hu, Ph.D. and Zhi-Jian Zhang, Ph.D., Medical College of Wisconsin, December 12, 2006
Found at the bulge of hair follicles, epidermal neural crest cells have the characteristics that combine some advantages of embryonic and adult stem cells. They can be expanded in culture, have a high degree of plasticity, and can be isolated at high levels of purity; all characteristics of embryonic stem cells. They are also comparable to adult stem cells because they are ethical unlike embryonic cells and are easily accessible through a minimally invasive procedure. A patientís own hair source could also be used for the therapy, eliminating immune rejection issues.
"We see the potential for cell replacement therapy in which patients can be their own donors, which would avoid ethical issues and reduce the possibility of tissue incompatibility," says Dr. Sieber.
Mice with spinal cord injuries were recently injected with these cells. The cells not only survived, but demonstrated several desirable characteristics that could lead to local nerve replacement and re-myelination (restoration of nerve pathways and sheaths) when grafted into the spine.
Along with smooth muscle, bone, and endocrine cells, neural crest stem cells actually give rise to the autonomic and enteric nervous systems by having the capability to generate wide array of cell types and tissues. The cells can be isolated from the hair follicle bulge as multipotent stem cells. Without losing stem cell markers, they can then be expanded in culture to produce millions of cells.
"We grafted the cells into mice that have spinal cord injuries and were encouraged by the results. The cells survived and integrated into the spinal cord, remaining at the site of transplantation and not forming tumors," Dr. Sieber says.
Oligodendrocytes are nerve-supporting cells that are essential for proper neuron function, and subsets of the epidermal neural crest stem cells express markers for these very cells according to Dr. Sieberís team. She is currently working with doctors at Marquette University to determine if the grafts lead to an improvement of spinal reflexes in the injured spinal cord of mice.
Parkinsonís disease, Hirschsprung's disease, ALS, stoke, peripheral neuropathies, and multiple sclerosis could all be treated with the epidermal neural crest cells. Replacement therapy could also treat certain defects of the heart, and bone defects (degeneration, craniofacial birth defects).
At an estimated annual cost of more than $170 billion, these conditions affect more than 11 million people in the US today.