Melanocytes Research Articles

Revealing the UV response of melanocytes in xeroderma pigmentosum group A using patient-derived induced pluripotent stem cells

BackgroundXeroderma pigmentosum (XP) is characterized by photosensitivity that causes pigmentary disorder and predisposition to skin cancers on sunlight-exposed areas due to DNA repair deficiency. Patients with XP group A (XP-A) develop freckle-like pigmented maculae and depigmented maculae within a year unless strict sun-protection is enforced. Although it is crucial to study pigment cells (melanocytes: MCs) as disease target cells, establishing MCs in primary cultures is challenging. ObjectiveElucidation of the disease pathogenesis by comparison between MCs differentiated from XP-A induced pluripotent stem cells (iPSCs) and healthy control iPSCs on the response to UV irradiation. MethodsiPSCs were established from a XP-A fibroblasts and differentiated into MCs. Differences in gene expression profiles between XP-A-iPSC-derived melanocytes (XP-A-iMCs) and Healthy control iPSC-derived MCs (HC-iMCs) were analyzed 4 and 12 h after irradiation with 30 or 150 J/m2 of UV-B using microarray analysis. ResultsXP-A-iMCs expressed SOX10, MITF, and TYR, and showed melanin synthesis. Further, XP-A-iMCs showed reduced DNA repair ability. Gene expression profile between XP-A-iMCs and HC-iMCs revealed that, numerous gene probes that were specifically upregulated or downregulated in XP-A-iMCs after 150-J/m2 of UV-B irradiation did not return to basal levels. Of note that apoptotic pathways were highly upregulated at 150 J/m2 UV exposure in XP-A-iMCs, and cytokine-related pathways were upregulated even at 30 J/m2 UV exposure. ConclusionWe revealed for the first time that cytokine-related pathways were upregulated even at low-dose UV exposure in XP-A-iMCs. Disease-specific iPSCs are useful to elucidate the disease pathogenesis and develop treatment strategies of XP.

Influence of Substrate Stiffness on iPSC-Derived Retinal Pigmented Epithelial Cells.

Retinal degenerative diseases are a major cause of blindness involving the dysfunction of photoreceptors, retinal pigmented epithelium (RPE), or both. A promising treatment approach involves replacing these cells via surgical transplantation, and previous work has shown that cell delivery scaffolds are vital to ensure sufficient cell survival. Thus, identifying scaffold properties that are conducive to cell viability and maturation (such as suitable material and mechanical properties) is critical to ensuring a successful treatment approach. In this study, we investigated the effect of scaffold stiffness on human RPE attachment, survival, and differentiation, comparing immortalized (ARPE-19) and stem cell-derived RPE (iRPE) cells. Polydimethylsiloxane was used as a model polymer substrate, and varying stiffness (~12 to 800 kPa) was achieved by modulating the cross-link-to-base ratio. Post-attachment changes in gene and protein expression were assessed using qPCR and immunocytochemistry. We found that while ARPE-19 and iRPE exhibited significant differences in morphology and expression of RPE markers, substrate stiffness did not have a substantial impact on cell growth or maturation for either cell type. These results highlight the differences in expression between immortalized and iPSC-derived RPE cells, and also suggest that stiffnesses in this range (~12-800 kPa) may not result in significant differences in RPE growth and maturation, an important consideration in scaffold design.

Tailored Fabrics with Biomimetic Janus Spectral Responsiveness for All‐Weather Switchable Thermoregulation

AbstractIn the face of global climate change, adapting to intensive temperature variation and maintaining stable body temperature in outdoor settings are crucial for keeping personal health and boosting labor productivity. Developing zero‐energy fabrics with switchable thermoregulation provides a feasible strategy for responding to this climate circumstance. However, integrating switchable thermoregulation into fabrics without compromising their structural integrity, comfortability, and fabrication scalability remains challenging. Here, inspired by the Bokermannohyla alvarengai, which adapts its skin color in Janus mode to different sunlight and temperature conditions by varying its pigment cells, the fabrics with Janus spectral responsiveness are designed. The radiative cooling micro‐fibers and photothermal micro‐fibers are assembled into tailored textures, constructing the single‐layer fabrics coupled with distinct thermoregulation functions on each side. The resulting Janus spectral responsiveness fabrics present a solar reflectivity of 83.9% in cooling mode and a solar absorptivity of 84.3% in heating mode, while the robust interlaced coil configuration of the fabrics not only maintains the rich porous structures but also enhances the structural integrity of the fabrics. Advancing single‐layer, dual‐mode fabrics may provide a promising pathway for all‐weather switchable personal thermoregulation, potentially optimizing the market for personal thermal management.

SASH1 S519N Variant Links Skin Hyperpigmentation and Premature Hair Graying to Dysfunction of Melanocyte Lineage

A better understanding of human melanocyte (MC) and MC stem cell biology is essential for treating MC-related diseases. This study employed an inherited pigmentation disorder carrying the SASH1S519N variant in a Hispanic family to investigate SASH1 function in the MC lineage and the underlying mechanism for this disorder. We used a multidisciplinary approach, including clinical examinations, human cell assays, yeast 2-hybrid screening, and biochemical techniques. Results linked early hair graying to the SASH1S519N variant, a previously unrecognized clinical phenotype in hyperpigmentation disorders. Invitro, we identified SASH1 as a regulator in MC stem cell maintenance and discovered that TNKS2 is crucial for SASH1's role. In addition, the S519N variant is located in one of multiple tankyrase-binding motifs and alters the binding kinetics and affinity of the interaction. In summary, this disorder links both gain and loss of pigmentation in the same individual, hinting to accelerated aging in human MC stem cells. The findings offer insights into the roles of SASH1 and TNKS2 in MC stem cell maintenance and the molecular mechanisms of pigmentation disorders. We propose that a comprehensive clinical evaluation of patients with MC-related disorders should include an assessment and history of hair pigmentation loss.

Transient receptor potential mucolipin 1 circumvents oxidative stress in primary human melanocytes.

Transient Receptor Potential Mucolipin 1 (TRPML1) serves as a pivotal reactive oxygen species (ROS) sensor in cells, which is implicated in the regulation of autophagy. However, its function in melanocyte autophagy under oxidative stress remains elusive. The expression and ion channel function of TRPML1 were investigated using immunofluorescence and calcium imaging in primary human melanocytes (MCs). After activating TRPML1 with MLSA1 (TRPML1 agonist), autophagy-related molecules were investigated via western blot. ROS level, apoptosis- and autophagy-related molecules were investigated after pretreatment with MLSA1. After interference with TRPML1 expression, mitochondrial structures were visualized by electron microscopy with hydrogen peroxide (H2O2）treatment. TRPML1 was expressed and functionally active in primary human MCs, and its activation promotes elevated expression of LC3-II and reduced apoptosis and ROS levels under oxidative stress. TRPML1 downregulation caused mitochondrial swelling and disruption of cristae structures under oxidative stress in primary human MCs. TRPML1 might mediate lysosomal autophagy in primary human MCs under oxidative stress, participating in mechanisms that maintain the oxidative and antioxidant systems in balance.

Histopathological Evaluation of the Curative Effects of EDTA on Lymnaea stagnalis Exposed to Subacute Cadmium.

We investigated the therapeutic effects of EDTA application for 14 and 28 days on cadmium (Cd) induced pond snail Lymnaea stagnalis (Linnaeus, 1758). The sublethal concentration of cadmium (63.4mg/l Cd) caused tissue damages to the snail after an exposure for 28 days.In the groups treated with EDTA, the concentration of Cd in the foot, mantle and hepatopancreas tissues showed significantly decreased during the recovery period. The curative effects of EDTA on Cd-induced damage were assessed using a scoring system. Cadmium exposure led to histopathological changes including increased mucositis, pigment and protein cells, foot epithelium desquamation, muscle fibril damage, connective tissue cell atrophy, and increased lipid vacuoles in the mantle and hepatopancreas. However, these changes were less severe in snails treated with EDTA (2.00 mL/L for 28day), indicating that EDTA reduces their susceptibility to heavy metal toxicity.

A novel homozygous missense variant identified in the myosin VIIA motor domain of a Moroccan patient with usher syndrome.

Usher syndrome 1 (USH1) is the most severe subtype of Usher syndrome characterized by severe sensorineural hearing impairment, retinitis pigmentosa, and vestibular areflexia. USH1 is usually induced by variants in MYO7A, a gene that encodes the myosin-VIIa protein. Myosin-VIIA is effectively involved in intracellular molecular traffic essential for the proper function of the cochlea, the retinal photoreceptors, and the retinal pigmented epithelial cells. In this study, we report a new homozygous missense variant (NM_000260.4: c.1657C > T p.(His553Tyr)) in MYO7A of a 28-year-old female with symptoms consistent with USH1. This variant, c.1657C > T p.(His553Tyr) is positioned in the highly conserved myosin-VIIA motor domain. Previous studies showed that variants in this domain might disrupt the ability of the protein to bind to actin and thus cause the disorder. Our findings contribute to our understanding of the phenotypic and mutational spectrum of USH1 associated with autosomal recessive MYO7A variants and emphasize the important role of molecular testing in accurately diagnosing this syndrome. More advanced research is required to understand the functional effect of the identified variant and the genotype-phonotype correlations of MYO7A-related Usher syndrome 1.

Identification and Characterization of microRNAs in Morphological Color Change of Polychromatic Midas Cichlids (Amphilophus citrinellus)

As a representative genetic and economic trait, pigmentation has a strong impact on speciation and adaptation. However, information and reports on microRNAs (miRNAs) associated with pigmentation remain limited. The Midas cichlid fish, with three typical distinct stages of body color pattern, “black-gray-gold”, is an ideal model system for investigating pigmentation traits. In this study, miRNA libraries from scale tissues with the attached epidermis of Midas cichlids at three distinct stages of color transformation, black (B), transition (T), and gold (G), were sequenced using Illumina sequencing technology. In total, 53 (B vs. G), 88 (B vs. T), and 57 (T vs. G) miRNAs were differentially expressed between the respective groups. Target genes of the identified miRNAs were predicted, and the results showed that multiple target genes were related to pigmentation and pigment–cell differentiation. The miRNA–mRNA regulatory network suggests that miR-183-x and miR-133-x were predicted to be involved in regulating morphological color changes in Midas cichlids. The results advance our understanding of potential functions of miRNAs in skin pigment differentiation and early skin color fading of fishes.

Temporal variability in the relationship between line height absorption and chlorophyll concentration: a case study from the Northern Gulf of Alaska

The Line Height Absorption (LHA) method uses absorption of light to estimate chlorophyll-a. While most users consider regional variability and apply corrections, the effect of temporal variability is typically not explored. The Northern Gulf of Alaska (NGA) was selected for this study because there was no published regional value and its large swings in temporal productivity would make it a good candidate to evaluate the effect of temporal variability on the relationship. The mean NGA value of 0.0114 obtained here should be treated with caution, as variation in the slope of the relationship (aLH*), and thus chlorophyll-a estimates, in the NGA region varied by ∼25% between spring (aLH* = 0.0109) and summer (aLH* = 0.0137). Results suggest that this change is driven by a shift in pigment packaging and cell size associated with changes in mixed layer depth and stratification. Consideration of how temporal variability may affect the accuracy of the LHA method in other regions is thus recommended.

Antioxidant, Enzyme Inhibitory, and Protective Effect of Amelanchier lamarckii Extract.

The present study aimed to investigate the chemical content of Romanian juneberries (Amelanchier lamarckii), their effect on antioxidant and enzyme inhibition activities, and their bioaccessibility after simulated in-vitro digestion. In Amelanchier lamarckii extract (AME), 16 polyphenolic compounds were identified by LC-ESI+-MS analysis. The most representative compounds found in the extract were cyanidin-galactoside, 3,4-dihydroxy-5-methoxybenzoic acid, feruloylquinic acid, and kaempferol, all belonging to the anthocyanins, phenolic acids, and flavonols subclasses. The polyphenols of AME exert quenching abilities of harmful reactive oxygen species, as the CUPRAC antioxidant assay value was 323.99 µmol Trolox/g fruit (FW), whereas the FRAP antioxidant value was 4.10 μmol Fe2+/g fruit (FW). Enzyme inhibition assays targeting tyrosinase (IC50 = 8.843 mg/mL), α-glucosidase (IC50 = 14.03 mg/mL), and acetylcholinesterase (IC50 = 49.55 mg/mL) were used for a screening of AME's inhibitory potential against these key enzymes as a common approach for the discovery of potential antidiabetic, skin pigmentation, and neurodegenerative effects. The screening for the potential antidiabetic effects due to the α-glucosidase inhibition was performed in glucose-induced disease conditions in a human retinal pigmented epithelial cell experimental model, proving that AME could have protective potential. In conclusion, AME is a valuable source of phenolic compounds with promising antioxidant potential and metabolic disease-protective effects, warranting further investigation for its use in the nutraceutical and health industries.

Streptomycin generates oxidative stress in melanin-producing cells: In vitro study with EPR spectroscopy evidence

Streptomycin (STR) is an aminoglycoside antibiotic with a broad-spectrum of activity and ototoxic potential. The mechanism of STR-induced inner ear damage has not been fully elucidated. It was previously found that STR binds to melanin, which may result in the accumulation of the drug in melanin-containing tissues. Melanin pigment is present in various parts of the inner ear, including the cochlea and vestibular organ.The present study aimed to assess if streptomycin generates oxidative stress and affects melanogenesis in normal human melanocytes. Moreover the variation of free radical concentration in STR-treated melanocytes was examined by electron paramagnetic resonance spectroscopy (EPR). We found that STR decreases cell metabolic activity and reduces melanin content. The observed changes in the activity of antioxidant enzymes activity in HEMn-DPs treated with streptomycin may suggest that the drug affects redox homeostasis in melanocytes. In this work EPR study expanded knowledge about free radicals in interactions of STR and melanin in melanocytes. The results may help elucidate the mechanisms of STR toxicity on pigment cells, including melanin-producing cells in the inner ear. This is important because understanding the mechanism of STR-induced ototoxicity would be helpful in developing new therapeutic strategies to protect patients' hearing.

Assessing Colouration in Ichthyology: Insights from the Melanophore Index Perspective

Fish colouration significantly influences various aspects of their biology, including communication, camouflage, and mate selection. Among the pigment cells responsible for generating colours, melanophores are particularly significant due to their ability to produce dark pigments called melanin. The Melanophore Index (MI) quantitatively evaluates melanophore density and distribution across different fish species. This comprehensive review delves into the significance of fish colouration, the biology of melanophores, methods for assessing MI, factors influencing MI variations, and the ecological and evolutionary implications of MI in fish populations. By synthesizing current research and highlighting gaps in knowledge, this review aims to provide a foundational understanding of assessing fish colouration through the lens of the Melanophore Index.

Genome-wide association study reveals candidate genes critical for skin pigmentation in common carp (Cyprinus carpio) strains including koi

The differentiation and variation of body color in fish is an important component of biological evolution and phylogenetic research, and is influenced by several factors such as heredity, nutrition, physiological hormones and rearing conditions, with heredity being the most critical factor. An improved comprehension of the genetic regulation in different carp populations will facilitate future applications of precision breeding and pigment cell development-related genes editing. In this study, we used restriction site-associated DNA sequencing (2d-RAD) to determine the distribution characteristics of single nucleotide polymorphisms (SNPs) in eight common carp strains including six koi strains, i.e., Kohaku (Hb), Taisho (Dz), Showa (Zh), Golden (Hj), Matsukawabake (Sch) and Five-color (Ws), and two genetically improved breeding strains, i.e., FFRC No. 2 strain (Fr) and red FFRC strain (Hfr), and then SNP markers to resolve genetic information on the population structure and skin color formation of these strains. We found that most individuals of eight strains were clearly divided into eight clades. Genetic diversity within Fr, Sch and Ws is relatively high, while it is low within Dz, Hb and Hfr. A comparison between the populations revealed that Hfr and Ws have the highest degree of genetic differences, while Hb and Dz have the lowest. The GWAS analysis for two strategies identified several SNPs that are significantly related to skin color variation and affect melanin synthesis (ephrinb2, slc22a23, herc2, ephb2), carotenoid metabolism (oca2, bcmo1, bco2) and circadian rhythm(cipc). To summarize, our study provides some information on the genetic structure and diversity of Japanese koi and Chinese FFRC carp. Furthermore, based on the data obtained on relevant genes related to skin color differentiation and pigmentation, it can provide a theoretical basis for the subsequent integration of dominant traits and precision breeding in carps.

Dermoscopy of pigmented basal cell carcinoma: a descriptive study in Indian population

Background: Pigmented basal cell carcinoma (BCC) is more common in brown-skinned than white-skinned individuals. Histopathology is the gold standard for the diagnosis. There is a paucity of published literature on dermoscopy of BCC in brown skin, particularly in the Indian population. Aims: To study the dermoscopic features of pigmented BCC in brown skin. Methods: This was a cross-sectional, hospital-based study in which dermoscopy was performed on 20 patients with pigmented BCC. Results: Out of 20 patients studied, 12 patients had noduloulcerative BCC, 3 patients had nodular BCC, 4 patients had superficial spreading BCC, and 1 patient had morpheaform BCC. Blue-grey globules, ulceration, and arborizing vessels were noted predominantly in nodular BCC. In contrast, whereas maple-leaf-like areas, spoke wheel structures, erosions, and short-fine telangiectasia were seen in superficially spreading BCC. Morpheaform BCC showed the characteristic stellate pattern of vessels, homogenous white areas, and signature pattern observed in a patient with multiple BCCs. Conclusion: Dermoscopy, a non-invasive investigation, cannot replace the gold standard histopathology but can provide valuable information for its diagnosis, identifying the subtype and presence of pigment, differentiating from its clinical mimickers, and helping in its management.

Protective Effect of Curcumin on the Tight Junction Integrity and Cellular Senescence in Human Retinal Pigment Epithelium of Early Diabetic Retinopathy.

Diabetic retinopathy (DR) is a secondary complication of diabetes that can lead to visual impairment and blindness. The retinal pigment epithelium (RPE) is a monolayer of pigment cells that forms the blood-retinal barrier (BRB) via tight junction (TJ) proteins and plays a crucial role in the physiological function of the retina. Hyperglycemia induces RPE death and BRB breakdown, which accelerates the process of DR. Curcumin, an active extract of Curcuma longa , has anti-inflammatory, antioxidant, antiapoptotic, and neuroprotective properties. However, the effect of Curcumin on the BRB under high glucose conditions remains unknown. This study aimed to investigate the protective effects of Curcumin on RPE physiology in vitro and in vivo . Curcumin significantly alleviated cell viability inhibition under high glucose conditions. Moreover, high glucose reduced extracellular signal-regulated kinase and Akt pathways activation to diminish RPE cell growth but reversed by Curcumin treatment. Curcumin protected not only TJ integrity but also retinoid regeneration through TJ proteins and isomerase modulation in diabetic retina. Furthermore, Curcumin decreased the expression of angiogenic factor to inhibit retinal neovascularization. Finally, Curcumin treatment markedly reduced apoptosis during hyperglycemia. In conclusion, Curcumin can alleviate the progression of DR by promoting RPE survival, TJ integrity, retinoid isomerase activity, RPE senescence inhibition, and neovascularization. Therefore, Curcumin exhibits high potential for use as a therapeutic agent for early DR.

Study on the Skincare Effects of Red Rice Fermented by Aspergillus oryzae In Vitro.

Red rice, a variety of pigmented grain, serves dual purposes as both a food and medicinal resource. In recent years, we have witnessed an increasing interest in the dermatological benefits of fermented rice extracts, particularly their whitening and hydrating effects. However, data on the skincare advantages derived from fermenting red rice with Aspergillus oryzae remain sparse. This study utilized red rice as a substrate for fermentation by Aspergillus oryzae, producing a substance known as red rice Aspergillus oryzae fermentation (RRFA). We conducted a preliminary analysis of RRFA's composition followed by an evaluation of its skincare potential through various in vitro tests. Our objective was to develop a safe and highly effective skincare component for potential cosmetic applications. RRFA's constituents were assessed using high-performance liquid chromatography (HPLC), Kjeldahl nitrogen determination, the phenol-sulfuric acid method, and enzyme-linked immunosorbent assay (ELISA). We employed human dermal fibroblasts (FB) to assess RRFA's anti-aging and antioxidative properties, immortalized keratinocytes (HaCaT cells) and 3D epidermal models to examine its moisturizing and reparative capabilities, and human primary melanocytes (MCs) to study its effects on skin lightening. Our findings revealed that RRFA encompasses several bioactive compounds beneficial for skin health. RRFA can significantly promote the proliferation of FB cells. And it markedly enhances the mRNA expression of ECM-related anti-aging genes and reduces reactive oxygen species production. Furthermore, RRFA significantly boosts the expression of Aquaporin 3 (AQP3), Filaggrin (FLG), and Hyaluronan Synthase 1 (HAS1) mRNA, alongside elevating moisture levels in a 3D epidermal model. Increases were also observed in the mRNA expression of Claudin 1 (CLDN1), Involucrin (IVL), and Zonula Occludens-1 (ZO-1) in keratinocytes. Additionally, RRFA demonstrated an inhibitory effect on melanin synthesis. Collectively, RRFA contains diverse ingredients which are beneficial for skin health and showcases multifaceted skincare effects in terms of anti-aging, antioxidant, moisturizing, repairing, and whitening capabilities in vitro, highlighting its potential for future cosmetic applications.

Insights into the mechanism of color formation of the freshwater prawn (Macrobrachium rosenbergii) revealed by de novo assembly transcriptome analysis

Body color is an important visual indicator of crustacean quality and plays a major role in consumer acceptability, perceived quality, and the market price of crustaceans. The freshwater prawn (Macrobrachium rosenbergii) has two distinct phenotypic variations, characterized by dark blue and light yellow body colors. However, the underlying mechanisms regulating the body color of M. rosenbergii remain unclear. In this study, the composition of shell color parameters and pigment cells of raw and cooked dark blue and light yellow M. rosenbergii was investigated and the mechanisms associated with body color were elucidated by transcriptome analysis. The results showed significant differences in the raw shells of the dark blue and light yellow M. rosenbergii (L: 26.20 ± 0.53 vs. 29.25 ± 0.45; a: −0.88 ± 0.19 vs. 0.35 ± 0.18; b: 1.73 ± 0.20 vs. 3.46 ± 0.37; dE: 70.33 ± 0.53 vs. 67.34 ± 0.45, respectively, p = 0.000) as well as the cooked shells (L: 58.14 ± 0.81 vs. 55.78 ± 0.55; a: 19.30 ± 0.56 vs. 16.42 ± 0.40; b: 23.60 ± 0.66 vs. 20.30 ± 0.40, respectively, p < 0.05). Transcriptome differential gene analysis obtained 39.02 Gb of raw data and 158,026 unigenes. Comprehensive searches of the SwissProt, Nr, KEGG, Pfam, and KOG databases resulted in successful annotations of 23,902 (33 %), 40,436 (25.59 %), 32,015 (20.26 %), 26,139 (16.54 %), and 22,155 (14.02 %) proteins, respectively. By KEGG pathway analysis, numerous differentially expressed genes were related to pigmentation-related pathways (MAPK signaling pathway, Wnt signaling pathway, melanin production, tyrosine metabolism, and cell-cell communication process). Candidate DEGs that may be involved in body color included apolipoprotein D, crustacyanin, cytochrome P450, and tyrosinase, as verified by quantitative real-time PCR. The results of this study provide useful references to further elucidate the molecular mechanisms of color formation of M. rosenbergii and other crustaceans.

Comparison between Two Adaptive Optics Methods for Imaging of Individual Retinal Pigmented Epithelial Cells.

The Retinal Pigment Epithelium (RPE) plays a prominent role in diseases such as age-related macular degeneration, but imaging individual RPE cells is challenging due to their high absorption and low autofluorescence emission. The RPE lies beneath the highly reflective photoreceptor layer (PR) and contains absorptive pigments, preventing direct backscattered light detection when the PR layer is intact. Here, we used near-infrared autofluorescence adaptive optics scanning laser ophthalmoscopy (NIRAF AOSLO) and transscleral flood imaging (TFI) in the same healthy eyes to cross-validate these approaches. Both methods revealed a consistent RPE mosaic pattern and appeared to reflect a distribution of fluorophores consistent with findings from histological studies. Interestingly, even in apparently healthy RPE, we observed dynamic changes over months, suggesting ongoing cellular activity or alterations in fluorophore distribution. These findings emphasize the value of NIRAF AOSLO and TFI in understanding RPE morphology and dynamics.

New Approaches to Photodynamic Therapy of Melanomas

SignificanceWe present new approaches to treat both primary cutaneous and ocular melanoma, with potential to reduce metastatic spread ApproachIn mouse models optical clearing combined with dual-photosensitizer PDT is used to treat primary cutaneous xenogafts. Two-photon PDT is used in ocular melanoma of extraocular (conjunctival) or intraocular (uveal) melanoma. Immune effects are investigated in immunocompetent mice using blood biomarkers and by tumor re-challenge. In vitro studies in pigmented and non-pigmented melanoma cells show melanin-mediated photosensitization as a novel mechanism of action of 2-γ PDT. ResultsFull-thickness primary tumor eradication has been achieved: ∼1 and 4 mm in immune deficient and competent mice, respectively. Marked reduction in metastatic tumor burden is observed in the latter. ConclusionsThese studies reopen the possibility of PDT as an effective modality in melanoma.

Development of an Undergraduate Cell Biology Laboratory to Assess Pigmentation and Cell Size in a Zebrafish Model of Uveal Melanoma.

This study outlines a 2-week laboratory module for an authentic cell biology undergraduate research experience that uses zebrafish (Danio rerio), a popular model organism for research. Previous research has indicated that course-based undergraduate research experiences such as this one increase student confidence, active learning, and retention. During this research experience, students investigate variations in pigmentation in the caudal fins of wild type (WT) and transgenic fish [Tg(mitfa:GNAQQ209L)]. The transgenic fish express a hyperactive Gα protein, GNAQQ209L, under the melanocyte-specific mitfa promoter, offering insights into uveal melanoma, a common eye cancer. Students specifically analyze the black pigmented cells, melanophores, within the caudal fin. We determined that the transgenic zebrafish have increased pigmentation in their caudal fins, but smaller melanophores. These results suggest there are more melanophores in the Tg(mitfa:GNAQQ209L) fish compared to the WT. Future undergraduate research could investigate these cellular differences. This research experience imparts microscopy and image analysis skills and instills the ability to grapple with large datasets, statistical tests, and data interpretation in alignment with biology education principles. Post-laboratory surveys reveal students attain confidence in the above skills and in handling animals, along with a deeper appreciation for model organism research and its relevance to cancer cell biology.