Role of growth differentiation factor 11 in development, physiology and disease

Novel insights into the pleiotropic health effects of growth differentiation factor 11 gained from genome-wide association studies in population biobanks

BACKGROUND

Growth differentiation factor 11 (GDF11) is a member of the transforming growth factor-β (TGF-β) superfamily that has gained considerable attention over the last decade for its observed ability to reverse age-related deterioration of multiple tissues, including the heart. Yet as many researchers have struggled to confirm the cardioprotective and anti-aging effects of GDF11, the topic has grown increasingly controversial, and the field has reached an impasse. We postulated that a clearer understanding of GDF11 could be gained by investigating its health effects at the population level.

METHODS AND RESULTS

We employed a comprehensive strategy to interrogate results from genome-wide association studies in population Biobanks. Interestingly, phenome-wide association studies (PheWAS) of GDF11 tissue-specific cis-eQTLs revealed associations with asthma, immune function, lung function, and thyroid phenotypes. Furthermore, PheWAS of GDF11 genetic variants confirmed these results, revealing similar associations with asthma, immune function, lung function, and thyroid health. To complement these findings, we mined results from transcriptome-wide association studies, which uncovered associations between predicted tissue-specific GDF11 expression and the same health effects identified from PheWAS analyses.

CONCLUSIONS

In this study, we report novel relationships between GDF11 and disease, namely asthma and hypothyroidism, in contrast to its formerly assumed role as a rejuvenating factor in basic aging and cardiovascular health. We propose that these associations are mediated through the involvement of GDF11 in inflammatory signaling pathways. Taken together, these findings provide new insights into the health effects of GDF11 at the population level and warrant future studies investigating the role of GDF11 in these specific health conditions.

Gene regulatory roles of growth and differentiation factors in retinal development

Retinal ganglion cell (RGC) differentiation is tightly controlled by extrinsic and intrinsic factors. Growth and differentiation factor 15 (GDF-15) promotes RGC differentiation, opposite to GDF-11 which inhibits RGC differentiation, both in the mouse retina and in human stem cells. To deepen our understanding of how these two closely related molecules confer opposing effects on retinal development, here we assess the transcriptional profiles of mouse retinal progenitors exposed to exogenous GDF-11 or -15. We find a dichotomous effect of GDF-15 on RGC differentiation, decreasing RGCs expressing residual pro-proliferative genes and increasing RGCs expressing non-proliferative genes, suggestive of greater RGC maturation. Furthermore, GDF-11 promoted the differentiation of photoreceptors and amacrine cells. These data enhance our understanding of the mechanisms underlying the differentiation of RGCs and photoreceptors from retinal progenitors and suggest new approaches to the optimization of protocols for the differentiation of these cell types.

Growth differentiation factor-11 upregulates matrix metalloproteinase 2 expression by inducing Snail in human extravillous trophoblast cells

The human extravillous trophoblast (EVT) cell invasion is an important process during placentation. Although the placenta is normal tissue, the EVT cells exhibit some features common to cancer cells, including high migratory and invasive properties. Snail and Slug are transcription factors that mediate the epithelial-mesenchymal transition (EMT), a crucial event for cancer cell migration and invasion. It has been shown that GDF-11-induced matrix metalloproteinase 2 (MMP2) expression is required for EVT cell invasion. Whether GDF-11 can regulate Snail and Slug expression in human EVT cells remains unknown. If it does, the involvement of Snail and Slug in GDF-11-induced MMP2 expression and EVT cell invasion must also be defined. In the present study, using the immortalized human EVT cell line, HTR-8/SVneo, and primary cultures of human EVT cells as experimental models, our results show that GDF-11 upregulates Snail and Slug expression. ALK4 and ALK5 mediate the stimulatory effects of GDF-11 on Snail and Slug expression. In addition, we demonstrate that SMAD2 and SMAD3 are required for the GDF-11-upregulated Snail expression, while only SMAD3 is involved in GDF-11-induced Slug expression. Moreover, our results reveal that Snail mediates GDF-11-induced MMP2 expression and cell invasion but not Slug. This study increases our understanding of the biological function of GDF-11 in human EVT cells and provides a novel mechanism for regulating MMP2 and EVT cell invasion.

GDF11 level and its effect on prognosis in patients with acute myeloid leukemia

Acute myeloid leukemia (AML) is a hematologic malignancy characterized by the proliferation of CD34 positive self-renewing malignant hematopoietic stem cells. Previous studies have shown that the transforming growth factor beta (TGFβ) pathway plays a role in AML pathogenesis, especially by affecting the microenvironment. Growth differentiation factor 11 (GDF11) is a member of the TGFβ superfamily, involved in embryological development and known as rejuvenating factor. In this study, our aim was to determine the serum GDF11 level in patients with AML, to compare it with the control group, to determine its relationship with follistatin, vimentin, and E-cadherin levels, and to determine whether GDF11 influences AML prognosis. Serum GDF11, vimentin, follistatin, and E-cadherin levels of newly diagnosed or relapsed/refractory AML patients and age- and gender-matched control group were measured by enzyme-linked immunosorbent assay. Serum GDF11 level was higher in the patient group (263.87 ± 126.54 ng/L) compared to the control group (211.54 ± 61.47 ng/L; p = 0.035). GDF11 level did not change according to age, gender, hemoglobin level, and bone marrow blast rate. No correlation was found between GDF11 level, response rates, and survival status of the patients. A positive correlation was detected between GDF11, E-cadherin, and vimentin levels. As a conclusion, increased serum GDF11 levels in AML patients may be linked to the regeneration ability of leukemic stem cells. There is a need for studies investigating GDF11 expression in myeloblasts.

GDF11: An emerging therapeutic target for liver diseases and fibrosis

Growth differentiation factor 11 (GDF11), also known as bone morphogenetic protein 11 (BMP11), has been identified as a key player in various biological processes, including embryonic development, aging, metabolic disorders and cancers. GDF11 has also emerged as a critical component in liver development, injury and fibrosis. However, the effects of GDF11 on liver physiology and pathology have been a subject of debate among researchers due to conflicting reported outcomes. While some studies suggest that GDF11 has anti-aging properties, others have documented its senescence-inducing effects. Similarly, while GDF11 has been implicated in exacerbating liver injury, it has also been shown to have the potential to reduce liver fibrosis. In this narrative review, we present a comprehensive report of recent evidence elucidating the diverse roles of GDF11 in liver development, hepatic injury, regeneration and associated diseases such as non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), liver fibrosis and hepatocellular carcinoma. We also explore the therapeutic potential of GDF11 in managing various liver pathologies.

Tissue Expression of Growth Differentiation Factor 11 in Patients with Breast Cancer

Protein growth differentiation factor 11 (GDF11) plays crucial roles in cellular processes, including differentiation and development; however, its clinical relevance in breast cancer patients is poorly understood. We enrolled 68 breast cancer patients who underwent surgery at our hospital and assessed the expression of GDF11 in tumorous, ductal carcinoma in situ (DCIS), and non-tumorous tissues using immunohistochemical staining, with interpretation based on histochemical scoring (H-score). Our results indicated higher GDF11 expressions in DCIS and normal tissues compared to tumorous tissues. In addition, the GDF11 H-score was lower in the patients with a tumor size ≥ 2 cm, pathologic T3 + T4 stages, AJCC III-IV stages, Ki67 ≥ 14% status, HER2-negative, and specific molecular tumor subtypes. Notably, the patients with triple-negative breast cancer exhibited a loss of GDF11 expression. Spearman correlation analysis revealed associations between GDF11 expression and various clinicopathological characteristics, including tumor size, stage, Ki67, and molecular subtypes. Furthermore, GDF11 expression was positively correlated with mean corpuscular hemoglobin concentration and negatively correlated with neutrophil count, as well as standard deviation and coefficient of variation of red cell distribution width. These findings suggest that a decreased GDF11 expression may play a role in breast cancer pathogenesis.

Roles of bone morphogenetic proteins in endometrial remodeling during the human menstrual cycle and pregnancy

BACKGROUND

During the human menstrual cycle and pregnancy, the endometrium undergoes a series of dynamic remodeling processes to adapt to physiological changes. Insufficient endometrial remodeling, characterized by inadequate endometrial proliferation, decidualization and spiral artery remodeling, is associated with infertility, endometriosis, dysfunctional uterine bleeding, and pregnancy-related complications such as preeclampsia and miscarriage. Bone morphogenetic proteins (BMPs), a subset of the transforming growth factor-β (TGF-β) superfamily, are multifunctional cytokines that regulate diverse cellular activities, such as differentiation, proliferation, apoptosis, and extracellular matrix synthesis, are now understood as integral to multiple reproductive processes in women. Investigations using human biological samples have shown that BMPs are essential for regulating human endometrial remodeling processes, including endometrial proliferation and decidualization.

OBJECTIVE AND RATIONALE

This review summarizes our current knowledge on the known pathophysiological roles of BMPs and their underlying molecular mechanisms in regulating human endometrial proliferation and decidualization, with the goal of promoting the development of innovative strategies for diagnosing, treating and preventing infertility and adverse pregnancy complications associated with dysregulated human endometrial remodeling.

SEARCH METHODS

A literature search for original articles published up to June 2023 was conducted in the PubMed, MEDLINE, and Google Scholar databases, identifying studies on the roles of BMPs in endometrial remodeling during the human menstrual cycle and pregnancy. Articles identified were restricted to English language full-text papers.

OUTCOMES

BMP ligands and receptors and their transduction molecules are expressed in the endometrium and at the maternal-fetal interface. Along with emerging technologies such as tissue microarrays, 3D organoid cultures and advanced single-cell transcriptomics, and given the clinical availability of recombinant human proteins and ongoing pharmaceutical development, it is now clear that BMPs exert multiple roles in regulating human endometrial remodeling and that these biomolecules (and their receptors) can be targeted for diagnostic and therapeutic purposes. Moreover, dysregulation of these ligands, their receptors, or signaling determinants can impact endometrial remodeling, contributing to infertility or pregnancy-related complications (e.g. preeclampsia and miscarriage).

WIDER IMPLICATIONS

Although further clinical trials are needed, recent advancements in the development of recombinant BMP ligands, synthetic BMP inhibitors, receptor antagonists, BMP ligand sequestration tools, and gene therapies have underscored the BMPs as candidate diagnostic biomarkers and positioned the BMP signaling pathway as a promising therapeutic target for addressing infertility and pregnancy complications related to dysregulated human endometrial remodeling.

Silencing of GDF11 suppresses hepatocyte apoptosis to relieve LPS/D-GalN acute liver failure

In this paper, we generated a short hairpin RNA growth differentiation factor-11 (sh-GDF11) and evaluated the effects of sh-GDF11 on the pathogenesis of acute liver failure (ALF) in vitro and in vivo. Through bioinformatics study, the key gene related to ALF was assayed. Lipopolysaccharide (LPS) and D-galactoamine (D-GalN) were applied to establish the mouse model of LPS/D-GalN-induced liver injury, and TNF-α and D-Gal were used to construct an in vitro cell model, followed by treatment of sh-GDF11 for analysis of liver cell proliferation. Bioinformatics analysis showed that the protective effect of sh-GDF11 on ALF may be mediated by phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathway. The results of in vitro study found that sh-GDF11 could promote cell proliferation and inhibit death by blocking the PI3K/Akt/mTOR signaling pathway. In vivo animal experiments further confirmed that sh-GDF11 could suppress hepatocyte apoptosis by inhibiting the PI3K/Akt/mTOR signaling pathway. sh-GDF11 relieved LPS/D-GalN-induced ALF by blocking the PI3K/Akt/mTOR signaling pathway, emphasizing its critical role in LPS/D-GalN-induced ALF treatment.

The regulatory effect of growth differentiation factor 11 on different cells

Growth differentiation factor 11 (GDF11) is one of the important factors in the pathophysiological process of animals. It is widely expressed in many tissues and organs of animals, showing its wide biological activity and potential application value. Previous research has demonstrated that GDF11 has a therapeutic effect on various diseases, such as anti-myocardial aging and anti-tumor. This has not only sparked intense interest and enthusiasm among academics but also spurred some for-profit businesses to attempt to develop GDF11 as a medication for regenerative medicine or anti-aging application. Currently, Sotatercept, a GDF11 antibody drug, is in the marketing application stage, and HS-235 and rGDF11 are in the preclinical research stage. Therefore, we believe that figuring out which cells GDF11 acts on and its current problems should be an important issue in the scientific and commercial communities. Only through extensive, comprehensive research and discussion can we better understand the role and potential of GDF11, while avoiding unnecessary risks and misinformation. In this review, we aimed to summarize the role of GDF11 in different cells and its current controversies and challenges, providing an important reference for us to deeply understand the function of GDF11 and formulate more effective treatment strategies in the future.

Relationships of GDF8 and 11 and Their Antagonists With Decline of Grip Strength Among Older Adults in the Baltimore Longitudinal Study of Aging

Although growth/differentiation factor 11 (GDF11), growth/differentiation factor 8 (GDF8), and their circulating antagonists, which include GDF11 and GDF8 propeptides, follistatin (FST), WAP, Follistatin/Kazal, Immunoglobulin, Kunitz And Netrin Domain Containing (WFIKKN)1, and WFIKKN2, have been shown to influence skeletal muscle and aging in mice, the relationship of these circulating factors with human phenotypes is less clear. This study aimed to characterize the relationship between plasma GDF8, GDF11, FST, WFIKKN1, and WFIKKN2 concentrations with the decline of grip strength in 534 adults, ≥65 years, who participated in the Baltimore Longitudinal Study of Aging and had grip strength measured over time. Plasma GDF8 and GDF11 mature proteins, GDF8 and GDF11 propeptides, FST (isoform FST315 and cleaved form FST303), WFIKKN1, and WFIKKN2 concentrations were measured using selected reaction monitoring-tandem mass spectrometry at baseline. Grip strength was measured at baseline and at follow-up visits (median follow-up 8.87 years). Mean (standard deviation) grip strength declined in men and women by -0.84 (2.45) and -0.60 (1.32) kg/year, respectively. Plasma GDF8 and GDF11 mature proteins, GDF8 and GDF11 propeptides, FST315, FST303, WFIKKN1, and WFIKKN2 concentrations were not independently predictive of the decline of grip strength in men or women in multivariable linear regression analyses that adjusted for potential confounders. In conclusion, circulating GDF8, GDF11, and their antagonists do not appear to influence the decline of grip strength in older men or women.

Effect of growth differentiation factor 11 expression after peripheral nerve injury in Sprague-Dawley rats

OBJECTIVES

We attempt to investigate the expression pattern of GDF11 in the sciatic nerves after injury.

METHODS

Thirty-six healthy male Sprague Dawley (SD) rats were divided into three groups at random and were labelled as: day 1, day 4, and day 7 post-surgery. The sciatic nerve crush model was established on the left-hind limb, while the right limb was untreated, and served as the control. Nerve samples were collected at post-injury day 1, day 4 and day 7. Nerve samples collected from the proximal and distal stump of the injury site underwent immunofluorescence staining with GDF11, NF200 and CD31. GDF11 mRNA expression was analyzed by qRT-PCR. CCK-8 assay, after si-GDF11 transfection in Schwann cells (RSC96) was applied to verify its effect in cell proliferation rate.

RESULTS

GDF11 was abundantly expressed in axons stained with NF200 and Schwann cells stained with S100. However, no GDF11 expression was observed in vascular endothelial tissues stained with CD31. From day 4 onwards, the level of GDF11 showed an increasing trend, up to a twofold level at day 7 after injury. Proliferation rate of RSC96 cells showed a significant decrease after the down-regulation of GDF11 by siRNAs compared to the control group.

CONCLUSIONS

GDF11 may play a role in the proliferation of Schwann cell during nerve regeneration process.

GDF11 as a friend or an enemy in the cancer biology?

The Growth and Differential Factor 11 (GDF11) is a recently discovered representative of Transforming Growth Factor β superfamily. The highest expression of GDF11 is detected in the nervous system, bladder, seminal vesicles and muscles whereas the lowest in the testis, liver or breast. GDF11 role in physiology is still not clear. GDF11 is a crucial factor in embryogenesis, cell cycle control and apoptosis, inasmuch it mainly targets cell retain stemness features, managing to the cell differentiation and the maturation. GDF11 is entangled in lipid metabolism, inflammatory processes and aging. GDF11 is strongly related to carcinogenesis and its expression in tumors is intruded. GDF11 can promote cancer growth in the colon or inhibit the cell proliferation in breast cancer. The aberrated expression is probably allied with the impaired maturation. In this article we summarized an impact of GDF11 on the tumor cells and review the all attitudes connecting GDF11 with carcinogenesis.

GDF-11 downregulates placental human chorionic gonadotropin expression by activating SMAD2/3 signaling

BACKGROUND

The production of human chorionic gonadotropin (hCG) by the placental trophoblast cells is essential for maintaining a normal pregnancy. Aberrant hCG levels are associated with reproductive disorders. The protein of hCG is a dimer consisting of an α subunit and a β subunit. The β subunit is encoded by the CGB gene and is unique to hCG. Growth differentiation factor-11 (GDF-11), a member of the transforming growth factor-β (TGF-β) superfamily, is expressed in the human placenta and can stimulate trophoblast cell invasion. However, whether the expression of CGB and the production of hCG are regulated by GDF-11 remains undetermined.

METHODS

Two human choriocarcinoma cell lines, BeWo and JEG-3, and primary cultures of human cytotrophoblast (CTB) cells were used as experimental models. The effects of GDF-11 on CGB expression and hCG production, as well as the underlying mechanisms, were explored by a series of in vitro experiments.

RESULTS

Our results show that treatment of GDF-11 downregulates the expression of CGB and the production of hCG in both BeWo and JEG-3 cells as well as in primary CTB cells. Using a pharmacological inhibitor and siRNA-mediated approach, we reveal that both ALK4 and ALK5 are required for the GDF-11-induced downregulation of CGB expression. In addition, treatment of GDF-11 activates SMAD2/3 but not SMAD1/5/8 signaling pathways. Moreover, both SMAD2 and SMAD3 are involved in the GDF-11-downregulated CGB expression. ELISA results show that the GDF-11-suppressed hCG production requires the ALK4/5-mediated activation of SMAD2/3 signaling pathways.

CONCLUSIONS

This study not only discovers the biological function of GDF-11 in the human placenta but also provides important insights into the regulation of the expression of hCG. Video Abstract.

In vivo modulation of endogenous gene expression via CRISPR/Cas9-mediated 3'UTR editing

The 3' untranslated regions (UTRs) modulate gene expression levels by regulating mRNA stability and translation. We previously showed that the replacement of the negative regulatory elements from the 3'UTR of glial cell line-derived neurotrophic factor (GDNF) resulted in increased endogenous GDNF expression while retaining its normal spatiotemporal expression pattern. Here, we have developed a methodology for the generation of in vivo hyper- and hypomorphic alleles via 3'UTR targeting using the CRISPR/Cas9 system. We demonstrate that CRISPR/Cas9-mediated excision of a long inhibitory sequence from Gdnf native 3'UTR in mouse zygotes increases the levels of endogenous GDNF with similar phenotypic alterations in embryonic kidney development as we described in GDNF constitutive and conditional hypermorphic mice. Furthermore, we show that CRISPR/Cas9-mediated targeting of 3'UTRs in vivo allows the modulation of the expression levels of two other morphogens, Gdf11 and Bdnf. Together, our work demonstrates the power of in vivo 3'UTR editing using the CRISPR/Cas9 system to create hyper- and hypomorphic alleles, suggesting wide applicability in studies on gene function and potentially, in gene therapy.

GDF11 inhibits adipogenesis of human adipose-derived stromal cells through ALK5/KLF15/β-catenin/PPARγ cascade

Obesity is a metabolic disease characterized by excessive fat storage, and the adipogenic differentiation of adipose-derived stromal cells (ADSCs) is closely linked to its occurrence. Growth differentiation factor 11 (GDF11), a well-known molecule in the field of anti-aging, also has great potential in regulating stem cell differentiation. In this study, we found that GDF11 inhibited adipogenic differentiation of human ADSCs in vitro by activating the WNT/β-catenin and SMAD2/3 pathways while inhibiting the AKT pathway. Moreover, the transcription factor Kruppel-like factor 15 (KLF15) was discovered to be an important downstream factor for GDF11 in inhibiting adipogenesis via the WNT/β-catenin pathway. Furthermore, AlphaFold2 structure prediction and inhibitor-blocking experiments revealed that ALK5 is a functional receptor of GDF11. Collectively, we demonstrated that GDF11 is a potential target for inhibiting adipogenic differentiation and combating obesity.

The hepatic effects of GDF11 on health and disease

The growth differentiation factor 11 (GDF11), a member of the superfamily of the transforming growth factor β, has gained relevance in the last few years due to its remarkable effects in cellular biology, particularly in the nervous system, skeletal muscle, the heart, and many epithelial tissues. Some controversies have been raised about this growth factor. Many of them have been related to technical factors but also the nature of the cellular target. In liver biology and pathobiology, the GDF11 has shown to be related in many molecular aspects, with a significant impact on the physiology and the initiation and progression of the natural history of liver diseases. GDF11 has been involved as a critical regulator in lipid homeostasis, which, as it is well known, is the first step in the progression of liver disease. However, also it has been reported that the GDF11 is involved in fibrosis, senescence, and cancer. Although there are some controversies, much of the literature indicates that GDF11 displays effects tending to solve or mitigate pathological states of the liver, with reasonable evidence of correlation with other organs or systems. To a large extent, the controversy, as mentioned, is due to technical problems, such as the specificity of GDF11 antibodies, confusion with its closer family member, myostatin, and the state of differentiation in the tissues. In the present work, we reviewed the specific effects of GDF11 in the biology and pathobiology of the liver as a potential and promising factor for therapeutic intervention shortly.

Erythropoiesis in lower-risk myelodysplastic syndromes and beta-thalassemia

The hematologic disorders myelodysplastic syndromes and beta-thalassemia are characterized by ineffective erythropoiesis and anemia, often managed with regular blood transfusions. Erythropoiesis, the process by which sufficient numbers of functional erythrocytes are produced from hematopoietic stem cells, is highly regulated, and defects can negatively affect the proliferation, differentiation, and survival of erythroid precursors. Treatments that directly target the underlying mechanisms of ineffective erythropoiesis are limited, and management of anemia with regular blood transfusions imposes a significant burden on patients, caregivers, and health care systems. There is therefore a strong unmet need for treatments that can restore effective erythropoiesis. Novel therapies are beginning to address this need by targeting a variety of mechanisms underlying erythropoiesis. Herein, we provide an overview of the role of ineffective erythropoiesis in myelodysplastic syndromes and beta-thalassemia, discuss unmet needs in targeting ineffective erythropoiesis, and describe current management strategies and emerging treatments for these disorders.

GDF11 Is a Novel Protective Factor Against Vascular Calcification

ABSTRACT

Vascular calcification (VC) occurs via an active cell-mediated process, which involves osteogenic differentiation, apoptosis, and phenotypic transformation of vascular smooth muscle cells (VSMCs). As a member of the transforming growth factor-β family, growth differentiation factor 11 (GDF11) can inhibit apoptosis and osteogenic differentiation and maintain the stability of atherosclerotic plaques. In this study, coronary artery calcium score (CACS) of participants with GDF11 measurements was measured using computed tomography angiography and was scored according to the Agatston score. β-glycerophosphate (10 mM), dexamethasone (100 nM), and l -ascorbic acid (50 µg/mL) [osteogenic medium (OM)] were used to induce calcification of human aortic smooth muscle cells. We found that CACS was negatively correlated with serum GDF11 levels in patients and GDF11 was a strong predictor of elevated CACS (OR = 0.967, 95% CI: 0.945-0.991; P = 0.006), followed by age (OR = 1.151, 95% CI: 1.029-1.286; P = 0.014), triglycerides (OR = 4.743, 95% CI: 1.170-19.236; P = 0.029), C-reactive protein (OR = 1.230, 95% CI: 1.010-1.498; P = 0.04), and hypertension (OR = 7.264, 95% CI: 1.099-48.002; P = 0.04). Furthermore, exogenous GDF11 inhibited OM-induced calcification by inhibiting osteogenic differentiation, the phenotypic transformation and apoptosis of human aortic smooth muscle cells. Our study demonstrates that GDF11 plays a crucial role in reducing vascular calcification and serves as a potential intervention target to vascular calcification.

Twisted Fiber Optic SPR Sensor for GDF11 Concentration Detection

There are few methods and insufficient accuracy for growth differentiation factor 11 (GDF11) concentration detection. In this paper, we designed a twisted fiber cladding surface plasmon resonance (SPR) sensor, which can achieve a high precision detection of GDF11 concentration. The new structure of the fiber cladding SPR sensor was realized by coupling the light in the fiber core to the cladding through fiber thermal fusion twisting micromachining technology; a series of functionalized modifications were made to the sensor surface to obtain a fiber sensor capable of GDF11 specific recognition. The experimental results showed when GDF11 antigen concentration was 1 pg/mL-10 ng/mL, the sensor had a detection sensitivity of 2.518 nm/lgC, a detection limit of 0.34 pg/mL, and a good log-linear relationship. The sensor is expected to play a role in the rapid and accurate concentration detection of pathological study for growth differentiation factors.

GDF11 inhibits adipogenesis and improves mature adipocytes metabolic function via WNT/β-catenin and ALK5/SMAD2/3 pathways

Objective

GDF11 is a member of the TGF‐β superfamily that was recently implicated as potential “rejuvenating” factor, which can ameliorate metabolic disorders. The main objective of the presented study was to closely characterize the role of GDF11 signaling in the glucose homeostasis and in the differentiation of white adipose tissue.

Methods

We performed microscopy imaging, biochemical and transcriptomic analyses of adipose tissues of 9 weeks old ob/ob mice and murine and human pre‐adipocyte cell lines.

Results

Our in vivo experiments employing GDF11 treatment in ob/ob mice showed improved glucose/insulin homeostasis, decreased weight gain and white adipocyte size. Furthermore, GDF11 treatment inhibited adipogenesis in pre‐adipocytes by ALK5‐SMAD2/3 activation in cooperation with the WNT/β‐catenin pathway, whose inhibition resulted in adipogenic differentiation. Lastly, we observed significantly elevated levels of the adipokine hormone adiponectin and increased glucose uptake by mature adipocytes upon GDF11 exposure.

Conclusion

We show evidence that link GDF11 to adipogenic differentiation, glucose, and insulin homeostasis, which are pointing towards potential beneficial effects of GDF11‐based “anti‐obesity” therapy.

ADSCs Promote Tenocyte Proliferation by Reducing the Methylation Level of lncRNA Morf4l1 in Tendon Injury

Objective: Tendons are the special connective tissue that connects bones to muscles and governs joint movement in response to loads passed by muscles. The healing of tendon injuries is still a challenge. In recent years, adipose-derived mesenchymal stem cells (ADSCs) have been increasingly used for tissue regeneration, but the underlying mechanism of tendon injury still remains unclear.

Methods: High-throughput sequencing was used to identify a novel lncRNA, whose expression was significantly decreased in injured tendon compared with normal tendon. Furthermore, pyrosequencing, nuclear-cytoplasmic separation, FISH assay and qRT-PCR analysis were used to verify the level of lncRNA methylation in the injured tenocytes. lncRNA was confirmed to promote the proliferation of tenocytes by flow cytometry, wound healing assay, qRT-PCR, and western blot, and the target gene of lncRNA was predicted and verified. To confirm that ADSCs could repair injured tendons, ADSCs and injured tenocytes were co-cultured in vitro, and ADSCs were injected into injured tendons in vitro, respectively.

Results: The lncRNA Morf4l1 promoter methylation in injured tendons led to down-regulation of its expression and inhibition of tenocyte proliferation. LncRNA Morf4l1 promoted the expression of TGF-β2 by targeting 3′U of miR-145-5p. After co-cultured ADSCs and injured tenocytes, the expression of lncRNA Morf4l1 was up-regulated, and the proliferation of injured tenocytes in vitro was promoted. The ADSCs were injected into the injured tendon to repair the injured tendon in vivo.

Conclusion: This study confirmed that ADSCs promoted tendon wound healing by reducing the methylation level of lncRNA Morf4l1.

Pathophysiology and Emerging Molecular Therapeutic Targets in Heterotopic Ossification

The term heterotopic ossification (HO) describes bone formation in tissues where bone is normally not present. Musculoskeletal trauma induces signalling events that in turn trigger cells, probably of mesenchymal origin, to differentiate into bone. The aetiology of HO includes extremely rare but severe, generalised and fatal monogenic forms of the disease; and as a common complex disorder in response to musculoskeletal, neurological or burn trauma. The resulting bone forms through a combination of endochondral and intramembranous ossification, depending on the aetiology, initiating stimulus and affected tissue. Given the heterogeneity of the disease, many cell types and biological pathways have been studied in efforts to find effective therapeutic strategies for the disorder. Cells of mesenchymal, haematopoietic and neuroectodermal lineages have all been implicated in the pathogenesis of HO, and the emerging dominant signalling pathways are thought to occur through the bone morphogenetic proteins (BMP), mammalian target of rapamycin (mTOR), and retinoic acid receptor pathways. Increased understanding of these disease mechanisms has resulted in the emergence of several novel investigational therapeutic avenues, including palovarotene and other retinoic acid receptor agonists and activin A inhibitors that target both canonical and non-canonical signalling downstream of the BMP type 1 receptor. In this article we aim to illustrate the key cellular and molecular mechanisms involved in the pathogenesis of HO and outline recent advances in emerging molecular therapies to treat and prevent HO that have had early success in the monogenic disease and are currently being explored in the common complex forms of HO.

GDF-11 promotes human trophoblast cell invasion by increasing ID2-mediated MMP2 expression

BACKGROUND

Growth differentiation factor-11 (GDF-11), also known as bone morphogenetic protein-11, belongs to the transforming growth factor-beta superfamily. GDF-11 was first identified as an important regulator during embryonic development. Increasing evidence has demonstrated that GDF-11 regulates the development of various organs and its aberrant expressions are associated with the risk of cardiovascular diseases and cancers. Extravillous trophoblast (EVT) cells invasion is a critical event for placenta development and needs to be finely regulated. However, to date, the biological function of GDF-11 in the human EVT cells remains unknown.

METHODS

HTR-8/SVneo, a human EVT cell line, and primary cultures of human EVT cells were used to examine the effect of GDF-11 on matrix metalloproteinase 2 (MMP2) expression. Matrigel-coated transwell invasion assay was used to examine cell invasiveness. A series of in vitro experiments were applied to explore the underlying mechanisms that mediate the effect of GDF-11 on MMP2 expression and cell invasion.

RESULTS

Treatment with GDF-11 stimulates MMP2 expression, in the HTR-8/SVneo and primary human EVT cells. Using a pharmacological inhibitor and siRNA-mediated knockdown approaches, our results demonstrated that the stimulatory effect of GDF-11 on MMP2 expression was mediated by the ALK4/5-SMAD2/3 signaling pathways. In addition, the expression of inhibitor of DNA-binding protein 2 (ID2) was upregulated by GDF-11 and that was required for the GDF-11-stimulated MMP2 expression and EVT cell invasion.

CONCLUSIONS

These findings discover a new biological function and underlying molecular mechanisms of GDF-11 in the regulation of human EVT cell invasion. Video Abstract.

The emerging translational potential of GDF11 in chronic wound healing

Chronic skin wounds impose immense suffers and economic burdens. Current research mainly focuses on acute wound management which exhibits less effective in chronic wound healing. Growth differentiation factor 11 (GDF11) has profound effects on several important physiological processes related to chronic wound healing, such as inflammation, cell proliferation, migration, angiogenesis, and neurogenesis. This review summarizes recent advances in biology of chronic wounds and the potential role of GDF11 on wound healing with its regenerative effects, as well as the potential delivery methods of GDF11. The challenges and future perspectives of GDF11-based therapy for chronic wound care are also discussed.

The Translational Potential of this Article: This review summarized the significance of GDF11 in the modulation of inflammation, vascularization, cell proliferation, and remodeling, which are important physiological processes of chronic wound healing. The potential delivery methods of GDF11 in the management of chronic wound healing is also summarized. This review may provide potential therapeutic approaches based on GDF11 for chronic wound healing.

GDF11 enhances therapeutic functions of mesenchymal stem cells for angiogenesis

BACKGROUND

The efficacy of stem cell therapy for ischemia repair has been limited by low cell retention rate. Growth differentiation factor 11 (GDF11) is a member of the transforming growth factor-β super family, which has multiple effects on development, physiology and diseases. The objective of the study is to investigate whether GDF11 could affect the efficacy of stem cell transplantation.

METHODS

We explored the effects of GDF11 on proangiogenic activities of mesenchymal stem cells (MSCs) for angiogenic therapy in vitro and in vivo.

RESULTS

Mouse bone marrow-derived MSCs were transduced with lentiviral vector to overexpress GDF11 (MSC^GDF11). After exposed to hypoxia and serum deprivation for 48 h, MSC^GDF11 were significantly better in viability than control MSCs (MSC^vector). MSC^GDF11 also had higher mobility and better angiogenic paracrine effects. The cytokine antibody array showed more angiogenic cytokines in the conditioned medium of MSC^GDF11 than that of MSC^vector, such as epidermal growth factor, platelet-derived growth factor-BB, placenta growth factor. When MSCs (1 × 10⁶ cells in 50 μl) were injected into ischemic hindlimb of mice after femoral artery ligation, MSC^GDF11 had higher retention rate in the muscle than control MSCs. Injection of MSC^GDF11 resulted in better blood reperfusion and limb salvage than that of control MSCs after 14 days. Significantly more CD31⁺ endothelial cells and α-SMA + smooth muscle cells were detected in the ischemic muscles that received MSC^GDF11. The effects of GDF11 were through activating TGF-β receptor and PI3K/Akt signaling pathway.

CONCLUSION

Our study demonstrated an essential role of GDF11 in promoting therapeutic functions of MSCs for ischemic diseases by enhancing MSC viability, mobility, and angiogenic paracrine functions.

Growth differentiation factor 11 attenuates cardiac ischemia reperfusion injury via enhancing mitochondrial biogenesis and telomerase activity

It has been reported that growth differentiation factor 11 (GDF11) protects against myocardial ischemia/reperfusion (IR) injury, but the underlying mechanisms have not been fully clarified. Considering that GDF11 plays a role in the aging/rejuvenation process and that aging is associated with telomere shortening and cardiac dysfunction, we hypothesized that GDF11 might protect against IR injury by activating telomerase. Human plasma GDF11 levels were significantly lower in acute coronary syndrome patients than in chronic coronary syndrome patients. IR mice with myocardial overexpression GDF11 (oe-GDF11) exhibited a significantly smaller myocardial infarct size, less cardiac remodeling and dysfunction, fewer apoptotic cardiomyocytes, higher telomerase activity, longer telomeres, and higher ATP generation than IR mice treated with an adenovirus carrying a negative control plasmid. Furthermore, mitochondrial biogenesis-related proteins and some antiapoptotic proteins were significantly upregulated by oe-GDF11. These cardioprotective effects of oe-GDF11 were significantly antagonized by BIBR1532, a specific telomerase inhibitor. Similar effects of oe-GDF11 on apoptosis and mitochondrial energy biogenesis were observed in cultured neonatal rat cardiomyocytes, whereas GDF11 silencing elicited the opposite effects to oe-GDF11 in mice. We concluded that telomerase activation by GDF11 contributes to the alleviation of myocardial IR injury through enhancing mitochondrial biogenesis and suppressing cardiomyocyte apoptosis.

Reduced leukocyte telomere lengths and sirtuin 1 gene expression in long-term survivors of type 1 diabetes: A Dialong substudy

AIMS/INTRODUCTION

The shortening of leukocyte telomere length with age has been associated with coronary disease, whereas the association with type 1 diabetes is unclear. We aimed to explore telomere lengths in diabetes patients with regard to coronary artery disease, compared with healthy controls. The longevity factors sirtuin 1 and growth-differentiating factor 11 were investigated accordingly.

MATERIALS AND METHODS

We carried out a cross-sectional study of 102 participants with long-term type 1 diabetes and 75 controls (mean age 62 and 63 years, respectively), where 88 cases and 60 controls without diagnosed coronary artery disease completed computed tomography coronary angiography. Telomere lengths and gene expression of sirtuin 1 and growth-differentiating factor 11 were quantified in leukocytes.

RESULTS

Telomere lengths and sirtuin 1 were reduced in diabetes patients versus controls, medians (25th to 75th percentiles): 0.97 (0.82-1.15) versus 1.08 (0.85-1.29) and 0.88 (0.65-1.14) vs 1.01 (0.78-1.36), respectively, adjusted P < 0.05, both. Previous coronary artery disease in diabetes patients (n = 15) was associated with lower sirtuin 1 and growth-differentiating factor 11 messenger ribonucleic acid expression (adjusted P < 0.03, both). In the combined diabetes and control group, previous artery coronary disease (n = 18) presented with significantly shorter telomeres (adjusted P = 0.038). Newly diagnosed obstructive coronary artery disease, defined as >50% stenosis, was not associated with the investigated variables.

CONCLUSIONS

Long-term type 1 diabetes presented with reduced telomeres and sirtuin 1 expression, with additional reduction in diabetes patients with previous coronary artery disease, showing their importance for cardiovascular disease development with potential as novel biomarkers in diabetes and coronary artery disease.

GDF11 rapidly increases lipid accumulation in liver cancer cells through ALK5-dependent signaling

Hepatocellular carcinoma (HCC) is one of the fastest-growing causes of cancer-related mortalities worldwide and this trend is mimicked by the surge of non-alcoholic fatty liver disease (NAFLD). Altered hepatic lipid metabolism promotes HCC development through inflammation and activation of oncogenes. GDF11 is a member of the TGF-β superfamily and recent data have implicated GDF11 as an anti-aging factor that can alleviate high-fat diet induced obesity, hyperglycemia, insulin resistance and NAFLD. However, its role in hepatic lipid metabolism is still not fully delineated. The aim of the present study was to characterize the role of GDF11 in hepatic and HCC cells lipid accumulation. To achieve this, we performed imaging, biochemical, lipidomic, and transcriptomic analyses in primary hepatocytes and in HCC cells treated with GDF11 to study the GDF11-activated signaling pathways. GDF11 treatment rapidly triggered ALK5-dependent SMAD2/3 nuclear translocation and elevated lipid droplets in HCC cells, but not in primary hepatocytes. In HCC cells, ALK5 inhibition hampered GDF11-mediated SMAD2/3 signaling and attenuated lipid accumulation. Using ultra-high-performance liquid chromatography/mass spectrometry, we detected increased accumulation of longer acyl-chain di/tri-acylglycerols and glycerophospholipids. Unbiased transcriptomic analysis identified TGF-β and PI3K-AKT signaling among the top pathways/cellular processes activated in GDF11 treated HCC cells. In summary, GDF11 supplementation promotes pro-lipogenic gene expression and lipid accumulation in HCC cells. Integration of our "omics" data pointed to a GDF11-induced upregulation of de novo lipogenesis through activation of ALK5/SMAD2/3/PI3K-AKT pathways. Thus, GDF11 could contribute to metabolic reprogramming and dysregulation of lipid metabolism in HCC cells, without effects on healthy hepatocytes.

Targeting the Activin Receptor Signaling to Counteract the Multi-Systemic Complications of Cancer and Its Treatments

Muscle wasting, i.e., cachexia, frequently occurs in cancer and associates with poor prognosis and increased morbidity and mortality. Anticancer treatments have also been shown to contribute to sustainment or exacerbation of cachexia, thus affecting quality of life and overall survival in cancer patients. Pre-clinical studies have shown that blocking activin receptor type 2 (ACVR2) or its ligands and their downstream signaling can preserve muscle mass in rodents bearing experimental cancers, as well as in chemotherapy-treated animals. In tumor-bearing mice, the prevention of skeletal and respiratory muscle wasting was also associated with improved survival. However, the definitive proof that improved survival directly results from muscle preservation following blockade of ACVR2 signaling is still lacking, especially considering that concurrent beneficial effects in organs other than skeletal muscle have also been described in the presence of cancer or following chemotherapy treatments paired with counteraction of ACVR2 signaling. Hence, here, we aim to provide an up-to-date literature review on the multifaceted anti-cachectic effects of ACVR2 blockade in preclinical models of cancer, as well as in combination with anticancer treatments.

The Interplay between Drivers of Erythropoiesis and Iron Homeostasis in Rare Hereditary Anemias: Tipping the Balance

Rare hereditary anemias (RHA) represent a group of disorders characterized by either impaired production of erythrocytes or decreased survival (i.e., hemolysis). In RHA, the regulation of iron metabolism and erythropoiesis is often disturbed, leading to iron overload or worsening of chronic anemia due to unavailability of iron for erythropoiesis. Whereas iron overload generally is a well-recognized complication in patients requiring regular blood transfusions, it is also a significant problem in a large proportion of patients with RHA that are not transfusion dependent. This indicates that RHA share disease-specific defects in erythroid development that are linked to intrinsic defects in iron metabolism. In this review, we discuss the key regulators involved in the interplay between iron and erythropoiesis and their importance in the spectrum of RHA.

Tumor Immune Evasion Induced by Dysregulation of Erythroid Progenitor Cells Development

Cancer cells harness normal cells to facilitate tumor growth and metastasis. Within this complex network of interactions, the establishment and maintenance of immune evasion mechanisms are crucial for cancer progression. The escape from the immune surveillance results from multiple independent mechanisms. Recent studies revealed that besides well-described myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages (TAMs) or regulatory T-cells (Tregs), erythroid progenitor cells (EPCs) play an important role in the regulation of immune response and tumor progression. EPCs are immature erythroid cells that differentiate into oxygen-transporting red blood cells. They expand in the extramedullary sites, including the spleen, as well as infiltrate tumors. EPCs in cancer produce reactive oxygen species (ROS), transforming growth factor β (TGF-β), interleukin-10 (IL-10) and express programmed death-ligand 1 (PD-L1) and potently suppress T-cells. Thus, EPCs regulate antitumor, antiviral, and antimicrobial immunity, leading to immune suppression. Moreover, EPCs promote tumor growth by the secretion of growth factors, including artemin. The expansion of EPCs in cancer is an effect of the dysregulation of erythropoiesis, leading to the differentiation arrest and enrichment of early-stage EPCs. Therefore, anemia treatment, targeting ineffective erythropoiesis, and the promotion of EPC differentiation are promising strategies to reduce cancer-induced immunosuppression and the tumor-promoting effects of EPCs.

BMP11 regulates thermogenesis in white and brown adipocytes

Bone morphogenetic protein-11 (BMP11), also known as growth differentiation factor-11 (GDF11), is implicated in skeletal development and joint morphogenesis in mammals. However, its functions in adipogenesis and energy homeostasis are mostly unknown. The present study investigates crucial roles of BMP11 in cultured 3T3-L1 white and HIB1B brown adipocytes, using Bmp11 gene depletion and pharmacological inhibition of BMP11. The silencing of Bmp11 markedly decreases the expression levels of brown-fat signature proteins and beige-specific genes in white adipocytes and significantly down-regulates the expression levels of brown fat-specific genes in brown adipocytes. The deficiency of Bmp11 reduces the expressions of lipolytic protein markers in white and brown adipocytes. Moreover, BMP11 induces browning of 3T3-L1 adipocytes via coordination of multiple signalling pathways, including mTORC1-COX2 and p38MAPK-PGC-1α as non-canonical pathways, as well as Smad1/5/8 as a canonical pathway. We believe this study is the first to provide evidence of the potential roles of BMP11 for improvement of lipid catabolism in both cultured white and brown adipocytes, as well as the effect on browning of white adipocytes. Taken together, these results demonstrate the therapeutic potential for the treatment of obesity.

Candidate rejuvenating factor GDF11 and tissue fibrosis: friend or foe?

Growth differentiation factor 11 (GDF11 or bone morphogenetic protein 11, BMP11) belongs to the transforming growth factor-β superfamily and is closely related to other family member-myostatin (also known as GDF8). GDF11 was firstly identified in 2004 due to its ability to rejuvenate the function of multiple organs in old mice. However, in the past few years, the heralded rejuvenating effects of GDF11 have been seriously questioned by many studies that do not support the idea that restoring levels of GDF11 in aging improves overall organ structure and function. Moreover, with increasing controversies, several other studies described the involvement of GDF11 in fibrotic processes in various organ setups. This review paper focuses on the GDF11 and its pro- or anti-fibrotic actions in major organs and tissues, with the goal to summarize our knowledge on its emerging role in regulating the progression of fibrosis in different pathological conditions, and to guide upcoming research efforts.

GDF11 induces mild hepatic fibrosis independent of metabolic health

Background & aims: Growth Differentiation Factor 11 (GDF11) is an anti-aging factor, yet its role in liver diseases is not established. We evaluated the role of GDF11 in healthy conditions and in the transition from non-alcoholic fatty liver disease (NAFLD) to non-alcoholic steatohepatitis (NASH).

Results: GDF11 mRNA levels positively correlated with NAFLD activity score and with CPT1, SREBP, PPARγ and Col1A1 mRNA levels, and associated to portal fibrosis, in morbidly obese patients with NAFLD/NASH. GDF11-treated mice showed mildly exacerbated hepatic collagen deposition, accompanied by weight loss and without changes in liver steatosis or inflammation. GDF11 triggered ALK5-dependent SMAD2/3 nuclear translocation and the pro-fibrogenic activation of HSC.

Conclusions: GDF11 supplementation promotes mild liver fibrosis. Even considering its beneficial metabolic effects, caution should be taken when considering therapeutics that regulate GDF11.

Methods: We analyzed liver biopsies from a cohort of 33 morbidly obese adults with NAFLD/NASH. We determined the correlations in mRNA expression levels between GDF11 and genes involved in NAFLD-to-NASH progression and with pathological features. We also exposed wild type or obese mice with NAFLD to recombinant GDF11 by daily intra-peritoneal injection and monitor the hepatic pathological changes. Finally, we analyzed GDF11-activated signaling pathways in hepatic stellate cells (HSC).

Growth differentiation factor-11 supplementation improves survival and promotes recovery after ischemic stroke in aged mice

Growth differentiation factor (GDF) 11 levels decline with aging. The age-related loss of GDF 11 has been implicated in the pathogenesis of a variety of age-related diseases. GDF11 supplementation reversed cardiac hypertrophy, bone loss, and pulmonary dysfunction in old mice, suggesting that GDF11 has a rejuvenating effect. Less is known about the potential of GDF11 to improve recovery after an acute injury, such as stroke, in aged mice. GDF11/8 levels were assessed in young and aged male mice and in postmortem human brain samples. Aged mice were subjected to a transient middle cerebral artery occlusion (MCAo). Five days after MCAo, mice received and bromodeoxyuridine / 5-Bromo-2'-deoxyuridine (BrdU) and either recombinant GDF11 or vehicle for five days and were assessed for recovery for one month following stroke. MRI was used to determine cerebrospinal fluid (CSF) volume, corpus callosum (CC) area, and brain atrophy at 30 days post-stroke. Immunohistochemistry was used to assess gliosis, neurogenesis, angiogenesis and synaptic density. Lower GDF11/8 levels were found with age in both mice and humans (p<0.05). GDF11 supplementation reduced mortality and improved sensorimotor deficits after stroke. Treatment also reduced brain atrophy and gliosis, increased angiogenesis, improved white matter integrity, and reduced inflammation after stroke. GDF11 may have a role in brain repair after ischemic injury.

Inhibition of GDF11 could promote bone healing in the tooth extraction socket and facilitate mesenchymal stem cell osteogenic differentiation in T2DM pigs

BACKGROUND

Growth differentiation factor 11 (GDF11) might be a key factor responsible for the weakening of mesenchymal stem cell (MSC) osteogenic differentiation in tooth extraction sockets in patients with type 2 diabetes mellitus (T2DM). This study aimed to confirm that inhibition of GDF11 could promote bone healing in tooth extraction sockets and facilitate MSC osteogenic differentiation under T2DM conditions.

METHODS

Three streptozotocin-induced T2DM pig models and two control pig models were established. The T2DM pigs were treated with an intrasocket injection of GDF11 inhibitor in the left mandible, whereas the right side was maintained for natural healing. The postextraction socket healing of the T2DM pigs was compared with that of nondiabetic controls. Healing was quantitatively verified by microcomputed tomography, and the GDF11 expression level was detected. MSCs from T2DM pig sockets were cultured and treated with a GDF11 inhibitor. The osteogenic differentiation ability of MSCs was also compared among groups.

RESULTS

The expression of GDF11 in the tooth extraction sockets from T2DM pigs increased significantly post extraction. Bone healing was promoted by periodic injection of the GDF11 inhibitor into the extraction sockets of T2DM pigs. Furthermore, the osteogenic differentiation ability of T2DM-MSCs was improved in pigs treated with the GDF11 inhibitor.

CONCLUSIONS

GDF11 inhibition could promote bone healing in the tooth extraction socket and facilitate MSC osteogenic differentiation under T2DM conditions. GDF11 could be a potential therapeutic target for undesirable alveolar bone healing in T2DM patients.

Anti-Aging Effects of GDF11 on Skin

Human skin is composed of three layers: the epidermis, the dermis, and the hypodermis. The epidermis has four major cell layers made up of keratinocytes in varying stages of progressive differentiation. Skin aging is a multi-factorial process that affects every phase of its biology and function. The expression profiles of inflammation-related genes analyzed in resident immune cells demonstrated that these cells have a strong ability to regenerate adult skin stem cells and to produce endogenous substances such as growth differentiation factor 11 (GDF11). GDF11 appears to be the key to progenitor proliferation and/or differentiation. The preservation of youthful phenotypes has been tied to the presence of GDF11 in different human tissues, and, in the skin, this factor inhibits inflammatory responses. The protective role of GDF11 depends on a multi-factorial process implicating various types of skin cells such as keratinocytes, fibroblasts and inflammatory cells. GDF11 should be further studied for the purpose of developing novel therapies for the treatment of skin diseases.

Korean Red Ginseng Plays An Anti-Aging Role by Modulating Expression of Aging-Related Genes and Immune Cell Subsets

Despite previous reports of anti-aging effects of Korean red ginseng (KRG), the underlying mechanisms remain poorly understood. Therefore, this study investigated possible mechanisms of KRG-mediated anti-aging effects in aged mice. KRG significantly inhibited thymic involution in old mice. Interestingly, KRG only increased protein expression, but not mRNA expression, of aging-related genes Lin28a, GDF-11, Sirt1, IL-2, and IL-17 in the thymocytes of old mice. KRG also modulated the population of some types of immune cells in old mice. KRG increased the population of regulatory T cells and interferon-gamma (IFN-γ)-expressing natural killer (NK) cells in the spleen of old mice, but serum levels of regulatory T cell-specific cytokines IL-10 and TGF-β were unaffected. Finally, KRG recovered mRNA expression of Lin28a, GDF-11, and Sirt1 artificially decreased by concanavalin A (Con A) in both thymocytes and splenocytes of old mice without cytotoxicity. These results suggest that KRG exerts anti-aging effects by preventing thymic involution, as well as modulating the expression of aging-related genes and immune cell subsets.

Hopes and Limits of Adipose-Derived Stem Cells (ADSCs) and Mesenchymal Stem Cells (MSCs) in Wound Healing

Adipose tissue derived stem cells (ADSCs) are mesenchymal stem cells identified within subcutaneous tissue at the base of the hair follicle (dermal papilla cells), in the dermal sheets (dermal sheet cells), in interfollicular dermis, and in the hypodermis tissue. These cells are expected to play a major role in regulating skin regeneration and aging-associated morphologic disgraces and structural deficits. ADSCs are known to proliferate and differentiate into skin cells to repair damaged or dead cells, but also act by an autocrine and paracrine pathway to activate cell regeneration and the healing process. During wound healing, ADSCs have a great ability in migration to be recruited rapidly into wounded sites added to their differentiation towards dermal fibroblasts (DF), endothelial cells, and keratinocytes. Additionally, ADSCs and DFs are the major sources of the extracellular matrix (ECM) proteins involved in maintaining skin structure and function. Their interactions with skin cells are involved in regulating skin homeostasis and during healing. The evidence suggests that their secretomes ensure: (i) The change in macrophages inflammatory phenotype implicated in the inflammatory phase, (ii) the formation of new blood vessels, thus promoting angiogenesis by increasing endothelial cell differentiation and cell migration, and (iii) the formation of granulation tissues, skin cells, and ECM production, whereby proliferation and remodeling phases occur. These characteristics would be beneficial to therapeutic strategies in wound healing and skin aging and have driven more insights in many clinical investigations. Additionally, it was recently presented as the tool key in the new free-cell therapy in regenerative medicine. Nevertheless, ADSCs fulfill the general accepted criteria for cell-based therapies, but still need further investigations into their efficiency, taking into consideration the host-environment and patient-associated factors.

GASP-2 overexpressing mice exhibit a hypermuscular phenotype with contrasting molecular effects compared to GASP-1 transgenics

Muscle atrophy is associated with many diseases including genetic disorders, sarcopenia, or cachexia syndromes. Myostatin (Mstn), a transforming growth factor-beta (TGF-β) member, plays a key role in skeletal muscle homeostasis as a powerful negative regulator. Over the last decade, about 15 clinical trials aimed at inhibiting the Mstn pathway, failed to produce conclusive results. In this context, we investigated whether growth and differentiation factor-associated serum protein-1 (GASP-1) or GASP-2, two natural inhibitors of Mstn, might represent a potential therapeutic. As we previously reported, mice overexpressing Gasp-1 (Tg(Gasp-1)) present an increase of muscle mass but develop metabolic disorders with aging. Here, we showed that overexpression of Gasp-2 increases the muscular mass without metabolic defects. We also found that Tg(Gasp-2) mice displayed, like Mstn^-/- mice, a switch from slow- to fast-twitch myofibers whereas Tg(Gasp-1) mice exhibit a reverse switch. Our studies supported the fact that GASP-2 has less affinity than GASP-1 for Mstn, leading to a constitutive Mstn upregulation only in Tg(Gasp-1) mice, responsible for the observed phenotypic differences. Altogether, our findings highlighted a gene expression regulatory network of TGF-β members and their inhibitors in muscle.

GDF11 ameliorated myocardial ischemia reperfusion injury by antioxidant stress and up-regulating autophagy in STZ-induced type 1 diabetic rats

Purpose:

To investigate whether GDF11 ameliorates myocardial ischemia reperfusion (MIR) injury in diabetic rats and explore the underlying mechanisms.

Methods:

Diabetic and non-diabetic rats subjected to MIR (30 min of coronary artery occlusion followed by 120 min of reperfusion) with/without GDF11 pretreatment. Cardiac function, myocardial infarct size, creatine kinase-MB (CK-MB), lactate dehydrogenase (LDH), superoxide dismutase (SOD) 15-F2tisoprostane, autophagosome, LC3II/I ratio and Belcin-1 level were determined to reflect myocardial injury, oxidative stress and autophagy, respectively. In in vitro study, H9c2 cells cultured in high glucose (HG, 30mM) suffered hypoxia reoxygenation (HR) with/without GDF11, hydrogen peroxide (H₂O₂) and autophagy inhibitor 3-methyladenine (3-MA) treatment, cell injury; oxidative stress and autophagy were assessed.

Results:

Pretreatment with GDF11 significantly improved cardiac morphology and function in diabetes, concomitant with decreased arrhythmia severity, infarct size, CK-MB, LDH and 15-F2tisoprostane release, increased SOD activity and autophagy level. In addition, GDF11 notably reduced HR injury in H9c2 cells with HG exposure, accompanied by oxidative stress reduction and autophagy up-regulation. However, those effects were completely reversed by H₂O₂ and 3-MA.

Conclusion:

GDF11 can provide protection against MIR injury in diabetic rats, and is implicated in antioxidant stress and autophagy up-regulation.

Decreased Plasma Levels of Growth Differentiation Factor 11 in Patients With Schizophrenia: Correlation With Psychopathology and Cognition

Schizophrenia is linked with abnormal neurodevelopment, on which growth differentiation factor 11 (GDF-11) has a great impact. However, a direct evidence linking GDF-11 to the pathophysiology of schizophrenia is still lacking. The current study aimed to investigate the relationship between plasma GDF-11 levels and both psychopathological symptoms and cognitive function in schizophrenia. Eighty-seven schizophrenia patients and 76 healthy controls were enrolled in the present study. The symptomatology of schizophrenia was evaluated using the Positive and Negative Syndrome Scale (PANSS). Cognitive function was assessed by Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) including twelve neurocognitive tests in five aspects of cognitive function. Plasma GDF-11 levels were determined by enzyme-linked immunosorbent assay (ELISA). We found that plasma levels of GDF-11 were significantly lower in schizophrenia patients relative to healthy controls. Correlation analysis showed significant negative correlations between the GDF-11 levels and the PANSS total score, the positive symptoms score, the negative symptoms score or the general score. Additionally, positive associations were observed between plasma GDF-11 levels and the visuospatial/constructional, attention, immediate memory, or delayed memory in patients. Partial correlation analysis showed that these correlations were still significant after adjusting for age, gender, education years, body mass index, duration of illness, and age of onset except for the visuospatial/constructional and attention index. Multiple regression analysis revealed that GDF-11 was an independent contributor to the immediate memory, delayed memory and RBANS total score in patients. Collectively, the correlations between plasma GDF-11 and psychopathological and cognitive symptoms suggest that abnormal GDF-11 signaling might contribute to schizophrenic psychopathology and cognitive impairments and GDF-11 could be a potential and promising biomarker for schizophrenia.

Gdf11 gene transfer prevents high fat diet-induced obesity and improves metabolic homeostasis in obese and STZ-induced diabetic mice

Background

The growth differentiation factor 11 (GDF11) was shown to reverse age-related hypertrophy on cardiomyocytes and considered as anti-aging rejuvenation factor. The role of GDF11 in regulating metabolic homeostasis is unclear. In this study, we investigated the functions of GDF11 in regulating metabolic homeostasis and energy balance.

Methods

Using a hydrodynamic injection approach, plasmids carrying a mouse Gdf11 gene were delivered into mice and generated the sustained Gdf11 expression in the liver and its protein level in the blood. High fat diet (HFD)-induced obesity was employed to examine the impacts of Gdf11 gene transfer on HFD-induced adiposity, hyperglycemia, insulin resistance, and hepatic lipid accumulation. The impacts of GDF11 on metabolic homeostasis of obese and diabetic mice were examined using HFD-induced obese and STZ-induced diabetic models.

Results

Gdf11 gene transfer alleviates HFD-induced obesity, hyperglycemia, insulin resistance, and fatty liver development. In obese and STZ-induced diabetic mice, Gdf11 gene transfer restores glucose metabolism and improves insulin resistance. Mechanism study reveals that Gdf11 gene transfer increases the energy expenditure of mice, upregulates the expression of genes responsible for thermoregulation in brown adipose tissue, downregulates the expression of inflammatory genes in white adipose tissue and those involved in hepatic lipid and glucose metabolism. Overexpression of GDF11 also activates TGF-β/Smad2, PI3K/AKT/FoxO1, and AMPK signaling pathways in white adipose tissue.

Conclusions

These results demonstrate that GDF11 plays an important role in regulating metabolic homeostasis and energy balance and could be a target for pharmacological intervention to treat metabolic disease.

TERT assists GDF11 to rejuvenate senescent VEGFR2+/CD133+ cells in elderly patients with myocardial infarction

Growth differentiation factor 11 (GDF11) is a transforming growth factor β superfamily member with a controversial role in rejuvenating old stem cells after acute injury in the elderly population. This study aimed to evaluate the effects of telomerase reverse transcriptase (TERT) on GDF11-mediated rejuvenation of senescent late-outgrowth endothelial progenitor cells (EPCs), defined as VEGFR2⁺/CD133⁺ cells, in elderly patients with acute myocardial infarction (AMI). We compared the quantity and capabilities of VEGFR2⁺/CD133⁺ cells from old (>60 years), middle-aged (45-60 years), and young (<45 years) AMI patients. The decline in circulating count and survival of VEGFR2⁺/CD133⁺ cells with age was accompanied by decrease in their TERT and GDF11 expression levels in patients with AMI. Further, upregulation of TERT could trigger GDF11-mediated rejuvenation of old VEGFR2⁺/CD133⁺ cells by renewing their survival and angiogenic abilities through activation of canonical (Smad2/3) and noncanonical (eNOS) signaling pathways. Depletion of GDF11 or TERT caused senescence of young VEGFR2⁺/CD133⁺ cells leading to impaired vascular function and angiogenesis in vitro and in vivo, whereas adTERT and rhGDF11 rescued this senescence. TERT cooperates with GDF11 to enhance regenerative capabilities of old VEGFR2⁺/CD133⁺ cells. When combined with TERT, GDF11 may represent a potential therapeutic target for the treatment of elderly patients with MI.

GDF11 Implications in Cancer Biology and Metabolism. Facts and Controversies

Growth Differentiation Factor 11 (GDF11), a member of the super family of the Transforming Growth Factor β, has gained more attention in the last few years due to numerous reports regarding its functions in other systems, which are different to those related to differentiation and embryonic development, such as age-related muscle dysfunction, skin biology, metabolism, and cancer. GDF11 is expressed in many tissues, including skeletal muscle, pancreas, kidney, nervous system, and retina, among others. GDF11 circulating levels and protein content in tissues are quite variable and are affected by pathological conditions or age. Although, GDF11 biology had a lot of controversies, must of them are only misunderstandings regarding the variability of its responses, which are independent of the tissue, grade of cellular differentiation or pathologies. A blunt fact regarding GDF11 biology is that its target cells have stemness feature, a property that could be found in certain adult cells in health and in disease, such as cancer cells. This review is focused to present and analyze the recent findings in the emerging research field of GDF11 function in cancer and metabolism, and discusses the controversies surrounding the biology of this atypical growth factor.

GDF11 contributes to hepatic hepcidin (HAMP) inhibition through SMURF1-mediated BMP-SMAD signalling suppression

Hepcidin (HAMP) synthesis is suppressed by erythropoiesis to increase iron availability for red blood cell production. This effect is thought to result from factors secreted by erythroid precursors. Growth differentiation factor 11 (GDF11) expression was recently shown to increase in erythroid cells of β-thalassaemia, and decrease with improvement in anaemia. Whether GDF11 regulates hepatic HAMP production has never been experimentally studied. Here, we explore GDF11 function during erythropoiesis-triggered HAMP suppression. Our results confirm that exogenous erythropoietin significantly increases Gdf11 as well as Erfe (erythroferrone) expression, and Gdf11 is also increased, albeit at a lower degree than Erfe, in phlebotomized wild type and β-thalassaemic mice. GDF11 is expressed predominantly in erythroid burst forming unit- and erythroid colony-forming unit- cells during erythropoiesis. Exogeneous GDF11 administration results in HAMP suppression in vivo and in vitro. Furthermore, exogenous GDF11 decreases BMP-SMAD signalling, enhances SMAD ubiquitin regulatory factor 1 (SMURF1) expression and induces ERK1/2 (MAPK3/1) signalling. ERK1/2 signalling activation is required for GDF11 or SMURF1-mediated suppression in BMP-SMAD signalling and HAMP expression. This research newly characterizes GDF11 in erythropoiesis-mediated HAMP suppression, in addition to ERFE.

Circulating factors in young blood as potential therapeutic agents for age-related neurodegenerative and neurovascular diseases

Recent animal studies on heterochronic parabiosis (a technique combining the blood circulation of two animals) have revealed that young blood has a powerful rejuvenating effect on brain aging. Circulating factors, especially growth differentiation factor 11 (GDF11) and C-C motif chemokine 11 (CCL11), may play a key role in this effect, which inspires hope for novel approaches to treating age-related cerebral diseases in humans, such as neurodegenerative and neurovascular diseases. Recently, attempts have begun to translate these astonishing and exciting findings from mice to humans and from bench to bedside. However, increasing reports have shown contradictory data, questioning the capacity of these circulating factors to reverse age-related brain dysfunction. In this review, we summarize the current research on the role of young blood, as well as the circulating factors GDF11 and CCL11, in the aging brain and age-related cerebral diseases. We highlight recent controversies, discuss related challenges and provide a future outlook.