Organ Regeneration Based on Developmental Biology

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6.7.4 Human Bioengineered Hair Follicle

One of the ultimate goals of research investigating hair follicle regeneration is the
clinical translation for the treatment of hair loss and various hair-associated disor-
ders. A number of researchers have reported the hair follicle-forming potential of
dissected tissues and cultured cells derived from human biopsies; however, no one
has provided conclusive evidence for the regeneration of a fully functional human
hair follicle. The human bioengineered hair follicle germ, which consists of dissoci-
ated bulge region-derived epithelial cells and scalp hair follicle-derived intact DPs
in an androgenetic alopecia patient, could regenerate the human hair follicle and
support the growth of a pigmented hair shaft in the intracutaneous transplantation
area of nude mice. This bioengineered hair follicle was composed of correct struc-
tures, consisting minimally of an infundibulum and sebaceous gland, hair shaft,
inner root sheath, ORS, hair matrix, and DP in the hair bulb structure, which were
confirmed to be of human origin (Toyoshima et al. 2012 ). This result indicates that
the bioengineered hair follicle germ method is applicable to human-derived cells
and contributes to future developments in hair follicle regenerative medicine
(Toyoshima et al. 2012 ).

6.8 Future Perspectives for the Hair Follicle

To achieve hair follicle regeneration using stem cells in the adult hair follicle,
defining the regeneration of the various stem cells and their niches is considered
essential. Based on the preceding studies, we can utilize the extensive knowledge
of various types of follicular stem cells in the hair follicle (Chuong et al. 2007 ).

APM

(donor/host)

Nerve

(host)

Bulge

ab

(donor)

Fig. 6.6 Analyses of connections to surrounding tissues and the piloerection capability of bioen-
gineered hair follicles. (a) Schematic representation of the connections of the bioengineered hair
follicles with surrounding tissues in adult skin. (b) The connections of the follicles of a EGFP-
labeled bioengineered pelage to arrector pili muscles (red signal) and nerve fibers (white signal)
were analyzed by immunohistochemical staining. The boxed areas in the left panel are shown at a
higher magnification on the right. The arrowheads indicate the muscle and nerve fibers connected
to the pelage follicles. Scale bars, 100 μm at low magnification and 50 μm at high magnification

6 Functional Hair Follicle Regeneration