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Cells secrete extracellular vesicles (EVs), exosomes and microvesicles, which transfer proteins, lipids and RNAs to regulate recipient cell functions. Skin pigmentation relies on a tight dialogue between keratinocytes and melanocytes in the epidermis. Here we report that exosomes secreted by keratinocytes enhance melanin synthesis by increasing both the expression and activity of melanosomal proteins. Furthermore, we show that the function of keratinocyte-derived exosomes is phototype-dependent and is modulated by ultraviolet B. In sum, this study uncovers an important physiological function for exosomes in human pigmentation and opens new avenues in our understanding of how pigmentation is regulated by intercellular communication in both healthy and diseased states. The activity of melanocytes determines skin pigmentation, and is regulated by a tight dialogue with keratinocytes. Here, the authors show that exosomes released by keratinocytes have a direct effect on melanocyte function, and exosome content is dependent on skin phototype and is modulated by ultraviolet B radiation.

Collagen is a crucial protein in the extracellular matrix (ECM) essential for preserving tissue architecture and supporting crucial cellular functions like proliferation and differentiation. There are twenty-eight identified types of collagen, which are further divided into different subgroups. This protein plays a critical role in regulating tissue homeostasis. However, in solid tumors, the balance can be disrupted, due to an abundance of collagen in the tumor microenvironment, which significantly affects tumor growth, cell invasion, and metastasis. It is important to investigate the specific types of collagens in cancer ECM and their distinct roles in tumor progression to comprehend their unique contribution to tumor behavior. The diverse pathophysiological functions of different collagen types in cancers illustrate collagen’s dual roles, offering potential therapeutic options and serving as prognostic markers.

Extracellular vesicles (EVs) have emerged as key mediators of intercellular communication, gaining recognition as tumor biomarkers and promising therapeutic targets. As the study of EVs advances, it has become increasingly clear that the cellular context in which they are produced significantly influences their composition and function. Traditional two-dimensional in vitro models are being progressively replaced by more advanced three-dimensional systems, such as tumor spheroids and organoids. These 3D models are particularly valuable in cancer research, providing a more accurate representation of the complex cellular and molecular heterogeneity that characterizes tumors, better mimicking the in vivo microenvironment compared to standard monolayer cultures. This review explores the role of EVs derived from tumor spheroids and organoids in key oncogenic processes, including tumor growth, metastasis, and interactions within the tumor microenvironment. We highlight how EVs contribute to the spread of cancer cells, affecting surrounding tissues, and promote immune evasion, which poses significant challenges in cancer therapy.

Hedgehog (Hh) is a secreted morphogen that elicits differentiation and patterning in developing tissues. Multiple proposed mechanisms to regulate Hh dispersion includes lipoprotein particles and exosomes. Here we report that vertebrate Sonic Hedgehog (Shh) is secreted on two types of extracellular-vesicles/exosomes, from human cell lines and primary chick notochord cells. Although largely overlapping in size as estimated from electron micrographs, the two exosomal fractions exhibited distinct protein and RNA composition. We have probed the functional properties of these vesicles using cell-based assays of Hh-elicited gene expression. Our results suggest that while both Shh-containing exo-vesicular fractions can activate an ectopic Gli-luciferase construct, only exosomes co-expressing Integrins can activate endogenous Shh target genes HNF3β and Olig2 during the differentiation of mouse ES cells to ventral neuronal progenitors. Taken together, our results demonstrate that primary vertebrate cells secrete Shh in distinct vesicular forms and support a model where packaging of Shh along with other signaling proteins such as Integrins on exosomes modulates target gene activation. The existence of distinct classes of Shh-containing exosomes also suggests a previously unappreciated complexity for fine-tuning of Shh-mediated gradients and pattern formation.

Electrospun hybrid scaffolds composed of synthetic and natural polymers have gained increasing interest in tissue engineering applications over the last decade. In this work, scaffolds composed of polylactic acid electrospun fibers, either treated (P-PLA) or non-treated (PLA) with air-plasma, were coated with high molecular weight chitosan to create a core–shell microfibrous structure. The effective thickness control of the chitosan layer was confirmed by gravimetric, spectroscopic (FTIR-ATR) and morphological (SEM) investigations. The chitosan coating increased the fiber diameter of the microfibrous scaffolds while the tensile mechanical tests, conducted in dry and wet environments, showed a reinforcing action of the coating layer on the scaffolds, in particular when deposited on P-PLA samples. The stability of the Chi coating on both PLA and P-PLA substrates was confirmed by gravimetric analysis, while their mineralization capacity was evaluated though scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) after immersing the scaffolds in simulated body fluids (SBF) at 37 °C for 1 week. Sample biocompatibility was investigated through cell viability assay and SEM analysis on mouse pre-osteoblastic MC3T3-E1 cells grown on scaffolds at different times (1, 7, 14 and 21 days). Finally, Alizarin Red assay and qPCR analysis suggested that the combination of plasma treatment and chitosan coating on PLA electrospun scaffolds influences the osteoblastic differentiation of MC3T3-E1 cells, thus demonstrating the great potential of P-PLA/chitosan hybrid scaffolds for bone tissue engineering applications.

Background Tumorigenesis is a complex and dynamic process in which the tumor microenvironment (TME) plays a central role. In solid tumors, the TME contributes to key mechanisms of tumor progression, including metastasis, immune evasion, and resistance to therapies. One major challenge in preclinical cancer research is the development of reliable three-dimensional (3D) in vitro models, which more accurately replicate the in vivo tumor architecture and microenvironmental conditions, such as hypoxia and extracellular matrix (ECM) organization. However, reproducing functional vascular networks and neo-angiogenesis within these models remains a key challenge. Methods In this study, an advanced 3D tumor model, referred to as angiotumoroids, was developed by co-culturing primary murine breast tumor cells (PTCs) with species-specific adipose-derived microvascular fragments (MVFs). Angiotumoroids were characterized using scanning electron microscopy and immunostaining, and angiogenesis was evaluated through collagen gel sprouting assays. High-resolution proteomic profiling was conducted, focusing on signatures associated with angiogenesis, extracellular matrix (ECM) composition, and tissue remodeling. Additionally, the response and internalization to anticancer drug treatments were evaluated. Results MVFs are successfully integrated in angiotumoroids, resulting in the formation of vasculature-like structures and demonstrating robust structural organization with dynamic modulation of matrix metalloproteinase 9. Formation of neovasculature was visualized through sprouting and branching, driven by both direct PTC–MVF interactions and PTC-conditioned media, highlighting the roles of juxtacrine and paracrine signaling. Proteomic profiling revealed distinct expression patterns associated with angiogenesis, ECM components (including collagen types I and IV), and active ECM remodeling with elevated MMP expression. Additionally, angiotumoroids showed increased expression of ATP-binding cassette (ABC) transporters, particularly ABCB1 (P-glycoprotein), suggesting potential mechanisms of drug efflux. Functionally, angiotumoroids demonstrated reduced sensitivity to doxorubicin compared to PTC spheroids, maintaining structural integrity and higher cell viability post-treatment. Time-course analysis revealed preferential doxorubicin accumulation in MVF-enriched regions, as confirmed by colocalization with CD31, indicating a spatially regulated distribution of the drug mediated by the vascular compartment. Conclusions Collectively, these findings establish angiotumoroids as a robust and physiologically relevant in vitro model for studying tumor vascularization, ECM dynamics, and therapeutic response. This platform holds significant promise for predictive cancer research and preclinical drug screening, bridging the gap between traditional in vitro systems and in vivo models.

Hutchinson-Gilford Progeria Syndrome (HGPS) is a rare genetic disorder that leads to premature aging. In this study, we used induced pluripotent stem cells to investigate the hypopigmentation phenotypes observed in patients with progeria. Accordingly, two iPS cell lines were derived from cells from HGPS patients and differentiated into melanocytes. Measurements of melanin content revealed a lower synthesis of melanin in HGPS melanocytes as compared to non-pathologic cells. Analysis of the melanosome maturation process by electron microscopy revealed a lower percentage of mature, fully pigmented melanosomes. Finally, a functional rescue experiment revealed the direct role of progerin in the regulation of melanogenesis. Overall, these results report a new dysregulated pathway in HGPS and open up novel perspectives in the study of pigmentation phenotypes that are associated with normal and pathological aging.

Hutchinson–Gilford progeria syndrome (HGPS) is a rare genetic disorder that causes systemic accelerated aging in children. This syndrome is due to a mutation in the LMNA gene that leads to the production of a truncated and toxic form of lamin A called progerin. Because the balance between the A-type lamins is controlled by the RNA-binding protein SRSF1, we have hypothesized that its inhibition may have therapeutic effects for HGPS. For this purpose, we evaluated the antidiabetic drug metformin and demonstrated that 48 h treatment with 5 mmol/l metformin decreases SRSF1 and progerin expression in mesenchymal stem cells derived from HGPS induced pluripotent stem cells (HGPS MSCs). The effect of metformin on progerin was then confirmed in several in vitro models of HGPS, i.e., human primary HGPS fibroblasts, Lmna G609G/G609G mouse fibroblasts and healthy MSCs previously treated with a PMO (phosphorodiamidate morpholino oligonucleotide) that induces progerin. This was accompanied by an improvement in two in vitro phenotypes associated with the disease: nuclear shape abnormalities and premature osteoblastic differentiation of HGPS MSCs. Overall, these results suggest a novel approach towards therapeutics for HGPS that can be added to the currently assayed treatments that target other molecular defects associated with the disease. A repurposed prescription for early aging A diabetes drug with a proven track record in the clinic may also offer an alternative treatment for a rare 'premature aging' disorder. A genetic mutation in patients with Hutchinson-Gilford progeria syndrome (HGPS) produces a defective protein called progerin, which causes children to develop skeletal, cardiovascular and other symptoms normally seen in the elderly. Researchers led by Xavier Nissan at I-Stem in France have demonstrated that metformin triggers a biochemical 'switch' that causes cells to decrease their production of progerin, and instead generate an alternative, non-toxic protein. Relative to untreated cells, metformin-treated cells were less prone to develop structural abnormalities or undergo premature maturation. Importantly, doctors have used metformin for over 20 years, suggesting that such a treatment approach should be safe for HGPS patients.

We argue that the field of extracellular vesicle (EV) biology needs more transparent reporting to facilitate interpretation and replication of experiments. To achieve this, we describe EV-TRACK, a crowdsourcing knowledgebase (http://evtrack.org) that centralizes EV biology and methodology with the goal of stimulating authors, reviewers, editors and funders to put experimental guidelines into practice.

Hutchinson-Gilford progeria syndrome (HGPS) is a rare fatal genetic disorder that causes systemic accelerated aging in children. Thanks to the pluripotency and self-renewal properties of induced pluripotent stem cells (iPSC), HGPS iPSC-based modeling opens up the possibility of access to different relevant cell types for pharmacological approaches. In this study, 2800 small molecules were explored using high-throughput screening, looking for compounds that could potentially reduce the alkaline phosphatase activity of HGPS mesenchymal stem cells (MSCs) committed into osteogenic differentiation. Results revealed seven compounds that normalized the osteogenic differentiation process and, among these, all-trans retinoic acid and 13-cis-retinoic acid, that also decreased progerin expression. This study highlights the potential of high-throughput drug screening using HGPS iPS-derived cells, in order to find therapeutic compounds for HGPS and, potentially, for other aging-related disorders.