Synergistically combined gene delivery for enhanced VEGF secretion and antiapoptosis

Human adipose-derived stem cells enriched with VEGF-modified mRNA promote angiogenesis and long-term graft survival in a fat graft transplantation model

Background

Fat grafting, as a standard treatment for numerous soft tissue defects, remains unpredictable and technique-dependent. Human adipose-derived stem cells (hADSCs) are promising candidates for cell-assisted therapy to improve graft survival. As free-living fat requires nutritional and respiratory sources to thrive, insufficient and unstable vascularization still impedes hADSC-assisted therapy. Recently, cytotherapy combined with modified mRNA (modRNA) encoding vascular endothelial growth factor (VEGF) has been applied for the treatment of ischemia-related diseases. Herein, we hypothesized that VEGF modRNA (modVEGF)-engineered hADSCs could robustly enhance fat survival in a fat graft transplantation model.

Methods

hADSCs were acquired from lipoaspiration and transfected with modRNAs. Transfection efficiency and expression kinetics of modRNAs in hADSCs were first evaluated in vitro. Next, we applied an in vivo Matrigel plug assay to assess the viability and angiogenic potential of modVEGF-engineered hADSCs at 1 week post-implantation. Finally, modVEGF-engineered hADSCs were co-transplanted with human fat in a murine model to analyze the survival rate, re-vascularization, proliferation, fibrosis, apoptosis, and necrosis of fat grafts over long-term follow-up.

Results

Transfections of modVEGF in hADSCs were highly tolerable as the modVEGF-engineered hADSCs facilitated burst-like protein production of VEGF in both our in vitro and in vivo models. modVEGF-engineered hADSCs induced increased levels of cellular proliferation and proangiogenesis when compared to untreated hADSCs in both ex vivo and in vivo assays. In a fat graft transplantation model, we provided evidence that modVEGF-engineered hADSCs promote the optimal potency to preserve adipocytes, especially in the long-term post-transplantation phase. Detailed histological analysis of fat grafts harvested at 15, 30, and 90 days following in vivo grafting suggested the release of VEGF protein from modVEGF-engineered hADSCs significantly improved neo-angiogenesis, vascular maturity, and cell proliferation. The modVEGF-engineered hADSCs also significantly mitigated the presence of fibrosis, apoptosis, and necrosis of grafts when compared to the control groups. Moreover, modVEGF-engineered hADSCs promoted graft survival and cell differentiation abilities, which also induced an increase in vessel formation and the number of surviving adipocytes after transplantation.

Conclusion

This current study demonstrates the employment of modVEGF-engineered hADSCs as an advanced alternative to the clinical treatment involving soft-tissue reconstruction and rejuvenation.

Fat extract improves fat graft survival via proangiogenic, anti-apoptotic and pro-proliferative activities

Background

Our previous study proved that nanofat could enhance fat graft survival by promoting neovascularization. Fat extract (FE), a cell-free component derived from nanofat, also possesses proangiogenic activity.

Objectives

The aim of this study was to investigate whether FE could improve fat graft survival and whether FE and nanofat could work synergistically to promote fat graft survival. The underlying mechanism was also investigated.

Methods

In the first animal study, human macrofat from lipoaspirate was co-transplanted into nude mice with FE or nanofat. The grafts were evaluated at 2, 4 and 12 weeks post-transplantation. In the second animal study, nude mice were transplanted with a mixture of macrofat and nanofat, followed by intra-graft injection of FE at days 1, 7, 14, 21 and 28 post-transplantation. The grafts were evaluated at 12 weeks post-transplantation. To detect the mechanism by which FE impacts graft survival, the proangiogenic, anti-apoptotic and pro-proliferative activities of FE were analysed in grafts in vivo and in cultured human vascular endothelial cells (HUVECs), adipose-derived stem cells (ADSCs) and fat tissue in vitro.

Results

In the first animal study, the weights of the fat grafts in the nanofat- and FE-treated groups were significantly higher than those of the fat grafts in the control group. In addition, higher fat integrity, more viable adipocytes, more CD31-positive blood vessels, fewer apoptotic cells and more Ki67-positive proliferating cells were observed in the nanofat- and FE-treated groups. In the second animal study, the weights of the fat grafts in the nanofat+FE group were significantly higher than those of the fat grafts in the control group. In vitro, FE showed proangiogenic effects on HUVECs, anti-apoptotic effects on fat tissue cultured under hypoxic conditions and an ability to promote ADSC proliferation and maintain their multiple differentiation capacity.

Conclusions

FE could improve fat graft survival via proangiogenic, anti-apoptotic and pro-proliferative effects on ADSCs. FE plus nanofat-assisted fat grafting is a new strategy that could potentially be used in clinical applications.

Angiogenic Endothelial Cell Signaling in Cardiac Hypertrophy and Heart Failure

Endothelial cells are, by number, one of the most abundant cell types in the heart and active players in cardiac physiology and pathology. Coronary angiogenesis plays a vital role in maintaining cardiac vascularization and perfusion during physiological and pathological hypertrophy. On the other hand, a reduction in cardiac capillary density with subsequent tissue hypoxia, cell death and interstitial fibrosis contributes to the development of contractile dysfunction and heart failure, as suggested by clinical as well as experimental evidence. Although the molecular causes underlying the inadequate (with respect to the increased oxygen and energy demands of the hypertrophied cardiomyocyte) cardiac vascularization developing during pathological hypertrophy are incompletely understood. Research efforts over the past years have discovered interesting mediators and potential candidates involved in this process. In this review article, we will focus on the vascular changes occurring during cardiac hypertrophy and the transition toward heart failure both in human disease and preclinical models. We will summarize recent findings in transgenic mice and experimental models of cardiac hypertrophy on factors expressed and released from cardiomyocytes, pericytes and inflammatory cells involved in the paracrine (dys)regulation of cardiac angiogenesis. Moreover, we will discuss major signaling events of critical angiogenic ligands in endothelial cells and their possible disturbance by hypoxia or oxidative stress. In this regard, we will particularly highlight findings on negative regulators of angiogenesis, including protein tyrosine phosphatase-1B and tumor suppressor p53, and how they link signaling involved in cell growth and metabolic control to cardiac angiogenesis. Besides endothelial cell death, phenotypic conversion and acquisition of myofibroblast-like characteristics may also contribute to the development of cardiac fibrosis, the structural correlate of cardiac dysfunction. Factors secreted by (dysfunctional) endothelial cells and their effects on cardiomyocytes including hypertrophy, contractility and fibrosis, close the vicious circle of reciprocal cell-cell interactions within the heart during pathological hypertrophy remodeling.

Biodegradable PEI modified complex micelles as gene carriers with tunable gene transfection efficiency for ECs

In recent years, gene therapy has evoked an increasing interest in clinical treatments of coronary diseases because it is a potential strategy to realize rapid endothelialization of artificial vascular grafts. The balance of high transfection efficiency and low cytotoxicity of nonviral gene carriers is an important issue to be solved. In this study, we aim to establish a gene delivery system offering an elegant way to tune the transfection activity and cytotoxicity. Biodegradable complex micelles were prepared from polyethylenimine-b-poly(lactide-co-3(S)-methyl-morpholine-2,5-dione)-b-polyethylenimine (PEI-b-PLMD-b-PEI) and methoxy-poly(ethylene glycol)-b-poly(lactide-co-3(S)-methyl-morpholine-2,5-dione) (mPEG-b-PLMD) copolymers by a co-assembly method. Then the ZNF580 gene plasmid (pDNA) was encapsulated into the complex micelles. The hydrodynamic size and zeta potential of these complex micelles and micelles/pDNA complexes indicated that they were feasible for use in cellular uptake and gene transfection. As expected, the transfection efficiency and cytotoxicity of these micelles/pDNA complexes could be conveniently tuned by changing the mass ratio of mPEG-b-PLMD to PEI-b-PLMD-b-PEI (3/1, 2/2, 1/3 and 0/4) in the mixed mPEG/PEI shell. The transfection efficiency increased as the mass ratio of mPEG-b-PLMD/PEI-b-PLMD-b-PEI decreased from 3/1 to 0/4, while the cytotoxicity showed an opposite tendency. Moreover, ZNF580 protein expression determined by Western blot analysis and the migration of transfected endothelial cells (ECs) by wound healing assay were consistent with the result of transfection efficiency. All these results indicated that the co-assembled complex micelles could act as suitable gene carriers with tunable gene transfection efficiency and cytotoxicity, which should have great potential for the transfection of vascular ECs.

Enhanced transfection efficiency and targeted delivery of self-assembling h-R3-dendriplexes in EGFR-overexpressing tumor cells

The efficient gene transfection, cellular uptake and targeted delivery in vivo are key issues for non-viral gene delivery vectors in cancer therapy. To solve these issues, we designed a new targeted gene delivery system based on epidermal growth factor receptor (EGFR) targeting strategy. An anti-EGFR monoclonal antibody h-R3 was introduced to dendriplexes of PAMAM and DNA via electrostatic interactions to form self-assembled h-R3-PAMAM-DNA complexes (h-R3-dendriplexes). Dendriplexes h-R3-dendriplexes represented excellent DNA encapsulation ability and formed unique nanostructures. Compared to dendriplexes, h-R3-dendriplexes presented lower cytotoxicity, higher gene transfection efficiency, excellent endosome escape ability and high nuclear accumulation in the EGFR-overexpressing HepG2 cells. Both ex vivo fluorescence imaging and confocal results of frozen section revealed that h-R3-dendriplexes showed higher targeted delivery and much better gene expression in the tumors than dendriplexes at the same N/P ratio, and h-R3-dendriplexes had accumulation primarily in the tumor and kidney. Moreover, h-R3-dendriplexes for p53 delivery indicated efficient cell growth inhibition and potentiated paclitaxel-induced cell death. These results indicate that the h-R3-dendriplexes represent a great potential to be used as efficient targeted gene delivery carriers in EGFR-overexpressing tumor cells.

Evaluation of dendrimer type bio-reducible polymer as a siRNA delivery carrier for cancer therapy

Small interfering ribonucleic acid (siRNA), 20-25 base pairs in length, can interfere with the expression of specific genes. Recently, many groups reported the therapeutic intervention of siRNA in various cancer cells. In this study, dendrimer type bio-reducible polymer (PAM-ABP) which was synthesized using arginine grafted bio-reducible poly(cystaminebisacrylamide-diaminohexane) (ABP) and polyamidoamine (PAMAM) was used to deliver anti-VEGF siRNA into cancer cell lines including human hepatocarcinoma (Huh-7), human lung adenocarcinoma (A549), and human fibrosarcoma (HT1080) cells and access their potential as a siRNA delivery carrier for cancer therapy. PAM-ABP and siRNA formed polyplexes with average diameter of 116 nm and charge of around +24.6 mV. The siRNA in the PAM-ABP/siRNA polyplex was released by 5mM DTT and heparin. VEGF gene silencing efficiency of PAM-ABP/siRNA polyplexes was shown to be more effective than PEI/siRNA polyplexes in three cell lines with the following order HT1080>A549>Huh-7.

Functional polymers of gene delivery for treatment of myocardial infarct

Ischemic heart disease is rapidly growing as the common cause of death in the world. It is a disease that occurs as a result of coronary artery stenosis and is caused by the lack of oxygen within cardiac muscles due to an imbalance between oxygen supply and demand. The conventional medical therapy is focused on the use of drug eluting stents, coronary-artery bypass graft surgery and anti-thrombosis. Gene therapy provides great opportunities for treatment of cardiovascular disease. In order for gene therapy to be successful, the development of proper gene delivery systems and hypoxia-regulated gene expression vectors is the most important factors. Several non-viral gene transfer methods have been developed to overcome the safety problems of viral transduction. Some of which include plasmids that regulate gene expression that is controlled by environment specific promoters in the transcriptional or the translational level. This review explores polymeric gene carriers that target the myocardium and hypoxia-inducible vectors, which regulate gene expression in response to hypoxia, and their application in animal myocardial infarction models.

Tumor targeting RGD conjugated bio-reducible polymer for VEGF siRNA expressing plasmid delivery

Targeted delivery of therapeutic genes to the tumor site is critical for successful and safe cancer gene therapy. The arginine grafted bio-reducible poly (cystamine bisacrylamide-diaminohexane, CBA-DAH) polymer (ABP) conjugated poly (amido amine) (PAMAM), PAM-ABP (PA) was designed previously as an efficient gene delivery carrier. To achieve high efficacy in cancer selective delivery, we developed the tumor targeting bio-reducible polymer, PA-PEG1k-RGD, by conjugating cyclic RGDfC (RGD) peptides, which bind αvβ3/5 integrins, to the PAM-ABP using polyethylene glycol (PEG, 1 kDa) as a spacer. Physical characterization showed nanocomplex formation with bio-reducible properties between PA-PEG1k-RGD and plasmid DNA (pDNA). In transfection assays, PA-PEG1k-RGD showed significantly higher transfection efficiency in comparison with PAM-ABP or PA-PEG1k-RAD in αvβ3/5 positive MCF7 breast cancer and PANC-1 pancreatic cancer cells. The targeting ability of PA-PEG1k-RGD was further established using a competition assay. To confirm the therapeutic effect, the VEGF siRNA expressing plasmid was constructed and then delivered into cancer cells using PA-PEG1k-RGD. PA-PEG1k-RGD showed 20-59% higher cellular uptake rate into MCF7 and PANC-1 than that of non-targeted polymers. In addition, MCF7 and PANC-1 cancer cells transfected with PA-PEG1k-RGD/pshVEGF complexes had significantly decreased VEGF gene expression (51-71%) and cancer cell viability (35-43%) compared with control. These results demonstrate that a tumor targeting bio-reducible polymer with an anti-angiogenic therapeutic gene could be used for efficient and safe cancer gene therapy.

Bioreducible polymers for therapeutic gene delivery

Most currently available cationic polymers have significant acute toxicity concerns such as cellular toxicity, aggregation of erythrocytes, and entrapment in the lung capillary bed, largely due to their poor biocompatibility and non-degradability under physiological conditions. To develop more intelligent polymers, disulfide bonds are introduced in the design of biodegradable polymers. Herein, the sustained innovations of biomimetic nano-sized constructs with bioreducible poly(disulfide amine)s demonstrate a viable clinical tool for the treatment of cardiovascular disease, anemia, diabetes, and cancer.

Effect of biodegradability on CXCR4 antagonism, transfection efficacy and antimetastatic activity of polymeric Plerixafor

Chemokine receptor CXCR4 and its sole ligand SDF-1 are key players in regulating cancer cell invasion and metastasis. Plerixafor (AMD3100) is a small-molecule CXCR4 antagonist that prevents binding of SDF-1 to CXCR4 and has potential in prevention of cancer metastasis. This study investigates the influence of biodegradability of a recently reported polymeric Plerixafor (PAMD) on CXCR4 antagonism, antimetastatic activity, and transfection efficacy of PAMD polyplexes with plasmid DNA. We show that PAMD exhibits CXCR4 antagonism and inhibition of cancer cell invasion in vitro regardless of its biodegradability. Biodegradable PAMD showed considerably enhanced transfection efficiency and decreased cytotoxicity when compared with the non-degradable PAMD. Despite similar CXCR4 antagonism in vitro, only biodegradable PAMD displayed antimetastatic activity in experimental lung metastasis model in vivo.

Treadmill Exercise Training Improves Vascular Endothelial Growth Factor Expression in the Cardiac Muscle of Type I Diabetic Rats

Background

Vascular endothelial growth factor (VEGF) expression is a potent mitogen for endothelial cells that is involved in angiogenesis. Cardiac VEGF is decreased in many pathologic conditions, including diabetes mellitus and aging. Exercise training has improved VEGF expression in the aging heart. Thus, the aim of our study is to illustrate the impact of treadmill exercise training on the cardiac VEGF expression in type I diabetic rats.

Methods

Twenty normal Sprague-Dawley rats and Sprague-Dawley rats with streptozotocin-induced diabetes were divided into the following equal groups: sedentary control (SC), exercised control (EC), sedentary diabetic rats (SD) and exercised diabetic rats (ED). Immunohistochemistry was used to investigate VEGF expression in the cardiac tissue in each of the four different groups.

Results

Cardiac VEGF expression was significantly (P < 0.05) lower in SD compared with that in SC. However, exercise training significantly (P < 0.01) enhanced VEGF expression in the cardiac tissue in ED compared with that in SD.

Conclusion

Our present data suggest that treadmill exercise training improved diabetes-induced downregulation in the cardiac VEGF expression.