rAAV-mediated angiogenin gene transfer induces angiogenesis and modifies left ventricular remodeling in rats with myocardial infarction

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.

Local pharmacological induction of angiogenesis: Drugs for cells and cells as drugs

The past decades have seen significant advances in pro-angiogenic strategies based on delivery of molecules and cells for conditions such as coronary artery disease, critical limb ischemia and stroke. Currently, three major strategies are evolving. Firstly, various pharmacological agents (growth factors, interleukins, small molecules, DNA/RNA) are locally applied at the ischemic region. Secondly, preparations of living cells with considerable bandwidth of tissue origin, differentiation state and preconditioning are delivered locally, rarely systemically. Thirdly, based on the notion, that cellular effects can be attributed mostly to factors secreted in situ, the cellular secretome (conditioned media, exosomes) has come into the spotlight. We review these three strategies to achieve (neo)angiogenesis in ischemic tissue with focus on the angiogenic mechanisms they tackle, such as transcription cascades, specific signalling steps and cellular gases. We also include cancer-therapy relevant lymphangiogenesis, and shall seek to explain why there are often conflicting data between in vitro and in vivo. The lion's share of data encompassing all three approaches comes from experimental animal work and we shall highlight common technical obstacles in the delivery of therapeutic molecules, cells, and secretome. This plethora of preclinical data contrasts with a dearth of clinical studies. A lack of adequate delivery vehicles and standardised assessment of clinical outcomes might play a role here, as well as regulatory, IP, and manufacturing constraints of candidate compounds; in addition, completed clinical trials have yet to reveal a successful and efficacious strategy. As the biology of angiogenesis is understood well enough for clinical purposes, it will be a matter of time to achieve success for well-stratified patients, and most probably with a combination of compounds.

AAV vectors for cardiac gene transfer: experimental tools and clinical opportunities

Since the first demonstration of in vivo gene transfer into myocardium there have been a series of advancements that have driven the evolution of cardiac gene delivery from an experimental tool into a therapy currently at the threshold of becoming a viable clinical option. Innovative methods have been established to address practical challenges related to tissue-type specificity, choice of delivery vehicle, potency of the delivered material, and delivery route. Most importantly for therapeutic purposes, these strategies are being thoroughly tested to ensure safety of the delivery system and the delivered genetic material. This review focuses on the development of recombinant adeno-associated virus (rAAV) as one of the most valuable cardiac gene transfer agents available today. Various forms of rAAV have been used to deliver "pre-event" cardiac protection and to temper the severity of hypertrophy, cardiac ischemia, or infarct size. Adeno-associated virus (AAV) vectors have also been functional delivery tools for cardiac gene expression knockdown studies and successfully improving the cardiac aspects of several metabolic and neuromuscular diseases. Viral capsid manipulations along with the development of tissue-specific and regulated promoters have greatly increased the utility of rAAV-mediated gene transfer. Important clinical studies are currently underway to evaluate AAV-based cardiac gene delivery in humans.

Atorvastatin prevents left ventricular remodeling in spontaneously hypertensive rats

Statins improve left ventricular (LV) remodeling in spontaneously hypertensive rats (SHRs). This study was designed to investigate the effects of atorvastatin administered in the early stage on LV remodeling in SHRs, and to explore the underlying mechanisms.Sixteen male 8-week-old SHRs were randomized to receive distilled water (SHR-DW) or atorvastatin (SHR-ATV) for 12 weeks. Age-matched male Wistar-Kyoto (WKY) rats gavaged with distilled water served as controls. LV remodeling was evaluated, myocardial CTGF expression levels were detected using Western blotting, and cardiomyocyte apoptosis was detected with the TUNEL method.Compared with WKY and SHR-DW, atorvastatin treatment significantly decreased systolic blood pressure in SHRs; atorvastatin significantly inhibited LV remodeling, as indicated by the reduced LV weight/body weight ratio (SHR-ATV: 4.0 ± 0.4 versus SHR-DW: 4.7 ± 0.4 mg/g, P < 0.05), cardiomyocyte diameter (SHR-ATV: 16.2 ± 2.8 versus SHR-DW: 19.0 ± 1.0 µm, P < 0.05), and interstitial fibrosis (SHR-ATV: 3.3 ± 2.1 versus SHR-DW: 4.5 ± 1.8%, P < 0.05). Compared with WKY, myocardial CTGF expression was significantly increased and cardiomyocyte apoptosis decreased in SHRs. Compared with the SHR-DW group, atorvastatin treatment significantly inhibited myocardial CTGF expression (SHR-ATV: 0.69 ± 0.21 versus SHR-DW: 1.12 ± 0.27, P < 0.05) and induced cardiomyocyte apoptosis in SHRs (SHR-ATV: 5.2 ± 0.6 versus SHR-DW: 1.9 ± 0.3%, P < 0.05).The results indicate that early-stage administration of atorvastatin effectively prevented LV remodeling in SHRs, and that inhibition of myocardial CTGF expression and induction of cardiomyocyte apoptosis may be the underlying mechanisms.

Human eosinophil cationic protein enhances stress fiber formation in Balb/c 3T3 fibroblasts and differentiation of rat neonatal cardiomyocytes

We found that eosinophil cationic protein (ECP) stimulated the growth of mouse Balb/c 3T3 fibroblasts. ECP-treated 3T3 cells were more flattened and exhibited enhanced stress fiber formation. The enhancement of cytoskeleton after addition of recombinant ECP appeared stable and was able to inhibit disassembly of actin filaments that was induced by fibroblast growth factor-2. The ROCK inhibitor, Y-27632, abrogated this enhancement on stress fiber formation that was induced by ECP indicating the involvement of Rho/ROCK signaling pathway. The effect of ECP was assessed on the differentiation of primary cardiomyocytes derived from rat neonatal heart since the development of actin filaments is significantly related with organization of stress fibers. As the result, both beating rate and the expression of cardiac muscle specific markers such as atrial natriuretic factor were enhanced in the presence of ECP. Thus ECP may also function as a cardiomyocyte differentiation factor.

Enhanced angiogenesis in porous collagen-chitosan scaffolds loaded with angiogenin

Artificial dermis lacks a vascular network, and angiogenesis is slow in vivo. Controlled delivery of angiogenin (ANG), a potent inducer of angiogenesis, should promote angiogenesis in artificial dermis. In this study, a porous collagen-chitosan scaffold was fabricated and heparinized using N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) and N-hydroxysuccinimide (NHS) with a freeze-drying method. Using radioiodine labeling, the effect of heparin on the binding of ANG to the scaffold was studied. The release of ANG from the heparinized scaffold was investigated using a radioiodine labeling method or an enzyme-linked immunosorbent assay method. In vivo angiogenesis of the scaffold was studied for 28 days. All scaffolds possess three-dimensional porous structures, and their mean pore sizes increase upon EDC-NHS cross-linking. The binding of ANG to the scaffold showed a linear correlation with ANG concentration. With ANG concentrations of 160 ng/mL, the binding of ANG to the heparinized scaffold was 36.5%. In vitro, ANG was released from the heparinized scaffold in a controlled manner. The presence of ANG enhanced the angiogenesis of the heparinized scaffold after subcutaneous implantation into rabbits. The results of this study indicate that a porous collagen-chitosan scaffold loaded with ANG may be valuable in the development of artificial dermis requiring enhanced angiogenesis.

Midkine prevents ventricular remodeling and improves long-term survival after myocardial infarction

Cardiac remodeling is thought to be the major cause of chronic heart dysfunction after myocardial infarction (MI). However, molecules involved in this process have not been thoroughly elucidated. In this study we investigated the long-term effects of the growth factor midkine (MK) in cardiac remodeling after MI. MI was produced by ligation of the left coronary artery. MK expression was progressively increased after MI in wild-type mice, and MK-deficient mice showed a higher mortality. Exogenous MK improved survival and ameliorated left ventricular dysfunction and fibrosis not only of MK-deficient mice but also of wild-type mice. Angiogenesis in the peri-infarct zone was also enhanced. These in vivo changes induced by exogenous MK were associated with the activation of phosphatidylinositol 3-kinase (PI3K)/Akt and MAPKs (ERK, p38) and the expression of syndecans in the left ventricular tissue. In vitro experiments using human umbilical vein endothelial cells confirmed the potent angiogenic action of MK via the PI3K/Akt pathway. These results suggest that MK prevents the cardiac remodeling after MI and improves the survival most likely through an enhancement of angiogenesis. MK application could be a new therapeutic strategy for the treatment of ischemic heart failure.