Clonal growth of human melanocytes using cell-free extracellular matrix

Extraciliary OFD1 Is Involved in Melanocyte Survival through Cell Adhesion to ECM via Paxillin

Primary cilia play a significant role in influencing cell fate, including apoptosis in multiple cell types. In the lesional epidermis of vitiligo patients, a reduced number of ciliated cells was observed. Our study also revealed a downregulation of oral-facial digital syndrome type 1 (OFD1) in the affected skin of vitiligo patients. However, it remains unknown whether primary cilia are involved in the control of melanocyte apoptosis. While both intraflagellar transport 88 (IFT88) and retinitis pigmentosa GTPase regulator-interacting protein-1 like (RPGRIP1L) are associated with ciliogenesis in melanocytes, only the knockdown of OFD1, but not IFT88 and RPGRIP1L, resulted in increased melanocyte apoptosis. OFD1 knockdown led to a decrease in the expression of proteins involved in cell-extracellular matrix (ECM) interactions, including paxillin. The OFD1 amino acid residues 601-1012 interacted with paxillin, while the amino acid residues 1-601 were associated with ciliogenesis, suggesting that the OFD1 domains responsible for paxillin binding are distinct from those involved in ciliogenesis. OFD1 knockdown, but not IFT88 knockdown, inhibited melanocyte adhesion to the ECM, a defect that was restored by paxillin overexpression. In summary, our findings indicate that the downregulation of OFD1 induces melanocyte apoptosis, independent of any impairment in ciliogenesis, by reducing melanocyte adhesion to the ECM via paxillin.

Organotypic Human Skin Cultures Incorporating Primary Melanocytes

Three-dimensional (3D) human organotypic skin cultures provide a physiologically relevant model that recapitulates in vivo skin features. Most commonly, organotypic skin cultures are created by seeding isolated epidermal keratinocytes onto a collagen/fibroblast plug and lifting to an air liquid interface. These conditions are sufficient to drive stratification and differentiation of the keratinocytes to form an epidermal-like sheet with remarkable similarities to human epidermis. Coupled with genetic or pharmacological treatments, these cultures provide a powerful tool for elucidating keratinocyte biology. Recent focus has been placed on increasing the utility of organotypic skin cultures by incorporating other cell types that are present in the skin, such as melanocytes, immune cells, and other cells. Here we describe a step-by-step protocol for the isolation of neonatal human epidermal keratinocytes and melanocytes from foreskins, and the creation of organotypic skin cultures that include both cell types. We also describe methods that can be used to assess melanocyte behavior in these organotypic cultures, including methods for whole mount staining, measurement of melanocyte dendricity, staining for pigment, and 5-bromo-2'-deoxyuridine (BrdU) labeling for identification of proliferating cells. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Isolation of primary cells Alternate Protocol: Isolation of primary cells using differential trypsinization Basic Protocol 2: Organotypic culture protocol Support Protocol 1: Culture and maintenance of NHEKs and melanocytes Support Protocol 2: Lentiviral transduction of melanocytes Support Protocol 3: Retroviral transduction of NHEKs Support Protocol 4: Whole mount immunostaining protocol Support Protocol 5: Measuring melanocyte dendricity Support Protocol 6: Fontana-Masson staining protocol Support Protocol 7: BrdU labeling and staining.

Adipose-Derived Stem Cell Coculturing Stimulates Integrin-Mediated Extracellular Matrix Adhesion of Melanocytes by Upregulating Growth Factors

Coculture with adipose-derived stem cells (ADSCs) can stimulate proliferation and migration of melanocytes. To enhance outcomes of skin disorders caused by melanocyte loss or death, mixed transplantation with ADSCs has been suggested. However, role of cocultured ADSCs in proliferation and migration of melanocytes remains unclear. This study determined the effect of ADSCs on production of growth factors and expression levels of intergrins in primary culture of adult human melanocytes with or without ADSCs and in nude mice grafted with such melanocytes. Higher amounts of growth factors for melanocytes, such as bFGF and SCF were produced and released from ADSCs by coculturing with melanocytes. Relative levels of integrins β1, α5, and α6 as well as adhesion to fibronectin and laminin were increased in melanocytes cocultured with ADSCs. Such increases were inhibited by neutralization of bFGF or SCF. Relative levels of bFGF, SCF and integrins were increased in nude mice skin after grafting with melanocyte+ADSC cocultures. Collectively, these results indicate that ADSCs can stimulate proliferation and migration of melanocytes by increasing expression of integrins in melanocytes through upregulation of production/release of melanocyte growth factors such as bFGF and SCF.

A reporter mouse model for in vivo tracing and in vitro molecular studies of melanocytic lineage cells and their diseases

Alterations in melanocytic lineage cells give rise to a plethora of distinct human diseases, including neurocristopathies, cutaneous pigmentation disorders, loss of vision and hearing, and melanoma. Understanding the ontogeny and biology of melanocytic cells, as well as how they interact with their surrounding environment, are key steps in the development of therapies for diseases that involve this cell lineage. Efforts to culture and characterize primary melanocytes from normal or genetically engineered mouse models have at times yielded contrasting observations. This is due, in part, to differences in the conditions used to isolate, purify and culture these cells in individual studies. By breeding ROSA^mT/mG and Tyr::CreER^T2 mice, we generated animals in which melanocytic lineage cells are identified through expression of green fluorescent protein. We also used defined conditions to systematically investigate the proliferation and migration responses of primary melanocytes on various extracellular matrix (ECM) substrates. Under our culture conditions, mouse melanocytes exhibit doubling times in the range of 10 days, and retain exponential proliferative capacity for 50-60 days. In culture, these melanocytes showed distinct responses to different ECM substrates. Specifically, laminin-332 promoted cell spreading, formation of dendrites, random motility and directional migration. In contrast, low or intermediate concentrations of collagen I promoted adhesion and acquisition of a bipolar morphology, and interfered with melanocyte forward movements. Our systematic evaluation of primary melanocyte responses emphasizes the importance of clearly defining culture conditions for these cells. This, in turn, is essential for the interpretation of melanocyte responses to extracellular cues and to understand the molecular basis of disorders involving the melanocytic cell lineage.