Beating Heart Cells from Hair-Follicle-Associated Pluripotent (HAP) Stem Cells

The neural stem-cell marker nestin is expressed in hair follicle stem cells located in the bulge area which are termed hair-follicle-associated pluripotent (HAP) stem cells. HAP stem cells can differentiate into neurons, glia, keratinocytes, smooth muscle cells, and melanocytes in vitro. Subsequently, we demonstrated that HAP stem cells could affect nerve and spinal cord regeneration in mouse models. We subsequently demonstrated that HAP stem cells differentiated into beating cardiac muscle cells. The differentiation potential to cardiac muscle is greatest in the upper part of the mouse whisker follicle. The beat rate of the cardiac muscle cells differentiated from HAP stem cells was stimulated by isoproterenol and inhibited by propanolol. The addition of activin A, bone morphogenetic protein 4, and basic fibroblast growth factor, along with isoproternal, induced the cardiac muscle cells to form tissue sheets of beating heart muscle cells. Under hypoxic conditions, HAP stem cells differentiated into troponin-positive cardiac-muscle cells at a higher rate that under normoxic conditions. Hypoxia did not influence the differentiation to other cell types. This method is appropriate for future use with human hair follicles to produce hHAP stem cells in sufficient quantities for future heart, nerve, and spinal cord regeneration in the clinic.