Circulating mouse Flk1+/c-Kit+/CD45- cells function as endothelial progenitors cells (EPCs) and stimulate the growth of human tumor xenografts

Endothelial progenitor cells control remodeling of uterine spiral arteries for the establishment of utero-placental circulation

Placental ischemia, resulting from inadequate remodeling of uterine spiral arteries, is a factor in the development of preeclampsia. However, the effect of endothelial progenitor cells that play a role in the vascular injury-repair program is largely unexplored during remodeling. Here, we observe that preeclampsia-afflicted uterine spiral arteries transition to a synthetic phenotype in vascular smooth muscle cells and characterize the regulatory axis in endothelial progenitor cells during remodeling in human decidua basalis. Excessive sEng, secreted by AMP-activated protein kinase (AMPK)-deficient endothelial progenitor cells through the inhibition of HO-1, damages residual endothelium and leads to the accumulation of extracellular matrix produced by vascular smooth muscle cells during remodeling, which is further confirmed by animal models. Collectively, our findings suggest that the impaired functionality of endothelial progenitor cells contributes to the narrowing of remodeled uterine spiral arteries, leading to reduced utero-placental perfusion. This mechanism holds promise in elucidating the pathogenesis of preeclampsia.

Osteohematology: To be or Notch to be

Osteohematology is an emerging research field that studies the crosstalk between hematopoietic and bone stromal cells, to elucidate the mechanisms of hematological and skeletal malignancies and diseases. The Notch is an evolutionary conserved developmental signaling pathway, with critical roles in embryonic development by controlling cell proliferation and differentiation. However, the Notch pathway is also critically involved in cancer initiation and progression, such as osteosarcoma, leukemia, and multiple myeloma. The Notch-mediated malignant cells dysregulate bone and bone marrow cells in the tumour microenvironment, resulting in disorders ranging from osteoporosis to bone marrow dysfunction. To date, the complex interplay of Notch signaling molecules in hematopoietic and bone stromal cells is still poorly understood. In this mini-review, we summarize the crosstalk between cells in bone and bone marrow and their influence under the Notch signaling pathway in physiological conditions and in tumour microenvironment.

Pulmonary endogenous progenitor stem cell subpopulation: Physiology, pathogenesis, and progress

Lungs are structurally and functionally complex organs consisting of diverse cell types from the proximal to distal axis. They have direct contact with the external environment and are constantly at risk of various injuries. Capable to proliferate and differentiate, pulmonary endogenous progenitor stem cells contribute to the maintenance of lung structure and function both under homeostasis and following injuries. Discovering candidate pulmonary endogenous progenitor stem cell types and underlying regenerative mechanisms provide insights into therapeutic strategy development for lung diseases. In this review, we reveal their compositions, roles in lung disease pathogenesis and injury repair, and the underlying mechanisms. We further underline the advanced progress in research approach and potential therapy for lung regeneration. We also demonstrate the feasibility and prospects of pulmonary endogenous stem cell transplantation for lung disease treatment.

TGF-β Signaling: From Tissue Fibrosis to Tumor Microenvironment

Transforming growth factor-β (TGF-β) signaling triggers diverse biological actions in inflammatory diseases. In tissue fibrosis, it acts as a key pathogenic regulator for promoting immunoregulation via controlling the activation, proliferation, and apoptosis of immunocytes. In cancer, it plays a critical role in tumor microenvironment (TME) for accelerating invasion, metastasis, angiogenesis, and immunosuppression. Increasing evidence suggest a pleiotropic nature of TGF-β signaling as a critical pathway for generating fibrotic TME, which contains numerous cancer-associated fibroblasts (CAFs), extracellular matrix proteins, and remodeling enzymes. Its pathogenic roles and working mechanisms in tumorigenesis are still largely unclear. Importantly, recent studies successfully demonstrated the clinical implications of fibrotic TME in cancer. This review systematically summarized the latest updates and discoveries of TGF-β signaling in the fibrotic TME.

Notch pathway activation mediated the senescence of endothelial progenitor cells in hypercholesterolemic mice

Hyperlipidemia is an important factor in the induction of cardiovascular diseases. However, the molecular mechanisms underlying the vascular injury involved in hyperlipidemia remains unclear. This study aimed to investigate the Notch pathway of endothelial progenitor cells (EPCs) in reendothelialization after vascular injury and to explore the involvement of Notch pathway in the senescence of EPCs. Our results demonstrated that high-fat diet (HFD) treatment inhibited reendothelialization after vascular injury in the mice model. In vitro studies showed that 7-ketocholesterol (7-keto) stimulation induced senescence in the isolated EPCs from mice. In addition, 7-keto markedly upregulated the protein expression of Notch1 and Delta-like ligand 4 and induced the transport of notch intracellular domain (NICD) to the nucleus. Mechanistically, treatment with NICD inhibitor reduced the senescence of the EPCs stimulated by cholesterol. In summary, our results showed that HFD treatment caused the disruption of reendothelialization after vascular injury in the mouse model. In vitro studies indicated that 7-keto-induced senescence of EPCs was at least via the activation of the Notch1 pathway. Mechanistic data suggested that 7-keto may activate the Notch1 pathway by regulating the generation and transport of NICD to the nucleus. Future investigations are warranted to confirm the role of Notch1 in the dysfunction of EPCs during obesity.

PEGylated immunoliposome-loaded endoglin single-chain antibody enhances anti-tumor capacity of porcine α1,3GT gene

Tumor could not be completely removed due to the absence of immune storm against tumor. The porcine α1,3 galactosyltransferase (α1,3 GT) induce the hyperacute rejection by synthesizing Galα1-3Galβ1-(3)4GlcNAc-R (αGal) on the surface of graft endothelial cells (ECs) during xeno-transplantation. This study aimed to develop anti-endoglin single-chain Fv fragments (ENG-scFv) conjugated PEGylated immunoliposomes (iLPs) to induce immune storm against tumor. Immune fluorescence was performed to detect the binding of ENG-scFv to human ENG, the endosomal/lysosomal escape of ENG-scFv-iLPs/α1,3 GT, and αGal expression in hENG-HEK293 cells. In vitro MTT assay was performed to measure ENG-scFv-iLPs/α1,3 GT cytotoxicity. NOD/SCID mouse born A549 tumor model was used to evaluate the therapeutic potency of ENG-scFv-iLPs/α1,3 GT. ENG-scFv-iLPs enabled efficient targeting delivery of α1,3 GT plasmid to ENG + tumors neovascular endothelial cells (TnECs), promoted endosomal/lysosomal escape due to the pH-sensitive ability, then synthesized carbohydrate epitope αGal on the surface of these cells to achieve the purpose of destroying the tumor. The mechanism of uptake for nanoparticles was energy driven, the clathrin-mediated endocytosis was the main endocytic pathway of the ENG-mAb-iLPs/α1,3 GT and lipid-raft-mediated of the ENG-scFv-iLPs/α1,3 GT, and macropinocytosis was also involved in intracellular entry. The inhibition of tumor angiogenesis and proliferation by ENG-scFv-iLPs/α1,3 GT was closely related to down-regulation of VEGF. Our findings establish an alternative therapeutic paradigm for scFv-conjugated nanoparticles to induce tumor cell apoptosis and inhibit tumor growth early. Such iLPs nanocarrier could efficiently release α1,3 GT to their distinct sites of action, where the endoglin + tumor neovascular endothelial cells (ENG + TnECs) exist, in a site-specific manner. Therefore, we believe that these scFv-targeted core-shell immunocomplexes are an important potential α1,3 GT delivery system for various solid tumor-targeted therapy.

Tumor endothelial cells as a potential target of metronomic chemotherapy

Drug resistance and toxic side effects are major therapeutic hurdles affecting cancer patients receiving conventional chemotherapy based on the maximum tolerated dose. Metronomic chemotherapy (MCT), a new therapeutic approach developed to avoid these problems generally, consists of the continuous administration of low-dose cytotoxic agents without extended intervals. This therapy targets the tumor microenvironment, rather than exerting a direct effect on tumor cells. As a result, the MCT regimen functionally impairs tumor endothelial cells and circulating endothelial progenitor cells, leading to tumor dormancy via anti-angiogenesis. Over the past 10 years, several studies have highlighted the impact of MCT on the tumor microenvironment and angiogenesis and demonstrated its potential as a switch from the pro-angiogenic to the anti-angiogenic state. However, the mechanisms of action are still obscure. Here, we systematically review the evidence regarding the anti-angiogenic potential of MCT as a crucial determinant of tumor dormancy and cancer treatment.

Genetic lineage tracing analysis of c-kit+ stem/progenitor cells revealed a contribution to vascular injury-induced neointimal lesions

AIMS

Accumulating evidence indicates the presence of vascular stem/progenitor cells that may play a role in endothelial repair and lesion formation in the injured artery, in which c-kit⁺ stem/progenitor cells have been reported to differentiate into endothelial and smooth muscle cells in vitro and in ischemic tissue. In this study, we investigated whether and how endogenous c-kit⁺ stem/progenitor cells contribute to vascular injury and neointima formation in vivo.

METHODS AND RESULTS

We created Kit-CreERxRosa26-RFP mice and performed genetic lineage tracing analysis of c-kit⁺ stem/progenitor cells in injury-induced neointima formation in vivo. We provide direct evidence that endogenous c-kit⁺ stem/progenitor cells minimally differentiate into endothelial or smooth muscle cells facilitating vascular repair, but predominantly generate monocytes/macrophages and granulocytes contributing to vascular immuno-inflammatory response to endothelial injury. Although c-kit⁺ cells reside in both bone marrow and vessel wall, bone marrow transplantation data indicate that bone marrow-derived c-kit⁺ cells are the main source for enhancing neointima formation. Furthermore, treatment of ACK2, a c-kit receptor antagonizer, attenuates neointimal hyperplasia after injury at least in part by depleting c-kit⁺ cells and their generated progeny.

CONCLUSIONS

c-kit⁺ stem/progenitor cells are not a main source for endothelial regeneration and smooth muscle accumulation of the large artery injury, but a plausible interventional approach to reduce vascular immuno-inflammatory response and subsequently to ameliorate vascular lesions.

CD31-labeled circulating endothelial cells as predictor in anlotinib-treated non-small-cell lung cancer: Analysis on ALTER-0303 study

Our previous studies revealed that the level of activated circulating endothelial cells (aCECs) was correlated with the progression‐free survival (PFS) in antiangiogenesis therapy. Anlotinib displayed affirmatory efficacies in several clinical trials of non‐small‐cell lung cancer (NSCLC). To find a marker predicting the efficacy of anlotinib treatment, we investigated the correlations of aCECs with PFS and overall survival (OS) in patients with NSCLC treated with anlotinib and the impact of anlotinib on human umbilical vascular endothelial cells (HUVECs). The blood samples of 78 patients with NSCLC were collected. aCECs were identified by flow cytometry as CD45⁻/CD146⁺/CD31⁺ cells and CD45⁻/CD146⁺/CD105⁺ cells. The mean value of baseline aCECs counts was defined as the cutoff value, according to which patients were divided into high and low baseline groups. Statistical correlation between high baseline CD31‐labeled aCECs counts and number of metastatic lesions (>3) (χ² = 4.905, P = .027) was analyzed. The 49 patients treated with anlotinib were stratified according to the ratio of minimal aCECs counts at any time points to baseline (aCECs min/baseline) as <1 or ≥1. Interestingly, the patients with aCECs (CD31) min/baseline <1 displayed longer PFS [HR = 0.439, 95%CI (0.211‐0.912), P = .023]. The biological effect of anlotinib on HUVECs was investigated using MTT assays. Western blot analysis was conducted to evaluate the expression levels of CD31 and CD105 under anlotinib treatment and the underlying mechanisms. In vitro experiment data demonstrated that CD31 exhibited more sensitive changes than CD105 under anlotinib treatment through PI3K‐AKT pathway. Thus, our finding provides new insights into the mechanism by which the CD31‐labeled aCECs are a more sensitive marker for predicting the efficiency of anlotinib treatment.

Proangiogenic effects of tumor cells on endothelial progenitor cells vary with tumor type in an in vitro and in vivo rat model

Endothelial progenitor cells (EPCs) contribute to neovascularization in tumors. However, the relationship of EPCs and tumor-induced angiogenesis still remains to be clarified. The present study aimed at investigating the influence of 4 different tumor types on angiogenic properties of EPCs in an in vitro and in vivo rat model. It could be demonstrated that in vitro proliferation, migration, and angiogenic abilities and genetic modifications of EPCs are controlled in a tumor-type-dependent manner. The proangiogenic effect of mammary carcinoma, osteosarcoma, and rhabdomyosarcoma cells was more pronounced compared to colon carcinoma cells. Coinjection of encapsulated tumor cells, especially mammary carcinoma cells, and EPCs in a rat model confirmed a contributing effect of EPCs in tumor vascularization. Cytokines secreted by tumors such as monocyte chemoattractant protein 1, macrophage inflammatory protein 2, and TNF-related apoptosis-inducing ligand play a pivotal role in the tumor cell-EPC interaction, leading to enhanced migration and angiogenesis. With the present study, we were able to decipher possible underlying mechanisms by which EPCs are stimulated by tumor cells and contribute to tumor vascularization. The present study will contribute to a better understanding of tumor-induced vascularization, thus facilitating the development of therapeutic strategies targeting tumor-EPC interactions.-An, R., Schmid, R., Klausing, A., Robering, J. W., Weber, M., Bäuerle, T., Detsch, R., Boccaccini, A. R., Horch, R. E., Boos, A. M., Weigand, A. Proangiogenic effects of tumor cells on endothelial progenitor cells vary with tumor type in an in vitro and in vivo rat model.

Vascular precursor cells in tissue injury repair

Vascular precursor cells include stem cells and progenitor cells giving rise to all mature cell types in the wall of blood vessels. When tissue injury occurs, local hypoxia and inflammation result in the generation of vasculogenic mediators which orchestrate migration of vascular precursor cells from their niche environment to the site of tissue injury. The intricate crosstalk among signaling pathways coordinates vascular precursor cell proliferation and differentiation during neovascularization. Establishment of normal blood perfusion plays an essential role in the effective repair of the injured tissue. In recent years, studies on molecular mechanisms underlying the regulation of vascular precursor cell function have achieved substantial progress, which promotes exploration of vascular precursor cell-based approaches to treat chronic wounds and ischemic diseases in vital organ systems. Verification of safety and establishment of specific guidelines for the clinical application of vascular precursor cell-based therapy remain major challenges in the field.

Effects of cryopreservation on excretory function, cellular adhesion molecules and vessel lumen formation in human umbilical vein endothelial cells

Cryopreservation is widely used in regenerative medicine for tissue preservation. In the present study, the effects of cryopreservation on excretory function, cellular adhesion molecules and vessel lumen formation in human umbilical vein endothelial cells (HUVECs) were investigated. After 0, 4, 8, 12 or 24 weeks of cryopreservation in liquid nitrogen, the HUVECs were thawed. The excretory functions markers (endothelin-1, prostaglandin E1, von Willebrand factor and nitric oxide) of HUVECs were measured by ELISA assay. The expression of intercellular adhesion molecule-1 (ICAM-1) in HUVECs was analyzed using flow cytometry. An angiogenesis assay was used to determine the angiogeneic capabilities of the thawed HUVECs. The results demonstrated that cryopreserved/thawed and recultivated HUVECs were unsuitable for tissue-engineered microvascular construction. Specifically, the excretory function of the cells was significantly decreased in the post-cryopreserved HUVECs at 24 weeks. In addition, the level of ICAM-1 in HUVECs was significantly upregulated from the fourth week of cryopreservation. Furthermore, the tube-like structure-forming potential was weakened with increasing cryopreservation duration, and the numbers of lumen and the length of the pipeline were decreased in the thawed HUVECs, in a time-dependent manner. In conclusion, the results of the present study revealed that prolonged cryopreservation may lead to HUVEC dysfunction and did not create stable cell lines for tissue-engineered microvascular construction.

Protective effect and mechanism of lycopene on endothelial progenitor cells (EPCs) from type 2 diabetes mellitus rats

Endothelial progenitor cells (EPCs), widely existing in bone marrow and peripheral blood, are involved in the repair of injured vascular endothelium and angiogenesis which are important to diabetic mellitus (DM) patients with vascular complications. The number and the function of EPCs are related to the advanced glycation end products (AGEs) generated in DM patients. Lycopene (Lyc) is an identified natural antioxidant that protects EPCs under the microenvironment of AGEs from damage. However, the underlying mechanism remains unclear. To investigate the effect of Lyc on EPCs, we isolated EPCs from DM rat bone marrow and determined cell proliferation, cell cycle,apoptosis and autophagy of EPCs. The present study showed that 10μg/mL Lyc improved cell proliferation and had low cytotoxicity in the presence of AGEs. In addition, Lyc rescued S phase of the cell cycle arrest, reduced apoptosis rate and decreased autophagic reaction including ROS and mitochondrial membrane potential (MMP) of EPCs. Moreover, Lyc combined use of autophagy inhibitors, 3-MA, had better protective effects. Taken together, our data suggests that Lyc promotes EPCs survival and protect EPCs from apoptosis and oxidative autophagy induced by AGEs, further remaining the number and function of EPCs. This study provides new insights into Lyc protective mechanism of AGEs-induced oxidative autophagy in EPCs from DM patients and offers a new therapy for DM vascular complications.

Endothelial progenitor cells from human fetal aorta cure diabetic foot in a rat model

OBJECTIVE

Recent evidence has suggested that circulating endothelial progenitor cells (EPCs) can repair the arterial endothelium during vascular injury. However, a reliable source of human EPCs is needed for therapeutic applications. In this study, we isolated human fetal aorta (HFA)-derived EPCs and analyzed the capacity of EPCs to differentiate into endothelial cells. In addition, because microvascular dysfunction is considered to be the major cause of diabetic foot (DF), we investigated whether transplantation of HFA-derived EPCs could treat DF in a rat model.

METHODS

EPCs were isolated from clinically aborted fetal aorta. RT-PCR, fluorescence-activated cell sorting, immunofluorescence, and an enzyme-linked immunosorbent assay were used to examine the expressions of CD133, CD34, CD31, Vascular Endothelial Growth Factor Receptor 2 (VEGFR2), von Willebrand Factor (vWF), and Endothelial Leukocyte Adhesion Molecule-1 (ELAM-1). Morphology and Dil-uptake were used to assess function of the EPCs. We then established a DF model by injecting microcarriers into the hind-limb arteries of Goto-Kakizaki rats and then transplanting the cultured EPCs into the ischemic hind limbs. Thermal infrared imaging, oxygen saturation apparatus, and laser Doppler perfusion imaging were used to monitor the progression of the disease. Immunohistochemistry was performed to examine the microvascular tissue formed by HFA-derived EPCs.

RESULTS

We found that CD133, CD34, and VEGFR2 were expressed by HFA-derived EPCs. After VEGF induction, CD133 expression was significantly decreased, but expression levels of vWF and ELAM-1 were markedly increased. Furthermore, tube formation and Dil-uptake were improved after VEGF induction. These observations suggest that EPCs could differentiate into endothelial cells. In the DF model, temperature, blood flow, and oxygen saturation were reduced but recovered to a nearly normal level following injection of the EPCs in the hind limb. Ischemic symptoms also improved. Injected EPCs were preferentially and durably engrafted into the blood vessels. In addition, anti-human CD31+-AMA+-vWF+ microvasculars were detected after transplantation of EPCs.

CONCLUSION

Early fetal aorta-derived EPCs possess strong self-renewal ability and can differentiate into endothelial cells. We demonstrated for the first time that transplanting HFA-derived EPCs could ameliorate DF prognosis in a rat model. These findings suggest that the transplantation of HFA-derived EPCs could serve as an innovative therapeutic strategy for managing DF.

Endothelial progenitor cells promote tumor growth and progression by enhancing new vessel formation

Tumor growth and progression require new blood vessel formation to deliver nutrients and oxygen for further cell proliferation and to create a neovascular network exit for tumor cell metastasis. Endothelial progenitor cells (EPCs) are a bone marrow (BM)-derived stem cell population that circulates in the peripheral circulation and homes to the tumor bed to participate in new blood vessel formation. In addition to structural support to nascent vessels, these cells can also regulate the angiogenic process by paracrine secretion of a number of proangiogenic growth factors and cytokines, thus playing a crucial role in tumor neovascularization and development. Inhibition of EPC-mediated new vessel formation may be a promising therapeutic strategy in tumor treatment. EPC-mediated neovascularization is a complex process that includes multiple steps and requires a series of cytokines and modulators, thus understanding the underlying mechanisms may provide anti-neovasculogenesis targets that may be blocked for the prevention of tumor development. The present review stresses the process and contribution of EPCs to the formation of new blood vessels in solid tumors, in an attempt to gain an improved understanding of the underlying cellular and molecular mechanisms involved, and to provide a potential effective therapeutic target for cancer treatment.

Caspase-1 mediates hyperlipidemia-weakened progenitor cell vessel repair

Caspase-1 activation senses metabolic danger-associated molecular patterns (DAMPs) and mediates the initiation of inflammation in endothelial cells. Here, we examined whether the caspase-1 pathway is responsible for sensing hyperlipidemia as a DAMP in bone marrow (BM)-derived Stem cell antigen-1 positive (Sca-(1+)) stem/progenitor cells and weakening their angiogenic ability. Using biochemical methods, gene knockout, cell therapy and myocardial infarction (MI) models, we had the following findings: 1) Hyperlipidemia induces caspase-1 activity in mouse Sca-(1+) progenitor cells in vivo; 2) Caspase-1 contributes to hyperlipidemia-induced modulation of vascular cell death-related gene expression in vivo; 3) Injection of Sca-1+ progenitor cells from caspase-1(-/-) mice improves endothelial capillary density in heart and decreases cardiomyocyte death in a mouse model of MI; and 4) Caspase-1(-/-) Sca-(1+) progenitor cell therapy improves mouse cardiac function after MI. Our results provide insight on how hyperlipidemia activates caspase-1 in Sca-(1+) progenitor cells, which subsequently weakens Sca-(1+) progenitor cell repair of vasculature injury. These results demonstrate the therapeutic potential of caspase-1 inhibition in improving progenitor cell therapy for MI.

Colony stimulating factor 1 receptor inhibition delays recurrence of glioblastoma after radiation by altering myeloid cell recruitment and polarization

BACKGROUND

Glioblastoma (GBM) may initially respond to treatment with ionizing radiation (IR), but the prognosis remains extremely poor because the tumors invariably recur. Using animal models, we previously showed that inhibiting stromal cell-derived factor 1 signaling can prevent or delay GBM recurrence by blocking IR-induced recruitment of myeloid cells, specifically monocytes that give rise to tumor-associated macrophages. The present study was aimed at determining if inhibiting colony stimulating factor 1 (CSF-1) signaling could be used as an alternative strategy to target pro-tumorigenic myeloid cells recruited to irradiated GBM.

METHODS

To inhibit CSF-1 signaling in myeloid cells, we used PLX3397, a small molecule that potently inhibits the tyrosine kinase activity of the CSF-1 receptor (CSF-1R). Combined IR and PLX3397 therapy was compared with IR alone using 2 different human GBM intracranial xenograft models.

RESULTS

GBM xenografts treated with IR upregulated CSF-1R ligand expression and increased the number of CD11b+ myeloid-derived cells in the tumors. Treatment with PLX3397 both depleted CD11b+ cells and potentiated the response of the intracranial tumors to IR. Median survival was significantly longer for mice receiving combined therapy versus IR alone. Analysis of myeloid cell differentiation markers indicated that CSF-1R inhibition prevented IR-recruited monocyte cells from differentiating into immunosuppressive, pro-angiogenic tumor-associated macrophages.

CONCLUSION

CSF-1R inhibition may be a promising strategy to improve GBM response to radiotherapy.

C-kit(+) resident cardiac stem cells improve left ventricular fibrosis in pressure overload

To investigate the effect of resident cardiac stem cells (RCSC) on myocardial remodeling, c-kit(+) RCSC were isolated from hearts of C57Bl/6-Tg (ACTb-EGFP)1Osb/J mice expressing green fluorescent protein and expanded in vitro. C57/Bl6N wildtype mice were subjected to transverse aortic constriction (TAC, 360 μm) or sham-operation. 5 × 10(5) c-kit(+) RCSC or c-kit(-) cardiac cells or cell buffer were infused intravenously 24 h post-surgery (n = 11-24 per group). Hypoxia-inducible factor-1α-mRNA in left ventricles of TAC mice was enhanced 24 h after transplantation. 35 days post-TAC, the density of c-kit(+) RCSC in the myocardium was increased by two-fold. Infusion of c-kit(+) resident cardiac stem cells post-TAC markedly reduced myocardial fibrosis and the expression of collagen Iα2 and connective tissue growth factor. Infusion of c-kit(-) cardiac cells did not ameliorate cardiac fibrosis. In parallel, expression of pro-angiogenic mediators (FGFb, IL-4, IL-6, TGFß, leptin) and the density of CD31(+) and CD31(+) GFP(+) endothelial cells were increased. Transplantation reduced brain- and atrial natriuretic peptides and the cardiomyocyte cross-sectional area. Infusion of c-kit(+) resident cardiac stem reduced the rate of apoptosis and oxidative stress in cardiomyocytes and in non-cardiomyocyte cells.

Safety and Pharmacokinetics of Lenvatinib in Patients with Advanced Hepatocellular Carcinoma

PURPOSE

To determine the maximum tolerable dose (MTD), safety, pharmacokinetics, pharmacodynamics, and preliminary efficacy of lenvatinib in patients with advanced hepatocellular carcinoma (HCC).

EXPERIMENTAL DESIGN

This multicenter, open-label, phase I, dose-escalation study included patients aged 20 to 80 years, refractory to standard therapy, and stratified by hepatic function measured using Child-Pugh (CP) scores: CP-A (score, 5-6) and CP-B (score, 7-8). Lenvatinib was administered continually once daily for 4-week cycles. MTD was defined as the maximum dose associated with ≤ 1 dose-limiting toxicity (DLT) occurring in cycle 1 among 6 patients.

RESULTS

In total, 20 patients (9 in CP-A and 11 in CP-B) were enrolled. The MTD was 12 and 8 mg once daily in CP-A and CP-B, respectively; DLTs included proteinuria, hepatic encephalopathy, and hyperbilirubinemia. The most common grade 3 toxicities included hypertension in CP-A and hyperbilirubinemia in CP-B. Lenvatinib plasma concentration at 24 hours after administration (C24 h) for 12 mg once daily was higher in patients with HCC than in patients with other solid tumors shown in a previous phase I study, but C24 h for 25 mg once daily lenvatinib was comparable. After lenvatinib treatment, the number of circulating endothelial and c-Kit(+) cells decreased and the levels of interleukin (IL)-6, IL10, granulocyte-colony stimulating factor, and vascular endothelial growth factor increased (P < 0.05). Partial responses were observed in 3 patients and tumor shrinkage occurred in 14 patients.

CONCLUSIONS

Lenvatinib (12 mg once daily) demonstrated preliminary efficacy with manageable toxicity and is the recommended dose for phase II studies in patients with HCC and CP-A.

The real face of endothelial progenitor cells - Circulating angiogenic cells as endothelial prognostic marker?

Endothelial progenitor cells (EPCs) have been extensively studied for almost 19 years now and were considered as a potential marker for endothelial regeneration ability. On the other hand, circulating endothelial cells (CEC) were studied as biomarker for endothelial injury. Yet, in the literature, there is also huge incoherency in regards to terminology and protocols used. This results in misleading conclusions on the role of so called "EPCs", especially in the clinical field. The discrepancies are mainly due to strong phenotypic overlap between EPCs and circulating angiogenic cells (CAC), therefore changes in "EPC" terminology have been suggested. Other factors leading to inconsistent results are varied definitions of the studied populations and the lack of universal data reporting, which could strongly affect data interpretation. The current review is focused on controversies concerning the use of "EPCs"/CAC and CEC as putative endothelial diagnostic markers.

Endothelial progenitor cells in tumor angiogenesis: another brick in the wall

Until 15 years ago, vasculogenesis, the formation of new blood vessels from undifferentiated cells, was thought to occur only during embryonic development. The discovery of circulating cells that are able to promote vascular regeneration and repair—the so-called endothelial progenitor cells (EPCs)—changed that, and EPCs have since been studied extensively. It is already known that EPCs include many subtypes of cells that play a variety of roles in promoting vascular growth. Some EPCs are destined to differentiate into endothelial cells, whereas others are capable of promoting and sustaining angiogenesis through paracrine mechanisms. Vasculogenesis and angiogenesis might constitute complementary mechanisms for postnatal neovascularization, and EPCs could be at the core of this process. Although the formation of new blood vessels from preexisting vasculature plays a beneficial role in many physiological processes, such as wound healing, it also contributes to tumor growth and metastasis. However, many aspects of the role played by EPCs in tumor angiogenesis remain unclear. This review aims to address the main aspects of EPCs differentiation and certain characteristics of their main function, especially in tumor angiogenesis, as well as the potential clinical applications.