G-CSF and HGF: combination of vasculogenesis and angiogenesis synergistically improves recovery in murine hind limb ischemia

Role of Adipose-Derived Mesenchymal Stem Cells in Bone Regeneration

Bone regeneration involves multiple factors such as tissue interactions, an inflammatory response, and vessel formation. In the event of diseases, old age, lifestyle, or trauma, bone regeneration can be impaired which could result in a prolonged healing duration or requiring an external intervention for repair. Currently, bone grafts hold the golden standard for bone regeneration. However, several limitations hinder its clinical applications, e.g., donor site morbidity, an insufficient tissue volume, and uncertain post-operative outcomes. Bone tissue engineering, involving stem cells seeded onto scaffolds, has thus been a promising treatment alternative for bone regeneration. Adipose-derived mesenchymal stem cells (AD-MSCs) are known to hold therapeutic value for the treatment of various clinical conditions and have displayed feasibility and significant effectiveness due to their ease of isolation, non-invasive, abundance in quantity, and osteogenic capacity. Notably, in vitro studies showed AD-MSCs holding a high proliferation capacity, multi-differentiation potential through the release of a variety of factors, and extracellular vesicles, allowing them to repair damaged tissues. In vivo and clinical studies showed AD-MSCs favoring better vascularization and the integration of the scaffolds, while the presence of scaffolds has enhanced the osteogenesis potential of AD-MSCs, thus yielding optimal bone formation outcomes. Effective bone regeneration requires the interplay of both AD-MSCs and scaffolds (material, pore size) to improve the osteogenic and vasculogenic capacity. This review presents the advances and applications of AD-MSCs for bone regeneration and bone tissue engineering, focusing on the in vitro, in vivo, and clinical studies involving AD-MSCs for bone tissue engineering.

Nanoceria-GO-intercalated multicellular spheroids revascularize and salvage critical ischemic limbs through anti-apoptotic and pro-angiogenic functions

Critical limb ischemia (CLI) is a serious form of peripheral arterial disease that involves severe blockage of blood flow in lower extremities, often leading to foot necrosis and limb loss. Lack of blood flow and high pro-inflammation with overproduced reactive oxygen species (ROS) in CLI aggravate the degenerative events. Among other therapies, cell delivery is considered potential for restoring regenerative capacity, and preservation of cell survival under high oxidative stress has been challenging and prerequisite to harness cellular functions. Here, we introduce a multicellular delivery system that is intercalated with nanoceria-decorated graphene oxide (CeGO), which is considered to have high ROS scavenging ability while providing cell-matrix interaction signals. The CeGO nano-microsheets (8-nm-nanoceria/0.9-μm-GO) incorporated in HUVEC/MSC (7/3) could form cell-material hybrid spheroids mediated by cellular contraction. Under in vitro oxidative-stress-challenge with H₂O₂, the CeGO-intercalation enhanced the survival and anti-apoptotic capacity of cellular spheroids. Pro-angiogenic events of cellular spheroids, including cell sprouting and expression of angiogenic markers (HIF1α, VEGF, FGF2, eNOS) were significantly enhanced by the CeGO-intercalation. Proteomics analysis also confirmed substantial up-regulation of a series of angiogenesis-related secretome molecules. Such pro-angiogenic events with CeGO-intercalation were proven to be mediated by the APE/Ref-1 signaling pathway. When delivered to ischemic hindlimb in mice, the CeGO-cell spheroids could inhibit the accumulation of in vivo ROS rapidly, preserving high cell survival rate (cells were more proliferative and less apoptotic vs. those in cell-only spheroids), and up-regulated angiogenic molecular expressions. Monitoring over 28 days revealed significantly enhanced blood reperfusion and tissue recovery, and an ultimate limb salvage with the CeGO-cell delivery (∼60% salvaged vs. ∼29% in cell-only delivery vs. 0% in ischemia control). Together, the CeGO intercalated in HUVEC/MSC delivery is considered a potential nano-microplatform for CLI treatment, by scavenging excessive ROS and enhancing transplanted cell survival, while stimulating angiogenic events, which collectively help revascularization and tissue recovery, salvaging critical ischemic limbs.

Liver Regeneration by Hematopoietic Stem Cells: Have We Reached the End of the Road?

The liver is the organ with the highest regenerative capacity in the human body. However, various insults, including viral infections, alcohol or drug abuse, and metabolic overload, may cause chronic inflammation and fibrosis, leading to irreversible liver dysfunction. Despite advances in surgery and pharmacological treatments, liver diseases remain a leading cause of death worldwide. To address the shortage of donor liver organs for orthotopic liver transplantation, cell therapy in liver disease has emerged as a promising regenerative treatment. Sources include primary hepatocytes or functional hepatocytes generated from the reprogramming of induced pluripotent stem cells (iPSC). Different types of stem cells have also been employed for transplantation to trigger regeneration, including hematopoietic stem cells (HSCs), mesenchymal stromal cells (MSCs), endothelial progenitor cells (EPCs) as well as adult and fetal liver progenitor cells. HSCs, usually defined by the expression of CD34 and CD133, and MSCs, defined by the expression of CD105, CD73, and CD90, are attractive sources due to their autologous nature, ease of isolation and cryopreservation. The present review focuses on the use of bone marrow HSCs for liver regeneration, presenting evidence for an ongoing crosstalk between the hematopoietic and the hepatic system. This relationship commences during embryogenesis when the fetal liver emerges as the crossroads between the two systems converging the presence of different origins of cells (mesoderm and endoderm) in the same organ. Ample evidence indicates that the fetal liver supports the maturation and expansion of HSCs during development but also later on in life. Moreover, the fact that the adult liver remains one of the few sites for extramedullary hematopoiesis—albeit pathological—suggests that this relationship between the two systems is ongoing. Can, however, the hematopoietic system offer similar support to the liver? The majority of clinical studies using hematopoietic cell transplantation in patients with liver disease report favourable observations. The underlying mechanism—whether paracrine, fusion or transdifferentiation or a combination of the three—remains to be confirmed.

Gene therapy for critical limb ischemia: Per aspera ad astra

Peripheral artery diseases remain a serious public health problem. Although there are many traditional methods for their treatment using conservative therapeutic techniques and surgery, gene therapy is an alternative and potentially more effective treatment option especially for "no option" patients. This review treats the results of many years of research and application of gene therapy as an example of treatment of patients with critical limb ischemia. Data on successful and unsuccessful attempts to use this technology for treating this disease are presented. Trends in changing the paradigm of approaches to therapeutic angiogenesis are noted: from viral vectors to non-viral vectors, from gene transfer to the whole organism to targeted transfer to cells and tissues, from single gene use to combination of genes; from DNA therapy to RNA therapy, from in vivo therapy to ex vivo therapy.

Adipose-Derived Stem Cells Secretome and Its Potential Application in "Stem Cell-Free Therapy"

Adipose-derived stem cells (ASCs) secrete many cytokines, proteins, growth factors, and extracellular vesicles with beneficial outcomes that can be used in regenerative medicine. It has great potential, and the development of new treatment strategies using the ASCs secretome is of global interest. Besides cytokines, proteins, and growth factors, the therapeutic effect of secretome is hidden in non-coding RNAs such as miR-21, miR-24, and miR-26 carried via exosomes secreted by adequate cells. The whole secretome, including ASC-derived exosomes (ASC-exos) has been proven in many studies to have immunomodulatory, proangiogenic, neurotrophic, and epithelization activity and can potentially be used for neurodegenerative, cardiovascular, respiratory, inflammatory, and autoimmune diseases as well as wound healing treatment. Due to limitations in the use of stem cells in cell-based therapy, its secretome with emphasis on exosomes seems to be a reasonable and safer alternative with increased effectiveness and fewer side effects. Moreover, the great advantage of cell-free therapy is the possibility of biobanking the ASCs secretome. In this review, we focus on the current state of knowledge on the use of the ASCs secretome in stem cell-free therapy.

A novel model of chronic limb ischemia to therapeutically evaluate the angiogenic effects of drug candidates

Critical limb ischemia (CLI) is a severe state of peripheral artery disease with high unmet clinical needs. Further, there are no effective treatment options for patients with CLI. Based on preclinical study results, predicting the clinical efficacy of CLI treatments is typically difficult because conventional hindlimb ischemia (HLI) rodent models display spontaneous recovery from ischemia, which is not observed in patients with CLI. Therefore, we aimed to develop a novel chronic and severe HLI model to properly evaluate the therapeutic effects of drug candidates for CLI. Severe HLI mice (Type-N) were generated by increasing the excised area of blood vessels in a hindlimb of NOG mice. Immunohistochemistry and gene expression analysis at 9 wk after the Type-N operation revealed that the ischemic limb was in a steady state with impaired angiogenesis, like that observed in patients with CLI. We did selection of chronic Type-N mice based on the number of necrotic nails and blood flow rate at 2 wk after surgery because some Type-N mice showed mild symptoms. Therapeutic treatment with cilostazol, which is used for intermittent claudication, did not restore blood flow in chronic Type-N mice. In contrast, therapeutic transplantation of pericytes and vascular endothelial cells, which can form new blood vessels in vivo, significantly improved blood flow in a subset of Type-N mice. These findings suggest that this novel chronic and severe HLI model may be a valuable standard animal model for therapeutic evaluation of the angiogenic effects of CLI drug candidates.NEW & NOTEWORTHY We developed a chronic and severe hindlimb ischemia (HLI) mouse model for preclinical research on critical limb ischemia (CLI). This model partially reflects human CLI pathology in that it does not show spontaneous restoration of blood flow or expression of angiogenic genes in the ischemic limb. This novel model may be valuable for therapeutic evaluation of the angiogenic effects of CLI drug candidates.

The impact of wavelengths of LED light-therapy on endothelial cells

Low level light therapy receives increasing interest in the fields of tissue regeneration and wound healing. Several in vivo studies demonstrated the positive effects of LLLT on angiogenesis. This study aimed to investigate the underlying properties in vitro by comparing the effects of light therapy by light emitting diodes of different wavelengths on endothelial cells in vitro. Human umbilical vein endothelial cells were treated with either 475 nm, 516 nm or 635 nm light. Control cells were not illuminated. 2D proliferation was quantified by manual counting. HUVEC migration was analyzed by performing a 2D wound scratch assay and a 3D bead assay. The influence of LLLT on early vasculogenic events was determined in a 3D fibrin co-culture model with adipose-derived stem cells. Stimulation with both red and green pulsed LED light significantly increased HUVEC proliferation and 3D migration. Moreover, HUVEC showed increased 2D migration potential with green light stimulation. The treatment with blue light was ineffective. Several parameters showed that green light was even more potent to stimulate proliferation and migration of endothelial cells than clinically well-established red light therapy. Further studies have to focus on intracellular mechanisms induced by different wavelengths in order to optimize this promising therapy in tissue regeneration.

Genetically modified human placenta‑derived mesenchymal stem cells with FGF‑2 and PDGF‑BB enhance neovascularization in a model of hindlimb ischemia

Ischemic diseases represent a challenging worldwide health burden. The current study investigated the therapeutic potential of genetically modified human placenta‑derived mesenchymal stem cells (hPDMSCs) with basic fibroblast growth factor (FGF2) and platelet‑derived growth factor‑BB (PDGF‑BB) genes in hindlimb ischemia. Mesenchymal stem cells obtained from human term placenta were transfected ex vivo with adenoviral bicistronic vectors carrying the FGF2 and PDGF‑BB genes (Ad‑F‑P). Unilateral hindlimb ischemia was surgically induced by excision of the right femoral artery in New Zealand White rabbits. Ad‑F‑P genetically modified hPDMSCs, Ad‑null (control vector)‑modified hPDMSCs, unmodified hPDMSCs or media were intramuscularly implanted into the ischemic limbs 7 days subsequent to the induction of ischemia. Four weeks after cell therapy, angiographic analysis revealed significantly increased collateral vessel formation in the Ad‑F‑P‑hPDMSC group compared with the control group. Histological examination revealed markedly increased capillary and arteriole density in the Ad‑F‑P‑hPDMSC group. The xenografted hPDMSCs survived in the ischemic tissue for at least 4 weeks subsequent to cell therapy. The current study demonstrated that the combination of hPDMSC therapy with FGF2 and PDGF‑BB gene therapy effectively induced collateral vessel formation and angiogenesis, suggesting a novel strategy for therapeutic angiogenesis.

From regenerative dentistry to regenerative medicine: progress, challenges, and potential applications of oral stem cells

Adult mesenchymal stem cells (MSCs) and epithelial stem cells play essential roles in tissue repair and self-healing. Oral MSCs and epithelial stem cells can be isolated from adult human oral tissues, for example, teeth, periodontal ligament, and gingiva. Cocultivated adult oral epithelial stem cells and MSCs could represent some developmental events, such as epithelial invagination and tubular structure formation, signifying their potentials for tissue regeneration. Oral epithelial stem cells have been used in regenerative medicine over 1 decade. They are able to form a stratified cell sheet under three-dimensional culture conditions. Both experimental and clinical data indicate that the cell sheets can not only safely and effectively reconstruct the damaged cornea in humans, but also repair esophageal ulcer in animal models. Oral MSCs include dental pulp stem cells (DPSCs), stem cells from exfoliated deciduous teeth (SHED), stem cells from apical papilla (SCAP), periodontal ligament stem cells (PDLSCs), and mesenchymal stem cells from gingiva (GMSCs). They are widely applied in both regenerative dentistry and medicine. DPSCs, SHED, and SCAP are able to form dentin–pulp complex when being transplanted into immunodeficient animals. They have been experimentally used for the regeneration of dental pulp, neuron, bone muscle and blood vessels in animal models and have shown promising results. PDLSCs and GMSCs are demonstrated to be ideal cell sources for repairing the damaged tissues of periodontal, muscle, and tendon. Despite the abovementioned applications of oral stem cells, only a few human clinical trials are now underway to use them for the treatment of certain diseases. Since clinical use is the end goal, their true regenerative power and safety need to be further examined.

Novel therapeutic strategies for cardioprotection

The morbidity and mortality from ischemic heart disease (IHD) remain significant worldwide. The treatment for acute myocardial infarction has improved over the past decades, including early reperfusion of occluded coronary arteries. Although it is essential to re-open the artery as soon as possible, paradoxically this leads to additional myocardial injury, called acute ischemia-reperfusion injury (IRI), for which currently no effective therapy is available. Therefore, novel therapeutic strategies are required to protect the heart from acute IRI in order to reduce myocardial infarction size, preserve cardiac function and improve clinical outcomes in patients with IHD. In this review article, we will first outline the pathophysiology of acute IRI and review promising therapeutic strategies for cardioprotection. These include novel aspects of mitochondrial function, epigenetics, circadian clocks, the immune system, microvesicles, growth factors, stem cell therapy and gene therapy. We discuss the therapeutic potential of these novel cardioprotective strategies in terms of pharmacological targeting and clinical application.

NGF promotes hemodynamic recovery in a rabbit hindlimb ischemic model through trkA- and VEGFR2-dependent pathways

Nerve growth factor (NGF) has been reported to play an important role in physiological and pathological angiogenesis. Based on these observations, we hypothesized that NGF may induce the formation of functional blood vessels in a hindlimb ischemic rabbit model. Hindlimb ischemia was induced in 34 rabbits bilaterally by endovascular embolization of femoral arteries. On the 7th, 14th, and 20th postembolization days, NGF was injected intramuscularly, in 1 ischemic limb, and vehicle was injected in the contralateral control limb. On the 40th day, newly developed collateral vessels (diameter >500 μm) were quantified by transauricular intraarterial subtraction angiography. Perfusion analysis of an in vivo dynamic computed tomography study was performed to the limbs to investigate the hemodynamic recovery of the distal ischemic tissues. Functional estimation of limb perfusion showed a statistically significant increase of blood flow and blood volume for NGF. However, the increase of the collateral vessels was not detectable angiographically, providing evidence for the existence of a NGF-stimulated capillary angiogenic network but not increase of arteriogenesis. The combination of NGF with either tropomyosin-related kinase type A or vascular endothelial growth factor receptor 2 antagonists abolished the NGF-induced hemodynamic recovery. These findings provide new insights into understanding the involvement of NGF in vascular formation and its applications in therapeutic angiogenesis.

Hypoxia-inducible factors in human pulmonary arterial hypertension: a link to the intrinsic myeloid abnormalities

Pulmonary arterial hypertension (PAH) is a proliferative vasculopathy characterized by high circulating CD34(+)CD133(+) proangiogenic progenitors, and endothelial cells that have pathologic expression of hypoxia-inducible factor 1 α (HIF-1α). Here, CD34(+)CD133(+) progenitor cell numbers are shown to be higher in PAH bone marrow, blood, and pulmonary arteries than in healthy controls. The HIF-inducible myeloid-activating factors erythropoietin, stem cell factor (SCF), and hepatocyte growth factor (HGF) are also present at higher than normal levels in PAH blood, and related to disease severity. Primary endothelial cells harvested from human PAH lungs produce greater HGF and progenitor recruitment factor stromal-derived factor 1 α (SDF-1α) than control lung endothelial cells, and thus may contribute to bone marrow activation. Even though PAH patients had normal numbers of circulating blood elements, hematopoietic alterations in myeloid and erythroid lineages and reticulin fibrosis identified a subclinical myeloproliferative process. Unexpectedly, evaluation of bone marrow progenitors and reticulin in nonaffected family members of patients with familial PAH revealed similar myeloid abnormalities. Altogether, the results show that PAH is linked to myeloid abnormalities, some of which may be related to increased production of HIF-inducible factors by diseased pulmonary vasculature, but findings in nonaffected family suggest myeloid abnormalities may be intrinsic to the disease process.

Neovascularization in a mouse model via stem cells derived from human fetal amniotic membranes

In this study, we evaluated the effect of culture-expanded mesenchymal stem cells (MSCs), derived from amniotic membranes, on neovascularization and blood flow, in an animal model of limb ischemia in immune-deficient mice. MSCs were cultured from human amniotic membranes by collagenase digestion. Human amniotic mesenchymal stem cells (hAMSCs) were administered intramuscularly at three different sites of the ischemic leg whose femoral vessels were ligated. After 4 weeks of culture, a population of homogeneous mesenchymal cells was isolated from the human amniotic membranes after confluence was reached. We performed three different groups of mice model [controls, hAMSCs, conditioned media from the hAMSCs (hAMSCs-CM)]. The blood flow recovery in the hindlimb ischemia model was significantly higher in the hAMSC-transplanted group than in the control group. Moreover, hAMSCs-CM significantly improved the cutaneous blood flow. The histological examination showed that red fluorescence (CM-DiI)-labeled hAMSCs was detected in the interstitial tissues between the muscle fibers 2 weeks after transplantation. The results of this study showed that hAMSCs may be an attractive, alternative source of progenitor or stem cells for basic research as well as clinical applications.

Targeting stem cell niches and trafficking for cardiovascular therapy

Regenerative cardiovascular medicine is the frontline of 21st-century health care. Cell therapy trials using bone marrow progenitor cells documented that the approach is feasible, safe and potentially beneficial in patients with ischemic disease. However, cardiovascular prevention and rehabilitation strategies should aim to conserve the pristine healing capacity of a healthy organism as well as reactivate it under disease conditions. This requires an increased understanding of stem cell microenvironment and trafficking mechanisms. Engagement and disengagement of stem cells of the osteoblastic niche is a dynamic process, finely tuned to allow low amounts of cells move out of the bone marrow and into the circulation on a regular basis. The balance is altered under stress situations, like tissue injury or ischemia, leading to remarkably increased cell egression. Individual populations of circulating progenitor cells could give rise to mature tissue cells (e.g. endothelial cells or cardiomyocytes), while the majority may differentiate to leukocytes, affecting the environment of homing sites in a paracrine way, e.g. promoting endothelial survival, proliferation and function, as well as attenuating or enhancing inflammation. This review focuses on the dynamics of the stem cell niche in healthy and disease conditions and on therapeutic means to direct stem cell/progenitor cell mobilization and recruitment into improved tissue repair.

Therapeutic angiogenesis by transplantation of induced pluripotent stem cell-derived Flk-1 positive cells

Background

Induced pluripotent stem (iPS) cells are the novel stem cell population induced from somatic cells. It is anticipated that iPS will be used in the expanding field of regenerative medicine. Here, we investigated whether implantation of fetal liver kinase-1 positive (Flk-1⁺) cells derived from iPS cells could improve angiogenesis in a mouse hind limb model of ischemia.

Results

Flk-1⁺ cells were induced from iPS cells after four to five days of culture. Hind limb ischemia was surgically induced and sorted Flk-1⁺ cells were directly injected into ischemic hind limbs of athymic nude mice. Revascularization of the ischemic hind limb was accelerated in mice that were transplanted with Flk-1⁺ cells compared with control mice, which were transplanted with vehicle, as evaluated by laser Doppler blood flowmetry. Transplantation of Flk-1⁺ cells also increased expression of VEGF mRNA in ischemic tissue compared to controls.

Conclusions

Direct local implantation of iPS cell-derived Flk-1⁺ cells would salvage tissues from ischemia. These data indicate that iPS cells could be valuable in the therapeutic induction of angiogenesis.

Granulocyte colony-stimulating factor activating HIF-1alpha acts synergistically with erythropoietin to promote tissue plasticity

Stroke and peripheral limb ischemia are serious clinical problems with poor prognosis and limited treatment. The cytokines erythropoietin (EPO) and granulocyte-colony stimulating factor (G-CSF) have been used to induce endogenous cell repair and angiogenesis. Here, we demonstrated that the combination therapy of EPO and G-CSF exerted synergistic effects on cell survival and functional recovery from cerebral and peripheral limbs ischemia. We observed that even under normoxic conditions, G-CSF activates hypoxia-inducible factor-1alpha (HIF-1alpha), which then binds to the EPO promoter and enhances EPO expression. Serum EPO level was significantly increased by G-CSF injection, with the exception of Tg-HIF-1alpha(+f/+f) mice. The neuroplastic mechanisms exerted by EPO combined with G-CSF included enhanced expression of the antiapoptotic protein of Bcl-2, augmented neurotrophic factors synthesis, and promoted neovascularization. Further, the combination therapy significantly increased homing and differentiation of bone marrow stem cells (BMSCs) and intrinsic neural progenitor cells (INPCs) into the ischemic area. In summary, EPO in combination with G-CSF synergistically enhanced angiogenesis and tissue plasticity in ischemic animal models, leading to greater functional recovery than either agent alone.

CD31+ T cells represent a functionally distinct vascular T cell phenotype

In contrast to CD3(+)/CD31(-) cells, CD3(+)/CD31(+) cells aid in endothelial repair and revascularization. There are limited data regarding the functional differences between circulating CD3(+)/CD31(+) and CD3(+)/CD31(-) cells that may contribute to their divergent cardiovascular effects. The aim of the present study was to characterize functional differences between CD3(+)/CD31(+) and CD3(+)/CD31(-) cells. To address this aim, migratory capacity, proangiogenic cytokine release and apoptotic susceptibility of CD3(+)/CD31(+) and CD3(+)/CD31(-) cells were determined. Human CD3(+)/CD31(+) and CD3(+)/CD31(-)cells from peripheral blood were isolated using magnetic-activated cell sorting. CD3(+)/CD31(+) cells demonstrated significantly higher ( approximately 60%) migratory capacity to the chemokines SDF-1alpha (655+/-99 vs. 273+/-54 AU) and VEGF (618+/-99 vs. 259+/-57 AU) vs. CD3(+)/CD31(-) cells. Release of angiogenic cytokines G-CSF, interleukin-8 and matrix metallopeptidase-9 were all approximately 100% higher (P<0.05) in CD3(+)/CD31(+) than CD3(+)/CD31(-) cells. CD3(+)/CD31(+) cells exhibited significantly higher intracellular concentrations of active caspase-3 (2.61+/-0.60 vs. 0.34+/-0.09 ng/mL) and cytochrome-c (21.8+/-1.4 vs. 13.7+/-1.0 ng/mL). In summary, CD3(+)/CD31(+) cells have greater migratory and angiogenic cytokine release capacity, but are more susceptible to apoptosis compared with CD3(+)/CD31(-) cells. Enhanced migratory capacity and angiogenic cytokine release may contribute to the vasculogenic properties of this unique T cell subpopulation.

Hepatocyte growth factor and granulocyte colony-stimulating factor form a combined neovasculogenic therapy for ischemic cardiomyopathy

BACKGROUND

Myocardial infarction (MI) is a significant cause of heart failure. Current therapies are limited and, therefore, the development of novel revascularization methods is potentially important. We investigated whether hepatocyte growth factor (HGF), expressed by genetically modified mesenchymal stromal cells (MSC), in combination with granulocyte colony-stimulating factor (G-CSF), exhibited a synergistic therapeutic benefit, as measured 8 weeks after MI induction in a rat model.

METHODS

Four weeks after MI, rats were randomly divided into a control group (n=11), HGF group (Adenovirus vector carrying human HGF (Ad-HGF)-transfected MSC transplanted into the infarct zone; n=11), G-CSF group (intraperitoneal injection with G-CSF; n=11), and HGF + G-CSF group (Ad-HGF-transfected MSC transplanted into the infarct zone and intraperitoneal injection with G-CSF; n=11). Four weeks later, hearts were analyzed for endothelial cell density and angiogenesis, ventricular geometry, myocardial function and levels of VCAM-1 and MMP-9 protein.

RESULTS

The HGF + G-CSF group exhibited improved left ventricular systolic and diastolic function and experienced less adverse ventricular remodeling, as manifested by decreased left ventricular dilatation and increased border zone wall thickness. Angiogenesis was significantly enhanced in HGF + G-CSF rats by inducing the proliferation of endothelial cells. Furthermore, HGF induced expression of VCAM-1, and HGF treatment together with G-CSF synergistically stimulated MMP-9 expression in ischemic hearts.

DISCUSSION

The combination of G-CSF and HGF exhibited a significant synergistic effect and enhanced myocardial endothelial density, angiogenesis, geometric preservation and heart function in an ischemic cardiomyopathy model.

Transfection of HGF gene enhances endothelial progenitor cell (EPC) function and improves EPC transplant efficiency for balloon-induced arterial injury in hypercholesterolemic rats

Risk factors for coronary heart disease can reduce the number of endothelial progenitor cells (EPCs) and impair EPC function, thus hindering their utility in the treatment of cardiovascular diseases. In the present study, we began exploring the feasibility of genetic modification of EPCs with hepatocyte growth factor (HGF) to counter the effects of these risk factors and enhance the biological functions of EPCs. The effects of HGF transfection on proliferation, migration and angiogenesis of EPCs were investigated. Additionally, the role of ERK1/2 in this process was evaluated through the observation of ERK1/2 and ERK1/2 phosphorylation as well as by pharmacological analysis. Finally, we evaluated the effect of HGF-transfected EPCs (HGF-EPCs) on neointima formation after balloon-induced arterial injury in hypercholesterolemic rats. Our data showed that EPCs transfected with the HGF gene released high levels of soluble HGF protein, which were maintained for at least nine days. Transfection with HGF also enhanced the proliferative, migratory and angiogenic capabilities of EPCs, and promoted the activation of ERK1/2 without affecting its expression. ERK1/2 blockade by the chemical inhibitor PD98059 partially inhibited these effects. In hypercholesterolemic rats, HGF-EPCs homed to the site of vascular injury at a significantly higher rate than did EPCs without the exogenous HGF gene. Furthermore, systemically applied HGF-EPCs were more effective in decreasing neointima formation and increasing re-endothelialization. These data suggest that gene delivery combined with EPC transplant may be a practical and promising therapy for the prevention of neointimal formation after vascular injury.

A thin carbon-fiber web as a scaffold for bone-tissue regeneration

Due to the rapid progress being made in tissue regeneration therapy, biomaterials used as scaffolds are expected to play an important role in future clinical application. We report the development of a 3D web (sheet) consisting of high-purity carbon fibers in a nanoscale structure. When the thin carbon-fiber web (TCFW) and recombinant human bone morphogenetic protein 2 (rhBMP-2) composite is implanted in the murine back muscle, new ectopic bone is formed, and the values of the bone mineral content and bone mineral density are significantly higher than those obtained with a collagen sheet. Observation of the interface between the carbon fibers and bone matrix reveal that the fibers are directly integrated into the bone matrix, indicating high bone-tissue compatibility. Further, the rhBMP-2/TCFW composite repairs a critical-size bone defect within a short time period. These results suggest that the TCFW functions as an effective scaffold material and will play an important role in tissue regeneration in the future.

A novel CXCR4 antagonist derived from human SDF-1beta enhances angiogenesis in ischaemic mice

AIMS

The effects on angiogenesis of a novel CXC chemokine receptor 4 (CXCR4) antagonist, SDF-1betaP2G, derived from human stromal cell-derived factor-1beta (SDF-1beta), were examined in a model of hind limb ischaemia in mice.

METHODS AND RESULTS

The antagonistic activities of SDF-1betaP2G against CXCR4 were evaluated in vitro and in vivo and compared with phosphate-buffered saline and AMD3100 (a small bicyclam antagonist of SDF-1). Angiogenesis, muscle regeneration and the expression of pro-angiogenic factors were evaluated in ischaemic gastrocnemius muscles. Distant toxic effects of SDF-1betaP2G were evaluated by inflammatory and apoptotic markers. SDF-1betaP2G induced CXCR4 internalization and competitively inhibited the chemotaxis of SDF-1beta but did not mediate migration, calcium influx, or the phosphorylation of Akt and extracellular signal-regulated kinase in cultured T-lymphoblastic leukaemia cells or H9C2 cells. SDF-1betaP2G enhanced blood flow, angiogenesis, and muscle regeneration in ischaemic hind limbs, and the enhancement was significantly better than that of AMD3100. Markers of angiogenesis and progenitor cell migration, including phosphorylated Akt, vascular endothelial growth factor (VEGF), SDF-1 and CXCR4, were up-regulated by SDF-1betaP2G and co-localized with CD31-positive cells. Neutralization of VEGF with its specific antibody abolished SDF-1betaP2G-induced blood reperfusion and angiogenesis. No apparent inflammatory and apoptotic effects were found in heart, liver, kidneys, and testes after SDF-1betaP2G administration.

CONCLUSION

Our findings indicate that the novel CXCR4 antagonist, SDF-1betaP2G, can efficiently enhance ischaemic angiogenesis, blood flow restoration, and muscle regeneration without apparent adverse effects, most likely through a VEGF-dependent pathway.

Cytokine treatment improves parenchymal and vascular damage of salivary glands after irradiation

PURPOSE

During radiotherapy for head and neck cancer, co-irradiation (IR) of salivary glands results in acute and often lifelong hyposalivation. Recently, we showed that bone marrow-derived cells (BMC) can partially facilitate postradiation regeneration of the mouse submandibular gland. In this study, we investigate whether optimized mobilization of BMCs can further facilitate regeneration of radiation-damaged salivary glands.

EXPERIMENTAL DESIGN

Salivary glands of mice reconstituted with eGFP+ bone marrow cells were irradiated with a single dose of 15 Gy. One month later, BMCs were mobilized using granulocyte colony-stimulating factor (G-CSF) or the combination of FMS-like tyrosine kinase-3 ligand, stem cell factor, and G-CSF (termed F/S/G) as mobilizing agents. Salivary gland function and morphology were evaluated at 90 days post-IR by measuring the saliva flow rate, the number of acinar cells, and the functionality of the vasculature.

RESULTS

Compared with G-CSF alone, the combined F/S/G treatment mobilized a 10-fold higher number and different types of BMCs to the bloodstream and increased the number of eGFP+ cells in the irradiated submandibular gland from 49% to 65%. Both treatments reduced radiation-induced hyposalivation from almost nothing in the untreated group to approximately 20% of normal amount. Surprisingly, however, F/S/G treatment resulted in significant less damage to submandibular blood vessels and induced BMC-derived neovascularization.

CONCLUSIONS

Post-IR F/S/G treatment facilitates regeneration of the submandibular gland and ameliorates vascular damage. The latter is partly due to BMCs differentiating in vascular cells but is likely to also result from direct stimulation of existing blood vessel cells.

Allogeneic injection of fetal membrane-derived mesenchymal stem cells induces therapeutic angiogenesis in a rat model of hind limb ischemia

Bone marrow-derived mesenchymal stem cells (BM-MSC) have been demonstrated to be an attractive therapeutic cell source for tissue regeneration and repair. However, it remains unknown whether or not allogeneic transplantation of mesenchymal stem cells (MSC) derived from fetal membranes (FM), which are generally discarded as medical waste after delivery, has therapeutic potential. FM-MSC were obtained from Lewis rats and had surface antigen expression and multipotent potential partly similar to those of BM-MSC. Compared with BM-MSC, FM-MSC secreted a comparable amount of hepatocyte growth factor despite a small amount of vascular endothelial growth factor. FM-MSC and BM-MSC both expressed major histocompatibility complex (MHC) class I but not MHC class II antigens and did not elicit allogeneic lymphocyte proliferation in mixed lymphocyte culture. FM-MSC or BM-MSC obtained from Lewis rats were injected into a MHC-mismatched August-Copenhagen-Irish rat model of hind limb ischemia. Three weeks after injection, blood perfusion and capillary density were significantly higher in the FM-MSC and BM-MSC groups than in the phosphate-buffered saline group, and allogeneic FM-MSC and BM-MSC were still observed. In nonischemic hind limb tissues, allogeneic FM-MSC and BM-MSC injection were associated with a comparatively small amount of T lymphocyte infiltration, compared with the injection of allogeneic splenic lymphocytes. In conclusion, allogeneic FM-MSC injection did not elicit a lymphocyte proliferative response and provided significant improvement in a rat model of hind limb ischemia, comparable to the response to BM-MSC. Thus, allogeneic injection of FM-MSC may be a new therapeutic strategy for the treatment of severe peripheral vascular disease. Disclosure of potential conflicts of interest is found at the end of this article.

Locally overexpressing hepatocyte growth factor prevents post-ischemic heart failure by inhibition of apoptosis via calcineurin-mediated pathway and angiogenesis

BACKGROUND

Myocardial infarction is a significant cause of heart failure. Currently, therapies are limited and novel revascularization methods may play a role. We investigated the effects of hepatocyte growth factor (HGF) expressed by bone marrow-derived mesenchymal stem cells (MSCs) on post-ischemic heart failure.

METHODS

Four weeks after myocardial infarction (MI), Sprague Dawley rats were randomly divided into saline control group, MSC-GFP group, MSC-HGF group, and MSC-HGF+CsA group. After another 4 weeks, hearts were analyzed for ventricular geometry, myocardial function, angiogenesis and endothelial cell density, apoptosis and the expression of calcineurin, Akt, and Bcl-2 protein.

RESULTS

In MSC-HGF group, rats exhibited better LV systolic and diastolic function compared with other groups after 8 weeks of MI. Angiogenesis was significantly enhanced by HGF through inducing proliferation of endothelial cells. The effects of HGF on apoptosis were associated with the expression level of calcineurin protein.

CONCLUSIONS

Our findings suggest that overexpression of HGF improved ischemic cardiac function through angiogenesis and reduction of apoptosis partly mediated by upregulation of calcineurin.