A combination of cytokines EGF and CNTF protects the functional beta cell mass in mice with short-term hyperglycaemia

Biochemical pancreatic β-cell lineage reprogramming: Various cell fate shifts

The incidence of pancreatic diseases has been continuously rising in recent years. Thus, research on pancreatic regeneration is becoming more popular. Chronic hyperglycemia is detrimental to pancreatic β-cells, leading to impairment of insulin secretion which is the main hallmark of pancreatic diseases. Obtaining plenty of functional pancreatic β-cells is the most crucial aspect when studying pancreatic biology and treating diabetes. According to the International Diabetes Federation, diabetes has become a global epidemic, with about 3 million people suffering from diabetes worldwide. Hyperglycemia can lead to many dangerous diseases, including amputation, blindness, neuropathy, stroke, and cardiovascular and kidney diseases. Insulin is widely used in the treatment of diabetes; however, innovative approaches are needed in the academic and preclinical stages. A new approach aims at synthesizing patient-specific functional pancreatic β-cells. The present article focuses on how cells from different tissues can be transformed into pancreatic β-cells.

A Supportive Role of Mesenchymal Stem Cells on Insulin-Producing Langerhans Islets with a Specific Emphasis on The Secretome

Type 1 Diabetes (T1D) is a chronic autoimmune disease characterized by a gradual destruction of insulin-producing β-cells in the endocrine pancreas due to innate and specific immune responses, leading to impaired glucose homeostasis. T1D patients usually require regular insulin injections after meals to maintain normal serum glucose levels. In severe cases, pancreas or Langerhans islet transplantation can assist in reaching a sufficient β-mass to normalize glucose homeostasis. The latter procedure is limited because of low donor availability, high islet loss, and immune rejection. There is still a need to develop new technologies to improve islet survival and implantation and to keep the islets functional. Mesenchymal stem cells (MSCs) are multipotent non-hematopoietic progenitor cells with high plasticity that can support human pancreatic islet function both in vitro and in vivo and islet co-transplantation with MSCs is more effective than islet transplantation alone in attenuating diabetes progression. The beneficial effect of MSCs on islet function is due to a combined effect on angiogenesis, suppression of immune responses, and secretion of growth factors essential for islet survival and function. In this review, various aspects of MSCs related to islet function and diabetes are described.

Acinar cells and the development of pancreatic fibrosis

Pancreatic fibrosis is caused by excessive deposition of extracellular matrixes of collagen and fibronectin in the pancreatic tissue as a result of repeated injury often seen in patients with chronic pancreatic diseases. The most common causative conditions include inborn errors of metabolism, chemical toxicity and autoimmune disorders. Its pathophysiology is highly complex, including acinar cell injury, acinar stress response, duct dysfunction, pancreatic stellate cell activation, and persistent inflammatory response. However, the specific mechanism remains to be fully clarified. Although the current therapeutic strategies targeting pancreatic stellate cells show good efficacy in cell culture and animal models, they are not satisfactory in the clinic. Without effective intervention, pancreatic fibrosis can promote the transformation from pancreatitis to pancreatic cancer, one of the most lethal malignancies. In the normal pancreas, the acinar component accounts for 82% of the exocrine tissue. Abnormal acinar cells may activate pancreatic stellate cells directly as cellular source of fibrosis or indirectly via releasing various substances and initiate pancreatic fibrosis. A comprehensive understanding of the role of acinar cells in pancreatic fibrosis is critical for designing effective intervention strategies. In this review, we focus on the role of and mechanisms underlying pancreatic acinar injury in pancreatic fibrosis and their potential clinical significance.

AAV9-Mediated Cardiac CNTF Overexpression Exacerbated Adverse Cardiac Remodeling in Streptozotocin-Induced Type 1 Diabetic Models

Ciliary neurotrophic factor (CNTF), which is a neural peptide, has been reported to confer cardioprotective effects. However, whether CNTF-based gene delivery could prevent cardiac remodeling in diabetes mellitus remains unknown. In this study, we used adeno-associated viral vector serotype 9 (AAV9)-based cardiac gene delivery to test the effects of CNTF overexpression on adverse ventricular remodeling in streptozotocin-induced type 1 diabetic mice models. Postnatal (P3-P10) mice were peritoneally injected with AAV9 recombinant virus carrying the CNTF gene or EGFP gene. Then, type 1 diabetic models were established by peritoneal injection of streptozotocin (200 mg/kg) in 7-week-old female mice injected with AAV9. 4 weeks later after the establishment of type 1 diabetes mellitus, mouse hearts were removed to assess the degree of cardiac remodeling. We found that CNTF overexpression in mouse cardiomyocytes exacerbated cell apoptosis and cardiac fibrosis coupled with an increased inflammatory response in the heart tissue of diabetic female mice. Taken together, our results suggested that cardiac CNTF gene delivery may not be beneficial in alleviating adverse cardiac remodeling in type 1 diabetes female mice.

Targeting β-cell dedifferentiation and transdifferentiation: opportunities and challenges

The most distinctive pathological characteristics of diabetes mellitus induced by various stressors or immune-mediated injuries are reductions of pancreatic islet β-cell populations and activity. Existing treatment strategies cannot slow disease progression; consequently, research to genetically engineer β-cell mimetics through bi-directional plasticity is ongoing. The current consensus implicates β-cell dedifferentiation as the primary etiology of reduced β-cell mass and activity. This review aims to summarize the etiology and proposed mechanisms of β-cell dedifferentiation and to explore the possibility that there might be a time interval from the onset of β-cell dysfunction caused by dedifferentiation to the development of diabetes, which may offer a therapeutic window to reduce β-cell injury and to stabilize functionality. In addition, to investigate β-cell plasticity, we review strategies for β-cell regeneration utilizing genetic programming, small molecules, cytokines, and bioengineering to transdifferentiate other cell types into β-cells; the development of biomimetic acellular constructs to generate fully functional β-cell-mimetics. However, the maturation of regenerated β-cells is currently limited. Further studies are needed to develop simple and efficient reprogramming methods for assembling perfectly functional β-cells. Future investigations are necessary to transform diabetes into a potentially curable disease.

Transcriptome analysis of the transdifferentiation of canine BMSCs into insulin producing cells

Background

Bone marrow mesenchymal stem cells are a potential resource for the clinical therapy of certain diseases. Canine, as a companion animal, living in the same space with human, is an ideal new model for human diseases research. Because of the high prevalence of diabetes, alternative transplantation islets resource (i.e. insulin producing cells) for diabetes treatment will be in urgent need, which makes our research on the transdifferentiation of Bone marrow mesenchymal stem cells into insulin producing cells become more important.

Result

In this study, we completed the transdifferentiation process and achieved the transcriptome profiling of five samples with two biological duplicates, namely, “BMSCs”, “islets”, “stage 1”, “stage 2” and “stage 3”, and the latter three samples were achieved on the second, fifth and eighth day of induction. A total of 11,530 differentially expressed transcripts were revealed in the profiling data. The enrichment analysis of differentially expressed genes revealed several signaling pathways that are essential for regulating proliferation and transdifferentiation, including focal adhesion, ECM-receptor interaction, tight junction, protein digestion and absorption, and the Rap1 signaling pathway. Meanwhile, the obtained protein–protein interaction network and functional identification indicating involvement of three genes, SSTR2, RPS6KA6, and VIP could act as a foundation for further research.

Conclusion

In conclusion, to the best of our knowledge, this is the first survey of the transdifferentiation of canine BMSCs into insulin-producing cells according with the timeline using next-generation sequencing technology. The three key genes we pick out may regulate decisive genes during the development of transdifferentiation of insulin producing cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-07426-3.

Mesenchymal stem cells promote pancreatic β-cell regeneration through downregulation of FoxO1 pathway

Background

Mesenchymal stem cells (MSC) are non-haematopoietic, fibroblast-like multipotent stromal cells. In the injured pancreas, these cells are assumed to secrete growth factors and immunomodulatory molecules, which facilitate the regeneration of pre-existing β-cells. However, when MSC are delivered intravenously, their majority is entrapped in the lungs and does not reach the pancreas. Therefore, the aim of this investigation was to compare the regenerative support of hTERT-MSC (human telomerase reverse transcriptase mesenchymal stem cells) via intrapancreatic (IPR) and intravenous route (IVR).

Methods

hTERT-MSC were administered by IPR and IVR to 50% pancreatectomized NMRI nude mice. After eight days, blood glucose level, body weight, and residual pancreatic weight were measured. Proliferating pancreatic β-cells were labelled and identified with bromodeoxyuridine (BrdU) in vivo. The number of residual islets and the frequency of proliferating β-cells were compared in different groups with sequential pancreatic sections. The pancreatic insulin content was evaluated by enzyme-linked immunosorbent assay (ELISA) and the presence of hTERT-MSC with human Alu sequence. Murine gene expression of growth factors, β-cell specific molecules and proinflammatory cytokines were inspected by real-time polymerase chain reaction (RT-PCR) and Western blot.

Results

This study evaluated the regenerative potential of the murine pancreas post-hTERT-MSC administration through the intrapancreatic (IPR) and intravenous route (IVR). Both routes of hTERT-MSC transplantation (IVR and IPR) increased the incorporation of BrdU by pancreatic β-cells compared to control. MSC induced epidermal growth factor (EGF) expression and inhibited proinflammatory cytokines (IFN-γ and TNF-α). FOXA2 and PDX-1 characteristics for pancreatic progenitor cells were activated via AKT/ PDX-1/ FoxO1 signalling pathway.

Conclusion

The infusion of hTERT-MSC after partial pancreatectomy (Px) through the IVR and IPR facilitated the proliferation of autochthonous pancreatic β-cells and provided evidence for a regenerative influence of MSC on the endocrine pancreas. Moderate benefit of IPR over IVR was observed which could be a new treatment option for preventing diabetes mellitus after pancreas surgery.

Supplementary information

The online version contains supplementary material available at at 10.1186/s13287-020-02007-9.

EGF suppresses the expression of miR-124a in pancreatic β cell lines via ETS2 activation through the MEK and PI3K signaling pathways

Diabetes mellitus is characterized by pancreatic β cell dysfunction. Previous studies have indicated that epidermal growth factor (EGF) and microRNA-124a (miR-124a) play opposite roles in insulin biosynthesis and secretion by beta cells. However, the underlying mechanisms remain poorly understood. In the present study, we demonstrated that EGF could inhibit miR-124a expression in beta cell lines through downstream signaling pathways, including mitogen-activated protein kinase kinase (MEK) and phosphatidylinositol 3-kinase (PI3K) cascades. Further, the transcription factor ETS2, a member of the ETS (E26 transformation-specific) family, was identified to be responsible for the EGF-mediated suppression of miR-124a expression, which was dependent on ETS2 phosphorylation at threonine 72. Activation of ETS2 decreased miR-124a promoter transcriptional activity through the putative conserved binding sites AGGAANA/TN in three miR-124a promoters located in different chromosomes. Of note, ETS2 played a positive role in regulating beta cell function-related genes, including miR-124a targets, Forkhead box a2 (FOXA2) and Neurogenic differentiation 1 (NEUROD1), which may have partly been through the inhibition of miR-124 expression. Knockdown and overexpression of ETS2 led to the prevention and promotion of insulin biosynthesis respectively, while barely affecting the secretion ability. These results suggest that EGF may induce the activation of ETS2 to inhibit miR-124a expression to maintain proper beta cell functions and that ETS2, as a novel regulator of insulin production, is a potential therapeutic target for diabetes mellitus treatment.

How, When, and Where Do Human β-Cells Regenerate?

PURPOSE OF REVIEW

Pancreatic β-cells play a critical role in whole-body glucose homeostasis by regulating the release of insulin in response to minute by minute alterations in metabolic demand. As such, β-cells are staunchly resilient but there are circumstances where they can become functionally compromised or physically lost due to pathophysiological changes which culminate in overt hyperglycemia and diabetes.

RECENT FINDINGS

In humans, β-cell mass appears to be largely defined in the postnatal period and this early replicative and generative phase is followed by a refractory state which persists throughout life. Despite this, efforts to identify physiological and pharmacological factors which might re-initiate β-cell replication (or cause the replenishment of β-cells by neogenesis or transdifferentiation) are beginning to bear fruit. Controlled manipulation of β-cell mass in humans still represents a holy grail for therapeutic intervention in diabetes, but progress is being made which may lead to ultimate success.

α-Amylase and α-glucosidase inhibitor effects and pancreatic response to diabetes mellitus on Wistar rats of Ephedra alata areal part decoction with immunohistochemical analyses

Ephedra alata, known as a medicinal plant in China, was used in this study as aqueous extract from aerial parts, for diabetes mellitus treatment. This study was carried out on two parts, in vitro, we tested the effect of the studied extract on the inhibition of α-glucosidase and α-amylase activities, and in vivo on Wistar male rats receiving alloxan intraperitoneally at a rate of 125 mg/kg. Extract (100, 200, and 300 mg/kg of body weight) was administrated for 28 days by oral gavage. Blood glucose, amylase, lipase, and lipid profile level were determined. Oxidative stress was evaluated by enzymatic activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), and by estimation of lipid peroxidation and protein carbonyl (PC) level. Histopathological changes in pancreas were investigated under photonic microscopy using immunohistochemical procedure. Our findings showed that aqueous extract inhibited in vitro both α-glucosidase and α-amylase activities and its use in vivo at 300 mg/kg of body weight restored pancreas weight and weight gain, ameliorated significantly (p ˂ 0.05) biochemical parameters; it prevented the increase in lipid and protein oxidation and the decrease in enzymatic and non-enzymatic defense system. Histological study of treated animals showed a comparable healed regeneration of beta cells.

Making β(-like)-cells from exocrine pancreas

Creating an abundant source of β(-like)-cells has been a major goal in diabetes research for many decades. The concept of cell plasticity has inspired many strategies towards regenerative medicine, but its successes have been limited until very recently. Today, most cell types in the pancreas are considered candidates for the generation of β(-like)-cells through transdifferentiation. While β(-like)-cells that are in vitro differentiated from human embryonic stem cells are already being grafted in patients, β(-like)-cells generated by transdifferentiation are not yet ready for clinical application. These cells would however offer several advantages over the current β(-like)-cells generated by directed differentiation, especially concerning safety issues. In addition, perfect control of the transdifferentiation efficiency would through targeted drug delivery support a non-invasive cell therapy for diabetes. Lastly, focusing on the exocrine pancreas as prime candidate makes sense in view of their abundance and high plasticity. Keeping these hopeful perspectives in mind, it is worth to continue focused research on the mechanisms that control transdifferentiation from pancreas exocrine to β-cells.