Gene therapy for cardiovascular disease

Development of novel method of non-viral efficient gene transfer into neonatal cardiac myocytes

To establish new treatment for cardiovascular disease, the development of safe and highly efficient vectors is necessary. Especially, non-viral vectors are considered to be ideal for human gene therapy, since recent adverse events with retroviral or adenoviral vectors have highlighted the issue of safety. Although we previously reported safety and high efficiency of HVJ-liposome method, we have modified the envelope of HVJ (Sendai virus). In this novel non-viral vector, the envelope of HVJ alone was utilized as a carrier to deliver proteins, genes and oligodeoxynucleotides (ODN). Thus, we optimized the transfection efficiency of HVJ-envelope vector into neonatal cardiac myocytes in this study, since cardiac myocytes is one of the most difficult cells to be transfected. HVJ-envelope, obtained after complete destruction of HVJ genome, containing FITC-labeled ODN or luciferase plasmid was incubated with cardiac myocytes. In addition, the concentration of protamine sulfate was modified (0-700 microg/ml) to increase transfection efficacy. Without HVJ-envelope vector, few cells showed fluorescence, whereas most cells demonstrated fluorescence with HVJ-envelope vector. Consistent with the high transfection efficiency of ODN, high luciferase activity was also detected using HVJ-envelope vector. Moreover, the transfection efficiency varied according to the concentration of protamine sulfate. No obvious cytotoxicity was observed in cells transfected with HVJ-envelope vector. The present study demonstrated the development of a highly efficient novel non-viral vector for cardiac myocytes, suggesting that further development may provide a new useful tool for research and clinical gene therapy in the field of cardiovascular disease.

Catheter-delivered in vivo gene transfer into rat myocardium using the fusigenic liposomal mediated method

We compared the efficacy of four different in vivo hemagglutinating virus of Japan (HVJ)-liposome gene transfer methods, i.e., direct myocardial injection (i.m.), injection into the left ventricular cavity (LV), infusion at the level of the coronary cusps (CI), or injection into the left ventricular cavity with a balloon catheter blocking aortic flow (LV+B) to transfer beta-galactosidase, FlTC-labeled oligodeoxynucleotide (ODN), and/or luciferase genes into the rat heart. I.m. caused highly efficient gene transfer in the limited area around the injection site, which suggests that i.m. may be a suitable method for targeted treatment of focal lesion. In the LV+B group, all rats had myocardial beta-galactosidase staining and fluorescence of FITC-labeled ODN in the nuclei of cardiac myocytes around the coronary arteries and the vasa vasorum, and some transfected myocytes were observed in the middle of the myocardium without any evidence of injury. In contrast, in the CI group, only half of the animals had myocardial expression of beta-galactosidase. In contrast, fluorescence or luciferase activity was present throughout the left ventricle in the LV+B group. However, the percentage of myocytes that exhibited fluorescence was less than 1% of the total ventricular myocyte population and luciferase activity in the LV+B group was 1.6% of that in the i.m. group. No evidence of luciferase expression was observed in brain, lung, liver, kidney, or testis in either the i.m. or LV+B group. These results suggest that HVJ-liposome gene transfer into the myocardium through the coronary arteries using a balloon-catheter technique is safe and has the potential for causing widespread transgene expression with organ-specificity, although the efficiency of gene transfer should be improved.

In vivo gene electroporation confers strong transient expression of foreign genes in the chicken testis

To attain foreign gene expression in vivo in the testis of living chickens, chloramphenicol acetyltransferase (CAT) and firefly luciferase reporter genes were transfected by electroporation (EP). Bioluminescence imaging indicated clear expression of the luciferase reporter gene localized in and around the injection site of the chicken testis. The CAT activity decreased sharply from 7 to 14 d posttransfection (P < 0.01) and remained low until 28 d. The presence of the self-replication sequence of Epstein-Barr virus did not give significantly higher CAT gene expression over the 28-d posttransfection. The results suggest that in vivo gene EP confers strong, likely transient, foreign gene expression in the testis of living chickens.

Molecular basis of familial hypercholesterolemia: An Indian experience

Familial hypercholesterolemia (FH) is an autosomal dominant disease caused by a multitude of low-density lipoprotein (LDL) receptor gene mutations. The LDL receptor is a cell surface trans-membrane protein that mediates the uptake & lysosomal degradation of plasma LDI., thereby providing cholesterol to cells. Affected individuals have elevated plasma levels of LDL, which causes premature coronary atherosclerosis. FH has an estimated worldwide prevalence of 0.2%. In some subpopulations there is an increased frequency of FH and specific LDL receptor mutations are found to be common due to 'founder gene effect'. Overall, more than 300 naturally occurring LDL receptor mutations have been described. To data upto ten LDL receptor gene mutations have been identified in Indians in South Africa, suggesting increased incidence of FH among Indians. Most mutations have occurred at CpG dinucleotide, a mutational hotspot in human genetic disease. In our study in 25 hypercholesterolemic subjects we have identified two novel insertion mutations in two patients. But the mutations underlying FH are still undefined in the majority of cases. Mutational heterogeneity on the other-hand has complicated disease diagnosis at DNA level. These findings warrant application of a generalized mutation screening method in search for new LDL receptor gene defects.

Systemic administration of HVJ viral coat-liposome complex containing human insulin vector decreases glucose level in diabetic mouse: A model of gene therapy

In this study, we examined the feasibility of a systemic administration of HVJ-liposome complex containing human insulin construct into the blood in mice via the tail vein. Transfection of human insulin vector resulted in a transient decrease in serum glucose in streptozotocin (SZT)-induced diabetic mice, accompanied by the detection of human insulin in the liver and spleen. In accordance with the decreased glucose, plasma immunoreactive insulin could be detected up to 14 days after a single transfection in mice transfected with insulin vector. Repeated intravenous injection of human insulin vector every week resulted in a sustained decrease in serum glucose over a 4-week period, accompanied by the detection of C-peptide fragments and a significant decrease in BUN and creatinine. Here, we demonstrated the feasibility of intravenous systemic administration of an insulin vector that results in a sustained improvement of diabetic glucose metabolism.

In vivo gene transfer to mouse spermatogenic cells using green fluorescent protein as a marker

Combination of the DNA injection into seminiferous tubules and the subsequent in vivo electroporation (EP) has become an efficient and convenient assay system for spermatogenic-specific gene expression during spermatogenesis of mice. In this study, we made methodological modifications to enhance the transfection efficiency, and evaluated the possibility of this technique to generate transgenic offspring using green fluorescent protein (GFP) as a marker. After the in vivo gene transfer, GFP expression could be monitored easily and repeatedly on the surface of the testis of live mice under fluorescent microscopy. The serial sections of the transfected testis revealed that transient expression of GFP was extended even in the innermost region of the testis uniformly, but confined to spermatogenic cells and Sertoli cells within the seminiferous tubules. Furthermore, long-lasting GFP expression could be detected in the spermatogenic cells even 2 months after EP. Natural mating with normal adult females revealed that 65% of the transfected males maintained fertilizable ability and could generate their offspring normally. Germ-line transmission of the GFP vector to the offspring was checked under fluorescent microscopy, but no transgenic offspring has been detected up to now. These results suggest that the application of additional techniques, such as cell sorting for GFP-positive germ cells followed by nuclear transfer to the oocytes, would make this method as a novel strategy for generating transgenic animals. J. Exp. Zool. 286:212-218, 2000.

Foreign gene expression by in vivo gene electroporation in the quail testis

To investigate whether or not foreign gene expression is attained in the testis of living Japanese quails, a firefly luciferase reporter gene was transfected by in vivo electroporation (EP), and transcriptional activity of different promoters was compared. In addition, the effect of the Epstein-Barr virus self-replication sequence was also tested. The results showed that luciferase activity in the testis reached almost a plateau value at 50 V. Under this EP condition, no difference was found in transcriptional activity between the simian virus 40 (SV40) and miw promoters. The reporter gene expression in the quail testis was observed over 28 days after in vivo gene EP, although the activity gradually decreased, and the presence of the Epstein-Barr virus self-replication sequence in the SV40 promoter did not significantly prolong the luciferase activity. These results suggest that in vivo gene EP confers strong, though transient, foreign gene expression in the Japanese quail, and it may provide a new powerful approach for studies on transcriptional regulation of genes during proliferation and differentiation of spermatogenic cells in the quail testis.

In vivo gene transfer to mouse spermatogenic cells by deoxyribonucleic acid injection into seminiferous tubules and subsequent electroporation

An in vivo gene transfer technique for living mouse testes was used to develop a novel transient expression assay system for transcriptional regulatory elements of spermatogenic specific genes. The combination of DNA injection into seminiferous tubules and subsequent in vivo electroporation resulted in an efficient and convenient assay system for gene expression during spermatogenesis. The transfer of the firefly luciferase reporting gene driven by the Protamine-1 (Prm-1) enhancer region revealed a significant increase in the activity of the reporter enzyme. Histochemical studies of the transfer of the lacZ gene driven by the Prm-1 enhancer showed specific lacZ expression only in haploid spermatid cells in adult testes, corresponding with the expression pattern of endogenous Prm-1. We were able to detect long-lasting transgene expression in the transfected spermatogenic cells. A group of spermatogenic differentiating cells maintained the transfected lacZ expression after more than 2 mo of transfection, suggesting that spermatogenic stem cells and/or spermatogonia could also incorporate foreign DNA and that the transgene could be transmitted to the progenitor cells derived from a transfected proliferating germ cell.

Real time detection of DNA.RNA hybridization in living cells

Demonstrating hybridization between an antisense oligodeoxynucleotide and its mRNA target has proven to be extremely difficult in living cells. To address this fundamental problem in antisense research, we synthesized "molecular beacon" (MB) reporter oligodeoxynucleotides with matched fluorescent donor and acceptor chromophores on their 5' and 3' ends. In the absence of a complementary nucleic acid strand, the MB remains in a stem-loop conformation where fluorescence resonance energy transfer prevents signal emission. On hybridization with a complementary sequence, the stem-loop structure opens increasing the physical distance between the donor and acceptor moieties thereby reducing fluorescence resonance energy transfer and allowing a detectable signal to be emitted when the beacon is excited by light of the appropriate wavelength. Solution hybridization studies revealed that in the presence of a complementary strand targeted MB could yield up to a 60-fold increase in fluorescence intensity in comparison to control MB. By using a fluorescence microscope fitted with UV fluoride lenses, the detection limit of preformed MB/target sequence duplexes microinjected into cells was found to be >/=1 x 10(-1) ag of MB, or approximately 10 molecules of mRNA. On the basis of this exquisite sensitivity, real-time detection of MB/target mRNA hybridization in living cells was attempted by microinjecting MB targeted to the vav protooncogene, or control MB, into K562 human leukemia cells. Within 15 min, confocal microscopy revealed fluorescence in cells injected with targeted, but not control, MB. These studies suggest that real-time visualization and localization of oligonucleotide/mRNA interactions is now possible. MB could find utility in studying RNA processing, trafficking, and folding in living cells. We hypothesize that MB may also prove useful for finding targetable mRNA sequence under physiologic conditions.

Gene gun-mediated in vivo analysis of tissue-specific repression of gene transcription driven by the chicken ovalbumin promoter in the liver and oviduct of laying hens

In order to search tissue-specific elements in the 5'-upstream promoter region, gene gun was used to transfect in vivo plasmid DNAs with varying lengths of truncated ovalbumin promoter fused to the CAT reporter gene to the oviduct and liver of laying hens. The results indicated that in the oviduct, consistently high reporter gene expression was observed irrespective of the length of the truncated ovalbumin gene promoters, whereas in the liver the ovalbumin promoter extending from -3200 to +8 bp suppressed substantially the reporter gene expression compared with consistently high gene expression obtained by the ovalbumin promoters from -2800 to +8 bp or shorter length. It was concluded, therefore, that a tissue-specific silencer-like element might reside most likely in the ovalbumin gene promoter region between -3200 and -2800 bp which represses the ovalbumin gene transcription in the liver, but not in the oviduct of laying hens.

Oligonucleotide-based gene therapy for cardiovascular disease

Gene therapy is emerging as a potential strategy for the treatment of cardiovascular disease such as restenosis after angioplasty, vascular bypass graft occlusion, transplant coronary vasculopathy, homozygous familial hypercholesterolemia and cystic fibrosis, for which no known effective therapy exists. Gene therapy requires efficient in vivo gene transfer technology. During the past decade, many gene transfer methods including viral transfer techniques have been developed, and some are being applied clinically in human gene therapy studies. Molecular biology and pathophysiology of the cardiovascular system have started to emerge, and the time is ripe for the introduction of gene therapy to the management of cardiovascular disorders. In this review, we have focused on the future potential of oligonucleotide-based gene therapy for the treatment of cardiovascular disease.

Foreign gene expression in the mouse testis by localized in vivo gene transfer

In order to attain foreign gene expression in vivo in the testis of living mice, chloramphenicol acetyltransferase (CAT), firefly luciferase and bacterial lacZ reporter genes were transfected by microparticle bombardment and electroporation. The results showed that CAT reporter gene was expressed in a dose-dependent fashion. The X-gal staining showed that in some spermatogenic-like cells, the bacterial lacZ gene was also expressed by in vivo electroporation, but not by in vivo microparticle bombardment. The possibility of in vivo gene transfer to the spermatogenic cells of the mouse testis was further confirmed by the fact that the CAT reporter gene expression was testis-specific when driven by the mouse-protamin 1 promoter. It was concluded, therefore, that in vivo microparticle bombardment and, especially, electroporation provide convenient and efficient means of gene transfer to the testis of living mice.

In vivo transfer efficiency of antisense oligonucleotides into the myocardium using HVJ-liposome method

Although antisense strategy has been at the center of interest in gene therapy, little is known about application of this strategy to cardiac diseases because of the lack of a suitable delivery method into the heart. Therefore, we compared the transfection efficiency of antisense oligodeoxynucleotides (ODN) using HVJ-liposome method and direct transfer in in vivo transfer into heart. To investigate the cellular fate and localization of ODN, transfer of "naked" FITC-labeled antisense ODN or ODN enwrapped in HVJ-liposome complex were examined. Following in vivo transfer using direct injection as well as in vitro transfer, fluorescence rapidly disappeared within 1 day, whereas transfer by HVJ-liposome method resulted in sustained fluorescence localized in the nucleus for at least 1 week. Measurement of fluorescence also demonstrated a significantly higher level in myocardium transfected by HVJ-liposome method than direct transfer. The present study demonstrated that HVJ-liposome method is more efficacious for ODN delivery by prolongation of half-life of ODN, suggesting its usefulness for gene therapy in cardiac diseases.

High-mobility-group proteins and cancer--an emerging link

In the last few years, considerable interest has been generated in the role of high-mobility-group (HMG) proteins, and HMG box proteins generally, in cancer development and therapy. These proteins were discovered in the early 1970s (Goodwin et al. 1973) as a group of nonhistone proteins. Some members of the HMG protein family (i) constitute a class of important architectural proteins involved in transcriptional regulation of genes, (ii) are frequently expressed in transformed cells at levels that correlate with the degree of neoplastic cell transformation, (iii) participate in gene rearrangements, which are linked to the emergence of benign solid tumors, (iv) confer the ability to recognize DNA-cisplatin adducts selectively, and (v) provide a new delivery system for efficient gene transfer. It should be considered that some HMG proteins, acting as architectural proteins that bring many of the transcription factors into precise three-dimensional shapes, may have a similar critical role in neoplastic transformation to that of some transcription factors themselves.

Genetic models of human vascular disease

The use of genetic models has greatly assisted investigations of the natural history, mechanisms, and potential therapy for human vascular disease. In the past, genetic models of vascular disease were obtained through serendipity and/or selective breeding to obtain inbred lines that express the phenotype of interest. This approach has yielded several valuable models of atherosclerosis and hypertension. In the past several years, the advent of molecular techniques has enabled investigators to produce additional novel genetic models of disease that have further enhanced the study of vascular biology and medicine. Transgenic techniques and the techniques of homologous recombination have allowed researchers to alter the genotype of an animal in a precise manner and to study the resultant change in phenotype. More recently, techniques of in vivo gene transfer have also accelerated and enhanced the development of novel models. The application of these methodologies has resulted in important breakthroughs in our understanding of the pathogenesis and treatment of vascular diseases. In this review, we compare and contrast these technologies along with examples of their use in the studies of vascular biology and medicine.

New perspectives in hypertension research. Potentials of vascular biology

The vessel wall was once considered to be a passive conduit responding to the circulating endocrine system. However, the emergence of molecular and vascular biology in hypertension research has redefined our understanding of the role of the vasculature as a vital organ in the pathogenesis of hypertension. It is now recognized that the vasculature can regulate its own tone by a variety of previously unknown autocrine and/or paracrine vasoactive systems. Recent evidence indicates that the process of vascular remodeling in hypertension appears to be mediated by locally generated factors within the vessel wall. This review examines the implications of this new paradigm in hypertension, focusing on five topics that have developed through the emergence of molecular vascular biology: the discovery and characterization of novel biologically active molecules synthesized by the vessel wall, the molecular mechanisms and consequences of vascular remodeling, the developmental biology of the blood vessel and the relation to pathobiology, the use of in vivo gene transfer to test hypotheses in vivo, and novel treatment strategies based on gene therapy of the vessel wall.