Calcium phosphate precipitates augment adenovirus-mediated gene transfer to blood vessels in vitro and in vivo

Mineralized vectors for gene therapy

There is an intense interest in developing materials for safe and effective delivery of polynucleotides using non-viral vectors. Mineralization of organic templates has long been used to produce complex materials with outstanding biocompatibility. However, a lack of control over mineral growth has limited the applicability of mineralized materials to a few in vitro applications. With better control over mineral growth and surface functionalization, mineralized vectors have advanced significantly in recent years. Here, we review the recent progress in chemical synthesis, physicochemical properties, and applications of mineralized materials in gene therapy, focusing on structure-function relationships. We contrast the classical understanding of the mineralization mechanism with recent ideas of mineralization. A brief introduction to gene delivery is summarized, followed by a detailed survey of current mineralized vectors. The vectors derived from calcium phosphate are articulated and compared to other minerals with unique features. Advanced mineral vectors derived from templated mineralization and specialty coatings are critically analyzed. Mineral systems beyond the co-precipitation are explored as more complex multicomponent systems. Finally, we conclude with a perspective on the future of mineralized vectors by carefully demarcating the boundaries of our knowledge and highlighting ambiguous areas in mineralized vectors. STATEMENT OF SIGNIFICANCE: Therapy by gene-based medicines is increasingly utilized to cure diseases that are not alleviated by conventional drug therapy. Gene medicines, however, rely on macromolecular nucleic acids that are too large and too hydrophilic for cellular uptake. Without tailored materials, they are not functional for therapy. One emerging class of nucleic acid delivery system is mineral-based materials. The fact that they can undergo controlled dissolution with minimal footprint in biological systems are making them attractive for clinical use, where safety is utmost importance. In this submission, we will review the emerging synthesis technology and the range of new generation minerals for use in gene medicines.

p116Rip promotes myosin phosphatase activity in airway smooth muscle cells

Myosin phosphatase-Rho interacting protein (p116^Rip ) was originally found as a RhoA-binding protein. Subsequent studies by us and others revealed that p116^Rip facilitates myosin light chain phosphatase (MLCP) activity through direct and indirect manners. However, it is unclear how p116^Rip regulates myosin phosphatase activity in cells. To elucidate the role of p116^Rip in cellular contractile processes, we suppressed the expression of p116^Rip by RNA interference in human airway smooth muscle cells (HASMCs). We found that knockdown of p116^Rip in HASMCs led to increased di-phosphorylated MLC (pMLC), that is phosphorylation at both Ser19 and Thr18. This was because of a change in the interaction between MLCP and myosin, but not an alteration of RhoA/ROCK signaling. Attenuation of Zipper-interacting protein kinase (ZIPK) abolished the increase in di-pMLC, suggesting that ZIPK is involved in this process. Moreover, suppression of p116^Rip expression in HASMCs substantially increased the histamine-induced collagen gel contraction. We also found that expression of the p116^Rip was decreased in the airway smooth muscle tissue from asthmatic patients compared with that from non-asthmatic patients, suggesting a potential role of p116^Rip expression in asthma pathogenesis.

ZIPK is critical for the motility and contractility of VSMCs through the regulation of nonmuscle myosin II isoforms

Migration of medial vascular smooth muscle cells (VSMCs) into the intimal layer contributes to pathological remodeling of the blood vessel in arterial hypertension and atherosclerosis. It is well established that reorganization of cytoskeletal networks is an essential component of cellular motile events. However, there is currently a lack of insight into the cellular characteristics of VSMC migration under three-dimensional environments. Here, we investigated the mechanisms of VSMC migration and remodeling using two different collagen matrix assays as in vitro models: migration of VSMCs within a collagen matrix for VSMC invasion and contraction of a collagen gel by VSMCs for VSMC remodeling and contraction. We found that nonmuscle myosin IIA (NMIIA) and nonmuscle myosin IIB (NMIIB) differentially contribute to the migratory capacity of VSMCs via NMII isoform-dependent cytoskeletal reorganization. Depletion of NMIIA by short hairpin RNA revealed a unique interplay between actomyosin and microtubules during VSMC migration. On the other hand, NMIIB was required for the structural maintenance of migrating VSMC. Interestingly, there was a significant difference between NMIIA and NMIIB knockdown in the VSMC migration but not in the VSMC-mediated collagen gel contraction. Furthermore, depletion of zipper-interacting protein kinase by short hairpin RNA resulted in an impairment of VSMC migration and a substantial decrease of VSMC-mediated collagen gel contraction. These results suggest that NMIIA and NMIIB uniquely control VSMC migration and may contribute to vascular remodeling, which are both regulated by zipper-interacting protein kinase.

High Efficiency Ex Vivo Gene Transfer to Primary Murine B Cells Using Plasmid or Viral Vectors

Primary autologous B-lymphocytes, following ex vivo gene transfer and re-implantation, have been successfully utilized to prevent autoimmune disease and adaptive responses to therapeutic proteins in several animal models. However, efficient gene transfer to primary B cells requires use of retroviral vectors, which increase the risk of insertional mutagenesis. Here, we evaluated several alternative gene transfer approaches. Resting splenic B cells were purified and activated with LPS, and ex vivo GFP gene transfer was performed by means of nucleofection, lipofectamine, adenoviral infection, or murine retroviral infection. The Adenoviral (Ad) vectors were added to B cell cultures with or without calcium phosphate precipitation. For transfection and nucleofection, naked plasmid DNA was utilized. Nucleofection technology represents a modified electroporation technique for effective transfer of nucleic acids to the nucleus and thus enhances the efficiency of transfer particularly for primary cells. Efficiency of ex vivo gene transfer was determined by flow cytometry using GFP, CD19, and a vital dye as markers. Nucleofection yielded the highest level of gene transfer with 60-65% of B cells being GFP+. Efficiencies were 30-35% for retrovirus, 20% for Ad5/11, 15% for Ad5/35, and 5% for lipofectamine-mediated transfection. Calcium phosphate precipitation increased efficiencies for Ad vectors to 30% (Ad5/11) and 25% (Ad5/35). Lipofectamin caused the greatest cell death at 80%, followed by nucleofection (35%), and viral vector (10-15% in each case). For all methods, gene transfer efficiencies were nearly identical for B cells from C57BL/6 or C3H/HeOuJ mice. In conclusion, recent advances in gene transfer technologies provide alternatives to retroviral vectors for primary B cells. If stable gene transfer is desired, non-integrating vector systems may be combined with transposon- or phage integrase-based systems or future site-specific systems to achieve integration into the host B cell genome.

Calcium gluconate in phosphate buffered saline increases gene delivery with adenovirus type 5

Background

Adenoviruses are attractive vectors for gene therapy because of their stability in vivo and the possibility of production at high titers. Despite exciting preclinical data with various approaches, there are only a few examples of clear efficacy in clinical trials. Effective gene delivery to target cells remains the key variable determining efficacy and thus enhanced transduction methods are important.

Methods/Results

We found that heated serum could enhance adenovirus 5 mediated gene delivery up to twentyfold. A new protein-level interaction was found between fiber knob and serum transthyretin, but this was not responsible for the observed effect. Instead, we found that heating caused the calcium and phosphate present in the serum mix to precipitate, and this was responsible for enhanced gene delivery. This finding could have relevance for designing preclinical experiments with adenoviruses, since calcium and phosphate are present in many solutions. To translate this into an approach potentially testable in patients, we used calcium gluconate in phosphate buffered saline, both of which are clinically approved, to increase adenoviral gene transfer up to 300-fold in vitro. Gene transfer was increased with or without heating and in a manner independent from the coxsackie-adenovirus receptor. In vivo, in mouse studies, gene delivery was increased 2-, 110-, 12- and 13-fold to tumors, lungs, heart and liver and did not result in increased pro-inflammatory cytokine induction. Antitumor efficacy of a replication competent virus was also increased significantly.

Conclusion

In summary, adenoviral gene transfer and antitumor efficacy can be enhanced by calcium gluconate in phosphate buffered saline.

A simple, lanthanide-based method to enhance the transduction efficiency of adenovirus vectors

Based upon the powerful bridging and charge-masking properties of lanthanide cations (Ln3+), we have investigated their use to improve the transduction efficiency of adenovirus vectors. Using a luciferase marker gene, it was possible to increase transgene expression by the murine mesenchymal stem cell line C3H10T(1/2) by up to four log orders when using very low multiplicities of infection in conjunction with Ln3+; La3+ was superior to Gd3+, Y3+ and Lu3+ in this regard. All Ln3+ were more effective than Ca2+. Flow cytometry, using a green fluorescent protein marker gene, confirmed that La3+ increased both the percentage of transduced cells and the level of transgene expression per cell. Transduction of primary cultures of a variety of different mesenchymal cells from human, rabbit, bovine and rat sources, as well as gene transfer to synovium and muscle in vivo, was also greatly enhanced. Our findings suggest that this lanthanide-based method holds much promise for expediting both experimental and clinical applications of gene transfer with adenoviral vectors.

High performance DNA nano-carriers of carbonate apatite: multiple factors in regulation of particle synthesis and transfection efficiency

Increasing attention is being paid on synthetic DNA delivery systems considering some potential life-threatening effects of viral particles, for development of gene-based nano-medicine in the 21st century. In the current nonviral approaches, most of the efforts have been engaged with organic macromolecules like lipids, polymers, and peptides, but comparatively fewer attempts were made to evaluate the potential of inorganic materials for gene delivery. We recently reported that biodegradable nanoparticles of carbonate apatite are highly efficient in transfecting a wide variety of mammalian cells. Here we show that a number of parameters actively regulate synthesis of the nanoparticles and their subsequent transfection efficacy. Development of “supersaturation”, which is the prerequisite for generation of such particles, could be easily modulated by reactant concentrations, pH of the buffered solution, and incubation temperatures, enabling us to establish a flexible particle generation process for highly productive trans-gene delivery. Carbonate incorporation into the particles have been proposed for generating nano-size particles resulting in cellular uptake of huge amount of plasmid DNA as well as endosome destabilization facilitating significant release of DNA from the endosomes.

Genetic modification of cerebral arterial wall: implications for prevention and treatment of cerebral vasospasm

Genetic modification of cerebral vessels represents a promising and novel approach for prevention and/or treatment of various cerebral vascular disorders, including cerebral vasospasm. In this review, we focus on the current understanding of the use of gene transfer to the cerebral arteries for prevention and/or treatment of cerebral vasospasm following subarachnoid hemorrhage (SAH). We also discuss the recent developments in vascular therapeutics, involving the autologous use of progenitor cells for repair of damaged vessels, as well as a cell-based gene delivery approach for the prevention and treatment of cerebral vasospasm.

pH-sensing nano-crystals of carbonate apatite: effects on intracellular delivery and release of DNA for efficient expression into mammalian cells

Two unique and fascinating properties of carbonate apatite which are well-known in hard tissue engineering, have been unveiled, for the first time, for the development of the simplest, but most efficient non-viral gene delivery device - ability of preventing the growth of crystals needed for high frequency DNA transfer across a plasma membrane and a fast dissolution rate for effective release of DNA during endosomal acidification, leading to a remarkably high transgene expression (5 to 100-fold) in mammalian cells compared to the widely used transfecting agents. Moreover, by modulating the crystal dissolution rate of carbonate apatite through incorporation of fluoride or strontium into it, transfection activity could be dramatically controlled, thus shedding light on a new barrier in the non-viral route, which was overlooked so far. Thus we have developed an innovative technology with significant insights, that would come as a promising tool for both basic research laboratories and clinical settings.

Role of calcium in gene delivery

The treatment of genetic diseases using therapeutic gene transfer is considered to be a significant development. This development has brought with it certain limitations, and the process of overcoming these barriers has seen a drastic change in gene delivery. Many metal ions such as Mg2+, Mn2+, Ba2+ and, most importantly, Ca2+ have been demonstrated to have significant roles in gene delivery. Recently, calcium phosphate alone, or in combination with viral and nonviral vectors, was found to exert a positive effect on gene transfer when incorporated in the colloidal particulate system, which is an advancing approach to gene delivery. This review elaborates on various successful methods of using calcium in gene delivery.

High-efficiency gene delivery for expression in mammalian cells by nanoprecipitates of Ca–Mg phosphate

Transfer of desirable genetic sequences into mammalian cells is an essential tool for analysis of gene structure, functions and regulation and industry-based production of therapeutically important proteins and pivotal for gene therapy and DNA vaccination strategies. Considering some severe limitations of viral systems including immunogenicity, carcinogenicity and so on, synthetic nonviral systems are highly desirable in the above applications. However, existing nonviral techniques are extremely inefficient compared to the viral ones. Therefore, we report here on the development of a highly efficient synthetic device for gene delivery and expression into mammalian cells, based on controllable growth of nanoapatite particles. Mg2+ incorporation into the apatite particles caused significant inhibition of particle growth, resulting in retention of nanosized particles which contributed remarkably to the cellular uptake of DNA and its subsequent expression (>10-fold) compared with classical calcium phosphate coprecipitation, one of the most widely used transfection methods.

Translational paradigms in cerebrovascular gene transfer

Gene transfer involves the use of an engineered biologic vehicle known as a vector to introduce a gene encoding a protein of interest into a particular tissue. In diseases with known defects at a genetic level, gene transfer offers a potential means of restoring a normal molecular environment via vector-mediated entry (transduction) and expression of genes encoding potentially therapeutic proteins selectively in diseased tissues. The technology of gene transfer therefore underlies the concept of gene therapy and falls under the umbrella of the current genomics revolution. Particularly since 1995, numerous attempts have been made to introduce genes into intracranial blood vessels to demonstrate and characterize viable transduction. More recently, in attempting to translate cerebrovascular gene transfer technology closer to the clinical arena, successful transductions of normal human cerebral arteries ex vivo and diseased animal cerebral arteries in vivo have been reported using vasomodulatory vectors. Considering the emerging importance of gene-based strategies for the treatment of the spectrum of human disease, the goals of the present report are to overview the fundamentals of gene transfer and review experimental studies germane to the clinical translation of a technology that can facilitate genetic modification of cerebral blood vessels.

Gene therapy for cerebral vascular disease: update 2003

Gene therapy is a promising strategy for cerebrovascular diseases. Several genes that encode vasoactive products have been transferred via cerebrospinal fluid for the prevention of vasospasm after subarachnoid hemorrhage. Transfer of neuroprotective genes, including targeting of proinflammatory mediators, is a current strategy of gene therapy for ischemic stroke. Stimulation of growth of collateral vessels, stabilization of atherosclerotic plaques, inhibition of thrombosis, and prevention of restenosis are important objectives of gene therapy for coronary and limb arteries, but application of these approaches to carotid and intracranial arteries has received little attention. Several fundamental advances, including development of safer vectors, are needed before gene therapy achieves an important role in the treatment of cerebrovascular disease and stroke.

Incorporation of calcium phosphate enhances recombinant adeno-associated virus-mediated gene therapy in diabetic mice

BACKGROUND

Increased efficiency of transgene expression is desired for virus-mediated gene delivery. In the present study, we examined the effect of calcium phosphate (CaPi) on recombinant adeno-associated virus (rAAV)-mediated insulin therapy in diabetic animals.

METHODS

The rAAV vector, rAAV.PEPCK.Ins.EGFP, containing the human insulin gene under control of the phosphoenolpyruvate carboxykinase (PEPCK) promoter and the enhanced green fluorescence protein (EGFP) gene driven by the cytomegalovirus (CMV) IE promoter, was employed in this study. C57BL/6J mice were made diabetic with streptozotocin (STZ), followed by injection into the livers with either rAAV alone, or noncovalent complexes with calcium phosphate. Body weight and blood glucose levels of the animals were routinely monitored after 6 h fasting. Secretion of human insulin in the rAAV-transduced animals was determined by radioimmunoassay (RIA). Expression of human insulin in the livers of the animals was detected by immunohistochemical staining.

RESULTS

Compared with the STZ-treated control mice, administration of rAAV containing the human insulin gene significantly decreased blood glucose levels and maintained body weight of the diabetic animals. Complexation of rAAV with calcium phosphate enhanced the hypoglycemic effect of rAAV-mediated gene transfer. Results obtained from both RIA and immunohistochemical staining demonstrated that incorporation of calcium phosphate enhanced rAAV-mediated gene transfer in vivo, leading to higher expression and secretion of human insulin.

CONCLUSIONS

Administration of rAAV harboring the human insulin gene into livers of the STZ-diabetic mice improved blood glucose levels, maintained body weight of the diabetic animals, and resulted in human insulin secretion. Complexation of rAAV with calcium phosphate significantly potentiated the efficiency of rAAV-mediated diabetic gene therapy.

A direct mechanical method for accurate and efficient adenoviral vector delivery to tissues

We describe a mechanical method for delivery of adenoviral vector to the adventitial surface of arteries and to other tissues. Our goal was to characterize, principally in intact carotid artery, the morphological, biochemical, and functional effects of mechanical delivery of a recombinant beta-galactosidase-expressing adenoviral vector following its direct application using a small paintbrush. Our ex vivo and in vivo data demonstrate efficient, accurate, and rapid transduction of arteries without compromise of their morphological, biochemical, and functional integrity. We also demonstrate the general applicability of this technique in vivo via transduction of skeletal muscle, fibrotendinous tissue, peritoneum, serosal surface of bowel, and wounded skin. We conclude that direct mechanical delivery of an adenoviral vector to tissues using a suitable paintbrush represents an intuitive, accurate, and effective means of augmenting gene transfer efficiency, and may be a useful adjunct to other delivery methods.

Gene therapy for acute diseases

The use of gene transfer systems to study cell function makes it apparent that overexpression of a transgene can restore or improve the function of a protein and positively influence cell function in a predetermined manner for purposes of counterbalancing cellular pathophysiology. The ability of some gene transfer vehicles to produce transgene product within hours of delivery positions gene transfer as a unique pharmaceutical administration system that can quickly affect production of biologic response modifiers in a highly compartmentalized fashion. This approach can be expected to overcome many of the adverse effects and high costs of systemic delivery of recombinant pharmaceuticals. This review highlights recent advances toward development of gene therapies for acute illnesses with particular emphasis on preclinical models of disease. In this context, a growing body of data suggests that gene therapies for polygenic and non-genetic diseases such as asthma, cardiogenic and non-cardiogenic pulmonary edema, stroke, subarachnoid hemorrhage, seizures, acute myocardial infarction, endovascular thrombosis, and infections may someday be options for the treatment of patients.

Cationic polymer and lipids augment adenovirus-mediated gene transfer to cerebral arteries in vivo

Adenovirus-mediated gene transfer to blood vessels is relatively inefficient because binding of adenovirus to vessels is limited. The authors have reported that incorporation of cationic polymer and lipids with adenovirus augments gene transfer to blood vessels ex vivo. In this study, the authors determined whether complexes of adenovirus and cations improve efficiency of gene transfer in vivo. Poly-L-lysine, lipofectamine, or lipofectin was complexed with adenovirus encoding beta-galactosidase. Optimum ratios of the cations per adenovirus were determined by gene transfer to fibroblasts. After injection of the adenovirus into the cisterna magna of anesthetized rabbits, transgene activity was greater in the adventitia of intracranial arteries and meninges after injection of the complexes than adenovirus alone. Thirty minutes after application of adenovirus with the cations, binding of adenovirus to fibroblast cells in vitro or the basilar artery in vivo (by Southern blot analysis) was augmented, which suggests that enhanced binding of virus contributes to augmentation of transgene expression. Thus, cationic polymer and lipids improve transgene expression in intracranial arteries, primarily in the adventitia, after adenovirus-mediated gene transfer in vivo. This strategy may be applicable to studies of gene transfer and eventually for gene therapy.

The future of gene therapy for stroke

New diagnostic and treatment strategies are being developed for stroke. Gene therapy has several potential advantages over classical pharmacologic therapy. Direct administration of DNA into the brain offers the advantage of producing high concentrations of therapeutic agents in a relatively localized environment. Gene transfer also provides longer duration of effect than traditional drug therapy. Recent studies indicate that gene transfer can produce functional proteins in brain parenchyma and cerebral blood vessels after stroke. In animal models, gene transfer may reduce effects of cerebral ischemia or subarachnoid hemorrhage. This review summarizes some current methods of gene transfer to the brain and recent progress that may lead to gene therapy for stroke.

Gene transfer for cerebrovascular disease

Gene transfer is a powerful, evolving technique that uses a biologic vehicle (eg, an engineered adenovirus) to introduce a specific gene of interest (ie, a recombinant gene) into a target tissue. This approach, which has considerable therapeutic potential, underlies the concept of gene therapy. Several studies have characterized the morphologic, biochemical, and functional effects of recombinant gene expression in animal and human cerebral arteries, and support the possibility of gene therapy for cerebrovascular disease. However, for successful integration into future clinical practice, key issues concerning vector safety, delivery methods, and transduction specificity need to be addressed. Alongside completion of the Human Genome Project, transfer of novel genes into the central nervous system is likely to impact greatly on our ability to favorably modify diseased human tissue. Knowledge of the fundamental concepts of cerebrovascular gene transfer is therefore useful to understanding both its molecular basis and potential clinical utility.