Danhong Promotes Angiogenesis in Diabetic Mice after Critical Limb Ischemia by Activation of CSE-H 2 S-VEGF Axis

Injectable thermosensitive selenium-containing hydrogel as mesenchymal stem cell carrier to improve treatment efficiency in limb ischemia

Limb ischemia is a refractory disease characterized by persistent inflammation, insufficient angiogenesis, and tissue necrosis. Although mesenchymal stem cells (MSCs) have shown potential for treating limb ischemia, their therapeutic effects are limited by low engraftment rates. Therefore, developing an optimal MSC delivery system that enhances cell viability is imperative. Selenium, known for its cytoprotective properties in various cell types, offers a potential strategy to enhance therapeutic effect of MSCs. In this study, we evaluated the cytoprotective effects of selenium on MSCs, and developed an injectable thermosensitive selenium-containing hydrogel based on PLGA-PEG-PLGA triblock copolymer, as a cell carrier to improve MSC viability after engraftment. The biocompatibility, biodegradability, and cytoprotective capabilities of selenium-containing hydrogels were assessed. Furthermore, the therapeutic potential of MSCs encapsulated within a thermosensitive selenium-containing hydrogel in limb ischemia was evaluated using cellular and animal experiments. Selenium protects MSCs from oxidative damage by upregulating GPX4 through a transcriptional mechanism. The injectable thermosensitive selenium-containing hydrogel exhibited favorable biocompatibility, biodegradability, and antioxidant properties. It can be easily injected into the target area in liquid form at room temperature and undergoes gelation at body temperature, thereby preventing the diffusion of selenium and promoting the cytoprotection of MSCs. Furthermore, MSCs encapsulated within the selenium-containing hydrogel effectively inhibited macrophage M1 polarization while promoting macrophage M2 polarization, thus accelerating angiogenesis and restoring blood perfusion in ischemic limbs. This study demonstrated the potential of an injectable thermosensitive selenium-containing hydrogel as a promising method for MSC delivery. By addressing the challenge of low retention rate, which is a major obstacle in MSC application, this strategy effectively improves limb ischemia.

Role of hydrogen sulphide in physiological and pathological angiogenesis

The role of hydrogen sulphide (H₂ S) in angiogenesis has been widely demonstrated. Vascular endothelial growth factor (VEGF) plays an important role in H₂ S-induced angiogenesis. H₂ S promotes angiogenesis by upregulating VEGF via pro-angiogenic signal transduction. The involved signalling pathways include the mitogen-activated protein kinase pathway, phosphoinositide-3 kinase pathway, nitric oxide (NO) synthase/NO pathway, signal transducer and activator of transcription 3 (STAT3) pathway, and adenosine triphosphate (ATP)-sensitive potassium (K_ATP ) channels. H₂ S has been shown to contribute to tumour angiogenesis, diabetic wound healing, angiogenesis in cardiac and cerebral ischaemic tissues, and physiological angiogenesis during the menstrual cycle and pregnancy. Furthermore, H₂ S can exert an anti-angiogenic effect by inactivating Wnt/β-catenin signalling or blocking the STAT3 pathway in tumours. Therefore, H₂ S plays a double-edged sword role in the process of angiogenesis. The regulation of H₂ S production is a promising therapeutic approach for angiogenesis-associated diseases. Novel H₂ S donors and/or inhibitors can be developed in the treatment of angiogenesis-dependent diseases.

Salvianolic Acid B Alleviates Limb Ischemia in Mice via Promoting SIRT1/PI3K/AKT Pathway-Mediated M2 Macrophage Polarization

Salvianolic acid B (Sal B) is an effective treatment agent for ischemic disease in China. However, Sal B's effects on peripheral arterial disease (PAD) and its mechanism remains poorly understood. Macrophage polarization plays a crucial role in PAD. Nevertheless, treatment modalities that increase the population of anti-inflammatory (M2) macrophages are limited. This study aimed to explore the protective effects of Sal B on limb perfusion and investigate the mechanism of Sal B-induced macrophage polarization. C57BL/6 male mice (6 weeks) were randomized into control, Model + NS, and Model + Sal B groups (n = 5). Then, we established a hind limb ischemia mouse model to assess the Sal B's role (15 mg/kg/d) in PAD. We quantified the blood perfusion via laser speckle contrast imaging (LSCI) and measured the capillary density and muscle edema with CD31 and H&E staining. The Sal B-induced macrophage polarization was confirmed by qPCR and ELISA. The results showed that the Sal B group exhibited a significant improvement in the blood perfusion, capillary density, muscle edema, and M2 markers gene expressions. Cell migration and tube formation were promoted in the endothelial cells stimulated with a culture supernatant from Sal B-treated macrophages. In contrast, endothelial functions improved by Sal B-treated macrophages were impaired in groups treated with SIRT1 and PI3K inhibitors. These findings provide evidence for Sal B's protective role in PAD and demonstrate the enhancement of macrophage polarization via the SIRT1/PI3K/AKT pathway.

Hydrogen sulfide: A new therapeutic target in vascular diseases

Hydrogen sulfide (H₂S) is one of most important gas transmitters. H₂S modulates many physiological and pathological processes such as inflammation, oxidative stress and cell apoptosis that play a critical role in vascular function. Recently, solid evidence show that H₂S is closely associated to various vascular diseases. However, specific function of H₂S remains unclear. Therefore, in this review we systemically summarized the role of H₂S in vascular diseases, including hypertension, atherosclerosis, inflammation and angiogenesis. In addition, this review also outlined a novel therapeutic perspective comprising crosstalk between H₂S and smooth muscle cell function. Therefore, this review may provide new insight inH₂S application clinically.

Hedgehog signaling modulates cigarette-induced COPD development

Hedgehog (Hh) signaling is involved in early embryogenesis and maintains quiescence in the adult lungs. The interruption of Hh signaling may lead to the development of chronic obstructive pulmonary disease (COPD). The current study aimed to assess whether the Hh pathway affects cigarette-induced emphysema and airway inflammation by regulating inflammatory cytokines. C57BL/6J mice were randomized into control, cigarette smoke (CS) or CS + cyclopamine (CSC) groups. Control mice were exposed to normal room air, CS mice were exposed to tobacco smoke and CSC mice were exposed to CS and received cyclopamine treatment. Histopathological examination of lung tissues was performed, and the expression of sonic hedgehog (HH), glioma-associated oncogene homolog 1 (Gli1), hedgehog-interacting protein (HIP) and several inflammatory mediators (intracellular adhesion molecule-1, IL-6, IL-8 and TNF-α) were compared using reverse transcription-quantitative PCR and western blotting. The emphysema of lung tissues by histopathological examination demonstrated partial amelioration in the CSC group compared with that in the CS group. Additionally, expression levels of SHH, Gli1 and inflammatory mediators were significantly higher in the CS group compared with the control group but were significantly decreased in the CSC group. The expression of HIP was decreased in the CS group, but significantly increased in the CSC group. Hh signaling may serve an important role in cigarette-induced emphysema and airway inflammation by regulating inflammatory cytokines in animal models. Therefore, diminishing the activation of the Hh signal may serve as a novel therapeutic strategy for patients suffering from smoking-related COPD.

A Defined Combination of Four Active Principles From the Danhong Injection Is Necessary and Sufficient to Accelerate EPC-Mediated Vascular Repair and Local Angiogenesis

Many compounds in Chinese medicine formulae, including Danhong injection (DHI) formulae, are capable of stimulating angiogenesis and promoting vascular repair, but their chemical basis and action mechanisms remain poorly defined. The aim of this study is to determine the minimal native chemical composition of DHI for the pro-angiogenesis activity and to evaluate its contribution from local endothelial cells (ECs) and bone marrow-derived endothelial progenitor cells (EPCs). Our study demonstrated that the action of DHI in accelerating the recovery of hindlimb blood flow in a ischemic rat model was attributable to its local CXCR4-mediated pro-angiogenesis activity in mature endothelial cells, as well as to its ability to promote the proliferation, migration, adhesion, and angiogenesis of EPCs via integrated activation of SDF-1α/CXCR4, VEGF/KDR, and eNOS/MMP-9 signal pathways. Combination experiments narrowed down the angiogenic activity into a few components in DHI. Reconstitution experiment defined that a combination of tanshinol, protocatechuic aldehyde, salvianolic acid B, and salvianolic acid C in their native proportion was necessary and sufficient for DHI's angiogenic activity. Compared with the full DHI, the minimal reconstituted four active principles had the same effects in promoting tube formation in vitro, improving perfusion and recovery of ischemic limb, and enhancing angiogenesis in ischemic mice post-hindlimb ischemia in vivo.

Danhong injection mobilizes endothelial progenitor cells to repair vascular endothelium injury via upregulating the expression of Akt, eNOS and MMP-9

BACKGROUD

Endothelial progenitor cells (EPCs) have been characterized as one of the key effectors of endothelial healing. The effect of Danhong injection (DHI), the most widely prescribed Chinese medicine for coronary heart disease (CHD), on EPCs mobilization remains unclear.

PURPOSE

We aimed to assess the effect of DHI on EPCs mobilization to repair percutaneous coronary intervention (PCI) induced vascular injury, and to investigate the characteristics and potential mechanism of DHI on EPCs mobilization.

METHOD

Forty-two patients with CHD underwent PCI and received stent implantation were enrolled in a Phase II clinical trials. All patients received routine western medical treatment after PCI, patients of DHI group received DHI in addition. The levels of CECs, cytokines (vWF, IL-6, CRP) and EPCs were analyzed at baseline, post-PCI and after treatment. To investigate the characteristics of DHI on EPCs mobilization, 12 healthy volunteers received intravenous infusion of DHI once and the other 12 received for 7 days. EPCs enumeration were done at a series of time points. At last we tested the effect of DHI and three chemical constituents of DHI (danshensu; lithospermic acid, LA; salvianolic acid D, SaD) on EPCs level and expression of Akt, eNOS and MMP-9 in bone marrow cells of myocardial infarction (MI) mice.

RESULTS

In the DHI group the angina symptoms were improved, the levels of cytokines and CECs were reduced; while EPCs population was increased after treatment. In the phase I clinical trials, EPCs counts reached a plateau phase in 9 h and maintained for more than 10 h after a single dose. After continuous administration, EPCs levels plateaued on the 3rd or 4th day, and maintain till 1 day after the withdrawal, then its levels gradually declined. DHI treatment induced a timely dependent mobilization of EPCs. DHI promoted EPCs mobilization via upregulating the expression of Akt, eNOS and MMP-9 in BM. LA and SaD have played a valuable role in EPCs mobilization.

CONCLUSION

These initial results demonstrated that DHI is effective in alleviating endothelial injury and promoting endothelial repair through enhancing EPCs mobilization and revealed the effect feature and possible mechanisms of DHI in mobilizing EPCs.

Salvia miltiorrhiza and Carthamus tinctorius Extract Prevents Cardiac Fibrosis and Dysfunction after Myocardial Infarction by Epigenetically Inhibiting Smad3 Expression

The incidence of cardiac dysfunction after myocardial infarction (MI) continues to increase despite advances in treatment. Excessive myocardial fibrosis plays a vital role in the development of adverse cardiac remodeling and deterioration of cardiac function. Understanding the molecular and cellular mechanism of the fibrosis process and developing effective therapeutics are of great importance. Salvia miltiorrhiza and Carthamus tinctorius extract (SCE) is indicated for angina pectoris and other ischemic cardiovascular diseases in China. SCE has been shown to inhibit the platelet activation and aggregation, ameliorate ROS-induced myocardial necrosis by inhibiting mitochondrial permeability transition pore opening, and promote angiogenesis by upregulating the expression of vascular endothelial growth factor (VEGF). However, whether SCE has effect on cardiac fibrosis after MI is not fully clear. Here, a mouse model of MI was established to observe the effect of SCE upon survival, cardiac function, myocardial fibrosis, and inflammation. Quantitative PCR and western blot assays were used to determine the expression of genes related to transforming growth factor-β (TGF-β) cascade and inflammatory responses in vivo. Additionally, the effects of SCE upon the collagen production, TGF-β/Smad3 (SMAD family member 3) signaling, and the levels of histone methylation in primary cardiac fibroblasts were detected. We found that SCE treatment significantly improved survival and left ventricular function in mice after MI. Inhibition of inflammation and fibrosis, as well as decreased expression of Smad3, was observed with SCE treatment. In TGF-β-stimulated cardiac fibroblasts, SCE significantly decreased the expression of collagen, α-smooth muscle actin (α-SMA), and Smad3. Furthermore, SCE treatment downregulated the levels of H3K4 trimethylation (H3K4me3) and H3K36 trimethylation (H3K36me3) at the Smad3 promoter region of cardiac fibroblasts, leading to inhibition of Smad3 transcription. Our findings suggested that SCE prevents myocardial fibrosis and adverse remodeling after MI with a novel mechanism of suppressing histone methylation of the Smad3 promoter and its transcription.