IntroductionDupuytren’s contracture (DC) is a chronic fibroproliferative disease of the hand, which is characterized by uncontrolled proliferation of atypical myofibroblasts at the cellular level. We hypothesized that specific areas of the DC tissue are sustaining the cell proliferation and studied the potential molecular determinants that might contribute to the formation of such niches.MethodsWe studied the expression pattern of cell proliferation marker Ki67, phosphorylated AKT (Ak mouse strain thymoma) kinase, DC-associated growth factors (connective tissue growth factor (CTGF), basic fibroblast growth factor (bFGF), insulin-like growth factor 2 (IGF-2)) and extracellular matrix components (laminins, fibronectin, collagen IV) in DC tissue and normal palmar fascia using immunofluorescence microscopy and quantitative real-time polymerase chain reaction (qPCR).ResultsWe found that proliferative cells in the DC nodules were concentrated in the immediate vicinity of small blood vessels and localized predominantly in the myofibroblast layer. Correspondingly, the DC-associated blood vessels contained increased levels of phosphorylated AKT, a hallmark of activated growth factor signaling. When studying the expression of potential activators of AKT signaling we found that the expression of bFGF was confined to the endothelium of the small blood vessels, IGF-2 was present uniformly in the DC tissue and CTGF was expressed in the DC-associated sweat gland acini. In addition, the blood vessels in DC nodules contained increased amounts of laminins 511 and 521, which have been previously shown to promote the proliferation and stem cell properties of different cell types.ConclusionsBased on our findings, we propose that in the DC-associated small blood vessels the presence of growth factors in combination with favorable extracellular matrix composition provide a supportive environment for sustained proliferation of myofibroblasts and thus the blood vessels play an important role in DC pathogenesis.Electronic supplementary materialThe online version of this article (doi:10.1186/s13075-015-0661-y) contains supplementary material, which is available to authorized users.

Background: Compared to exome sequencing, genome sequencing is widely appreciated for its superior ability to detect a wide range of genetic variations including copy-number variants (CNVs) and mitochondrial (mtDNA) variants. We assessed whether low-coverage genome sequencing, a considerably cheaper approach, would detect clinically relevant CNVs and mtDNA variants and would thus be a cost-efficient supplement to exome sequencing in rare disease diagnostics. Methods: To assess the level of sequencing depth needed for variant detection, first, 30x mean coverage genome sequencing data were subsampled to 0.5x, 1x, 2x, and 4x coverage files in silico followed by CNV and mtDNA detection. Based on the analysis, 2x short-read sequencing was selected to be performed in 16 patients with putatively pathogenic CNVs or mtDNA variants to assess the empirical sensitivity. Results: For CNV calling, 2x coverage was sufficient to detect all heterozygous CNVs greater than 10kb in size from in silico subsampled data. In experimental data, the results were similar, although a 16kb heterozygous deletion was once not detected. Regarding mtDNA variants, 2x coverage sufficed for variant confident variant calling and heteroplasmy assessment for all samples. Conclusions: Low-coverage genome sequencing may be used to complement exome sequencing for simultaneous mtDNA variant and CNV detection.

Lgr5‐LacZ mice harbor the Escherichia coli LacZ gene encoding β‐galactosidase (β‐gal) under the control of the Lgr5 promoter, a stem/progenitor cell marker. In injured livers of Lgr5‐LacZ mice, cells expressing β‐galactosidase (β‐gal) are considered as potential bipotent liver progenitors; however, their origin and identity remain unknown. Unexpectedly, using lineage tracing, we demonstrate that the β‐gal+ cells do not originate from liver parenchymal cells. Instead, β‐gal+ cells, isolated from injured livers of both Lgr5‐LacZ and wild‐type mice, are positive for markers of Kupffer cells, liver‐resident macrophages. The β‐gal expression in these cells is a result of elevated expression of the endogenous beta‐galactosidase Glb1. In injured livers of Lgr5‐LacZ mice, bacterial β‐gal expression is very low, suggesting transgene silencing. The gene expression profile of the β‐gal+ Kupffer cells from injured livers suggests a role in liver regeneration.