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Skin ageing is a complex and multifaceted biological process that involves the accumulation of senescent dermal fibroblasts. While fractional microneedle radiofrequency (MNRF) is widely used for skin rejuvenation, the underlying molecular mechanisms are unknown. This study aimed to investigate the efficacy of fractional MNRF in altering the cellular milieu of aged skin and to evaluate clinical skin improvements. Thirty female volunteers aged ≥ 60 years with visible periorbital wrinkles received four consecutive treatments of either microneedling or MNRF on randomly assigned facial sides. Based on biophysical measurements, MNRF treatment improved wrinkles, elasticity, hydration, and transepidermal water loss compared to baseline. Histological analysis revealed that the MNRF-treated sides exhibited increased proliferation of non-senescent fibroblasts, a reduced number of senescent fibroblasts, and elevated collagen and elastin levels, compared to the MN-treated sides. In additional analyses, differences in collagen density and hydration between the two sides of the face were statistically significant only in subjects with a marked reduction in senescent fibroblasts in MNRF-treated sides. Our data suggest that, compared to MN, MNRF induces greater clinical and histological improvements in aged skin, likely by altering the dermal fibroblast milieu through the dual effect of eliminating senescent fibroblasts and increasing the number of non-senescent fibroblasts.

Exosome production from cancer-associated fibroblasts seems to be an important driver of tumor progression. We report the first in-depth biotype characterization of ncRNAs, analyzed by Next Generation Sequencing and Bioinformatics, expressed in established primary human normal and cancer-associated fibroblasts (CAFs) from cancer and normal mucosa tissues from 9 colorectal cancer patients, and/or packaged in their derived exosomes. Differential representation and enrichment analyses based on these ncRNAs revealed a significant number of differences between the ncRNA content of exosomes and the expression patterns of the normal and cancer-associated fibroblast cells. ncRNA regulatory elements are specifically packaged in CAF-derived exosomes, supporting a specific cross-talk between CAFs and colon cancer cells and/or other stromal cells, mediated by exosomes. These sncRNAs are potential biomarkers present in cancer-associated fibroblast-derived exosomes, which should thereby contribute to developing new non-invasive diagnostic, prognostic and predictive methods for clinical applications in management of cancer patients.

Reprogramming of somatic cells into pluripotent stem cells has been reported by introducing a combination of several transcription factors (Oct3/4, Sox2, Klf4 and c-Myc). The induced pluripotent stem (iPS) cells from patient's somatic cells could be a useful source for drug discovery and cell transplantation therapies. However, to date, most iPS cells were made using viral vectors, such as retroviruses and lentiviruses. Here we describe an alternative method to generate iPS cells from mouse embryonic fibroblasts (MEFs) by continual transfection of plasmid vectors. This protocol takes around 2 months to complete, from MEF isolation to iPS cell establishment. Although the reprogramming efficiency of this protocol is still low, the established iPS cells are most likely free from plasmid integration. This virus-free technique reduces the safety concern for iPS cell generation and application, and provides a source of cells for the investigation of the mechanisms underlying reprogramming and pluripotency.

Spinal muscular atrophy (SMA) is a devastating motoneuron (MN) disorder caused by homozygous loss of SMN1. Rarely, SMN1 -deleted individuals are fully asymptomatic despite carrying identical SMN2 copies as their SMA III-affected siblings suggesting protection by genetic modifiers other than SMN2 . High plastin 3 (PLS3) expression has previously been found in lymphoblastoid cells but not in fibroblasts of asymptomatic compared to symptomatic siblings. To find out whether PLS3 is also upregulated in MNs of asymptomatic individuals and thus a convincing SMA protective modifier, we generated induced pluripotent stem cells (iPSCs) from fibroblasts of three asymptomatic and three SMA III-affected siblings from two families and compared these to iPSCs from a SMA I patient and control individuals. MNs were differentiated from iPSC-derived small molecule neural precursor cells (smNPCs). All four genotype classes showed similar capacity to differentiate into MNs at day 8. However, SMA I-derived MN survival was significantly decreased while SMA III- and asymptomatic-derived MN survival was moderately reduced compared to controls at day 27. SMN expression levels and concomitant gem numbers broadly matched SMN2 copy number distribution; SMA I presented the lowest levels, whereas SMA III and asymptomatic showed similar levels. In contrast, PLS3 was significantly upregulated in mixed MN cultures from asymptomatic individuals pinpointing a tissue-specific regulation. Evidence for strong PLS3 accumulation in shaft and rim of growth cones in MN cultures from asymptomatic individuals implies an important role in neuromuscular synapse formation and maintenance. These findings provide strong evidence that PLS3 is a genuine SMA protective modifier.

To determine if a human fibroblast-derived dermal substitute could promote the healing of diabetic foot ulcers. A randomized, controlled, multicenter study was undertaken at 35 centers throughout the U.S. and enrolled 314 patients to evaluate complete wound closure by 12 weeks. Patients were randomized to either the Dermagraft treatment group or control (conventional therapy). Except for the application of Dermagraft, treatment of study ulcers was identical for patients in both groups. All patients received pressure-reducing footwear and were allowed to be ambulatory during the study. The results demonstrated that patients with chronic diabetic foot ulcers of >6 weeks duration experienced a significant clinical benefit when treated with Dermagraft versus patients treated with conventional therapy alone. With regard to complete wound closure by week 12, 30.0% (39 of 130) of Dermagraft patients healed compared with 18.3% (21 of 115) of control patients (P = 0.023). The overall incidence of adverse events was similar for both the Dermagraft and control groups, but the Dermagraft group experienced significantly fewer ulcer-related adverse events. The data from this study show that Dermagraft is a safe and effective treatment for chronic diabetic foot ulcers.

The enamel matrix derivative (EMD) contains hundreds of peptides in different levels of proteolytic processing that may provide a range of biological effects of importance in wound healing. The aim of the present study was to compare the effect of EMD and its fractions on the cytokine profiles from human gingival fibroblasts in vitro and in gingival crevicular fluid (GCF) in a randomized controlled split-mouth clinical study (n = 12). Levels of cytokines in cell culture medium and in GCF were measured by Luminex over a 2-week period. In the clinical study, levels of pro-inflammatory cytokines and chemokines were increased, whereas the levels of transforming growth factor-α (TGF-α) and platelet-derived growth factor-BB (PDGF-BB) were reduced. The in vitro study showed that EMD and its high and low molecular weight fractions reduced the secretion of pro-inflammatory cytokines and chemokines compared to untreated cells. EMD had an effect on levels of cytokines related to fibroplasia, angiogenesis, inflammation and chemotaxis both in vitro and in vivo , however, the anti-inflammatory effect induced by EMD observed in the in vitro study could not be confirmed clinically.

Many important cell types in adult vertebrates have a mesenchymal origin, including fibroblasts and vascular mural cells. Although their biological importance is undisputed, the level of mesenchymal cell heterogeneity within and between organs, while appreciated, has not been analyzed in detail. Here, we compare single-cell transcriptional profiles of fibroblasts and vascular mural cells across four murine muscular organs: heart, skeletal muscle, intestine and bladder. We reveal gene expression signatures that demarcate fibroblasts from mural cells and provide molecular signatures for cell subtype identification. We observe striking inter- and intra-organ heterogeneity amongst the fibroblasts, primarily reflecting differences in the expression of extracellular matrix components. Fibroblast subtypes localize to discrete anatomical positions offering novel predictions about physiological function(s) and regulatory signaling circuits. Our data shed new light on the diversity of poorly defined classes of cells and provide a foundation for improved understanding of their roles in physiological and pathological processes. To define and distinguish fibroblasts from vascular mural cells have remained challenging. Here, using single-cell RNA sequencing and tissue imaging, the authors provide a molecular basis for cell type classification and reveal inter- and intra-organ diversity of these cell types.

Hypertrophic scars (HTS), the excessive deposition of scar tissue by fibroblasts, is one of the most common skin disorders. Fibroblasts derived from surgical scar tissue produce high levels of α-smooth muscle actin (α-SMA) and transforming growth factor-β1 (TGF-β1). However, the molecular mechanisms for this phenomenon is poorly understood. Thus, the purpose of this study was to evaluate the molecular mechanisms of HTS and their potential therapeutic implications. Fibroblasts derived from skin HTS were cultured and characterized in vitro. The fibroblasts were synchronized and randomly assigned to two groups: cyclic stretch and cyclic stretch pre-treated with SB203580 (a p38MAPK inhibitor). Cyclic stretch at 10% strain was applied at a loading frequency of 10 cycles per minute (i.e. 5 seconds of tension and 5 seconds of relaxation) for 0 h, 6 h and 12 h. Cyclic stretch on HTS fibroblasts led to an increase in the expression of α-SMA and TGF-β1 mRNA and protein and the phosphorylation of p38MAPK. SB203580 reversed these effects and caused a decrease in matrix contraction. Furthermore, HTS fibroblast growth was partially blocked by p38MAPK inhibition. Therefore, the mechanism of cyclic stretch involves p38 MAPK, and its inhibition is suggested as a novel therapeutic strategy for HTS.

Ever since Stephen Paget’s 1889 hypothesis, metastatic organotropism has remained one of cancer’s greatest mysteries. Here we demonstrate that exosomes from mouse and human lung-, liver- and brain-tropic tumour cells fuse preferentially with resident cells at their predicted destination, namely lung fibroblasts and epithelial cells, liver Kupffer cells and brain endothelial cells. We show that tumour-derived exosomes uptaken by organ-specific cells prepare the pre-metastatic niche. Treatment with exosomes from lung-tropic models redirected the metastasis of bone-tropic tumour cells. Exosome proteomics revealed distinct integrin expression patterns, in which the exosomal integrins α 6 β 4 and α 6 β 1 were associated with lung metastasis, while exosomal integrin α v β 5 was linked to liver metastasis. Targeting the integrins α 6 β 4 and α v β 5 decreased exosome uptake, as well as lung and liver metastasis, respectively. We demonstrate that exosome integrin uptake by resident cells activates Src phosphorylation and pro-inflammatory S100 gene expression. Finally, our clinical data indicate that exosomal integrins could be used to predict organ-specific metastasis. Exosomes originating from lung-, liver- and brain-tropic tumour cells are preferentially incorporated by specific resident cells of the target organs, thus preparing the site for metastasis; the expression of distinct combinations of exosomal integrin proteins determines the exosomal targeting to each of the three organs, and blocking these integrins reduces organotropic exosome uptake by the target organs, thereby reducing the likelihood of organotropic metastasis. Metastasis site selection involves tumour exosomes How do cancer cells choose the next organ to target? David Lyden and colleagues show that extracellular vesicles (exosomes) that originate from tumour cells can preferentially fuse with specific resident cells of the target organs — lung, liver and brain — to prepare the site of metastasis. At a molecular level, expression of distinct combinations of integrin proteins on exosomes seems to mediate their targeting to one of the three organs. By blocking these integrins, the authors could reduce the uptake of the associated exosomes by the target organs and so the likelihood of metastasis. Moreover, the exosomal integrins could be used to predict organ-specific metastasis in cancer patients.

The function of a cell is defined by its intrinsic characteristics and its niche: the tissue microenvironment in which it dwells. Here we combine single-cell and spatial transcriptomics data to discover cellular niches within eight regions of the human heart. We map cells to microanatomical locations and integrate knowledge-based and unsupervised structural annotations. We also profile the cells of the human cardiac conduction system 1 . The results revealed their distinctive repertoire of ion channels, G-protein-coupled receptors (GPCRs) and regulatory networks, and implicated FOXP2 in the pacemaker phenotype. We show that the sinoatrial node is compartmentalized, with a core of pacemaker cells, fibroblasts and glial cells supporting glutamatergic signalling. Using a custom CellPhoneDB.org module, we identify trans-synaptic pacemaker cell interactions with glia. We introduce a druggable target prediction tool, drug2cell, which leverages single-cell profiles and drug–target interactions to provide mechanistic insights into the chronotropic effects of drugs, including GLP-1 analogues. In the epicardium, we show enrichment of both IgG + and IgA + plasma cells forming immune niches that may contribute to infection defence. Overall, we provide new clarity to cardiac electro-anatomy and immunology, and our suite of computational approaches can be applied to other tissues and organs. Single-cell and spatial transcriptomic analysis of eight human heart tissues reveals the cellular profiles and tissue architecture of niches including the cardiac conduction system, and a new tool, drug2cell, identifies drug target expression.