What Can We Learn from FGF-2 Isoform-Specific Mouse Mutants? Differential Insights into FGF-2 Physiology In Vivo

Fibroblast growth factor 2 (FGF-2), ubiquitously expressed in humans and mice, is functionally involved in cell growth, migration and maturation in vitro and in vivo. Based on the same mRNA, an 18-kilo Dalton (kDa) FGF-2 isoform named FGF-2 low molecular weight (FGF-2LMW) isoform is translated in humans and rodents. Additionally, two larger isoforms weighing 21 and 22 kDa also exist, summarized as the FGF-2 high molecular weight (FGF-2HMW) isoform. Meanwhile, the human FGF-2HMW comprises a 22, 23, 24 and 34 kDa protein. Independent studies verified a specific intracellular localization, mode of action and tissue-specific spatiotemporal expression of the FGF-2 isoforms, increasing the complexity of their physiological and pathophysiological roles. In order to analyze their spectrum of effects, FGF-2LMW knock out (ko) and FGF-2HMWko mice have been generated, as well as mice specifically overexpressing either FGF-2LMW or FGF-2HMW. So far, the development and functionality of the cardiovascular system, bone formation and regeneration as well as their impact on the central nervous system including disease models of neurodegeneration, have been examined. This review provides a summary of the studies characterizing the in vivo effects modulated by the FGF-2 isoforms and, thus, offers a comprehensive overview of its actions in the aforementioned organ systems.

Biological Characteristics and Osteogenic Differentiation of Ovine Bone Marrow Derived Mesenchymal Stem Cells Stimulated with FGF-2 and BMP-2

Cell-based therapies using mesenchymal stem cells (MSCs) are a promising tool in bone tissue engineering. Bone regeneration with MSCs involves a series of molecular processes leading to the activation of the osteoinductive cascade supported by bioactive factors, including fibroblast growth factor-2 (FGF-2) and bone morphogenetic protein-2 (BMP-2). In this study, we examined the biological characteristics and osteogenic differentiation potential of sheep bone marrow MSCs (BM-MSCs) treated with 20 ng/mL of FGF-2 and 100 ng/mL BMP-2 in vitro. The biological properties of osteogenic-induced BM-MSCs were investigated by assessing their morphology, proliferation, phenotype, and cytokine secretory profile. The osteogenic differentiation was characterized by Alizarin Red S staining, immunofluorescent staining of osteocalcin and collagen type I, and expression levels of genetic markers of osteogenesis. The results demonstrated that BM-MSCs treated with FGF-2 and BMP-2 maintained their primary MSC properties and improved their osteogenic differentiation capacity, as confirmed by increased expression of osteocalcin and collagen type I and upregulation of osteogenic-related gene markers BMP-2, Runx2, osterix, collagen type I, osteocalcin, and osteopontin. Furthermore, sheep BM-MSCs produced a variety of bioactive factors involved in osteogenesis, and supplementation of the culture medium with FGF-2 and BMP-2 affected the secretome profile of the cells. The results suggest that sheep osteogenic-induced BM-MSCs may be used as a cellular therapy to study bone repair in the preclinical large animal model.

MicroRNA-148a-3p alleviates high glucose-induced diabetic retinopathy by targeting TGFB2 and FGF2

AIMS

Diabetic retinopathy (DR), a common complication of type 1 or type 2 diabetes mellitus, has become the leading cause of blindness among adults in working age. The dysregulation of microRNA has been reported to be strongly related to the initiation or progression of DR. However, neither the biological role nor the molecular mechanism of miR-148a-3p has been researched in DR. This study is designed to investigate the function and mechanism of miR-148a-3p in DR.

METHODS

The bioinformatics analysis (Targetscan: https://www.targetscan.org/vert_72/ ) and numerous experiments including real-time quantitative polymerase chain reaction, terminal deoxynucleotidyltransferase dUTP nick end labeling, CCK-8, western blot, vasculogenesis and luciferase reporter assays were used to research the function and mechanism of miR-148a-3p in DR.

RESULTS

We constructed DR cell model by treating human retinal microvascular endothelial cells (HRECs) with different concentration gradients of high glucose (HG). Additionally, HG treatment reduced miR-148a-3p level in HRECs. In function, overexpression of miR-148a-3p caused an increase in cell viability and a decrease in cell apoptosis. Besides, miR-148a-3p overexpression led to a damage on blood-retinal barrier (BRB) and suppressed angiogenesis. In mechanism, miR-148a-3p specifically bound to 3' untranslated region of TGFB2 and FGF2. At least, rescue assays demonstrated that the inhibitive influence of miR-148a-3p mimics on BRB injury was offset by overexpression of TGFB2 and the attenuation of angiogenesis resulting from miR-148a-3p mimics was abrogated by overexpression of FGF2 CONCLUSIONS: In a word, we discovered that miR-148a-3p alleviated HG-induced DR by targeting TGFB2 and FGF2. This novel discovery indicated miR-148a-3p as a potential target for DR diagnosis or treatment.

LncRNA PCGEM1 promotes renal carcinoma progression by targeting miR-433-3p to regulate FGF2 expression

Long non-coding RNAs (lncRNAs) are implicated in the development of carcinomas, containing renal carcinoma. The competing endogenous RNA (ceRNA) network is well-known in modulating the pathological and physiological processes of tumors. Still and all, the function role of oncogenic lncRNA PCGEM1 prostate-specific transcript (PCGEM1) in renal carcinoma was undefined till now. This paper aimed to figure out the role and mechanism of PCGEM1 in renal carcinoma. In this study, PCGEM1 was observed to be lifted in renal carcinoma cells. Loss-of-function experiments displayed that silencing of PCGEM1 repressed cell proliferation and migration, and activated apoptosis in renal carcinoma. FISH assay and subcellular fractionation assay indicated that PCGEM1 was largely located in the cytoplasm. As demonstrated, PCGEM1 interacted with microRNA433-3p (miR-433-3p). Subsequently, luciferase reporter and RIP experiments together with qRT-PCR certified that PCGEM1 and fibroblast growth factor 2 (FGF2) functioned as ceRNA for miR-433-3p, leading to the upregulation of FGF2 expression. Finally, rescue assays exhibited that FGF2 overexpression rescued the inhibited cell progression caused by PCGEM1 downregulation. MiR-433-3p inhibitor could reverse the cell growth and migration caused by PCGEM1 downregulation. The present research investigated the molecular mechanism underlying PCGEM1 in renal carcinoma, exposing a PCGEM1-mediated therapy for the treatment of patients with renal carcinoma.

Fibroblast growth factor 2 exacerbates inflammation in adipocytes through NLRP3 inflammasome activation

Chronic inflammation in adipose tissue is the hallmark of obesity and a major risk factor for the development of obesity-induced insulin resistance. NLRP3 inflammasome regulates the maturation and secretion of pro-inflammatory cytokines, such as IL-1β and IL-18, and was recently discovered to be involved in obesity-related metabolic diseases. Fibroblast growth factors (FGFs) such as FGF1, FGF10, and FGF21 are adipokines that regulate adipocyte development and metabolism, but reports on the effect of other FGFs on adipocytes are lacking. In the present study, the novel role of FGF2 in NLRP3 inflammasome activation was elucidated. Our results showed that FGF2 levels were increased during adipocyte differentiation and in the adipose tissue of high-fat diet (HFD)-induced obese mice. Recombinant FGF2 treatment upregulated inflammasome markers such as NLRP3, which was further exaggerated by TNF-ɑ treatment. Interestingly, β-Klotho, a co-receptor of FGF21, was significantly decreased by FGF2 treatment. Results from mice confirmed the positive correlation between FGF2 and NLRP3 expression in epididymal and subcutaneous adipose tissue, while exercise training effectively reversed HFD-induced NLRP3 expression as well as FGF2 levels in both adipose depots. Our results suggest that FGF2 is an adipokine that may exacerbate the inflammatory response in adipocytes through NLRP3 inflammasome activation.

Connexin43 Region 266-283, via Src Inhibition, Reduces Neural Progenitor Cell Proliferation Promoted by EGF and FGF-2 and Increases Astrocytic Differentiation

Neural progenitor cells (NPCs) are self-renewing cells that give rise to the major cells in the nervous system and are considered to be the possible cell of origin of glioblastoma. The gap junction protein connexin43 (Cx43) is expressed by NPCs, exerting channel-dependent and -independent roles. We focused on one property of Cx43—its ability to inhibit Src, a key protein in brain development and oncogenesis. Because Src inhibition is carried out by the sequence 266–283 of the intracellular C terminus in Cx43, we used a cell-penetrating peptide containing this sequence, TAT-Cx43_266–283, to explore its effects on postnatal subventricular zone NPCs. Our results show that TAT-Cx43_266–283 inhibited Src activity and reduced NPC proliferation and survival promoted by epidermal growth factor (EGF) and fibroblast growth factor-2 (FGF-2). In differentiation conditions, TAT-Cx43_266–283 increased astrocyte differentiation at the expense of neuronal differentiation, which coincided with a reduction in Src activity and β-catenin expression. We propose that Cx43, through the region 266–283, reduces Src activity, leading to disruption of EGF and FGF-2 signaling and to down-regulation of β-catenin with effects on proliferation and differentiation. Our data indicate that the inhibition of Src might contribute to the complex role of Cx43 in NPCs and open new opportunities for further research in gliomagenesis.

An HIV-Tat inducible mouse model system of childhood HIV-associated nephropathy

Modern antiretroviral therapies (ART) have decreased the prevalence of HIV-associated nephropathy (HIVAN). Nonetheless, we continue to see children and adolescents with HIVAN all over the world. Furthermore, once HIVAN is established in children, it is difficult to revert its long-term progression, and we need better animal models of childhood HIVAN to test new treatments. To define whether the HIV-1 trans-activator (Tat) gene precipitates HIVAN in young mice, and to develop an inducible mouse model of childhood HIVAN, an HIV-Tat gene cloned from a child with HIVAN was used to generate recombinant adenoviral vectors (rAd-Tat). rAd-Tat and LacZ control vectors (2×109) were expressed in the kidney of newborn wild-type and HIV-transgenic (Tg26) FVB/N mice without significant proteinuria (n=5; 8 per group). Mice were sacrificed 7 and 35 days later to assess their renal outcome, the expression of HIV-genes and growth factors, and markers of cell growth and differentiation by RT-qPCR, immunohistochemistry and/or western blots. HIV-Tat induced the expression of HIV-1 genes and heparin-binding growth factors in the kidney of HIV-Tg26 mice, and precipitated HIVAN in the first month of life. No significant renal changes were detected in wild-type mice infected with rAd-Tat vectors, suggesting that HIV-Tat alone does not induce renal disease. This new mouse model of childhood HIVAN highlights the critical role that HIV-Tat plays in the pathogenesis of HIVAN, and could be used to study the pathogenesis and treatment of HIVAN in children and adolescents.

Modulating electrospun polycaprolactone scaffold morphology and composition to alter endothelial cell proliferation and angiogenic gene response

The aim of this study was to look at how the composition and morphology of polymer scaffolds could be altered to create an optimized environment for endothelial cells. Four polycaprolactone (PCL) scaffolds were electrospun with increasing fibre diameters ranging from 1.64 μm to 4.83 μm. The scaffolds were seeded with human umbilical vein endothelial cells (HUVEC) and cultured for 12 days. PCL scaffolds were then electrospun incorporating decellularized bovine aorta ECM and cultured in a hypoxic environment. We noted deeper cell infiltration on the largest fibre diameter compared to the other three scaffolds which resulted in an increase in the gene expression of CD31; a key angiogenic marker. Increased cell viability and cell proliferation were also noted on the largest fibre. Furthermore, we noted that the incorporation of extracellular matrix (ECM) had minimal effect on cell viability, both in normoxic and hypoxic culture conditions. Our results showed that these environments had limited influences on hypoxic gene expression. Interestingly, the major findings from this study was the production of excretory ECM components as shown in the scanning electron microscopy (SEM) images. The results from this study suggest that fibre diameter had a bigger impact on the seeded HUVECs than the incorporation of ECM or the culture conditions. The largest fibre dimeter (4.83 μm) is more suitable for seeding of HUVECs.

Growth Factors in the Carotid Body-An Update

The carotid body may undergo plasticity changes during development/ageing and in response to environmental (hypoxia and hyperoxia), metabolic, and inflammatory stimuli. The different cell types of the carotid body express a wide series of growth factors and corresponding receptors, which play a role in the modulation of carotid body function and plasticity. In particular, type I cells express nerve growth factor, brain-derived neurotrophic factor, neurotrophin 3, glial cell line-derived neurotrophic factor, ciliary neurotrophic factor, insulin-like-growth factor-I and -II, basic fibroblast growth factor, epidermal growth factor, transforming growth factor-α and -β, interleukin-1β and -6, tumor necrosis factor-α, vascular endothelial growth factor, and endothelin-1. Many specific growth factor receptors have been identified in type I cells, indicating autocrine/paracrine effects. Type II cells may also produce growth factors and express corresponding receptors. Future research will have to consider growth factors in further experimental models of cardiovascular, metabolic, and inflammatory diseases and in human (normal and pathologic) samples. From a methodological point of view, microarray and/or proteomic approaches would permit contemporary analyses of large groups of growth factors. The eventual identification of physical interactions between receptors of different growth factors and/or neuromodulators could also add insights regarding functional interactions between different trophic mechanisms.

Collagen extract obtained from Nile tilapia (Oreochromis niloticus L.) skin accelerates wound healing in rat model via up regulating VEGF, bFGF, and α-SMA genes expression

BACKGROUND

Collagen is the most abundant structural protein in the mammalian connective tissue and represents approximately 30% of animal protein. The current study evaluated the potential capacity of collagen extract derived from Nile tilapia skin in improving the cutaneous wound healing in rats and investigated the underlying possible mechanisms. A rat model was used, and the experimental design included a control group (CG) and the tilapia collagen treated group (TCG). Full-thickness wounds were conducted on the back of all the rats under general anesthesia, then the tilapia collagen extract was applied topically on the wound area of TCG. Wound areas of the two experimental groups were measured on days 0, 3, 6, 9, 12, and 15 post-wounding. The stages of the wound granulation tissues were detected by histopathologic examination and the expression of vascular endothelial growth factor (VEGF), and transforming growth factor (TGF-ß1) were investigated using immunohistochemistry. Moreover, relative gene expression analysis of transforming growth factor-beta (TGF-ß1), basic fibroblast growth factor (bFGF), and alpha-smooth muscle actin (α-SMA) were quantified by real-time qPCR.

RESULTS

The histopathological assessment showed noticeable signs of skin healing in TCG compared to CG. Immunohistochemistry results revealed remarkable enhancement in the expression levels of VEGF and TGF-β1 in TCG. Furthermore, TCG exhibited marked upregulation in the VEGF, bFGF, and α-SMA genes expression. These findings suggested that the topical application of Nile tilapia collagen extract can promote the cutaneous wound healing process in rats, which could be attributed to its stimulating effect on recruiting and activating macrophages to produce chemotactic growth factors, fibroblast proliferation, and angiogenesis.

CONCLUSIONS

The collagen extract could, therefore, be a potential biomaterial for cutaneous wound healing therapeutics.

Structure-guided design, generation, and biofunction of PEGylated fibroblast growth factor 2 variants for wound healing

Fibroblast growth factor 2 (FGF2) plays an important role in multiple physiological functions such as tissue repair. However, FGF2 has a short half-life in vivo due to protease degradation, thus limiting its clinical application. Traditional PEGylation has typically focused on the N-terminal α-amino group of FGF2. These modifications do not consider potential effects on protein function or structure, and sometimes lead to decreased bioactivity. In this study, we generated three PEGylated FGF2 variants based on the structure of the FGF2-FGFR-heparin ternary complex via gene mutation and PEGylation, and investigated the effects of these PEGylated sites on protein stability and bioactivity. Compared with native FGF2, all PEG-FGF2 conjugates exhibited significantly improved stability. Conjugates PEGylated at a site separated from both binding regions more effectively promoted proliferation, migration and angiogenesis than FGF2 in vitro, and exhibited excellent wound healing activity in vivo, making these conjugates potential therapeutic candidates for wound healing. Computer-assisted modification based on structure reveals the detailed structural characteristics of proteins, allowing efficient protein modification for improved stability and activity. This structure-guided PEGylation offers a more reliable modification strategy and should be applied for the rational design of protein-based therapeutics.

The In Vitro M1/M2 Polarization of Macrophages of BCG-Infected Mice

Cultured peritoneal macrophages from intact (control) and BCG-infected (experiment) male BALB/c mice were studied 90 days after infection. Polarization of macrophages by M1 (expression of GM-CSF, IFN_γ, and CD16/32) and M2 (expression of bFGF and CD36) differentiation pathways was studied with consideration for their the nuclearity class. Mononuclear cells predominated (90% and higher) in macrophage cultures of both groups and presumably, were presented by mainly epithelioid cells. The results indicated polarization of mononuclear and multinuclear macrophages in the M2 direction under conditions of BCG granulomatosis and a higher initial M2 polarization of binuclear macrophages. In control cultures, the ratio of M2 to M1 macrophages was 0.57, in experimental cultures this ratio was 1.6. It seems that long persistence of Mycobacterium tuberculosis in macrophages served as a factor stimulating the plastic processes and transformation of macrophages into epithelioid cells that form the "core" of granulomas and their enlargement upon incorporation of macrophages.

[Ethanol induced increase of fibroblast growth factor 2 mRNA content in emotiogenic brain structures of rats]

We studied the effects of acute, subacute, and chronic alcohol treatment of rats on the content of fibroblast growth factor 2 (FGF2) mRNA in various brain structures. Results suggest a possible role of FGF2 in the functioning of dopaminergic neurons in the midbrain. In our experiment, ethanol treatment of rats was accompanied by an increase in the FGF2 mRNA level in the emotiogenic structures of the brain. This effect was blocked by pretreatment of animals with chlorpromazine. This suggests FGF2 involvement in the mechanisms of alcohol dependence and can be considered as a possible diagnostic and therapeutic target in alcoholism.

Exosomal shuttled miR-424-5p from ischemic preconditioned microglia mediates cerebral endothelial cell injury through negatively regulation of FGF2/STAT3 pathway

Exosomes secreted by microglia have been found to play a role in neurovascular unit injury under the ischemic/hypoxic state. However, the modulatory effect of exosomes shuttled miRNAs produced by microglia in endothelial cells remains undefined. Here, an oxygen-glucose deprivation (OGD) model was constructed both in microglia and brain microvascular endothelial cells (BMEC). The exosomes secreted by microglia were isolated, and the exosomal miRNA profile was detected. Next, gain- and loss- functions of miR-424-5p, one of the most differentially expressed miRNAs in microglia derived exosomes, were conducted in BMEC. The results demonstrated that exosomes from OGD-activated microglia aggravated OGD induced BMEC viability and integrity damage as well as the loss of vascular formation. While the damaging effects were markedly attenuated by inhibiting miR-424-5p. In addition, miR-424-5p overexpression significantly aggravated OGD induced BMEC damage and permeability. Mechanistically, bioinformatics analysis indicated that miR-424-5p targeted the FGF2 mediated STAT3 signaling pathway, which was verified via dual luciferase activity assay and RIP experiment. Furthermore, in vivo experiments in the middle cerebral artery occlusion (MCAO) model mice were conducted. The results revealed that inhibition of miR-424-5p markedly reduced neurological dysfunctions and endothelial cell injury induced by MCAO. The above results confirmed that exosomes from OGD activated microglia induced significant cell damage and permeability of BMEC, in which the upregulated miR-424-5p in the exosomes functioned by regulating FGF2/STAT3 pathway.

Stable Fibroblast Growth Factor 2 Dimers with High Pro-Survival and Mitogenic Potential

Fibroblast growth factor 2 (FGF2) is a heparin-binding growth factor with broad mitogenic and cell survival activities. Its effector functions are induced upon the formation of 2:2 FGF2:FGFR1 tetrameric complex. To facilitate receptor activation, and therefore, to improve the FGF2 biological properties, we preorganized dimeric ligand by a covalent linkage of two FGF2 molecules. Mutations of the FGF2 WT protein were designed to obtain variants with a single surface-exposed reactive cysteine for the chemical conjugation via maleimide-thiol reaction with bis-functionalized linear PEG linkers. We developed eight FGF2 dimers of defined topology, differing in mutual orientation of individual FGF2 molecules. The engineered proteins remained functional in terms of FGFR downstream signaling activation and were characterized by the increased stability, mitogenic potential and anti-apoptotic activity, as well as induced greater migration responses in normal fibroblasts, as compared to FGF2 monomer. Importantly, biological activity of the dimers was much less dependent on the external heparin administration. Moreover, some dimeric FGF2 variants internalized more efficiently into FGFR overexpressing cancer cells. In summary, in the current work, we showed that preorganization of dimeric FGF2 ligand increased the stability of the growth factor, and therefore, enhanced its biological activity.

Muscle transcriptome analysis identifies genes involved in ciliogenesis and the molecular cascade associated with intramuscular fat content in Large White heavy pigs

Intramuscular fat content (IMF) is a complex trait influencing the technological and sensorial features of meat products and determining pork quality. Thus, we aimed at analyzing through RNA-sequencing the Semimembranosus muscle transcriptome of Italian Large White pigs to study the gene networks associated with IMF deposition. Two groups of samples were used; each one was composed of six unrelated pigs with extreme and divergent IMF content (0.67 ± 0.09% in low IMF vs. 6.81 ± 1.17% in high IMF groups) that were chosen from 950 purebred individuals. Paired-end RNA sequences were aligned to Sus scrofa genome assembly 11.1 and gene counts were analyzed using WGCNA and DeSeq2 packages in R environment. Interestingly, among the 58 differentially expressed genes (DEGs), several were related to primary cilia organelles (such as Lebercilin 5 gene), in addition to the genes involved in the regulation of cell differentiation, in the control of RNA-processing, and G-protein and ERK signaling pathways. Together with cilia-related genes, we also found in high IMF pigs an over-expression of the Fibroblast Growth Factor 2 (FGF2) gene, which in other animal species was found to be a regulator of ciliogenesis. Four WGCNA gene modules resulted significantly associated with IMF deposition: grey60 (P = 0.003), darkturquoise (P = 0.022), skyblue1 (P = 0.022), and lavenderblush3 (P = 0.030). The genes in the significant modules confirmed the results obtained for the DEGs, and the analysis with “cytoHubba” indicated genes controlling RNA splicing and cell differentiation as hub genes. Among the complex molecular processes affecting muscle fat depots, genes involved in primary cilia may have an important role, and the transcriptional reprogramming observed in high IMF pigs may be related to an FGF-related molecular cascade and to ciliogenesis, which in the literature have been associated with fibro-adipogenic precursor differentiation.

Limb functional recovery is impaired in fibroblast growth factor-2 (FGF2) deficient mice despite chronic ischaemia-induced vascular growth

FGF2 is a potent stimulator of vascular growth; however, even with a deficiency of FGF2 (Fgf2-/-), developmental vessel growth or ischaemia-induced revascularization still transpires. It remains to be elucidated as to what function, if any, FGF2 has during ischaemic injury. Wildtype (WT) or Fgf2-/- mice were subjected to hindlimb ischaemia for up to 42 days. Limb function, vascular growth, inflammatory- and angiogenesis-related proteins, and inflammatory cell infiltration were assessed in sham and ischaemic limbs at various timepoints. Recovery of ischaemic limb function was delayed in Fgf2-/- mice. Yet, vascular growth response to ischaemia was similar between WT and Fgf2-/- hindlimbs. Several angiogenesis- and inflammatory-related proteins (MCP-1, CXCL16, MMPs and PAI-1) were increased in Fgf2-/- ischaemic muscle. Neutrophil or monocyte recruitment/infiltration was elevated in Fgf2-/- ischaemic muscle. In summary, our study indicates that loss of FGF2 induces a pro-inflammatory microenvironment in skeletal muscle which exacerbates ischaemic injury and delays functional limb use.

Inhibition of FGFR Signaling Partially Rescues Osteoarthritis in Mice Overexpressing High Molecular Weight FGF2 Isoforms

Fibroblast growth factor 2 (FGF2) and fibroblast growth factor receptors (FGFRs) are key regulatory factors in osteoarthritis (OA). HMWTg mice overexpress the high molecular weight FGF2 isoforms (HMWFGF2) in osteoblast lineage and phenocopy both Hyp mice (which overexpress the HMWFGF2 isoforms in osteoblasts and osteocytes) and humans with X-linked hypophosphatemia (XLH). We previously reported that, similar to Hyp mice and XLH subjects who develop OA, HMWTg mice also develop an OA phenotype associated with increased degradative enzymes and increased FGFR1 compared with VectorTg mice. Therefore, in this study, we examined whether in vivo treatment with the FGFR tyrosine kinase inhibitor NVP-BGJ398 (BGJ) would modulate development of the OA phenotype in knee joints of HMWTg mice. VectorTg and HMWTg mice (21 days of age) were treated with vehicle or BGJ for 13 weeks. Micro-computed tomography images revealed irregular shape and thinning of the subchondral bone with decreased trabecular number and thickness within the epiphyses of vehicle-treated HMWTg knees, which was partially rescued following BGJ treatment. Articular cartilage thickness was decreased in vehicle-treated HMWTg mice, and was restored to the cartilage thickness of VectorTg mice in the BGJ-treated HMWTg group. Increased OA degradative enzymes present in HMWTg vehicle-treated joints decreased after BGJ treatment. OA in HMWTg mice was associated with increased Wnt signaling that was rescued by BGJ treatment. This study demonstrates that overexpression of the HMWFGF2 isoforms in preosteoblasts results in osteoarthropathy that can be partially rescued by FGFR inhibitor via reduction in activated Wnt signaling.

Organoid Derivation and Orthotopic Xenotransplantation for Studying Human Intestinal Stem Cell Dynamics

Intestinal stem cells continuously self-renew throughout life to maintain gut homeostasis. With the advent of the organoid culture system, we are now able to indefinitely expand healthy and diseased tissue-derived human intestinal stem cells in vitro and use them for various applications. Nonetheless, investigating the behavior of human intestinal stem cells in vivo still remains challenging. We recently developed an orthotopic xenotransplantation system that realizes in vivo reconstruction of human intestinal epithelial tissue with preserved stem cell hierarchy by engrafting human normal colon organoids onto the mouse colon surface. We also introduced new growth factors, namely, insulin-like growth factor-1 (IGF-1) and fibroblast growth factor-2 (FGF-2), into the culture condition for human intestinal organoids that significantly increase scalability and transfectability of the organoids. By integrating these recent advances, we organized a tissue-oriented platform encompassing derivation of patient-derived intestinal organoids and their orthotopic xenotransplantation. The research platform based on orthotopic xenotransplantation of human intestinal organoids provides a powerful tool for studying human intestinal stem cell biology in native tissue-relevant contexts as well as for establishing novel disease modeling systems.

The association between maternal nicotine exposure and adipose angiogenesis in female rat offspring: A mechanism of adipose tissue function changes

Maternal smoking during pregnancy and lactation is associated with increased fat mass in the offspring, but the mechanism by which this occurs is not fully understood. Our study focused on the relationships among maternal nicotine exposure, adipose angiogenesis and adipose tissue function in female offspring. Pregnant rats were randomly assigned to nicotine or control groups. Microvascular density, lipid metabolism and α7nAChR-Egr1-FGF2 signaling pathway genes/proteins were tested in 4-, 12- and 26-week female offspring. In vitro, nicotine concentration- and time-response experiments were conducted in 3T3-L1. Lipid metabolism and α7nAChR-Egr1-FGF2 signaling pathway genes/proteins were tested. The conditioned media of differentiated 3T3-L1 treated with nicotine were used to observe tube formation in human umbilical vein endothelial cells (HUVECs). Nicotine-exposed females presented higher adipose microvascular density. The gene expression of α7nAChR, Egr1 and FGF2 was significantly increased in gonadal white adipose tissue (gWAT) and inguinal subcutaneous WAT (igSWAT) of nicotine-exposed females at 4 weeks of age. The protein expression of α7nAChR, Egr1 and FGF2 was increased in gWAT and igSWAT of nicotine-exposed females at 4 weeks of age, and increased in gWAT at 26 weeks. In vitro, nicotine increased the expression of lipid metabolism and α7nAChR-Egr1-FGF2 signaling pathway genes/proteins in a concentration- and time-dependent manner. In the tube formation experiment, adipocytes affected by nicotine promoted HUVEC angiogenesis. Therefore, maternal nicotine exposure promoted the early angiogenesis of adipose tissue via the α7nAChR-Egr1-FGF2 signaling pathway, and this angiogenesis mechanism was associated with increased adipogenesis in adipose tissue of female offspring.

Local supplementation with plant-derived recombinant human FGF2 protein enhances bone formation in critical-sized calvarial defects

Numerous studies have demonstrated the advantages of plant cell suspension culture systems in producing bioactive recombinant human growth factors. This study investigated the biological activity of recombinant basic human fibroblast growth factor (rhFGF2) protein produced by a plant culture system to enhance new bone formation in a bone defect mouse model. The human FGF2 cDNA gene was cloned into a plant expression vector driven by the rice α-amylase 3D promoter. The vector was introduced into rice calli (Oryza sativa L. cv. Dongjin), and the clone with the highest expression of rhFGF2 was selected. Maximum accumulation of rhFGF2 protein (approximately 28 mg/l) was reached at 13 day post-incubation. Male C57BL/6 mice underwent calvarial defect surgery and the defects were loaded with absorbable collagen sponge (ACS) only (ACS group) or ACS impregnated with 5 μg of plant-derived rhFGF2 (p-FGF2) protein or E. coli-derived rhFGF2 (e-FGF2) protein. Similar to the effects of e-FGF2, local delivery with p-FGF2 enhanced bone healing in the damaged region to higher levels than the ACS group. Exogenous addition of p-FGF2 or e-FGF2 exhibited similar effects on proliferation, mineralization, and osteogenic marker expression in MC3T3-E1 cells. Together, the current findings support the usefulness of this plant-based expression system for the production of biologically active rhFGF2.

The synergistic effect of electroacupuncture and bone mesenchymal stem cell transplantation on repairing thin endometrial injury in rats

BACKGROUND

Tissue regeneration disorder after endometrial injury is an important cause of intrauterine adhesions, amenorrhea, and infertility in women. Both bone marrow mesenchymal stem cell (BMSC) transplantation and electroacupuncture (EA) are promising therapeutic applications for endometrial injury. This study examined their combined effects on thin endometrium in rats and the possible mechanisms underlying these effects.

METHODS

A thin endometrial model was established in Sprague-Dawley (SD) rats by perfusing 95% ethanol into the right side of the uterus. The wounds were randomly treated with PBS (model group), BMSCs only (BMSC group), EA only (EA group), and BMSCs combined with EA (BMSC + EA group). Endometrial morphological alterations were observed by hematoxylin and eosin (H&E) staining. Changes in markers of epithelial and stromal endometrium cells, endometrial receptivity-related chemokines, and paracrine factors were detected using immunohistochemistry, western blotting, and quantitative reverse-transcription polymerase chain reaction (qRT-PCR). Finally, the functional recovery of the uterus was evaluated by determining the rate of embryo implantation.

RESULTS

As shown by endometrial morphology, the damaged uteri in all the treatment groups recovered to some extent, with the best effects observed in the BMSC + EA group. Further studies showed that EA promoted the migration of transplanted BMSCs to damaged uteri by activating the stromal cell-derived factor-1/C-X-C chemokine receptor type 4 (SDF-1/CXCR4) axis. As compared with the other groups, upregulated expression of endometrial cytokeratin and vimentin, increased secretion of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in endometrial lesions, and improved embryo implantation rates on the 8th day of pregnancy were found in the BMSC + EA group.

CONCLUSIONS

EA plays an important role in supporting BMSCs in the repair of thin endometrium, most likely by promoting the migration of BMSCs and enhancing the paracrine effect of BMSCs.

Influence of Strontium on Vascular Endothelial Growth Factor and Fibroblast Growth Factor 2 Expression in Rat Chondrocytes Cultured In Vitro

Strontium (Sr) can reduce cartilage degeneration and stimulate cartilage matrix formation. Angiogenesis plays a developmental role in chondrogenesis, and was stimulated by growth factors such as vascular endothelial growth factor (VEGF) and fibroblast growth factor 2 (FGF2). However, the direct influence of Sr on VEGF and FGF2 expressions in chondrocytes is not entirely clear. The objective of this study was to investigate the effects of different Sr concentrations on VEGF and FGF2 expressions in rat chondrocytes in vitro. Chondrocytes were isolated from Wistar rat articular by enzymatic digestion. As a Sr source, strontium chloride hexahydrate (SrCl₂·6H₂O) was added to the culture solution at final concentrations of 0, 0.5, 1.0, 2.0, 5.0, 20.0, and 100.0 μg/mL. After 72 h of continuous culture, mRNA abundance and protein expression levels of VEGF and FGF2 in the chondrocytes were determined by real-time polymerase chain reaction (real-time PCR) and Western blot, respectively. The results showed that VEGF and FGF2 expressions were dose-dependently elevated with Sr concentration in chondrocytes. The mRNA abundance and protein expression levels of VEGF were extremely significantly higher than those in the control group (P < 0.01) at 1.0 μg/mL Sr treatment. For FGF2, there were markedly significant differences in mRNA and protein expression from control group (P < 0.01) when the Sr-treated concentration exceeded 5.0 μg/mL and 20.0 μg/mL, respectively. These results indicated that Sr might involve in the cartilage angiogenesis via regulating expression of VEGF and FGF2z.

Tissue-specific role of Nrf2 in the treatment of diabetic foot ulcers during hyperbaric oxygen therapy

Hyperbaric oxygen (HBO) therapy is proven to be very successful for diabetic foot ulcer (DFU) treatment due to its antimicrobial effect, increased angiogenesis and enhanced collagen synthesis. The molecular mechanism underlying HBO therapy particularly the involvement of Nrf2 in the wound healing process was investigated in the present study. In addition, we have studied the levels of angiogenic markers in ulcer tissues and their correlation with Nrf2 during HBO therapy compared with standard therapy (Non-HBO) for DFU. A total of 32 Patients were recruited and randomized to standard wound care procedure alone (n = 17) or HBO therapy in combination with standard wound care procedure (n = 15) for 20 days. Our results showed that the tissue levels of Nrf2 along with its downstream targets were significantly increased in patients who underwent HBO therapy when compared to Non-HBO therapy. Further, HBO therapy induced angiogenesis as assessed by increased levels of angiogenesis markers such as EGF, VEGF, PDGF, FGF-2 and CXCL10 in the tissue samples. The expressions of eNOS and nitrite concentrations were also significantly increased in HBO therapy when compared to Non-HBO therapy subjects. Moreover, HBO therapy sensitises the macrophages to release FGF-2 and EGF thereby promotes angiogenesis. Further, it increased the levels of neutrophil attractant CXCL-8 thereby promotes the release of chemokine CCL2, a well-known mediator of neovascularization. The Pearson correlation showed that Nrf2 has a positive correlation with EGF, VEGF and PDGF. In conclusion, the findings of the present study suggest that HBO therapy promotes wound healing by increasing oxygen supply and distribution to damaged tissues, stimulating angiogenesis, decreasing inflammation, and increasing the nitrite levels. Increased levels of Nrf2 transiently regulate the expression of angiogenic genes in wound biopsies, which may result in accelerated healing of chronic wounds.

Effect of Testosterone on FGF2, MRF4, and Myostatin in Hypogonadotropic Hypogonadism: Relevance to Muscle Growth

CONTEXT

Fibroblast growth factor (FGF)2 is an important stimulatory modulator of satellite cells in skeletal muscle. Satellite cells play a cardinal role in muscle growth and repair.

OBJECTIVE

We evaluated whether skeletal muscle expression of FGF2 and muscle growth and differentiation factors are reduced in patients with hypogonadotropic hypogonadism (HH) and whether testosterone replacement therapy results in their restoration.

DESIGN

This is a secondary analysis of a previously completed trial of testosterone replacement in men with type 2 diabetes and HH.

SETTING

Clinical Research Center at a university.

PATIENTS

Twenty-two men with HH and 20 eugonadal men were compared at baseline.

INTERVENTIONS

Twelve men with HH were treated with intramuscular injections of 250 mg testosterone every 2 weeks for 22 weeks, and 10 men received placebo injections. Quadriceps muscle biopsies and blood samples were obtained before and after testosterone therapy.

OUTCOME MEASURES AND RESULTS

The expression of FGF2 and FGF receptor (FGFR)2 in skeletal muscle of men with HH was significantly lower than that in eugonadal men by 57% and 39%, respectively (P < 0.05). After 22 weeks of testosterone, the expression of FGF2 increased, whereas that of myogenic regulatory factor (MRF)4 and myostatin decreased significantly. There was no change in expression of FGFR2, myogenin, or myogenic differentiation protein in the skeletal muscle. Plasma FGF2 and IGF-1 concentrations increased after testosterone therapy.

CONCLUSIONS

These data show that testosterone is a major modulator of FGF2, MRF4, and myostatin expression in skeletal muscle. These effects may contribute to the increase in muscle mass after testosterone therapy.