Sonic Hedgehog signaling regulates vascular differentiation and function in human CD34 positive cells: vasculogenic CD34(+) cells with Sonic Hedgehog

Ex-vivo expanded CD34+ cell transplantation alleviates fibrotic liver injury via innate immune modulation in metabolic dysfunction-associated steatohepatitis mice

BACKGROUND

In drug-induced liver injury, vascular endothelial progenitor cells, specifically the CD34+ cell fractions, have been found to decrease liver fibrosis and promote regeneration. However, it is unclear whether CD34+ cell transplantation has anti-fibrogenic effects on MASH, which has previously been treated effectively with anti-angiogenic therapy. We investigated the efficacy of ex vivo-expanded CD34+ cells in treating MASH livers.

MATERIALS AND METHODS

Diet-induced MASH mice were fed a choline-deficient, L-amino acid-defined, high-fat diet for 12 or 20 weeks, and were designated as a mild and a severe fibrosis model, respectively. Mouse bone marrow CD34+ cells were expanded for 7 days, transplanted into each mouse once or twice 2 weeks later, and sacrificed at 4 weeks after the first transplantation.

RESULTS

Expanded CD34+ cell transplantation ameliorated liver fibrosis, regardless of fibrosis degree, as indicated by the decrease in α-smooth muscle actin-positive cells, hydroxyproline concentration, and fibrogenic gene expression of Col1a1 and Timp1. Furthermore, engrafted CD34+ cells reduced alanine transaminase levels, the number of TUNEL+ hepatocytes, and 8-OHdG concentration. RNA-sequencing data showed that "defense response to virus" was the most down-regulated category in the Gene Ontology analysis and subsequent analysis revealed the suppression of RIG-I-like receptors/Irf7/Stat1/Cxcl10 axis in expanded CD34+ cell-transplanted livers. Finally, the downregulation of CXCL10 expression inhibits the mobilization of inflammatory immune cells, macrophages, T cells, and natural killer cells to the MASH liver.

CONCLUSIONS

These findings suggest that transplanted expanded CD34+ cells alleviate fibrotic liver injury in MASH mouse models through possible modulation of the innate immune response, which is abnormally activated by hepatocyte lipotoxicity.

Signaling pathways and targeted therapy for myocardial infarction

Although the treatment of myocardial infarction (MI) has improved considerably, it is still a worldwide disease with high morbidity and high mortality. Whilst there is still a long way to go for discovering ideal treatments, therapeutic strategies committed to cardioprotection and cardiac repair following cardiac ischemia are emerging. Evidence of pathological characteristics in MI illustrates cell signaling pathways that participate in the survival, proliferation, apoptosis, autophagy of cardiomyocytes, endothelial cells, fibroblasts, monocytes, and stem cells. These signaling pathways include the key players in inflammation response, e.g., NLRP3/caspase-1 and TLR4/MyD88/NF-κB; the crucial mediators in oxidative stress and apoptosis, for instance, Notch, Hippo/YAP, RhoA/ROCK, Nrf2/HO-1, and Sonic hedgehog; the controller of myocardial fibrosis such as TGF-β/SMADs and Wnt/β-catenin; and the main regulator of angiogenesis, PI3K/Akt, MAPK, JAK/STAT, Sonic hedgehog, etc. Since signaling pathways play an important role in administering the process of MI, aiming at targeting these aberrant signaling pathways and improving the pathological manifestations in MI is indispensable and promising. Hence, drug therapy, gene therapy, protein therapy, cell therapy, and exosome therapy have been emerging and are known as novel therapies. In this review, we summarize the therapeutic strategies for MI by regulating these associated pathways, which contribute to inhibiting cardiomyocytes death, attenuating inflammation, enhancing angiogenesis, etc. so as to repair and re-functionalize damaged hearts.

Dysfunction of Shh signaling activates autophagy to inhibit trophoblast motility in recurrent miscarriage

In early pregnancy, the placenta anchors the conceptus and supports embryonic development and survival. This study aimed to investigate the underlying functions of Shh signaling in recurrent miscarriage (RM), a serious disorder of pregnancy. In the present study, Shh and Gli2 were mainly observed in cytotrophoblasts (CTBs), Ptch was mainly observed in syncytiotrophoblasts (STBs), and Smo and Gli3 were expressed in both CTBs and STBs. Shh signaling was significantly impaired in human placenta tissue from recurrent miscarriage patients compared to that of gestational age-matched normal controls. VEGF-A and CD31 protein levels were also significantly decreased in recurrent miscarriage patients. Furthermore, inhibition of Shh signaling impaired the motility of JAR cells by regulating the expression of Gli2 and Gli3. Intriguingly, inhibition of Shh signaling also triggered autophagy and autolysosome accumulation. Additionally, knockdown of BECN1 reversed Gant61-induced motility inhibition. In conclusion, our results showed that dysfunction of Shh signaling activated autophagy to inhibit trophoblast motility, which suggests the Shh pathway and autophagy as potential targets for RM therapy.

Skin wound healing assisted by angiogenic targeted tissue engineering: A comprehensive review of bioengineered approaches

Skin injuries and in particular, chronic wounds, are one of the major prevalent medical problems, worldwide. Due to the pivotal role of angiogenesis in tissue regeneration, impaired angiogenesis can cause several complications during the wound healing process and skin regeneration. Therefore, induction or promotion of angiogenesis can be considered as a promising approach to accelerate wound healing. This article presents a comprehensive overview of current and emerging angiogenesis induction methods applied in several studies for skin regeneration, which are classified into the cell, growth factor, scaffold, and biological/chemical compound-based strategies. In addition, the advantages and disadvantages of these angiogenic strategies along with related research examples are discussed in order to demonstrate their potential in the treatment of wounds.

Paired box 9 regulates VSMC phenotypic transformation, proliferation, and migration via sonic hedgehog

AIMS

Vascular smooth muscle cells (VSMCs) play a crucial role in the progression of atherosclerosis. Paired box 9 (Pax9) is a member of the Pax gene family which participates in the development of various tissues and organs. However, the effect of Pax9 on atherosclerosis and VSMCs and the underlying mechanisms remain unclear.

MAIN METHODS

Western blotting was performed to assess Pax9 expression in atherosclerosis and VSMCs. Pax9 siRNA and overexpression plasmid were constructed to explore the biological function. Cell proliferation assay, phalloidin staining, and Transwell assay, accompanied by the sonic hedgehog (Shh) signaling pathway antagonist, cyclopamine (5 μM) and agonist, SAG (100 nM), were used to evaluate the VSMC phenotype, proliferation, and migration, as well as explore the associated mechanisms.

KEY FINDINGS

We first discovered Pax9 to be significantly increased in atherosclerotic mice and platelet-derived growth factor-BB (PDGF-BB)-induced VSMCs. Pax9 knockdown inhibited the phenotypic transformation, proliferation, and migration of VSMCs, whereas the opposite effect was observed when Pax9 was overexpressed. Next, we established that Shh was activated in PDGF-BB-induced VSMCs. Moreover, Pax9 overexpression further activated Shh and exacerbated the phenotypic transformation, proliferation, and migration of PDGF-BB-induced VSMCs. These changes were effectively inhibited by treatment with the Shh signaling pathway antagonist. Consistently, Pax9 knockdown down-regulated Shh expression and inhibited the phenotypic transformation, proliferation, and migration of PDGF-BB-induced VSMCs. Treatment with the Shh signaling pathway agonist prevented these changes.

SIGNIFICANCE

Pax9 regulated VSMC phenotypic transformation, proliferation, and migration via Shh, which may represent a novel target for the treatment of atherosclerosis.

Increased expression of Sonic hedgehog restores diabetic endothelial progenitor cells and improves cardiac repair after acute myocardial infarction in diabetic mice

Damaged endothelial progenitor cells (EPCs) are associated with poor prognosis in diabetic myocardial infarction (DMI). Our previous studies revealed that an impaired Sonic hedgehog (Shh) pathway contributes to insufficient function in diabetic EPCs; however, the roles of the Shh pathway in diabetic EPC apoptosis under basal and hypoxic/ischemic conditions remain unknown. Therefore, the present study investigated whether Shh revitalized diabetic EPCs and consequently improved the deteriorative status of DMI. For this purpose, streptozotocin injection was used in male C57/BL6 mice to induce type-1 diabetes, and diabetic EPCs were isolated from the bone marrow. Apoptosis, cell function, and protein expression were investigated in EPCs in vitro. Mouse hearts were injected with adenovirus Shh-modified diabetic EPCs (DM-EPC^Shh) or control DM-EPC^Null immediately after coronary artery ligation in vivo. Cardiac function, capillary numbers, fibrosis, and cell apoptosis were then detected. First, the in vitro results demonstrated that the apoptosis of diabetic EPCs was reduced following treatment with Shh protein for 24 h, under normal or hypoxic conditions. BMI1 proto-oncogene (Bmi1), an antiapoptotic protein found in several cells, was reduced in diabetic EPCs under normal or hypoxic conditions, but was upregulated after Shh protein stimulation. When Bmi1-siRNA was administered, the antiapoptotic effect of Shh protein was significantly reversed. In addition, p53, a Bmi1-targeted gene, was demonstrated to mediate the antiapoptotic effect of the Shh/Bmi1 pathway in diabetic EPCs. The Shh/Bmi1/p53 axis also enhanced the diabetic EPC function. In vivo, Shh-modified diabetic EPCs exhibited increased EPC retention and decreased apoptosis at 3 days post-DMI. At 14 days post-DMI, these cells presented enhanced capillary density, reduced myocardial fibrosis and improved cardiac function. In conclusion, the present results demonstrated that the Shh pathway restored diabetic EPCs through the Shh/Bmi1/p53 axis, suppressed myocardial apoptosis and improved myocardial angiogenesis, thus reducing cardiac fibrosis and finally restoring myocardial repair and cardiac function in DMI. Thus, the Shh pathway may serve as a potential target for autologous cell therapy in diabetic myocardial ischemia.

Autologous CD34+ Cell Therapy for Ischemic Tissue Repair

In 1997, the seminal manuscript by Asahara, Murohara, Isner et al outlined the evidence for the existence of circulating, bone marrow-derived cells capable of stimulating and contributing to the formation of new blood vessels. Consistent with the paradigm shift that this work represented, it triggered much scientific debate and controversy, some of which persists 2 decades later. In contrast, the clinical application of autologous CD34 cell therapy has been marked by a track record of consistent safety and clinical benefit in multiple ischemic conditions. In this review, we summarize the preclinical and clinical evidence from over 700 patients in clinical trials of CD34 cell therapy.

Sonic Hedgehog Expression is Associated with Lymph Node Invasion in Urothelial Bladder Cancer

Bladder cancer (BC) is a deadly disease characterized by high recurrence rates and frequent progression to an aggressive phenotype. Dysregulation of various signaling pathways have been implicated in BC tumorigenesis, however, the clinical relevance of sonic hedgehog pathway (Shh) remains under investigated. The aim of the current study was to analyze the prognostic value of Shh expression in patients with bladder carcinoma. Immunohistochemical expression of Shh was performed using tissue microarray with 128 specimens from bladder cancer patients. Kaplan-meier survival was analysed and correlation between Shh protein expression and patients' clinicopathological parameters wasexamined using Fisher's exact test. The immuno-staining results revealed that Shh protein exhibits cytoplasmic localization and is expressed in 49% of the analyzed bladder cancer cohort. Our data indicated that high Shh expression significantly correlated with increased lymph node metastasis (p = 0.02), however no association was reported between Shh expression and other clinicopatholigical parameters. High expression of sonic hedgehog was associated with lymph node invasion which may indicate that Shh might play an important role in progression and metastasis of bladder cancer.

Sonic Hedgehog Signaling Pathway in Endothelial Progenitor Cell Biology for Vascular Medicine

The Hedgehog (HH) signaling pathway plays an important role in embryonic and postnatal vascular development and in maintaining the homeostasis of organs. Under physiological conditions, Sonic Hedgehog (SHH), a secreted protein belonging to the HH family, regulates endothelial cell growth, promotes cell migration and stimulates the formation of new blood vessels. The present review highlights recent advances made in the field of SHH signaling in endothelial progenitor cells (EPCs). The canonical and non-canonical SHH signaling pathways in EPCs and endothelial cells (ECs) related to homeostasis, SHH signal transmission by extracellular vesicles (EVs) or exosomes containing single-strand non-coding miRNAs and impaired SHH signaling in cardiovascular diseases are discussed. As a promising therapeutic tool, the possibility of using the SHH signaling pathway for the activation of EPCs in patients suffering from cardiovascular diseases is further explored.

Functional convergence of Akt protein with VEGFR-1 in human endothelial progenitor cells exposed to sera from patient with type 2 diabetes mellitus

Diabetes mellitus type 2 predisposes patients to various microvascular complications. In the current experiment, the potent role of diabetes mellitus was investigated on the content of VEGFR-1, -2, Tie-1 and -2, and Akt in human endothelial progenitor cells. The gene expression profile of mTOR and Hedgehog signaling pathways were measured by PCR array. The possible crosstalk between RTKs, mTOR and Hedgehog signaling was also studied by bioinformatic analysis. Endothelial progenitor cells were incubated with serum from normal and diabetic for 7days. Compared to non-treated cells, diabetic serum-induced cell apoptosis (~2-fold) and prohibited cell migration toward bFGF (p<0.001). ELISA analysis showed that diabetes exposed cells had increased abundance of Tie-1, -2 and VEGFR-2 and reduced amount of VEGFR-1 (p<0.0001) in diabetic cells. Western blotting showed a marked reduction in the protein level of Akt after cells exposure to serum from diabetic subjects (p<0.0001). PCR array revealed a significant stimulation of both mTOR and Hedgehog signaling pathways in diabetic cells (p<0.05). According to data from bioinformatic datasets, we showed VEGFR-1, -2 and Tie-2, but not Tie-1, are master regulators of angiogenesis. There is a crosstalk between RTKs and mTOR signaling by involving P62, GABARAPL1, and HTT genes. It seems that physical interaction and co-expression of Akt decreased the level of VEGFR-1 in diabetic cells. Regarding data from the present experiment, diabetic serum contributed to uncontrolled induction of both mTOR and Hedgehog signaling in endothelial progenitor cells. Diabetes mellitus induces mTOR pathway by involving receptor tyrosine kinases while Hedgehog stimulation is independent of these receptors.

Hh signaling in regeneration of the ischemic heart

Myocardial infarction (MI) is caused by the occlusion of a coronary artery due to underlying atherosclerosis complicated by localized thrombosis. The blockage of blood flow leads to cardiomyocyte (CM) death in the infarcted area. Adult mammalian cardiomyocytes have little capacity to proliferate in response to injury; however, some pathways active during embryogenesis and silent during adult life are recruited in response to tissue injury. One such example is hedgehog (Hh) signaling. Hh is involved in the embryonic development of the heart and coronary vascular system. Pathological conditions including ischemia activate Hh signaling in adult tissues. This review highlights the involvement of Hh signaling in ischemic tissue regeneration with a particular emphasis on heart regeneration and discusses its potential role as a therapeutic agent.

Bone Marrow-Derived Endothelial Progenitor Cells Reduce Recurrent Miscarriage in Gestation

Bone marrow-derived endothelial progenitor cells (EPCs) have been shown to contribute to not only angiogenesis in ischemic tissue but also neovascularization in uterine endometrium formation. Reduced neovascularization and elevation of serum soluble Flt1, a functional blockage of VEGF, in the development of placenta is thought to be one of the major causes of repeated miscarriages in gestation. We then examined whether transfusion of VEGF-expressing extrinsic EPCs prevented frequent miscarriage via its promotional effect on neovascularization with a VEGFeNOS signaling pathway in a mouse miscarriage model. The results showed that systemic EPC transfusion significantly reduced the rate of miscarriage, and EPCs were frequently observed in the miscarriage placenta. In contrast, only a few EPCs were detected in the placenta of normal gestation. The vascular pattern was irregular, and vessel size was small in the miscarriage placenta compared with that of normal gestation. The placental vascular pattern in miscarriage tended to be normalized with increased vessel size up to a similar level as normal gestation by EPC recruitment. For the mechanistic insight, since soluble Flt1 inhibits EPC functions, it was suggested that the increased soluble Flt1 could suppress the recruited EPC functional activity in the miscarriage placenta. In vitro experiments by soluble Flt1 treatment in cultured EPCs suggested that the vascular abnormality could be partly due to the inhibition of eNOS expression by the increased amounts of soluble Flt1. These findings from animal experiments indicated that autologous EPC therapy may be a novel therapy to prevent miscarriage in high-risk pregnancies, such as preeclampsia.

Signaling involved in stem cell reprogramming and differentiation

Stem cell differentiation is regulated by multiple signaling events. Recent technical advances have revealed that differentiated cells can be reprogrammed into stem cells. The signals involved in stem cell programming are of major interest in stem cell research. The signaling mechanisms involved in regulating stem cell reprogramming and differentiation are the subject of intense study in the field of life sciences. In this review, the molecular interactions and signaling pathways related to stem cell differentiation are discussed.