Methods for ex vivo propagation of somatic hair follicle stem cells
The present invention is directed to methods for readily propagating somatic hair follicle stem cells or melanocyte stem cells. The methods comprise enhancing guanine nucleotide (GNP) biosynthesis, thereby expanding guanine nucleotide pools. This in turn conditionally suppresses asymmetric cell kinetics in the explanted cells. The methods of the invention include pharmacological methods and genetic methods. For example, the resulting cultured somatic hair follicle stem cells can be used for a variety of applications including cell replacement therapies such as hair transplants, gene therapies, and tissue engineering applications, such as the generation of artificial skin and skin regeneration strategies including skin grafts.
1. A method of proliferating undifferentiated hair follicle cells in vitro, comprising:
a) isolating undifferentiated hair follicle cells from a mammal; and
b) culturing said undifferentiated hair follicle cells in a culture medium comprising xanthine under conditions, and for a time sufficient, to result in proliferation of the undifferentiated hair follicle cells.
2. The method of claim 1 , wherein said xanthine is present in an amount of 1-5,000 μM.
3. The method of claim 2 , wherein said xanthine is present in an amount of 50-1,500 μM.
4. A method for administering undifferentiated hair follicle cells to a subject, wherein said method comprises:
a) isolating undifferentiated hair follicle cells from said subject or from an individual who is histologically matched to said subject;
b) culturing said isolated undifferentiated hair follicle cells in a culture medium comprising xanthine for at least 10 days under conditions sufficient to result in proliferation of the undifferentiated hair follicle cells; and
c) administering said undifferentiated hair follicle cells to said subject.
5. A method for deriving clonal cell lines of undifferentiated hair follicle cells, comprising:
a) isolating a hair follicle from a mammal;
b) transecting the isolated hair follicle;
c) culturing the transected hair follicle in the presence of xanthine to yield a culture of hair follicle epithelial cells;
d) performing limiting dilution plating on the culture of hair follicle epithelial cells to isolate single undifferentiated hair follicle cells; and
e) culturing the isolated single undifferentiated hair follicle cells in the presence of xanthine to produce clonally expanded undifferentiated hair follicle cells.
6. The method of any one of claims 1 , 4 , or 5 , wherein the undifferentiated hair follicle cells are somatic hair follicle stem cells.