Extracellular Vesicle-Encapsulated Adeno-Associated Viruses for Therapeutic Gene Delivery to the Heart

BACKGROUND

Adeno-associated virus (AAV) has emerged as one of the best tools for cardiac gene delivery due to its cardiotropism, long-term expression, and safety. However, a significant challenge to its successful clinical use is preexisting neutralizing antibodies (NAbs), which bind to free AAVs, prevent efficient gene transduction, and reduce or negate therapeutic effects. Here we describe extracellular vesicle-encapsulated AAVs (EV-AAVs), secreted naturally by AAV-producing cells, as a superior cardiac gene delivery vector that delivers more genes and offers higher NAb resistance.

METHODS

We developed a 2-step density-gradient ultracentrifugation method to isolate highly purified EV-AAVs. We compared the gene delivery and therapeutic efficacy of EV-AAVs with an equal titer of free AAVs in the presence of NAbs, both in vitro and in vivo. In addition, we investigated the mechanism of EV-AAV uptake in human left ventricular and human induced pluripotent stem cell-derived cardiomyocytes in vitro and mouse models in vivo using a combination of biochemical techniques, flow cytometry, and immunofluorescence imaging.

RESULTS

Using cardiotropic AAV serotypes 6 and 9 and several reporter constructs, we demonstrated that EV-AAVs deliver significantly higher quantities of genes than AAVs in the presence of NAbs, both to human left ventricular and human induced pluripotent stem cell-derived cardiomyocytes in vitro and to mouse hearts in vivo. Intramyocardial delivery of EV-AAV9-sarcoplasmic reticulum calcium ATPase 2a to infarcted hearts in preimmunized mice significantly improved ejection fraction and fractional shortening compared with AAV9-sarcoplasmic reticulum calcium ATPase 2a delivery. These data validated NAb evasion by and therapeutic efficacy of EV-AAV9 vectors. Trafficking studies using human induced pluripotent stem cell-derived cells in vitro and mouse hearts in vivo showed significantly higher expression of EV-AAV6/9-delivered genes in cardiomyocytes compared with noncardiomyocytes, even with comparable cellular uptake. Using cellular subfraction analyses and pH-sensitive dyes, we discovered that EV-AAVs were internalized into acidic endosomal compartments of cardiomyocytes for releasing and acidifying AAVs for their nuclear uptake.

CONCLUSIONS

Together, using 5 different in vitro and in vivo model systems, we demonstrate significantly higher potency and therapeutic efficacy of EV-AAV vectors compared with free AAVs in the presence of NAbs. These results establish the potential of EV-AAV vectors as a gene delivery tool to treat heart failure.

EV Cargo Sorting in Therapeutic Development for Cardiovascular Disease

Cardiovascular disease remains the leading cause of morbidity and mortality in the world. Thus, therapeutic interventions to circumvent this growing burden are of utmost importance. Extracellular vesicles (EVs) actively secreted by most living cells, play a key role in paracrine and endocrine intercellular communication via exchange of biological molecules. As the content of secreted EVs reflect the physiology and pathology of the cell of their origin, EVs play a significant role in cellular homeostasis, disease pathogenesis and diagnostics. Moreover, EVs are gaining popularity in clinics as therapeutic and drug delivery vehicles, transferring bioactive molecules such as proteins, genes, miRNAs and other therapeutic agents to target cells to treat diseases and deter disease progression. Despite our limited but growing knowledge of EV biology, it is imperative to understand the complex mechanisms of EV cargo sorting in pursuit of designing next generation EV-based therapeutic delivery systems. In this review, we highlight the mechanisms of EV cargo sorting and methods of EV bioengineering and discuss engineered EVs as a potential therapeutic delivery system to treat cardiovascular disease.

Abstract MP165: Exosome-mediated Encapsulation Alters AAV Antigenicity and Infectivity: Implications for Gene Delivery in the Heart

Gene therapy is a promising approach for the treatment of cardiovascular disease. Current strategies for myocardial gene transfer include the use of adeno-associated virus (AAV) vectors. However, AAVs may not be ideal for gene therapy vectors owing to pre-existing AAV capsid immunity in the human population that may reduce transduction efficacy and hinder preclinical-to-clinical translation. Interestingly, recent studies suggest that exosome-mediated encapsulation may protect viruses from neutralizing antibodies (NAbs) against the capsid and promote viral infectivity. Here, we describe the ability of exosome-enveloped AAVs, i.e. exosomal AAVs (eAAVs), to evade NAbs and serve as a highly efficient gene delivery tool for cardiovascular therapeutics. We have developed a method to purifiy eAAVs from AAV-producing HEK-293T cells, and used electron/confocal microscopy, qPCR, immunoblotting, dynamic light scattering and interferometric imaging measurements to characterize eAAV morphology, contents and mechanism of action. We confirmed eAAVs represent vesicular fractions that exhibit common exosome phenotype, along with the presence of virus particles, and demonstrated that eAAV infectious entry potentially involves trafficking via endocytic compartments. Using flow cytometry, Langendorff perfusion system and bioluminescence imaging, we then evaluated efficiency of heart targeting for eAAV9/eAAV6 and standard AAV9/AAV6 encoding for mCherry or firefly luciferase in human cardiomyocytes in vitro and in mouse model in vivo . Regardless of the presence or absence of NAbs, we showed that eAAVs are more efficient in transduction in the same titer ranges as compared to standard AAVs. To test therapeutic efficacy, we intramyocardially injected eAAV9 or AAV9 vectors encoding for SERCA2a in NAb+ post-myocardial infarction mice and further evaluated cardiac function using echocardiography. Remarkably, eAAV9-SERCA2a outperformed standard AAVs significantly improving cardiac function in the presence of NAbs (%EF 55.14 ± 3.50 compared to 27.31 ± 1.63 at 6 weeks, respectively). In summary, delivery of AAVs protected by carrier exosomes (i.e. eAAVs) may retain the clinical benefits of AAVs while addressing one of its major challenges.

A Testosterone Metabolite 19-Hydroxyandrostenedione Induces Neuroendocrine Trans-Differentiation of Prostate Cancer Cells via an Ectopic Olfactory Receptor

Olfactory receptor OR51E2, also known as a Prostate Specific G-Protein Receptor, is highly expressed in prostate cancer but its function is not well understood. Through in silico and in vitro analyses, we identified 24 agonists and 1 antagonist for this receptor. We detected that agonist 19-hydroxyandrostenedione, a product of the aromatase reaction, is endogenously produced upon receptor activation. We characterized the effects of receptor activation on metabolism using a prostate cancer cell line and demonstrated decreased intracellular anabolic signals and cell viability, induction of cell cycle arrest, and increased expression of neuronal markers. Furthermore, upregulation of neuron-specific enolase by agonist treatment was abolished in OR51E2-KO cells. The results of our study suggest that OR51E2 activation results in neuroendocrine trans-differentiation. These findings reveal a new role for OR51E2 and establish this G-protein coupled receptor as a novel therapeutic target in the treatment of prostate cancer.

Exciton Emission Intensity Modulation of Monolayer MoS2 via Au Plasmon Coupling

Modulation of photoluminescence of atomically thin transition metal dichalcogenide two-dimensional materials is critical for their integration in optoelectronic and photonic device applications. By coupling with different plasmonic array geometries, we have shown that the photoluminescence intensity can be enhanced and quenched in comparison with pristine monolayer MoS2. The enhanced exciton emission intensity can be further tuned by varying the angle of polarized incident excitation. Through controlled variation of the structural parameters of the plasmonic array in our experiment, we demonstrate modulation of the photoluminescence intensity from nearly fourfold quenching to approximately threefold enhancement. Our data indicates that the plasmonic resonance couples to optical fields at both, excitation and emission bands, and increases the spontaneous emission rate in a double spacing plasmonic array structure as compared with an equal spacing array structure. Furthermore our experimental results are supported by numerical as well as full electromagnetic wave simulations. This study can facilitate the incorporation of plasmon-enhanced transition metal dichalcogenide structures in photodetector, sensor and light emitter applications.

Evaluation of Glycemia Control Achieved by Glargine and Lispro Versus Detemir and Aspart Insulin Regimes in Type 2 Diabetics Undergoing Surgery

There is paucity of scientific literature regarding the clinical outcome of long lasting basal insulin and rapid acting mealtime insulin regimes in surgical situations although employed in non-surgical situations. This study has evaluated the clinical outcome of two subcutaneous split-mixed Glargine+Lispro and Detemir+Aspart insulin regimes in type 2 diabetics undergoing surgery.

A clinical study to compare the efficacy and safety of pregabalin sustained release formulation with pregabalin immediate release formulation in patients of diabetic peripheral neuropathic pain

OBJECTIVE

To compare the efficacy and safety of sustained release (SR) formulation of pregabalin with immediate release (IR) formulation in patient with diabetic peripheral neuropathic pain.

MATERIALS AND METHODS

In this open label, randomized, comparative, multicentric study, the primary efficacy measure was reduction in visual analogue scale (VAS) of short form McGill pain questionnaire (SF-MPQ) score from baseline to last visit. The secondary evaluation measures included reduction in SF-MPQ descriptive score and present pain intensity score and change in clinical global impression - improvement of illness (CGI-I) and clinical global impression - severity of illness (CGI-S) from baseline to last visit. Total duration of the study was 12 weeks. Safety evaluation was done by recording treatment emergent adverse events and laboratory investigations at baseline and end of treatment.

RESULTS

Of 265 randomized patients, 133 received pregabalin SR tablets and 132 pregabalin IR. Patients randomized to both treatments responded to respective treatments. The least square means of VAS score in both the groups were reduced significantly (P <0.01). Reduction in both groups was similar (P = ns). At the end of the trial in both the groups, there was a significant reduction in the SF-MPQ descriptive score (P <0.01), severity of illness as well as clinically significant improvement in the symptoms. Difference between the groups for CGI-I (P = 0.37) and CGI-S (P = 0.41) score was not statistically significant. Treatment in both the groups was found safe and well tolerated.

CONCLUSION

The study shows that the pregabalin SR is safe and effective in patients of diabetic peripheral neuropathic pain. The results of the study demonstrated that pregabalin SR has comparable efficacy and safety as pregabalin IR.

CYLD mutations in familial skin appendage tumours

BACKGROUND

Germ-line mutations in CYLD are found in patients with familial skin appendage tumours. The protein product functions as a deubiquitinase enzyme, which negatively regulates NF-kappaB and c-Jun N-terminal kinase signalling. Brooke-Spiegler syndrome (BSS) is characterised by cylindromas, trichoepitheliomas and spiradenomas, whereas in familial cylindromatosis (FC) patients present with cylindromas and in multiple familial trichoepitheliomas (MFT) with trichoepitheliomas as the only skin tumour type. Although described as distinct entities, recent studies suggest that they are within the spectrum of a single entity.

OBJECTIVE

To investigate the mutation spectrum of CYLD and possible genotype-phenotype correlations.

METHODS

25 families including 13 BSS, 3 FC, and 9 MFT families were examined and evaluated for mutations in the CYLD gene.

RESULTS

In total, 18 mutations in CYLD, including 6 novel mutations, were identified in 25 probands (72%). The mutation frequencies among distinct phenotypes were 85% for BSS, 100% for FC, and 44% for MFT. The majority of the mutations were insertions, deletions or nonsense mutations leading to formation of truncated proteins. All mutations were located between exons 9 to 20, encoding the NEMO binding site and the catalytic domain. Genotype-phenotype analysis failed to reveal a correlation between the types of mutations and their location within the gene and the patients' phenotypes and disease severity.

CONCLUSIONS

This study provides further evidence on the role of CYLD in the pathogenesis of skin appendage tumours characterised by cylindromas, trichoepitheliomas and/or spiradenomas, but the molecular mechanisms of CYLD in skin tumorigenesis and the reasons for phenotypic variability remain to be explored.

ProFeel: low cost visual-haptic perceptualization of protein structure-structure alignments

We describe ProFeel, an application for exploring molecular data from protein structure-structure alignments using a force-feedback joystick. Protein structure analysis is a useful application for multimodal information perceptualization because researchers in this area typically use several independent measures in assessment. A system that allows the user to simultaneously evaluate different criteria would therefore be quite useful. Four variables are assigned three different haptic effects each to allow the user to discern twelve separate data values. The haptic representation is coupled with a traditional molecular graphics visual display.

Follicular carcinoma in a functioning struma ovarii

We describe a case of follicular carcinoma in a functioning struma ovarii, which presented as an ovarian mass in a patient who had undergone a near-total thyroidectomy for a benign lesion. She underwent bilateral salpingo-oophorectomy and received radiotherapy and L-thyroxine treatment with no evidence of metastases in 4 years follow-up.

PROMUSE: a system for multi-media data presentation of protein structural alignments

We present and evaluate PROMUSE: an integrated visualization/sonification system for analyzing pairwise protein structural alignments (superpositions of two protein structures in three-dimensional space). We also explore how the use of sound can enhance the perception and recognition of specific aspects of the local environment at given positions in the represented molecular structure. Sonification presents several opportunities to researchers. For those with visual impairment, data sonification can be a useful alternative to visualization. Sonification can further serve to improve understanding of information in several ways. One use for data sonification is in tasks such as background monitoring, in which case sounds can be used to indicate thresholding events. With PROMUSE, data represented visually may be enhanced or disambiguated by adding sound to the presentation. This aspect of data representation is particularly important for showing features that are difficult to represent visually, due to occlusion or other factors. Another feature of our system is that by representing some variables through sound and others visually, the amount of information that may be represented simultaneously is extended. Our tool aims to augment the power of data visualization rather than replace it. To maximize the utility of our sonifications to represent data, we employed musical voices and melodic components with unique characteristics. We also used sound effects such as panning a voice to the left or right speaker and changing its volume to maximize the individuality of the sonification elements. By making the sonification parameters distinct, we allow the user to focus on those portions of the sonification necessary to resolve possible ambiguities in the visual display. Sonifications of low level data such as raw protein or DNA sequences tend to sound random, and not very musical. We chose instead to sonify an analysis of data features, and thereby present a higher level view of the data. We also used brief melodic phrases rather than single notes in order to generate sounds that were more pleasing and musically idiomatic. To validate the utility of our system, we present the results of an experiment in which PROMUSE was used to test the use of sound as an aid for clarifying visual information. We also compare the overall effectiveness of visual versus aural information delivery.

Cortisol response to arginine-vasopressin does not compare with cortisol response to insulin-hypoglycemia in pituitary tumors

Timed cortisol responses to insulin-hypoglycemia (IH) and arginine-vasopressin (AVP) were compared in 16 patients with pituitary tumors and six healthy controls. Serum cortisol was estimated by a specific and sensitive radioimmunoassay as per the WHO protocol. The basal cortisol (AM) was normal (> 290 nmol/l) in 9 patients and low in seven. With IH peak cortisol response was normal (> 550 nmol/l) in 10 patients, 8 of whom had normal and 2 had low basal (AM) cortisol. In contrast AVP evoked normal cortisol responses in only 5 of these patients, all of whom had normal basal (AM) cortisol and none had low basal (AM) cortisol. The data indicate lower sensitivity for AVP stimulation test (50%) and favour IH as the standard cortisol stimulation test in patients with pituitary tumors awaiting surgery.

Assessing the hypothalamo-pituitary-adrenocortical axis using physiological doses of adrenocorticotropic hormone

We compared cortisol responses to 1 microgram adrenocorticotropic hormone (ACTH), 250 micrograms ACTH and insulin-induced hypoglycaemia (IIH), in patients suspected to have secondary hypocortisolism. Twenty-four patients (16 with hypothalamopituitary disorders and 8 on long-term glucocorticoid therapy) and eight healthy controls, underwent all three test protocols, with intervals of one day between each test. Mean cortisol responses to all three tests were comparable in both groups, but were more closely correlated for IIH vs. the 1 microgram ACTH test (r = 0.96) than for IIH vs. the 250 micrograms ACTH test (r = 0.88). Seven patients had discrepant results; all had a normal peak cortisol response to 250 micrograms ACTH (> 550 nmol/l), but a subnormal response to 1 microgram ACTH. Six of these also had a subnormal response to IIH. Cortisol responses to IIH match more closely those for 1 microgram ACTH in individual instances than those for 250 micrograms ACTH. The standard 250 micrograms ACTH stimulation, being supraphysiological, leads to underdiagnosis of the hypocortisolaemic state. The 1 microgram ACTH stimulation test should replace the standard 250 micrograms ACTH stimulation test in assessing the hypothalamo-pituitary-adrenocortical axis in secondary hypocortisolism.