Culture medium induced morphological changes of melanoma cells associated with change in sensitivity to lysis by lymphokine-activated killer cells

Transwell-Hypoxia Method Facilitates the Outgrowth of 3D-Printed Collagen Scaffolds Loaded with Cryopreserved Patient-Derived Melanoma Explants

A previous study from our laboratory demonstrated the effects of in vitro three-dimensional (3D)-printed collagen scaffolds on the maintenance of cryopreserved patient-derived melanoma explants (PDMEs). However, it remains unknown whether 3D-printed collagen scaffolds (3D-PCSs) can be harmonized with any external culture conditions to increase the growth of cryopreserved PDMEs. In this study, 3D-PCSs were manufactured with a 3DX bioprinter. The 3D-printed collagen scaffold-on-frame construction was loaded with fragments of cryopreserved PDMEs (approximately 1-2 mm). 3D-PCSs loaded with patient-derived melanoma explants (3D-PCS-PDMEs) were incubated using two types of methods: (1) in transwells in the presence of a low concentration of oxygen (transwell-hypoxia method) and (2) using a traditional adherent attached to the bottom flat surface of a standard culture dish (traditional flat condition). In addition, we used six different types of media (DMEM high glucose, MEM α, DMEM/F12, RPMI1640, fibroblast basal medium (FBM), and SBM (stem cell basal medium)) for 7 days. The results reveal that the culture conditions of MEM α, DMEM/F12, and FBM using the transwell-hypoxia method show greater synergic effects on the outgrowth of the 3D-PCS-PDME compared to the traditional flat condition. In addition, the transwell-hypoxia method shows a higher expression of the MMP14 gene and the multidrug-resistant gene product 1 (MDR1) than in the typical culture method. Taken together, our findings suggest that the transwell-hypoxia method could serve as an improved, 3D alternative to animal-free testing that better mimics the skin's microenvironment using in vitro PDMEs.

Study of Oligonucleotides Access and Distribution in Human Peripheral Blood Mononuclear Cells

Therapeutic oligonucleotides have achieved great clinical interest since their approval as drug agents by regulatory agencies but their access and distribution in blood cells are not completely known. We evaluated by flow cytometry the ability of short fluorescent scramble oligonucleotides (ON*) to access human peripheral blood mononuclear cells (PBMC) after incubating with ON* during 1 h and 7 days of culture follow-up 'in vitro'. Blood samples were treated with chemically modified oligonucleotides (phosphorothioate backbone and 2' O-Me ends) to resist nuclease digestion under culture conditions. The ON* internalization was determined after discarding the membrane-associated fluorescence by trypan blue quenching. Whereas the oligonucleotide accessed neutrophils and monocytes rapidly, achieving their maximum in 1 h and 24 h, respectively, lymphocytes required 7 days to achieve the maximum (80% of cells) transfection. The ON*ability to access lymphocyte types (T, B, and NK) and T cell subtypes (CD4+, CD8+, and CD4-CD8-) were similar, with T cells being more accessible. Regulatory CD4+ and CD8+ T cells were classified in low and high Foxp3 expressers, whose expression proved not to alter the ON* internalization during the first hour, achieving 53% of CD4+Foxp3+ and 40% of CD8+Foxp3+ cells. Our results contribute to understanding and improving the management of therapeutic ONs.

A Novel and Effective Method for Human Primary Skin Melanocytes and Metastatic Melanoma Cell Isolation

Simple Summary

The present paper describes a simple, non-enzymatic and effective method of melanocyte or metastatic melanoma cell isolation from skin or lymph node explants, respectively. The method is based on selective harvesting of melanocytes or melanoma cells emigrating from the explants. Thus, isolated cells display specific phenotypical and functional features of melanocytes/melanoma cells such as tyrosinase and Melan-A expression and melanin production. Furthermore, melanocyte or melanoma cell cultures are not contaminated by keratinocytes and/or fibroblasts. The method appears to be a useful tool for studies on the biology of melanocytes and malignant melanoma.

Abstract

The development of an effective method of melanocyte isolation and culture is necessary for basic and clinical studies concerning skin diseases, including skin pigmentation disorders and melanoma. In this paper, we describe a novel, non-enzymatic and effective method of skin melanocyte and metastatic melanoma cell isolation and culture (along with the spontaneous spheroid creation) from skin or lymph node explants. The method is based on the selective harvesting of melanocytes and melanoma cells emigrating from the cultured explants. Thereby, isolated cells retain their natural phenotypical features, such as expression of tyrosinase and Melan-A as well as melanin production and are not contaminated by keratinocytes and fibroblasts. Such melanocyte and melanoma cell cultures may be very useful for medical and cosmetology studies, including studies of antitumor therapies.

What is the relationship between P-glycoprotein and adhesion molecule expression in melanoma cells?

A number of studies have reported that increased P-glycoprotein expression in drug-resistant tumour cells may be associated with decreased expression of a family of surface glycoproteins. However, despite its potential biological and clinical relevance, this phenomenon has not been extensively studied. In this study the phenotypic alterations that are associated with the acquisition of the multidrug-resistant phenotype in tumour cells, together with drug transporter overexpression, were investigated in human melanoma cells. The expression of cell adhesion molecules was analysed in a panel of multidrug-resistant melanoma cell lines (M14Dx) showing different degrees of resistance to doxorubicin and different levels of the expression of the drug transporter P-glycoprotein. In particular, expression of intercellular adhesion molecule-1 (ICAM-1), CD44, very late activation antigen (VLA)-5 and VLA-2 was determined by flow cytometry in the different resistant cell lines. A progressive downregulation of all the adhesion molecules examined was revealed in M14Dx cells, in parallel with an increasing level of expression of the drug transporter P-glycoprotein. The results obtained raise the question of the role of P-glycoprotein in the invasive and metastatic behaviour of tumour cells.