Role of Stromal Cell-Derived Factor-1 in Endothelial Progenitor Cell-Mediated Vascular Repair and Regeneration

Comprehensive analysis of skin growth-related hub genes and microenvironment characterization in a mouse expanded skin model

Background

Mechanical stretch-mediated tissue expansion is effective for obtaining extra skin and soft tissue required for the repair of defects or reconstruction of surface organs. Understanding the cellular and molecular mechanisms and identifying hub genes and key cell types associated with skin expansion could help predict the success of skin growth during expansion procedures.

Methods

We analyzed murine chip sequencing data and single-cell sequencing data available from the Gene Expression Omnibus database. Based on the differentially expressed and epithelial-mesenchymal transition-related genes, random forest and protein-protein interaction network analysis identified hub genes for predicting skin regeneration in tissue expansion. The fate of the cell subpopulations, expression of hub genes in different cell types, and their communication were also assessed.

Results

Five genes, integrin beta 5 (Itgb5), tropomyosin 1 (Tpm1), secreted frizzled-related protein-1 (Sfrp1), Notch1, and insulin-like growth factor binding protein 2 (Igfbp2), were identified as having the greatest impact on prediction accuracy. These hub genes were primarily enriched in the Notch and phosphoinositide 3-kinase-AKT pathways. Immune cell infiltration analysis further revealed that mast cell infiltration was significantly higher in the expanded skin group than that in the control group. According to single-cell data, the interactions between epithelial cells, stem cells, and other cell types were higher in the expanded skin group than those in the control group. Moreover, Tpm1, Sfrp1, and Notch1 were highly expressed in all epithelial and stem cell subgroups.

Conclusions

The hub genes, Notch1, Tpm1 and Sfrp1, and their associated signaling pathways such as Notch and Wnt signaling and functions in key cell subsets highlight prospective therapeutic strategies to enhance skin growth under mechanical expansion. Moreover, mast cell activation and infiltration may trigger immune responses in the expanded skin, which requires further investigation.

Translational potential of mesenchymal stem cells in regenerative therapies for human diseases: challenges and opportunities

Advances in stem cell technology offer new possibilities for patients with untreated diseases and disorders. Stem cell-based therapy, which includes multipotent mesenchymal stem cells (MSCs), has recently become important in regenerative therapies. MSCs are multipotent progenitor cells that possess the ability to undergo in vitro self-renewal and differentiate into various mesenchymal lineages. MSCs have demonstrated promise in several areas, such as tissue regeneration, immunological modulation, anti-inflammatory qualities, and wound healing. Additionally, the development of specific guidelines and quality control methods that ultimately result in the therapeutic application of MSCs has been made easier by recent advancements in the study of MSC biology. This review discusses the latest clinical uses of MSCs obtained from the umbilical cord (UC), bone marrow (BM), or adipose tissue (AT) in treating various human diseases such as pulmonary dysfunctions, neurological disorders, endocrine/metabolic diseases, skin burns, cardiovascular conditions, and reproductive disorders. Additionally, this review offers comprehensive information regarding the clinical application of targeted therapies utilizing MSCs. It also presents and examines the concept of MSC tissue origin and its potential impact on the function of MSCs in downstream applications. The ultimate aim of this research is to facilitate translational research into clinical applications in regenerative therapies.

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.

Human Cord Blood Endothelial Progenitor Cells and Pregnancy Complications (Preeclampsia, Gestational Diabetes Mellitus, and Fetal Growth Restriction)

Hemangioblasts give rise to endothelial progenitor cells (EPCs), which also express the cell surface markers CD133 and c-kit. They may differentiate into the outgrowth endothelial cells (OECs) that control neovascularization in the developing embryo. According to numerous studies, reduced levels of EPCs in circulation have been linked to human cardiovascular disorders. Furthermore, preeclampsia and senescence have been linked to levels of EPCs produced from cord blood. Uncertainties surround how preeclampsia affects the way EPCs function. It is reasonable to speculate that preeclampsia may have an impact on the function of fetal EPCs during the in utero period; however, the present literature suggests that maternal vasculopathies, including preeclampsia, damage fetal circulation. Additionally, the differentiation potential and general activity of EPCs may serve as an indicator of the health of the fetal vascular system as they promote neovascularization and repair during pregnancy. Thus, the purpose of this review is to compare-through the assessment of their quantity, differentiation potency, angiogenic activity, and senescence-the angiogenic function of fetal EPCs obtained from cord blood for normal and pregnancy problems (preeclampsia, gestational diabetes mellitus, and fetal growth restriction). This will shed light on the relationship between the angiogenic function of fetal EPCs and pregnancy complications, which could have an effect on the management of long-term health issues like metabolic and cardiovascular disorders in offspring with abnormal vasculature development.

The effects of SDF-1 combined application with VEGF on femoral distraction osteogenesis in rats

Bone regeneration and mineralization can be achieved by means of distraction osteogenesis (DO). In the present study, we investigated the effect of stromal cell-derived factor 1 (SDF-1) and vascular endothelial growth factor (VEGF) on the new bone formation during DO in rats. Forty-eight Sprague-Dawley rats were randomized into four groups of 12 rats each. We established the left femoral DO model in rats and performed a mid-femoral osteotomy, which was fixed with an external fixator. DO was performed at 0.25 mm/12 h after an incubation period of 5 days. Distraction was continued for 10 days, resulting in a total of 5 mm of lengthening. After distraction, the solution was locally injected into the osteotomy site, once a day 1 ml for 1 week. One group received the solvent alone and served as the control, and the other three groups were treated with SDF-1, VEGF, and SDF-1with VEGF in an aqueous. Sequential X-ray radiographs were taken two weekly. The regeneration was monitored with the use of micro-CT analysis, mechanical testing, and histology. Radiographs showed accelerated regenerate ossification in the SDF-1, VEGF, and SDF-1 with the VEGF group, with a larger amount of new bone compared with the control group, especially SDF-1 with the VEGF group. Micro-CT analysis and biomechanical tests showed Continuous injection of the SDF-1, VEGF, and SDF-1 with VEGF during the consolidation period significantly increased bone mineral density bone volume, mechanical maximum loading, and bone mineralization of the regenerate. Similarly, the expression of osteogenic-specific genes, as determined by real-time polymerase chain reaction , was significantly higher in SDF-1 with the VEGF group than in the other groups. Histological examination revealed more new trabeculae in the distraction gap and more mature bone tissue for the SDF-1 with the VEGF group. SDF-1 and VEGF promote bone regeneration and mineralization during DO, and there is a synergistic effect between the SDF-1 and VEGF. It is possible to provide a new and feasible method to shorten the period of treatment of DO.

Endothelial progenitor cells in pregnancy-related diseases

Placental neovascularization plays a crucial role in fetomaternal circulation throughout pregnancy and is dysregulated in several pregnancy-related diseases, including preeclampsia, gestational diabetes mellitus, and fetal growth restriction. Endothelial progenitor cells (EPCs) are a heterogeneous population of cells that differentiate into mature endothelial cells, which influence vascular homeostasis, neovascularization, and endothelial repair. Since their discovery in 1997 by Asahara et al., the role of EPCs in vascular biology has garnered a lot of interest. However, although pregnancy-related conditions are associated with changes in the number and function of EPCs, the reported findings are conflicting. This review discusses the discovery, isolation, and classification of EPCs and highlights discrepancies between current studies. Overviews of how various diseases affect the numbers and functions of EPCs, the role of EPCs as biomarkers of pregnancy disorders, and the potential therapeutic applications involving EPCs are also provided.

The Impact of Modern Anti-Diabetic Treatment on Endothelial Progenitor Cells

Diabetes is one of the leading chronic diseases globally with a significant impact on mortality. This condition is associated with chronic microvascular and macrovascular complications caused by vascular damage. Recently, endothelial progenitor cells (EPCs) raised interest due to their regenerative properties. EPCs are mononuclear cells that are derived from different tissues. Circulating EPCs contribute to regenerating the vessel's intima and restoring vascular function. The ability of EPCs to repair vascular damage depends on their number and functionality. Diabetic patients have a decreased circulating EPC count and impaired EPC function. This may at least partially explain the increased risk of diabetic complications, including the increased cardiovascular risk in these patients. Recent studies have confirmed that many currently available drugs with proven cardiovascular benefits have beneficial effects on EPC count and function. Among these drugs are also medications used to treat different types of diabetes. This manuscript aims to critically review currently available evidence about the ways anti-diabetic treatment affects EPC biology and to provide a broader context considering cardiovascular complications. The therapies that will be discussed include lifestyle adjustments, metformin, sulphonylureas, gut glucosidase inhibitors, thiazolidinediones, dipeptidyl peptidase 4 inhibitors, glucagon-like peptide 1 receptor analogs, sodium-glucose transporter 2 inhibitors, and insulin.

A Multimodal Scaffold for SDF1 Delivery Improves Cardiac Function in a Rat Subacute Myocardial Infarct Model

Ischemic heart disease is one of the leading causes of death worldwide. The efficient delivery of therapeutic growth factors could counteract the adverse prognosis of post-myocardial infarction (post-MI). In this study, a collagen hydrogel that is able to load and appropriately deliver pro-angiogenic stromal cell-derived factor 1 (SDF1) was physically coupled with a compact collagen membrane in order to provide the suture strength required for surgical implantation. This bilayer collagen-on-collagen scaffold (bCS) showed the suitable physicochemical properties that are needed for efficient implantation, and the scaffold was able to deliver therapeutic growth factors after MI. In vitro collagen matrix biodegradation led to a sustained SDF1 release and a lack of cytotoxicity in the relevant cell cultures. In vivo intervention in a rat subacute MI model resulted in the full integration of the scaffold into the heart after implantation and biocompatibility with the tissue, with a prevalence of anti-inflammatory and pro-angiogenic macrophages, as well as evidence of revascularization and improved cardiac function after 60 days. Moreover, the beneficial effect of the released SDF1 on heart remodeling was confirmed by a significant reduction in cardiac tissue stiffness. Our findings demonstrate that this multimodal scaffold is a desirable matrix that can be used as a drug delivery system and a scaffolding material to promote functional recovery after MI.

The role of liver sinusoidal endothelial cells in liver remodeling after injury

Liver transplantation is the optimal treatment for patients with end-stage liver disease, metabolic liver diseases, and hepatic malignancies that are not amenable to resection. Hepatic ischemia-reperfusion injury (IRI) is the main problem in liver transplantation and liver resection, leading to parenchymal cell injury and organ dysfunction. The damage of liver sinusoidal endothelial cells (LSECs) is a critical event in IRI. LSECs work as an important regulating factor of liver regeneration after partial hepatectomy. This review primarily describes the mechanisms of LSECs injury in IRI and explores the roles of LSECs in liver regeneration, and briefly introduces the protective strategies targeting LSECs damaged in IRI.

Stem Cells in Regenerative Medicine

Stem cells constitute a set of undifferentiated cells with the capacity to differentiate into other cell types and to self-renew [...].

Homing of mRNA-Modified Endothelial Progenitor Cells to Inflamed Endothelium

Endothelial progenitor cells (EPCs) are one of the most important stem cells for the neovascularization of tissues damaged by ischemic diseases such as myocardial infarction, ischemic stroke, or critical limb ischemia. However, their low homing efficiency in the treatment of ischemic tissues limits their potential clinical applications. The use of synthetic messenger RNA (mRNA) for cell engineering represents a novel and promising technology for the modulation of cell behavior and tissue regeneration. To improve the therapeutic potential of EPCs, in this study, murine EPCs were engineered with synthetic mRNAs encoding C-X-C chemokine receptor 4 (CXCR4) and P-selectin glycoprotein ligand 1 (PSGL-1) to increase the homing and migration efficiency of EPCs to inflamed endothelium. Flow cytometric measurements revealed that the transfection of EPCs with CXCR4 and PSGL-1 mRNA resulted in increased expressions of CXCR4 and PSGL-1 on the cell surface compared with the unmodified EPCs. The transfection of EPCs with mRNAs did not affect cell viability. CXCR4-mRNA-modified EPCs showed significantly higher migration potential than unmodified cells in a chemotactic migration assay. The binding strength of the EPCs to inflamed endothelium was determined with single-cell atomic force microscopy (AFM). This showed that the mRNA-modified EPCs required a three-fold higher detachment force to be released from the TNF-α-activated endothelium than unmodified EPCs. Furthermore, in a dynamic flow model, significantly increased binding of the mRNA-modified EPCs to inflamed endothelium was detected. This study showed that the engineering of EPCs with homing factors encoding synthetic mRNAs increases the homing and migration potentials of these stem cells to inflamed endothelium. Thus, this strategy represents a promising strategy to increase the therapeutic potential of EPCs for the treatment of ischemic tissues.

Evaluation of circulating endothelial progenitor cells and the severity of transient ischemic attack

OBJECTIVE

Endothelial progenitor cells (EPCs) are believed to have a positive effect on maintaining endothelial integrity and participate in angiogenesis after cerebral infarction. Numerous studies have demonstrated that EPCs promote ischemic tissue angiogenesis after stroke. However, there are few studies on the relationship between the level of EPCs and the severity of transient ischemic attacks (TIAs). The current study aimed to investigate the evaluation value of EPCs and serum stromal cell-derived factor-1α(SDF-1α) levels on the severity of TIA.

METHODS

A total of 144 patients with TIA who had an onset of symptoms within 24 h were enrolled and divided into a high-risk TIA (HR-TIA) group (79 cases) and a nonhigh-risk TIA (NHR-TIA) group (65 cases). Clinical data of these patients were collected. Flow cytometry (FCM) was used to measure the number of CD34⁺KDR⁺ EPCs, and enzyme-linked immunosorbent assay (ELISA) was used to determine the concentration of serum SDF-1α and vascular endothelial growth factor (VEGF). Fifteen healthy donors were selected as the normal control (NC) group. Circulating EPCs were isolated by density gradient centrifugation from the first 15 patients in the high-risk TIA group, the nonhigh-risk TIA group, and the NC group. A colony assay and MTT assay were used to determine the proliferation ability of each group, and a Boyden chamber was used to determine the migration potential of EPCs.

RESULTS

Compared with the nonhigh-risk group, patients in the high-risk TIA group were older and had a higher incidence of hypertension and diabetes and stroke recurrence. Patients in the high-risk TIA group had higher levels of triglycerides, cholesterol, and low-density lipoprotein. However, there were no significant differences between the two groups in sex, time from onset to blood draw, smoking, body mass index, or homocysteine (P > 0.05). The number of circulating EPCs in the nonhigh-risk TIA group was higher than that in the high-risk TIA group (P < 0.01). SDF-1α and VEGF levels in the nonhigh-risk TIA group were lower than those in the high-risk TIA group (P < 0.01). The results of multivariate regression analysis showed that age, hypertension, diabetes, smoking, and SDF-1α were risk factors for high-risk TIA, and EPCs were protective factors for high-risk TIA. EPCs were separated and cultured for 72 h. Compared with the NC group, EPCs functions were weakened in the high-risk TIA group and nonhigh-risk TIA group (P < 0.05). Compared with the nonhigh-risk TIA group, EPC functions were decreased in the high-risk TIA group (P < 0.01).

CONCLUSION

CD34⁺KDR⁺ EPCs are protective factors for high-risk TIA. The number of circulating CD34⁺KDR⁺ EPCs and the concentration of SDF-1α have important clinical value in predicting the progression of TIA to high-risk TIA.

Vascular Stem/Progenitor Cells in Vessel Injury and Repair

Vascular repair upon vessel injury is essential for the maintenance of arterial homeostasis and function. Stem/progenitor cells were demonstrated to play a crucial role in regeneration and replenishment of damaged vascular cells during vascular repair. Previous studies revealed that myeloid stem/progenitor cells were the main sources of tissue regeneration after vascular injury. However, accumulating evidences from developing lineage tracing studies indicate that various populations of vessel-resident stem/progenitor cells play specific roles in different process of vessel injury and repair. In response to shear stress, inflammation, or other risk factors-induced vascular injury, these vascular stem/progenitor cells can be activated and consequently differentiate into different types of vascular wall cells to participate in vascular repair. In this review, mechanisms that contribute to stem/progenitor cell differentiation and vascular repair are described. Targeting these mechanisms has potential to improve outcome of diseases that are characterized by vascular injury, such as atherosclerosis, hypertension, restenosis, and aortic aneurysm/dissection. Future studies on potential stem cell-based therapy are also highlighted.

Regulation of endothelial progenitor cell functions during hyperglycemia: new therapeutic targets in diabetic wound healing

Diabetes is primarily characterized by hyperglycemia, and its high incidence is often very costly to patients, their families, and national economies. Unsurprisingly, the number and function of endothelial progenitor cells (EPCs) decrease in patients resulting in diabetic wound non-healing. As precursors of endothelial cells (ECs), these cells were discovered in 1997 and found to play an essential role in wound healing. Their function, number, and role in wound healing has been widely investigated. Hitherto, a lot of complex molecular mechanisms have been discovered. In this review, we summarize the mechanisms of how hyperglycemia affects the function and number of EPCs and how the affected cells impact wound healing. We aim to provide a complete summary of the relationship between diabetic hyperglycosemia, EPCs, and wound healing, as well as a better comprehensive platform for subsequent related research.