Cryopreservation of the Hair Follicle Maintains Pluripotency of Nestin-Expressing Hair Follicle-Associated Pluripotent Stem Cells

Cryopreservation of engineered hair follicle germs for hair regenerative medicine

Hair regenerative medicine must involve practical procedures, such as cryopreservation of tissue grafts. This can aid in evaluating tissue safety and quality, as well as transportation to a clinic and multiple transplants. Hair follicle germs (HFGs), identified during in vivo development, are considered effective tissue grafts for hair regenerative medicine. However, to the best of our knowledge, methods for cryopreserving HFGs have not been explored yet. This study investigated the efficacy of slow vitrification methods for freezing HFGs. Cryoprotectants such as dimethyl sulfoxide (DMSO) and carboxylated poly-l-lysine were used for vitrification. The results indicate that DMSO vitrification yielded the most efficient de novo hair regeneration in mouse skin, comparable to that of non-cryoprotected HFGs. A microfinger was fabricated to scale up the cryopreservation method, considering that thousands of tissue grafts were required per patient in clinical practice. The microfinger can be used for a series of processes, holding the HFG, replacing it with a cryopreservation solution, freezing it in liquid nitrogen, thawing it in a warm medium, and transplanting it into the skin. Although de novo hair regeneration by HFGs cryopreserved using microfingers was reduced by approximately 20 % compared to those cryopreserved using flat plates for fertilized eggs, it exceeded 50 %. These findings demonstrate that vitrification with DMSO and microfingers could be a useful approach for the cryopreservation of tissue grafts in hair regenerative medicine for hair loss.

One-step generation of core-shell biomimetic microspheres encapsulating double-layer cells using microfluidics for hair regeneration

Tissue engineering of hair follicles (HFs) has enormous potential in the treatment of hair loss. HF morphogenesis is triggered by reciprocal interactions between HF germ epithelial and mesenchymal layers. Here, a microfluidic-assisted technology is developed for the preparation of double aqueous microdroplets that entrap double-layer cells and growth factors to ultimately be used for hair regeneration. Mouse mesenchymal cells (MSCs) and epidermal cells (EPCs) are encapsulated in gelatin methacrylate (GelMA) cores and photo-curable catechol-grafted hyaluronic acid (HAD) shells to fabricate GelMA-MSC/HAD-EPC (G/HAD) microspheres. The findings show that the G/HAD microspheres exhibit ultrafast gelation, aqueous phase separation, superior biocompatibility, and favorable wet adhesion properties. G/HAD microspheres can also support cell proliferation and sustain growth factor release. These composite cell microspheres are capable of efficient HF generation upon transplantation into the dorsal dermis of nude mice. This finding facilitates the large-scale preparation of approximately 80 double-layer cell spheres per min. This simple double-layer cell sphere preparation approach is a promising strategy for improving current hair-regenerative medicine techniques and can potentially be applied along with other organoid techniques for extended applications.

Direct implantation of hair-follicle-associated pluripotent (HAP) stem cells repairs intracerebral hemorrhage and reduces neuroinflammation in mouse model

Intracerebral hemorrhage (ICH) is a leading cause of mortality with ineffective treatment. Hair-follicle-associated pluripotent (HAP) stem cells can differentiate into neurons, glial cells and many other types of cells. HAP stem cells have been shown to repair peripheral-nerve and spinal-cord injury in mouse models. In the present study, HAP stem cells from C57BL/6J mice were implanted into the injured brain of C57BL/6J or nude mice with induced ICH. After allo transplantation, HAP stem cells differentiated to neurons, astrocytes, oligodendrocytes, and microglia in the ICH site of nude mice. After autologous transplantation in C57BL/6J mice, HAP stem cells suppressed astrocyte and microglia infiltration in the injured brain. The mRNA expression levels of IL-10 and TGF-β1, measured by quantitative Real-Time RT-PCR, in the brain of C57BL/6J mice with ICH was increased by HAP-stem-cell implantation compared to the non-implanted mice. Quantitative sensorimotor function analysis, with modified limb-placing test and the cylinder test, demonstrated a significant functional improvement in the HAP-stem-cell-implanted C57BL/6J mice, compared to non-implanted mice. HAP stem cells have critical advantages over induced pluripotent stem cells, embryonic stem cells as they do not develop tumors, are autologous, and do not require genetic manipulation. The present study demonstrates future clinical potential of HAP-stem-cell repair of ICH, currently a recalcitrant disease.

Hair follicle associated pluripotent (HAP) stem cells jump from transplanted whiskers to pelage follicles and stimulate hair growth

Stimulation of hair growth in hair loss has been a difficult goal to achieve. Hair follicle-associated pluripotent (HAP) stem cells express nestin and have been shown to differentiate to multiple cell types including keratinocytes, neurons, beating cardiac muscles and numerous other cell types. HAP stem cells originate in the bulge area of the hair follicle and have been shown to migrate within and outside the hair follicle. In the present study, the upper part of vibrissa follicles from nestin-driven green-fluorescent protein (GFP) transgenic mice, containing GFP-expressing HAP stem cells, were transplanted in the dorsal area of athymic nude mice. Fluorescence microscopy and immunostaining showed the transplanted HAP stem cells jumped and targeted the bulge and hair bulb and other areas of the resident nude mouse pelage follicles where they differentiated to keratinocytes. These results indicate that transplanted nestin-GFP expressing HAP stem cells jumped from the upper part of the whisker follicles and targeted nude-mouse hair follicles, which are genetically deficient to grow normal hair shafts, and differentiated to keratinocytes to produce normal mature hair shafts. The resident nude-mouse pelage follicles targeted by jumping whisker HAP stem cells produced long hair shafts from numerous hair follicles for least 2 hair cycles during 36 days, demonstrations that HAP stem cells can stimulate hair growth. The present results for hair loss therapy are discussed.

Hair-follicle-associated pluripotent (HAP) stem cells differentiate into mature beating cardiomyocyte sheets on flexible substrates in vitro

Cardiomyocytes have been differentiated from various stem cells such as human embryonic stem cells (ESC) and induced pluripotent stem cells (iPSC), but it is difficult to produce mature cardiomyocytes. We showed rat hair-follicle-associated pluripotent (HAP) stem cells have pluripotency and produced mature beating cardiomyocyte sheets differentiated from rat HAP stem cells. The upper parts of rat vibrissa hair follicles were cultured in 10% FBS DMEM and stained with antibodies of the ectoderm, mesoderm, endoderm system to show the differentiation of multiple cell types. Moreover, HAP stem cells were cultured under three different conditions to decide the most suitable culture conditions for making beating cardiomyocyte sheets. The beating cardiomyocyte sheets were shown to be mature by staining sarcomere structures. Isoproterenol alone and the combination of isoproterenol, activin A, bone morphogenetic protein 4 (BMP4) and basic fibroblast growth factor (bFGF) effectively induced beating long-fiber cardiomyocytes, which formed beating sheets, only in the presence of all four agents. Flexible substrates were essential for the differentiation of sheets of mature beating cardiomyocytes for HAP stem cells. The features of the cardiomyocytes differentiated from HAP stem cells demonstrate they have clinical potential for heart regeneration.

Chronic spinal cord injury functionally repaired by direct implantation of encapsulated hair-follicle-associated pluripotent (HAP) stem cells in a mouse model: Potential for clinical regenerative medicine

Chronic spinal cord injury (SCI) is a highly debilitating and recalcitrant disease with limited treatment options. Although various stem cell types have shown some clinical efficacy for injury repair they have not for SCI. Hair-follicle-associated pluripotent (HAP) stem cells have been shown to differentiate into neurons, Schwan cells, beating cardiomyocytes and many other type of cells, and have effectively regenerated acute spinal cord injury in mouse models. In the present report, HAP stem cells from C57BL/6J mice, encapsulated in polyvinylidene fluoride membranes (PFM), were implanted into the severed thoracic spinal cord of C57BL/6J or athymic nude mice in the early chronic phase. After implantation, HAP stem cells differentiated to neurons, astrocytes and oligodendrocytes in the regenerated thoracic spinal cord of C57BL/6J and nude mice. Quantitative motor function analysis, with the Basso Mouse Scale for Locomotion (BMS) score, demonstrated a significant functional improvement in the HAP-stem-cell-implanted mice, compared to non-implanted mice. HAP stem cells have critical advantages over other stem cells: they do not develop teratomas; do not loose differentiation ability when cryopreserved and thus are bankable; are autologous, readily obtained from anyone; and do not require genetic manipulation. HAP stem cells therefore have greater clinical potential for SCI repair than induced pluripotent stem cells (iPSCs), neuronal stem cells (NSCs)/neural progenitor cells (NPCs) or embryonic stem cells (ESCs). The present report demonstrates future clinical potential of HAP-stem-cell repair of chronic spinal cord injury, currently a recalcitrant disease.

Establishment of Angora rabbits' whisker hair follicle model and optimal culture conditions

To establish the model of whisker hair follicle culture in vitro and explore the best culture conditions, the whisker hair follicles of Angora rabbits were separated with stereomicroscope and cultured in William's E, DMEM, MEM media. The surface of the cultured whisker hair follicles was not damaged due to manual operation, resulting in the hair shaft's growth. This indicated the success of the in vitro whisker hair follicle model. The hair shaft grew at the fastest rate in the William's E culture (p < 0.05), which was significantly higher than that in the DMEM and MEM media. The hematoxylin-eosin results showed that compared to the William's E group, the atrophy of whisker hair follicles in the DMEM and MEM media was evident, especially in the MEM medium. PCNA immunofluorescence staining was employed to detect the expression of whisker hair follicles. The results showed that the PCNA positive expression of the William's E group was significantly stronger than that of the DMEM and MEM groups. Furthermore, CCK-8 and Annexin V-FITC/PI methods were used to detect the proliferation and apoptosis of the dermal papilla cells (DPCs). The results of this study provide a model for studying the hair growth of fur animals.

Hair-Follicle-Associated Pluripotent (HAP) Stem Cells Can Extensively Differentiate to Tyrosine-Hydroxylase-Expressing Dopamine-Secreting Neurons

Hair-follicle-associated pluripotent (HAP) stem cells are located in the bulge area of hair follicles from mice and humans and have been shown to differentiate to neurons, glia, keratinocytes, smooth muscle cells, melanocytes and beating cardiac muscle cells in vitro. Subsequently, we demonstrated that HAP stem cells could effect nerve and spinal-cord regeneration in mouse models, differentiating to Schwann cells and neurons in this process. HAP stem cells can be banked by cryopreservation and preserve their ability to differentiate. In the present study, we demonstrated that mouse HAP stem cells cultured in neural-induction medium can extensively differentiate to dopaminergic neurons, which express tyrosine hydroxylase and secrete dopamine. These results indicate that the dopaminergic neurons differentiated from HAP stem cells may be useful in the future to improve the symptoms of Parkinson's disease in the clinic.

Hair-Follicle-Associated Pluripotent (HAP) Stem Cells Encapsulated on Polyvinylidene Fluoride Membranes (PFM) Promote Functional Recovery from Spinal Cord Injury

Our previous studies showed that nestin-expressing hair follicle-associated-pluripotent (HAP) stem cells, which reside in the bulge area of the hair follicle, could restore injured nerve and spinal cord and differentiate into cardiac muscle cells. Here we transplanted mouse green fluorescent protein (GFP)-expressing HAP stem-cell colonies enclosed on polyvinylidene fluoride membranes (PFM) into the severed thoracic spinal cord of nude mice. After seven weeks of implantation, we found the differentiation of HAP stem cells into neurons and glial cells. Our results also showed that PFM-captured GFP-expressing HAP stem-cell colonies assisted complete reattachment of the thoracic spinal cord. Furthermore, our quantitative motor function analysis with the Basso Mouse Scale for Locomotion (BMS) score demonstrated a significant improvement in the implanted mice compared to non-implanted mice with a severed spinal cord. Our study also showed that it is easy to obtain HAP stem cells, they do not develop teratomas, and do not loose differentiation ability when cryopreserved. Collectively our results suggest that HAP stem cells could be a better source compared to induced pluripotent stem cells (iPS) or embryonic stem (ES) cells for regenerative medicine, specifically for spinal cord repair.

Expression of anti-aging type-XVII collagen (COL17A1/BP180) in hair follicle-associated pluripotent (HAP) stem cells during differentiation

Hair-follicle-associated pluripotent (HAP) stem cells reside in the upper part of the bulge area of the the hair follicle. HAP stem cells are nestin-positive and keratin 15-negative and have the capacity to differentiate into various types of cells in vitro. HAP stem cells are also involved in nerve and spinal cord regeneration in mouse models. Recently, it was shown that the DNA-damage response in non-HAP hair follicle stem cells induces proteolysis of type-XVII collagen (COL17A1/BP180), which is involved in hair-follicle stem-cell maintenance. COL17A1 proteolysis stimulated hair-follicle stem-cell aging, characterized by the loss of stemness signatures and hair-follicle miniaturization associated with androgenic alopecia. In the present study, we demonstrate that HAP stem cells co-express nestin and COL17A1 in vitro and in vivo. The expression of HAP stem cell markers (nestin and SSEA1) increased after HAP stem-cell colonies were formed, then decreased after differentiation to epidermal keratinocytes. In contrast COL17A1 increased after differentiation to epidermal keratinocytes. These results suggest that COL17A1 is important in differentiation of HAP stem cells.

Hair-follicle-associated pluripotent stem cells derived from cryopreserved intact human hair follicles sustain multilineage differentiation potential

The bulge area of the hair follicle contains hair-follicle-associated pluripotent (HAP) stem cells. Here, we present effective cryopreservation procedures of the human hair follicle that preserve the differentiation potential of HAP stem cells. Whole hair follicles isolated from human scalp were cryopreserved by a slow-rate cooling medium and stored in liquid nitrogen. A careful thawing method was used to collect the upper parts of the human hair follicles which were cultured for four weeks in a Dulbecco’s Modified Eagle’s Medium with fetal bovine serum (FBS). Proliferating hair follicle cells were then shifted to DMEM/Ham’s Nutrient Mixture F-12 medium without FBS and allowed to grow for one week. These proliferating cells were able to produce HAP stem cell colonies with multilineage differentiation capacity. They produced keratinocytes, smooth muscle cells, cardiac muscle cells, neurons and glial cells. Interestingly, these cryopreserved hair follicles produced pluripotent HAP stem cell colonies similar to fresh follicles. These findings suggest that the cryopreserved whole human hair follicle preserves the ability to produce HAP stem cells, which will enable any individual to preserve a bank of these stem cells for personalized regenerative medicine.

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.

Protocols for Cryopreservation of Intact Hair Follicle That Maintain Pluripotency of Nestin-Expressing Hair-Follicle-Associated Pluripotent (HAP) Stem Cells

Hair follicles contain nestin-expressing pluripotent stem cells, the origin of which is above the bulge area, below the sebaceous gland. We have termed these cells hair-follicle-associated pluripotent (HAP) stem cells. Cryopreservation methods of the hair follicle that maintain the pluripotency of HAP stem cells are described in this chapter. Intact hair follicles from green fluorescent protein (GFP) transgenic mice were cryopreserved by slow-rate cooling in TC-Protector medium and storage in liquid nitrogen. After thawing, the upper part of the hair follicle was isolated and cultured in DMEM with fetal bovine serum (FBS). After 4 weeks culture, cells from the upper part of the hair follicles grew out. The growing cells were transferred to DMEM/F12 without FBS. After 1 week culture, the growing cells formed hair spheres, each containing approximately 1 × 10(2) HAP stem cells. The hair spheres contained cells which could differentiate to neurons, glial cells, and other cell types. The formation of hair spheres by the thawed and cultured upper part of the hair follicle produced almost as many pluripotent hair spheres as fresh follicles. The hair spheres derived from cryopreserved hair follicles were as pluripotent as hair spheres from fresh hair follicles. These results suggest that the cryopreservation of the whole hair follicle is an effective way to store HAP stem cells for personalized regenerative medicine, enabling any individual to maintain a bank of pluripotent stem cells for future clinical use.

Peripheral-Nerve and Spinal-Cord Regeneration in Mice Using Hair-Follicle-Associated Pluripotent (HAP) Stem Cells

Nestin, a neural stem cell marker protein, is expressed in hair follicle cells above the bulge area. These nestin-positive hair follicle-associated-pluripotent (HAP) stem cells are negative for the keratinocyte marker K15 and can differentiate into neurons, glia, keratinocytes, smooth muscle cells, cardiac muscle cells, and melanocytes in vitro. HAP stem cells are positive for the stem cell marker CD34, as well as K15-negative, suggesting their relatively undifferentiated state. HAP stem cells promoted the functional recovery of injured peripheral nerves and the spinal cord. HAP stem cells differentiated into glial fibrillary acidic protein (GFAP)-positive Schwann cells when implanted in severed sciatic nerves and spinal cords in mice. These results suggest that HAP stem cells provide an important accessible, autologous source of adult stem cells for regenerative medicine, that have critical advantages over ES and iPS stem cells.

Implanted hair-follicle-associated pluripotent (HAP) stem cells encapsulated in polyvinylidene fluoride membrane cylinders promote effective recovery of peripheral nerve injury

Hair follicle-associated-pluripotent (HAP) stem cells are located in the bulge area of the hair follicle, express the stem-cell marker, nestin, and have been shown to differentiate to nerve cells, glial cells, keratinocytes, smooth muscle cells, cardiac muscle cells, and melanocytes. Transplanted HAP stem cells promote the recovery of peripheral nerve and spinal cord injuries and have the potential for heart regeneration as well. In the present study, we implanted mouse green fluorescent protein (GFP)-expressing HAP stem-cell spheres encapsulated in polyvinylidene fluoride (PVDF)-membrane cylinders into the severed sciatic nerve of immunocompetent and immunocompromised (nude) mice. Eight weeks after implantation, immunofluorescence staining showed that the HAP stem cells differentiated into neurons and glial cells. Fluorescence microscopy showed that the HAP stem cell hair spheres promoted rejoining of the sciatic nerve of both immunocompetent and immunodeficient mice. Hematoxylin and eosin (H&E) staining showed that the severed scatic nerves had regenerated. Quantitative walking analysis showed that the transplanted mice recovered the ability to walk normally. HAP stem cells are readily accessible from everyone, do not form tumors, and can be cryopreserved without loss of differentiation potential. These results suggest that HAP stem cells may have greater potential than iPS or ES cells for regenerative medicine.

Hair follicle-associated-pluripotent (HAP) stem cells

Various types of stem cells reside in the skin, including keratinocyte progenitor cells, melanocyte progenitor cells, skin-derived precursors (SKPs), and nestin-expressing hair follicle-associated-pluripotent (HAP) stem cells. HAP stem cells, located in the bulge area of the hair follicle, have been shown to differentiate to nerve cells, glial cells, keratinocytes, smooth muscle cells, cardiac muscle cells, and melanocytes. HAP stem cells are positive for the stem-cell marker CD34, as well as K15-negative, suggesting their relatively undifferentiated state. Therefore, HAP stem cells may be the most primitive stem cells in the skin. Moreover, HAP stem cells can regenerate the epidermis and at least parts of the hair follicle. These results suggest that HAP stem cells may be the origin of other stem cells in the skin. Transplanted HAP stem cells promote the recovery of peripheral-nerve and spinal-cord injuries and have the potential for heart regeneration as well. HAP stem cells are readily accessible from everyone, do not form tumors, and can be cryopreserved without loss of differentiation potential. These results suggest that HAP stem cells may have greater potential than iPS or ES cells for regenerative medicine.

Aging hair follicles rejuvenated by transplantation to a young subcutaneous environment

We demonstrate in the present study that young host mice rejuvenate aged hair follicles after transplantation. Young mice promote the hair shaft growth of transplanted old hair follicles, as well as young follicles, in contrast to old host mice, which did not support hair-shaft growth from transplanted old or young follicles. Nestin-expressing hair follicle-associated pluripotent (HAP) stem cells of transplanted old and young hair follicles remained active in young host nude mice. In contrast, the nestin-expressing HAP stem cells in young and old hair follicles transplanted to old nude mice were not as active as in young nude host mice. The present study shows that transplanted old hair follicles were rejuvenated by young host mice, suggesting that aging may be reversible.

Early-age-dependent selective decrease of differentiation potential of hair-follicle-associated pluripotent (HAP) stem cells to beating cardiac-muscle cells

We have previously discovered nestin-expressing hair-follicle-associated pluripotent (HAP) stem cells and have shown that they can differentiate to neurons, glia, and many other cell types. HAP stem cells can be used for nerve and spinal cord repair. We have recently shown the HAP stem cells can differentiate to beating heart-muscle cells and tissue sheets of beating heart-muscle cells. In the present study, we determined the efficiency of HAP stem cells from mouse vibrissa hair follicles of various ages to differentiate to beating heart-muscle cells. We observed that the whiskers located near the ear were more efficient to differentiate to cardiac-muscle cells compared to whiskers located near the nose. Differentiation to cardiac-muscle cells from HAP stem cells in cultured whiskers in 4-week-old mice was significantly greater than in 10-, 20-, and 40-week-old mice. There was a strong decrease in differentiation potential of HAP stem cells to cardiac-muscle cells by 10 weeks of age. In contrast, the differentiation potential of HAP stem cells to other cell types did not decrease with age. The possibility of rejuvenation of HAP stem cells to differentiate at high efficiency to cardiac-muscle cells is discussed.

Cryopreservation of Hair-Follicle Associated Pluripotent (HAP) Stem Cells Maintains Differentiation and Hair-Growth Potential

Hair follicles contain nestin-expressing pluripotent stem cells which originate above the bulge area of the follicle, below the sebaceous gland. We have termed these cells hair follicle-associated pluripotent (HAP) stem cells. We have established efficient cryopreservation methods of the hair follicle that maintain the pluripotency of HAP stem cells as well as hair growth. We cryopreserved the whole hair follicle by slow-rate cooling in TC-Protector medium or in DMSO-containing medium and storage in liquid nitrogen or at -80 °C. After thawing and culture of the cryopreserved whisker follicles, growing HAP stem cells formed hair spheres. The hair spheres contained cells that differentiated to neurons, glial cells, and other cell types. The hair spheres derived from slow-cooling cryopreserved hair follicles were as pluripotent as hair spheres from fresh hair follicles. We have also previously demonstrated that cryopreserved mouse whisker hair follicles maintain their hair-growth potential. DMSO better cryopreserved mouse whisker follicles compared to glycerol. DMSO-cryopreserved hair follicles also maintained the HAP stem cells, evidenced by P75_ntr expression. Subcutaneous transplantation of DMSO-cryopreserved hair follicles in nude mice resulted in extensive hair fiber growth over 8 weeks, indicating the functional recovery of hair-shaft growth of cryopreserved hair follicles. HAP stem cells can be used for nerve and spinal-cord repair. This biobanking of hair follicles can allow each patient the potential for their own stem cell use for regenerative medicine or hair transplantation.

Extensive Hair Shaft Growth after Mouse Whisker Follicle Isolation, Cryopreservation and Transplantation in Nude Mice

We previously demonstrated that whole hair follicles could be cryopreserved to maintain their stem-cells differentation potential. In the present study, we demonstrated that cryopreserved mouse whisker hair follicles maintain their hair growth potential. DMSO better cryopreserved mouse whisker follicles compared to glycerol. Cryopreserved hair follicles also maintained the hair follicle-associated-pluripotent (HAP) stem cells, evidenced by P75^NTR expression. Subcutaneous transplantation of DMSO-cryopreserved hair follicles in nude mice resulted in extensive hair fiber growth over 8 weeks, indicating the functional recovery of hair shaft growth of cryopreserved hair follicles.

From hair to heart: nestin-expressing hair-follicle-associated pluripotent (HAP) stem cells differentiate to beating cardiac muscle cells

We have previously demonstrated that 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 from mouse and human could form spheres in culture, termed hair spheres, which are keratin 15-negative and CD34-positive and could differentiate to neurons, glia, keratinocytes, smooth muscle cells, and melanocytes in vitro. Subsequently, we demonstrated that nestin-expressing stem cells could effect nerve and spinal cord regeneration in mouse models. In the present study, we demonstrated that HAP stem cells differentiated to beating cardiac muscle cells. We separated the mouse vibrissa hair follicle into 3 parts (upper, middle, and lower), and suspended each part separately in DMEM containing 10% FBS. All three parts of hair follicle differentiated to beating cardiac muscle cells as well as neurons, glial cells, keratinocytes and smooth muscle cells. The differentiation potential to cardiac muscle is greatest in the upper part of the follicle. The beat rate of the cardiac muscle cells was stimulated by isoproterenol and inhibited by propanolol. HAP stem cells have potential for regenerative medicine for heart disease as well as nerve and spinal cord repair.