Role of FGF1, FGF2 and FGF7 in the development of the pancreas from control and streptozotocin-treated hamsters

FGF7 enhances the expression of ACE2 in human islet organoids aggravating SARS-CoV-2 infection

The angiotensin-converting enzyme 2 (ACE2) is a primary cell surface viral binding receptor for SARS-CoV-2, so finding new regulatory molecules to modulate ACE2 expression levels is a promising strategy against COVID-19. In the current study, we utilized islet organoids derived from human embryonic stem cells (hESCs), animal models and COVID-19 patients to discover that fibroblast growth factor 7 (FGF7) enhances ACE2 expression within the islets, facilitating SARS-CoV-2 infection and resulting in impaired insulin secretion. Using hESC-derived islet organoids, we demonstrated that FGF7 interacts with FGF receptor 2 (FGFR2) and FGFR1 to upregulate ACE2 expression predominantly in β cells. This upregulation increases both insulin secretion and susceptibility of β cells to SARS-CoV-2 infection. Inhibiting FGFR counteracts the FGF7-induced ACE2 upregulation, subsequently reducing viral infection and replication in the islets. Furthermore, retrospective clinical data revealed that diabetic patients with severe COVID-19 symptoms exhibited elevated serum FGF7 levels compared to those with mild symptoms. Finally, animal experiments indicated that SARS-CoV-2 infection increased pancreatic FGF7 levels, resulting in a reduction of insulin concentrations in situ. Taken together, our research offers a potential regulatory strategy for ACE2 by controlling FGF7, thereby protecting islets from SARS-CoV-2 infection and preventing the progression of diabetes in the context of COVID-19.

FGF-1 modulates pancreatic β-cell functions/metabolism: An in vitro study

Fibroblast growth factor 1 (FGF-1), also known as acidic fibroblast growth factor (aFGF), is a growth factor and signaling protein encoded by the Fgf1 gene. Previous studies have shown that FGF-1 may also participate in the regulation of glucose metabolism, both in healthy organisms and in pathological conditions such as diabetes. Because insulin the main regulator of glucose metabolism is secreted from pancreatic beta cells, we investigated whether FGF-1 directly affects the secretion of this hormone and regulates the metabolism of beta cells and isolated pancreatic islets. By using insulin-producing INS-1E cells and isolated pancreatic islets, we investigated the effect of FGF-1 on cell proliferation, viability, apoptosis, and insulin expression and secretion. Our study showed that FGF1 and fibroblast growth factor receptors (FgfRs: FgfR1, FgfR2, FgfR3, and FgfR4) are present on mRNA level in INS-1E cells and isolated rat pancreatic islets. We also proved that FGF1 stimulates the proliferation of INS-1E beta cells and enhances the viability of these cells and that of isolated pancreatic islet cells, and that ERK1/2 kinase is involved in the regulation of INS-1E cell proliferation. Moreover, we found that FGF1 can stimulate insulin secretion from both INS-1E cells and isolated rat pancreatic islets. Thus, the FGF1 peptide increases cell survival and decreases cell death. The obtained results indicate that FGF1 may play a role in controlling the physiology and metabolism of pancreatic beta cells as well as glycemia.

[Fibroblast growth factors and their effects in pancreas organogenesis]

Fibroblast growth factors (FGF) - growth factors that regulate many important biological processes, including proliferation and differentiation of embryonic cells during organogenesis. In this review, we will summarize current information about the involvement of FGFs in the pancreas organogenesis. Pancreas organogenesis is a complex process, which involves constant signaling from mesenchymal tissue. This orchestrates the activation of various regulator genes at specific stages, determining the specification of progenitor cells. Alterations in FGF/FGFR signaling pathway during this process lead to incorrect activation of the master genes, which leads to different pathologies during pancreas development. Understanding the full picture about role of FGF factors in pancreas development will make it possible to more accurately understand their role in other pathologies of this organ, including carcinogenesis.

A Combinatorial Protein Microarray for Probing Materials Interaction with Pancreatic Islet Cell Populations

Pancreatic islet transplantation has become a recognized therapy for insulin-dependent diabetes mellitus. During isolation from pancreatic tissue, the islet microenvironment is disrupted. The extracellular matrix (ECM) within this space not only provides structural support, but also actively signals to regulate islet survival and function. In addition, the ECM is responsible for growth factor presentation and sequestration. By designing biomaterials that recapture elements of the native islet environment, losses in islet function and number can potentially be reduced. Cell microarrays are a high throughput screening tool able to recreate a multitude of cellular niches on a single chip. Here, we present a screening methodology for identifying components that might promote islet survival. Automated fluorescence microscopy is used to rapidly identify islet derived cell interaction with ECM proteins and immobilized growth factors printed on arrays. MIN6 mouse insulinoma cells, mouse islets and, finally, human islets are progressively screened. We demonstrate the capability of the platform to identify ECM and growth factor protein candidates that support islet viability and function and reveal synergies in cell response.

Fibroblast growth factor 1 levels are elevated in newly diagnosed type 2 diabetes compared to normal glucose tolerance controls

Fibroblast growth factor 1 (FGF1) has been recently characterized as a potent insulin sensitizer that regulates adipose tissue remodeling, but the physiological role of FGF1 remains unclear. This study measured serum FGF1 levels for the first time in patients with newly diagnosed type 2 diabetes mellitus (T2DM), and further explored the correlations between FGF1 levels and various metabolic parameters in T2DM. Serum FGF1 levels were determined using ELISA in age-, sex- and BMI- matched subjects with normal glucose tolerance (NGT) (n=80) and newly diagnosed T2DM (n=80). Oral glucose tolerance test (OGTT), glycosylated hemoglobin (HbA1C), blood lipids, and insulin secretion were also measured. Insulin resistance and pancreatic β-cell function were assessed by homeostasis model assessment of insulin resistance (HOMA-IR) and homeostasis model assessment of beta cell function (HOMA-β), respectively. Serum FGF1 levels were significantly higher in T2DM patients than in normal glucose tolerance subjects (74.52 [55.91∼101.34] vs. 60.31 [48.99∼83.91] pg/mL; P<0.05). In addition, serum FGF1 level positively correlated with body mass index (BMI), waist circumference (WC), waist to hip ratio (WHR), fasting plasma glucose (FPG), 2-h post-OGTT glucose (2h PG), and HbA1C (all P values <0.05) in T2DM subjects. Multivariate regression analyses showed that BMI and HbA1C were the independent factors influencing serum FGF1 levels. Logistic regression analyses demonstrated that serum FGF1 was significantly associated with type 2 diabetes (P<0.01). Circulating concentrations of FGF1 are significantly increased in T2DM patients. Our results suggest that FGF1 may play a role in the pathogenesis of T2DM.

The Comparison of Adipose Stem Cell and Placental Stem Cell in Secretion Characteristics and in Facial Antiaging

Background. Mesenchymal stem cells are the most commonly used seed cells in biomedical research and tissue engineering. Their secretory proteins have also been proven to play an important role in tissue healing. Methods. We isolated adipose stem cells and placental stem cells and performed analysis examining characteristics. The secretory proteins were extracted from conditioned medium and analyzed by MALDI-TOF/TOF. The antiaging effect of conditioned mediums was evaluated by the results of facial skin application. Results. Adipose stem cells and placental stem cells were found to be very similar in their surface markers and multipotency. The specific proteins secreted from adipose stem cells were more adept at cell adhesion, migration, wound healing, and tissue remodeling, while the proteins secreted by placental stem cells were more adept at angiogenesis, cell proliferation, differentiation, cell survival, immunomodulation, and collagen degradation. While these two types of conditioned medium could improve the facial index, the improvement of Melanin index after injection of the adipose stem cell conditioned medium was much more significant. Conclusion. The results suggest that the secreted proteins are ideal cell-free substances for regeneration medicine, especially in the antiaging field.

Purified human pancreatic duct cell culture conditions defined by serum-free high-content growth factor screening

The proliferation of pancreatic duct-like CK19+ cells has implications for multiple disease states including pancreatic cancer and diabetes mellitus. The in vitro study of this important cell type has been hampered by their limited expansion compared to fibroblast-like vimentin+ cells that overgrow primary cultures. We aimed to develop a screening platform for duct cell mitogens after depletion of the vimentin+ population. The CD90 cell surface marker was used to remove the vimentin+ cells from islet-depleted human pancreas cell cultures by magnetic-activated cell sorting. Cell sorting decreased CD90+ cell contamination of the cultures from 34±20% to 1.3±0.6%, yielding purified CK19+ cultures with epithelial morphology. A full-factorial experimental design was then applied to test the mitogenic effects of bFGF, EGF, HGF, KGF and VEGF. After 6 days in test conditions, the cells were labelled with BrdU, stained and analyzed by high-throughput imaging. This screening assay confirmed the expected mitogenic effects of bFGF, EGF, HGF and KGF on CK19+ cells and additionally revealed interactions between these factors and VEGF. A serum-free medium containing bFGF, EGF, HGF and KGF led to CK19+ cell expansion comparable to the addition of 10% serum. The methods developed in this work should advance pancreatic cancer and diabetes research by providing effective cell culture and high-throughput screening platforms to study purified primary pancreatic CK19+ cells.