Melanin pigment interrupts the fluorescence staining of mitochondria in melanocytes

Ando, Hironori; Ohagi, Yoshiaki; Yoshida, Moemi; Yoshimoto, Satoshi; Higashi, Yusuke; Yagi, Minoru; Monji, Keisuke; Uchiumi, Takeshi; Kang, Dongchon; Ichihashi, Masamitsu

doi:10.1016/j.jdermsci.2016.08.533

Cited by 7 publications

(6 citation statements)

References 6 publications

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“…The staining of PtdSer was performed using Annexin V, a calcium-dependent phospholipid-binding protein that has a high affinity for PtdSer [ 17 ]. Since Alexa Fluor ® 488 is resistant to the disruptive effect of melanin pigment on fluorescence intensities [ 42 ], Annexin V, Alexa Fluor ® 488 conjugate (Invitrogen, Carlsbad, CA, USA, A13201) was employed. Briefly, cells were washed with cold Ca 2+ and Mg 2+ free Dulbecco’s phosphate buffered saline (D-PBS) and then a viable cell staining solution composed of Annexin V-binding buffer (10 mM HEPES, 140 mM NaCl and 2.5 mM CaCl 2 , pH 7.4) and the same volume of culture medium (Cascade Biologics, medium 254) was added.…”

Section: Methodsmentioning

confidence: 99%

Dermal Fibroblasts Internalize Phosphatidylserine-Exposed Secretory Melanosome Clusters and Apoptotic Melanocytes

Ando

Yoshimoto

Yoshida

et al. 2020

IJMS

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Pigmentation in the dermis is known to be caused by melanophages, defined as melanosome-laden macrophages. In this study, we show that dermal fibroblasts also have an ability to uptake melanosomes and apoptotic melanocytes. We have previously demonstrated that normal human melanocytes constantly secrete melanosome clusters from various sites of their dendrites. After adding secreted melanosome clusters collected from the culture medium of melanocytes, time-lapse imaging showed that fibroblasts actively attached to the secreted melanosome clusters and incorporated them. Annexin V staining revealed that phosphatidylserine (PtdSer), which is known as an ‘eat-me’ signal that triggers the internalization of apoptotic cells by macrophages, is exposed on the surface of secreted melanosome clusters. Dermal fibroblasts were able to uptake secreted melanosome clusters as did macrophages, and those fibroblasts express TIM4, a receptor for PtdSer-mediated endocytosis. Further, co-cultures of fibroblasts and melanocytes demonstrated that dermal fibroblasts internalize PtdSer-exposed apoptotic melanocytes. These results suggest that not only macrophages, but also dermal fibroblasts contribute to the collection of potentially toxic substances in the dermis, such as secreted melanosome clusters and apoptotic melanocytes, that have been occasionally observed to drop down into the dermis from the epidermis.

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Section: Methodsmentioning

confidence: 99%

Dermal Fibroblasts Internalize Phosphatidylserine-Exposed Secretory Melanosome Clusters and Apoptotic Melanocytes

Ando

Yoshimoto

Yoshida

et al. 2020

IJMS

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“…There was no significant difference in SBR between the two most common intracranial metastases (lung and breast), but melanomas did demonstrate weaker signals. We hypothesize that this may be caused by the intrinsic property of melanin pigment to block light penetration, as similar findings have been documented with 5-ALA. 10,22,29 Therefore, caution should be taken when interpreting fluorescence profiles in melanoma metastases intraoperatively. In addition, while there was no significant difference in the SBR of gross tumors between the two ICG doses (2.5 vs 5 mg/kg), dose was a significant predictor of SBR within the lung pathology subset, suggesting that BMs from the lung are more responsive to the dose of ICG.…”

Section: Swig Leads To Strong Nir Signal In Almost All Gadolinium-enhancing Bmsmentioning

confidence: 99%

Second window ICG predicts gross-total resection and progression-free survival during brain metastasis surgery

Teng

Cho

Singh

et al. 2021

Journal of Neurosurgery

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OBJECTIVEMetastases are the most common intracranial malignancies and complete resection can provide relief of neurological symptoms and reduce recurrence. The authors’ prospective pilot study in 2017 demonstrated promising results for the application of high-dose, delayed imaging of indocyanine green (ICG), known as second window ICG (SWIG), in patients undergoing surgery for brain metastases. In this prospective cohort study, the authors evaluated intraoperative imaging and clinical outcomes of treatment using SWIG.METHODSPatients were prospectively enrolled in an approved study of high-dose, delayed ICG (SWIG) and received 5 mg/kg (2014–2018) or 2.5 mg/kg (2018–2019) ICG 24 hours preoperatively. Intraoperatively, near-infrared (NIR) imaging was performed using a dedicated NIR exoscope. NIR images were analyzed and the signal-to-background ratio (SBR) was calculated to quantify fluorescence. Residual fluorescence on the postresection NIR view was compared and correlated to the residual gadolinium enhancement on postoperative MRI. Patient survival and predictive factors were analyzed.RESULTSIn total, 51 intracranial metastases were surgically treated in 47 patients in this cohort. All 51 metastatic tumors demonstrated strong NIR fluorescence (mean SBR 4.9). In tumors ≤ 10 mm from the cortical surface, SWIG with 5 mg/kg ICG produced enhanced transdural tumor visibility (91.3%) compared to 2.5 mg/kg (52.9%; p = 0.0047). Neoplastic margin detection using NIR fluorescence compared to white light improved sensitivity, albeit lowered specificity; however, increasing the SBR cutoff for positive fluorescence significantly improved specificity without sacrificing sensitivity, increasing the overall accuracy from 57.5% to 72.5%. A lack of residual NIR fluorescence after resection was closely correlated with a lack of residual enhancement on postoperative MRI (p = 0.007). Among the 16 patients in whom tumor recurred at the site of surgery, postoperative MRI successfully predicted 8 cases, whereas the postresection NIR view predicted 12 cases. Progression-free survival rate at 12 months was greater for patients without residual NIR fluorescence (38%) than for those without residual enhancement on postoperative MRI (29%).CONCLUSIONSThe current study demonstrates the clinical benefits of the SWIG technique in surgery for patients with brain metastases. Specifically, this technique allows for dose-dependent, transdural localization of neoplasms and improved sensitivity in neoplastic margin detection. Postresection residual fluorescence can be a powerful tool to evaluate extent of resection in conjunction with MRI, and it may guide decisions on brain metastasis management.

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“…Melanin is an irregular pigment that is widely present in various organisms 1 , 2 . The pigment has a wide range of biological effects, including antioxidant, antitumor, antivenin, and radiation resistance activity 3 , 4 .…”

Section: Introductionmentioning

confidence: 99%

“…Melanin can be used not only as natural melanin in the food industry but also in the cosmetics industry to prepare products such as hair dyes and sunscreen. Biological pesticides are being developed in agriculture, while antiviral and antifungal drugs are being developed in the medical field 2 , 10 .…”

Section: Introductionmentioning

confidence: 99%

Characterization of the physicochemical properties, antioxidant activity, and antiproliferative activity of natural melanin from S. reiliana

Xie

et al. 2022

Sci Rep

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This study aimed to characterize the physicochemical properties and stability of L-25 melanin extracted from Sporisorium reilianum (S. reiliana). The results showed that the maximum absorption wavelength of melanin was 215 nm. Reducing agents, heat, light, microwaving, oxidants, and common food additives did not affect the melanin. Additionally, it has a good metal stability except Mn2+. The IR spectra revealed the presence of O–H, N–H, C=O, and C=C bonds as well as carboxyl, alcohol hydroxyl, and phenolic hydroxyl groups and a pyran ring. L-25 melanin could be defined as DL-hydroxy phenylalanine (DOPA)-melanin. The antioxidant and antiproliferative were also measured. The melanin has a specific stability and high antioxidant activity, including a strong DPPH free radical scavenging ability, and protected damaged HepG2 cells by reducing reactive oxygen species, malondialdehyde, and lactate dehydrogenase content. In conclusion, S. reilianum represents a novel source of melanin, that could be applied to health food or food additives. Our results show that melanin from S. reilianum is a natural pigment with good stability that has a great prospect of development and application, providing a theoretical basis and methods for its further processing and development as a functional food.

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Melanin pigment interrupts the fluorescence staining of mitochondria in melanocytes

Cited by 7 publications

References 6 publications

Dermal Fibroblasts Internalize Phosphatidylserine-Exposed Secretory Melanosome Clusters and Apoptotic Melanocytes

Dermal Fibroblasts Internalize Phosphatidylserine-Exposed Secretory Melanosome Clusters and Apoptotic Melanocytes

Second window ICG predicts gross-total resection and progression-free survival during brain metastasis surgery

Characterization of the physicochemical properties, antioxidant activity, and antiproliferative activity of natural melanin from S. reiliana

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