Hair follicle graft from tissue engineered skin
The present invention provides a hair graft comprising (a) tissue engineered skin comprising a tissue engineered epidermal layer, a tissue engineered dermal layer, and hair follicle progenitor cells and (b) a scaffold. The invention also provides methods of making and using the hair grafts of the present invention.
1. A method of making a hair graft, comprising: a) incubating a tissue engineered dermal layer on a bioabsorbable scaffold until the tissue engineered dermal layer attaches to the bioabsorable scaffold; b) placing hair follicle progenitor cells on the tissue engineered dermal layer; c) placing a tissue engineered epidermal layer comprising a sheet of keratinocytes on the hair follicle progenitor cells to form a construct; d) allowing the construct to mature in vitro; and e) cutting the construct into one or more implantable grafts.
2. A method of implanting a hair graft comprising creating a wound in skin of a subject and implanting the graft of claim 1 into the wound, wherein the graft is at least about 2 millimeters thick.
3. The method of claim 1 , wherein the tissue engineered dermal layer comprises human dermal fibroblasts.
4. The method of claim 1 , wherein the hair follicle progenitor cells are selected from the group consisting of mesenchymal stem cells, dermal papilla cells, dermal sheath cells, and follicular epidermal stem cells.
5. The method of claim 1 , wherein the tissue engineered epidermal layer comprises human epidermal keratinocytes.
6. The method of claim 1 , wherein the bioabsorbable scaffold comprises collagen and glycosaminoglycan.
7. The method of claim 1 , wherein the bioabsorbable scaffold comprises one or more moieties selected from the group consisting of a growth factor, an angiogenesis factor, a cell attachment binding site moiety, a cell signaling molecule, a polypeptide, a glycoprotein, and a bioactive molecule.
8. The method of claim 1 , wherein one or more cells types selected from the group consisting of fat cells, pre-adipocytes, vascular endothelial cells, and bone marrow cells are added to the bioabsorbable scaffold prior to incubating the tissue engineered dermal layer with the bioabsorbable scaffold.
9. The method of claim 1 , wherein the implantable grafts are about 1 to about 9 square millimeters in surface area.
10. The method of claim 1 wherein the tissue engineered dermal layer is a sheet of dermal cells.
11. The method of claim 1 wherein the bioabsorbable scaffold comprises a layer of collagen onto which the tissue engineered dermal layer is seeded and cultured to form a sheet prior to hair follicle progenitor cells on the tissue engineered dermal layer.
12. The method of claim 1 wherein the hair follicle progenitor cells are aggregated or clumped together prior to placement on the dermal layer.
13. The method of claim 12 wherein the size of the aggregates or clumps is 10 to 500 microns.
14. The method of claim 13 wherein the size of the aggregates or clumps is 20 to 200 microns.
15. The method of claim 14 wherein the size of the aggregates or clumps is 30 to 60 microns.
16. The method of claim 10 wherein the sheet of dermal cells and the sheet of keratinocytes are prepared separately by culturing isolated cells in vitro without the use of a scaffold.
17. The method of claim 1 wherein the construct is allowed to mature in vitro until the follicle neogenesis process is initiated.