Published papers

The dermal papilla (DP) is a specialised mesenchymal component of the hair follicle (HF) that plays key roles in HF morphogenesis and regeneration. Current technical difficulties in preparing trichogenic human DP cells could be overcome by the use of highly proliferative and plastic human induced pluripotent stem cells (hiPSCs). In this study, hiPSCs were differentiated into induced mesenchymal cells (iMCs) with a bone marrow stromal cell phenotype. A highly proliferative and plastic LNGFR(+)THY-1(+) subset of iMCs was subsequently programmed using retinoic acid and DP cell activating culture medium to acquire DP properties. The resultant cells (induced DP-substituting cells [iDPSCs]) exhibited up-regulated DP markers, interacted with human keratinocytes to up-regulate HF related genes, and when co-grafted with human keratinocytes in vivo gave rise to fibre structures with a hair cuticle-like coat resembling the hair shaft, as confirmed by scanning electron microscope analysis. Furthermore, iDPSCs responded to the clinically used hair growth reagent, minoxidil sulfate, to up-regulate DP genes, further supporting that they were capable of, at least in part, reproducing DP properties. Thus, LNGFR(+)THY-1(+) iMCs may provide material for HF bioengineering and drug screening for hair diseases.

BACKGROUND: Autosomal recessive woolly hair/hypotrichosis (ARWH/H) is caused by mutations in LIPH. Homozygotes for the LIPH c.736T>A (p.C246S) mutation, the most prevalent genotype in Japanese patients, present varying degrees of hair loss; however, determinants of this phenotypic diversity remain elusive. OBJECTIVES: To establish methodologies for quantitative assessment of clinical severity and provide a detailed characterization to elucidate the factors contributing to phenotypic divergence. METHODS: Digital image analyses were conducted to convert clinical severities into numerical values. Eight patients with ARWH/H were classified into three groups (mild, severe, very severe), based on severity scores. Dermoscopic images were collected and assessed for total hair numbers and hair thickness for intergroup comparisons. RESULTS: The image analysis detected a difference in hair thickness but not in total hair numbers, between mild and severe cases. A marked decrease in total hair number was noted in an atypical very severe case. Histopathologically, a patient with a mild case demonstrated hair miniaturization and a high telogen/anagen ratio without a decrease in total hair count, endorsing dermoscopic observations. Two children demonstrated spontaneous improvement without an increase in total hair numbers, and two adults responded well to topical minoxidil with increased total hair numbers and hair thickness. CONCLUSIONS: The difference in the frequency of underdeveloped hairs may be a major factor contributing to the clinical diversity of hair sparseness in LIPH c.736T>A homozygotes with ARWH/H. Hence, pharmacological modification to thicken existing fine hairs may provide a therapeutic strategy.

Background: Autosomal recessive woolly hair/hypotrichosis (ARWH/H) is caused by mutations in LIPH. Homozygotes for the LIPH c.736T>A (p.C246S) mutation, the most prevalent genotype in Japanese patients, present varying degrees of hair loss; however, determinants of this phenotypic diversity remain elusive. Objectives: To establish methodologies for quantitative assessment of clinical severity and provide a detailed characterization to elucidate the factors contributing to phenotypic divergence. Methods: Digital image analyses were conducted to convert clinical severities into numerical values. Eight patients with ARWH/H were classified into three groups (mild, severe, very severe), based on severity scores. Dermoscopic images were collected and assessed for total hair numbers and hair thickness for intergroup comparisons. Results: The image analysis detected a difference in hair thickness but not in total hair numbers, between mild and severe cases. A marked decrease in total hair number was noted in an atypical very severe case. Histopathologically, a patient with a mild case demonstrated hair miniaturization and a high telogen/anagen ratio without a decrease in total hair count, endorsing dermoscopic observations. Two children demonstrated spontaneous improvement without an increase in total hair numbers, and two adults responded well to topical minoxidil with increased total hair numbers and hair thickness. Conclusions: The difference in the frequency of underdeveloped hairs may be a major factor contributing to the clinical diversity of hair sparseness in LIPH c.736T>A homozygotes with ARWH/H. Hence, pharmacological modification to thicken existing fine hairs may provide a therapeutic strategy.

Pachydermoperiostosis is a rare hereditary disease, which presents with the cutaneous manifestations of pachydermia and cutis verticis gyrata. Histological findings in pachydermia frequently include dermal edema, mucin deposition, elastic fiber degeneration, dermal fibrosis and adnexal hyperplasia. However, the severity of these findings varies between clinical reports, and a systematic multiple-case clinicopathological correlative analysis has not been performed to date. In the present study, we reviewed the skin biopsy specimens obtained from the pachydermia of six pachydermoperiostosis patients. The severity of the characteristic histological features was semiquantitatively evaluated and correlated with the grade of pachydermia. Dermal edema, mucin deposition and elastic fiber degeneration were observed in all cases. Patients with severe pachydermia had sebaceous gland hyperplasia and fibrosis. These results suggest that the triad of mucin deposition, dermal edema and elastic fiber degeneration are found from very early stage pachydermia, and could be considered diagnostic findings. To ensure an earlier diagnosis of pachydermoperiostosis, a biopsy should be taken when a patient has grade 1 pachydermia to determine the presence of this histological triad.

Vertebrates have a unique 3D body shape in which correct tissue and organ shape and alignment are essential for function. For example, vision requires the lens to be centred in the eye cup which must in turn be correctly positioned in the head. Tissue morphogenesis depends on force generation, force transmission through the tissue, and response of tissues and extracellular matrix to force. Although a century ago D'Arcy Thompson postulated that terrestrial animal body shapes are conditioned by gravity, there has been no animal model directly demonstrating how the aforementioned mechano-morphogenetic processes are coordinated to generate a body shape that withstands gravity. Here we report a unique medaka fish (Oryzias latipes) mutant, hirame (hir), which is sensitive to deformation by gravity. hir embryos display a markedly flattened body caused by mutation of YAP, a nuclear executor of Hippo signalling that regulates organ size. We show that actomyosin-mediated tissue tension is reduced in hir embryos, leading to tissue flattening and tissue misalignment, both of which contribute to body flattening. By analysing YAP function in 3D spheroids of human cells, we identify the Rho GTPase activating protein ARHGAP18 as an effector of YAP in controlling tissue tension. Together, these findings reveal a previously unrecognised function of YAP in regulating tissue shape and alignment required for proper 3D body shape. Understanding this morphogenetic function of YAP could facilitate the use of embryonic stem cells to generate complex organs requiring correct alignment of multiple tissues.

Previously, we described the safety and therapeutic potential of neurospheres (NSs) derived from a human induced pluripotent stem cell (iPSC) clone, 201B7, in a spinal cord injury (SCI) mouse model. However, several safety issues concerning iPSC-based cell therapy remain unresolved. Here, we investigated another iPSC clone, 253G1, that we established by transducing OCT4, SOX2, and KLF4 into adult human dermal fibroblasts collected from the same donor who provided the 201B7 clone. The grafted 253G1-NSs survived, differentiated into three neural lineages, and promoted functional recovery accompanied by stimulated synapse formation 47 days after transplantation. However, long-term observation (for up to 103 days) revealed deteriorated motor function accompanied by tumor formation. The tumors consisted of Nestin(+) undifferentiated neural cells and exhibited activation of the OCT4 transgene. Transcriptome analysis revealed that a heightened mesenchymal transition may have contributed to the progression of tumors derived from grafted cells.

UNLABELLED: During vertebrate embryogenesis, the liver develops at a precise location along the endodermal primitive gut tube because of signaling delivered by adjacent mesodermal tissues. Although several signaling molecules have been associated with liver formation, the molecular mechanism that regulates liver specification is still unclear. We previously performed a screen in medaka to isolate mutants with impaired liver development. The medaka hio mutants exhibit a profound (but transient) defect in liver specification that resembles the liver formation defect found in zebrafish prometheus (prt) mutants, whose mutation occurs in the wnt2bb gene. In addition to their liver abnormality, hio mutants lack pectoral fins and die after hatching. Positional cloning indicated that the hio mutation affects the raldh2 gene encoding retinaldehyde dehydrogenase type2 (RALDH2), the enzyme principally responsible for retinoic acid (RA) biosynthesis. Mutations of raldh2 in zebrafish preclude the development of pectoral fins. Interestingly, in hio mutants, expression of wnt2bb in the lateral plate mesoderm (LPM) directly adjacent to the liver-forming endoderm was completely lost. CONCLUSION: Our data reveal the unexpected finding that RA signaling positively regulates the wnt2bb gene expression required for liver specification in medaka. These results suggest that a common molecular mechanism may underlie liver and pectoral fin specification during piscine embryogenesis.