The species origin of the cellular microenvironment influences markers of beta cell fate and function in EndoC-βH1 cells

Changes to the identity of EndoC-βH1 beta cells may be mediated by stress-induced depletion of HNRNPD

Background

Beta cell identity changes occur in the islets of donors with diabetes, but the molecular basis of this remains unclear. Protecting residual functional beta cells from cell identity changes may be beneficial for patients with diabetes.

Results

A somatostatin-positive cell population was induced in stressed clonal human EndoC-βH1 beta cells and was isolated using FACS. A transcriptomic characterisation of somatostatin-positive cells was then carried out. Gain of somatostatin-positivity was associated with marked dysregulation of the non-coding genome. Very few coding genes were differentially expressed. Potential candidate effector genes were assessed by targeted gene knockdown. Targeted knockdown of the HNRNPD gene induced the emergence of a somatostatin-positive cell population in clonal EndoC-βH1 beta cells comparable with that we have previously reported in stressed cells.

Conclusions

We report here a role for the HNRNPD gene in determination of beta cell identity in response to cellular stress. These findings widen our understanding of the role of RNA binding proteins and RNA biology in determining cell identity and may be important for protecting remaining beta cell reserve in diabetes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-021-00658-6.

Towards More Predictive, Physiological and Animal-free In Vitro Models: Advances in Cell and Tissue Culture 2020 Conference Proceedings

Experimental systems that faithfully replicate human physiology at cellular, tissue and organ level are crucial to the development of efficacious and safe therapies with high success rates and low cost. The development of such systems is challenging and requires skills, expertise and inputs from a diverse range of experts, such as biologists, physicists, engineers, clinicians and regulatory bodies. Kirkstall Limited, a biotechnology company based in York, UK, organised the annual conference, Advances in Cell and Tissue Culture (ACTC), which brought together people having a variety of expertise and interests, to present and discuss the latest developments in the field of cell and tissue culture and in vitro modelling. The conference has also been influential in engaging animal welfare organisations in the promotion of research, collaborative projects and funding opportunities. This report describes the proceedings of the latest ACTC conference, which was held virtually on 30th September and 1st October 2020, and included sessions on in vitro models in the following areas: advanced skin and respiratory models, neurological disease, cancer research, advanced models including 3-D, fluid flow and co-cultures, diabetes and other age-related disorders, and animal-free research. The roundtable session on the second day was very interactive and drew huge interest, with intriguing discussion taking place among all participants on the theme of replacement of animal models of disease.

Characterization of immortalized human islet stromal cells reveals a MSC-like profile with pancreatic features

BACKGROUND

Mesenchymal stromal cells (MSCs) represent an interesting tool to improve pancreatic islet transplantation. They have immunomodulatory properties and secrete supportive proteins. However, the functional properties of MSCs vary according to many factors such as donor characteristics, tissue origin, or isolation methods. To counteract this heterogeneity, we aimed to immortalize and characterize adherent cells derived from human pancreatic islets (hISCs), using phenotypic, transcriptomic, and functional analysis.

METHODS

Adherent cells derived from human islets in culture were infected with a hTERT retrovirus vector and then characterized by microarray hybridization, flow cytometry analysis, and immunofluorescence assays. Osteogenic, adipogenic, and chondrogenic differentiation as well as PBMC proliferation suppression assays were used to compare the functional abilities of hISCs and MSCs. Extracellular matrix (ECM) gene expression profile analysis was performed using the SAM (Significance Analysis of Microarrays) software, and protein expression was confirmed by western blotting.

RESULTS

hISCs kept an unlimited proliferative potential. They exhibited several properties of MSCs such as CD73, CD90, and CD105 expression and differentiation capacity. From a functional point of view, hISCs inhibited the proliferation of activated peripheral blood mononuclear cells. The transcriptomic profile of hISCs highly clusterized with bone marrow (BM)-MSCs and revealed a differential enrichment of genes involved in the organization of the ECM. Indeed, the expression and secretion profiles of ECM proteins including collagens I, IV, and VI, fibronectin, and laminins, known to be expressed in abundance around and within the islets, were different between hISCs and BM-MSCs.

CONCLUSION

We generated a new human cell line from pancreatic islets, with MSCs properties and retaining some pancreatic specificities related to the production of ECM proteins. hISCs appear as a very promising tool in islet transplantation by their availability (as a source of inexhaustible source of cells) and ability to secrete a supportive "pancreatic" microenvironment.

Cellular stressors may alter islet hormone cell proportions by moderation of alternative splicing patterns

Changes to islet cell identity in response to type 2 diabetes (T2D) have been reported in rodent models, but are less well characterized in humans. We assessed the effects of aspects of the diabetic microenvironment on hormone staining, total gene expression, splicing regulation and the alternative splicing patterns of key genes in EndoC-βH1 human beta cells. Genes encoding islet hormones [somatostatin (SST), insulin (INS), Glucagon (GCG)], differentiation markers [Forkhead box O1 (FOXO1), Paired box 6, SRY box 9, NK6 Homeobox 1, NK6 Homeobox 2] and cell stress markers (DNA damage inducible transcript 3, FOXO1) were dysregulated in stressed EndoC-βH1 cells, as were some serine arginine rich splicing factor splicing activator and heterogeneous ribonucleoprotein particle inhibitor genes. Whole transcriptome analysis of primary T2D islets and matched controls demonstrated dysregulated splicing for ~25% of splicing events, of which genes themselves involved in messenger ribonucleic acid processing and regulation of gene expression comprised the largest group. Approximately 5% of EndoC-βH1 cells exposed to these factors gained SST positivity in vitro. An increased area of SST staining was also observed ex vivo in pancreas sections recovered at autopsy from donors with type 1 diabetes (T1D) or T2D (9.3% for T1D and 3% for T2D, respectively compared with 1% in controls). Removal of the stressful stimulus or treatment with the AKT Serine/Threonine kinase inhibitor SH-6 restored splicing factor expression and reversed both hormone staining effects and patterns of gene expression. This suggests that reversible changes in hormone expression may occur during exposure to diabetomimetic cellular stressors, which may be mediated by changes in splicing regulation.

miRNAs responsive to the diabetic microenvironment in the human beta cell line EndoC-βH1 may target genes in the FOXO, HIPPO and Lysine degradation pathways

Altered expression of miRNAs is evident in the islets of diabetic human donors, but the effects of specific aspects of the diabetic microenvironment and identity of gene ontology pathways demonstrating target gene enrichment in response to each is understudied. We assessed changes in the miRNA milieu in response to high/low glucose, hypoxia, dyslipidaemia and inflammatory factors in a humanised EndoC-βH1 beta cell culture system and performed miRPath analysis for each treatment individually. The 10 miRNAs demonstrating the greatest dysregulation across treatments were then independently validated and Gene Set Enrichment Analysis to confirm targeted pathways undertaken. 171 of 392 miRNAs displayed altered expression in response to one or more cellular stressors. miRNA changes were treatment specific, but their target genes were enriched in conserved pathways. 5 miRNAs (miR-136-5p, miR299-5p, miR-454-5p, miR-152 and miR-185) were dysregulated in response to multiple stressors and survived validation in independent samples (p = 0.008, 0.002, 0.012, 0.005 and 0.024 respectively). Target genes of dysregulated miRNAs were clustered into FOXO1, HIPPO and Lysine degradation pathways (p = 0.02, p = 5.84 × 10^-5 and p = 3.00 × 10^-3 respectively). We provide evidence that the diabetic microenvironment may induce changes to the expression of miRNAs targeting genes enriched in pathways involved in cell stress response and cell survival.

Nanoscaled and microscaled parallel topography promotes tenogenic differentiation of ASC and neotendon formation in vitro

Background

Topography at different scales plays an important role in directing mesenchymal stem cell differentiation including adipose-derived stem cells (ASCs) and the differential effect remains to be investigated.

Purpose

This study aimed to investigate the similarity and difference between micro- and nanoscaled aligned topography for inducing tenogenic differentiation of human ASCs (hASCs).

Methods

Parallel microgrooved PDMS membrane and a parallel aligned electrospun nanofibers of gelatin/poly-ε-caprolactone mixture were employed as the models for the study.

Results

Aligned topographies of both microscales and nanoscales could induce an elongated cell shape with parallel alignment, as supported by quantitative cell morphology analysis (cell area, cell body aspect, and cell body major axis angle). qPCR analysis also demonstrated that the aligned topography at both scales could induce the gene expressions of various tenogenic markers at the 7th day of in vitro culture including tenomodulin, collagen I and collagen VI, decorin, tenascin-C and biglycan, but with upregulated expression of scleraxis and tenascin-C only in microscaled topography. Additionally, tenogenic differentiation at the 3rd day was confirmed only at microscale. Furthermore, microscaled topography was confirmed for its tenogenic induction at tissue level as neotendon tissue was formed with the evidence of mature type I collagen fibers only in parallel aligned polyglycolic acid (PGA) microfibers after in vitro culture with mouse ASCs. Instead, only fat tissue was formed in random patterned PGA microfibers.

Conclusion

Both microscaled and nanoscaled aligned topographies could induce tenogenic differentiation of hASCs and micro-scaled topography seemed better able to induce elongated cell shape and stable tenogenic marker expression when compared to nanoscaled topography. The microscaled inductive effect was also confirmed at tissue level by neotendon formation in vitro.