Queering the genome: ethical challenges of epigenome editing in same-sex reproduction.

In this article, I explore the ethical dimensions of same-sex reproduction achieved through epigenome editing-an innovative and transformative technique. For the first time, I analyse the potential normativity of this disruptive approach for reproductive purposes, focusing on its implications for lesbian couples seeking genetically related offspring. Epigenome editing offers a compelling solution to the complex ethical challenges posed by traditional gene editing, as it sidesteps genome modifications and potential long-term genetic consequences. The focus of this article is to systematically analyse the bioethical issues related to the use of epigenome editing for same-sex reproduction. I critically assess the ethical acceptability of epigenome editing with reproductive purposes from multiple angles, considering harm perspectives, the comparison of ethical issues related to gene and epigenome editing, and feminist theories. This analysis reveals that epigenome editing emerges as an ethically acceptable means for lesbian couples to have genetically related children. Moreover, the experiments of a reproductive use of epigenome editing discussed in this article transcend bioethics, shedding light on the broader societal implications of same-sex reproduction. It challenges established notions of biological reproduction and prompts a reevaluation of how we define the human embryo, while poses some issues in the context of gender self-identification and family structures. In a world that increasingly values inclusivity and diversity, this article aims to reveal a progressive pathway for reproductive medicine and bioethics, as well as underscores the need for further philosophical research in this emerging and fertile domain.

In vivo transfection of cytokine genes into tumor cells using a synthetic vehicle promotes antitumor immune responses in a visceral tumor model.

The tumor microenvironment (TME) strongly affects the clinical outcomes of immunotherapy. This study aimed to activate the antitumor immune response by manipulating the TME by transfecting genes encoding relevant cytokines into tumor cells using a synthetic vehicle, which is designed to target tumor cells and promote the expression of transfected genes. Lung tumors were formed by injecting CT26.WT intravenously into BALB/c mice. Upon intravenous injection of the green fluorescent protein-coding plasmid encapsulated in the vehicle, 14.2% tumor-specific expression was observed. Transfection of the granulocyte-macrophage colony-stimulating factor (GM-CSF) and CD40 ligand (L)-plasmid combination and interferon gamma (IFNγ) and CD40L-plasmid combination showed 45.5% and 54.5% complete remission (CR), respectively, on day 60; alternate treatments with both the plasmid combinations elicited 66.7% CR, while the control animals died within 48 days. Immune status analysis revealed that the density of dendritic cells significantly increased in tumors, particularly after GM-CSF- and CD40L-gene transfection, while that of regulatory T cells significantly decreased. The proportion of activated killer cells and antitumoral macrophages significantly increased, specifically after IFNγ and CD40L transfection. Furthermore, the level of the immune escape molecule programmed death ligand-1 decreased in tumors after transfecting these cytokine genes. As a result, tumor cell-specific transfection of these cytokine genes by the synthetic vehicle significantly promotes antitumor immune responses in the TME, a key aim for visceral tumor therapy.

Genealogical obscurement: mitochondrial replacement techniques and genealogical research.

Mitochondrial replacement techniques (MRTs) are a new group of biotechnologies that aim to aid women whose eggs have disease-causing deleteriously mutated mitochondria to have genetically related healthy children. These techniques have also been used to aid women with poor oocyte quality and poor embryonic development, to have genetically related children. Remarkably, MRTs create humans with DNA from three sources: nuclear DNA from the intending mother and father, and mitochondrial DNA from the egg donor. In a recent publication Françoise Baylis argued that MRTs are detrimental for genealogical research via mitochondrial DNA because they would obscure the lines of individual descent. In this paper, I argue that MRTs do not obscure genealogical research, but rather that MRT-conceived children can have two mitochondrial lineages. I argue for this position by showing that MRTs are reproductive in nature and, thus, they create genealogy.

Genetically engineered E. coli invade epithelial cells and transfer their genetic cargo into the cells: an approach to a gene delivery system.

PURPOSE: Despite advances in gene therapy, the lack of safe and efficient gene delivery systems limited the clinical effectiveness of gene therapy. Due to the inherent potential of bacteria, they can be considered as a good option for the gene transfer system. This study aimed to create a genetically engineered bacterium capable of entering epithelial cells and transferring its genetic cargo to the cell's cytoplasm, eventually expressing the gene of interest in the cell. METHODS: The invasin (inv) gene from Yersinia pseudotuberculosis and the listeriolysin (hlyA) gene from Listeria monocytogenes were isolated by PCR assay and inserted into a pACYCDuet-1 vector. The recombinant plasmid was then transformed into E. coli strain BL21. Subsequently, pEGFP-C1 plasmids containing a CMV promoter were transformed into the engineered bacteria. Finally, the engineered bacteria containing the reporter genes were incubated with the HeLa and LNCaP cell lines. Fluorescence microscopy, flow cytometry, and TEM were used to monitor bacterial entry into the cells and gene expression. We used native E. coli strain BL21 as a control. RESULTS: A fluorescence microscope showed that, in contrast to the control group, the manipulated E. coli were able to penetrate the cells and transport the plasmid pEGFP-C1 to the target cells. Flow cytometry also showed fluorescence intensity of 54.7% in HeLa cells and 71% in LNCaP cells, respectively. In addition, electron micrographs revealed the presence of bacteria in the cell endosomes and in the cytoplasm of the cells. CONCLUSION: This study shows that genetically engineered E. coli can enter cells, transport cargo into cells, and induce gene expression in the target cell. In addition, flow cytometry shows that the gene transfer efficiency was sufficient for protein expression.

Interleukins, growth factors, and transcription factors are key targets for gene therapy in osteoarthritis: A scoping review.

Objective: Osteoarthritis (OA) is the most common degenerative joint disease, characterized by a progressive loss of cartilage associated with synovitis and subchondral bone remodeling. There is however no treatment to cure or delay the progression of OA. The objective of this manuscript was to provide a scoping review of the preclinical and clinical studies reporting the effect of gene therapies for OA. Method: This review followed the JBI methodology and was reported in accordance with the PRISMA-ScR checklist. All research studies that explore in vitro, in vivo, or ex vivo gene therapies that follow a viral or non-viral gene therapy approach were considered. Only studies published in English were included in this review. There were no limitations to their date of publication, country of origin, or setting. Relevant publications were searched in Medline ALL (Ovid), Embase (Elsevier), and Scopus (Elsevier) in March 2023. Study selection and data charting were performed by two independent reviewers. Results: We found a total of 29 different targets for OA gene therapy, including studies examining interleukins, growth factors and receptors, transcription factors and other key targets. Most articles were on preclinical in vitro studies (32 articles) or in vivo animal models (39 articles), while four articles were on clinical trials related to the development of TissueGene-C (TG-C). Conclusion: In the absence of any DMOAD, gene therapy could be a highly promising treatment for OA, even though further development is required to bring more targets to the clinical stage.

The ethics of gene therapy for hemophilia: a narrative review.

Gene therapy is expected to become a promising treatment, and potentially even a cure, for hemophilia. After several years of research, the first gene therapy product has been granted conditional market authorization by the European Union in August 2022. The recent progress in the field also has implications on the ethical aspects of hemophilia gene therapy. Reviews conducted in the 2000s mainly identified questions on the ethics of conducting early-phase clinical trials. However, since then, the knowledge on safety and efficacy has improved, and the field has moved toward clinical application, a phase that has its own ethical aspects. Therefore, we conducted a narrative review to take stock of the ethical aspects of hemophilia gene therapy. Based on our analysis of the literature, we identified 3 ethical themes. The theme Living up to expectations describes the existing hopes for gene therapy and the unlikelihood of the currently approved product becoming a permanent cure. In the theme Psychosocial impacts, we discuss the fear that gene therapy will impact the identity of people with hemophilia and their need for psychosocial support. The theme Costs and access discusses the expected cost-effectiveness of gene therapy and its implications on accessibility worldwide. We conclude that it may be necessary to change the narratives surrounding gene therapy, from describing it as a cure to describing it as one of the many treatments that temporarily relieve symptoms and that there is a need to reevaluate the desirability of gene therapy for hemophilia, given the availability of other treatments.

Vibropolyfection: coupling polymer-mediated gene delivery to mechanical stimulation to enhance transfection of adherent cells.

BACKGROUND: With the success of recent non-viral gene delivery-based COVID-19 vaccines, nanovectors have gained some public acceptance and come to the forefront of advanced therapies. Unfortunately, the relatively low ability of the vectors to overcome cellular barriers adversely affects their effectiveness. Scientists have thus been striving to develop ever more effective gene delivery vectors, but the results are still far from satisfactory. Therefore, developing novel strategies is probably the only way forward to bring about genuine change. Herein, we devise a brand-new gene delivery strategy to boost dramatically the transfection efficiency of two gold standard nucleic acid (NA)/polymer nanoparticles (polyplexes) in vitro. RESULTS: We conceived a device to generate milli-to-nanoscale vibrational cues as a function of the frequency set, and deliver vertical uniaxial displacements to adherent cells in culture. A short-lived high-frequency vibrational load (t = 5 min, f = 1,000 Hz) caused abrupt and extensive plasmalemma outgrowths but was safe for cells as neither cell proliferation rate nor viability was affected. Cells took about 1 hr to revert to quasi-naïve morphology through plasma membrane remodeling. In turn, this eventually triggered the mechano-activated clathrin-mediated endocytic pathway and made cells more apt to internalize polyplexes, resulting in transfection efficiencies increased from 10-to-100-fold. Noteworthy, these results were obtained transfecting three cell lines and hard-to-transfect primary cells. CONCLUSIONS: In this work, we focus on a new technology to enhance the intracellular delivery of NAs and improve the transfection efficiency of non-viral vectors through priming adherent cells with a short vibrational stimulation. This study paves the way for capitalizing on physical cell stimulation(s) to significantly raise the effectiveness of gene delivery vectors in vitro and ex vivo.

Durability of transgene expression after rAAV gene therapy.

Recombinant adeno-associated virus (rAAV) gene therapy has the potential to transform the lives of patients with certain genetic disorders by increasing or restoring function to affected tissues. Following the initial establishment of transgene expression, it is unknown how long the therapeutic effect will last, although animal and emerging human data show that expression can be maintained for more than 10 years. The durability of therapeutic response is key to long-term treatment success, especially since immune responses to rAAV vectors may prevent re-dosing with the same therapy. This review explores the non-immunological and immunological processes that may limit or improve durability and the strategies that can be used to increase the duration of the therapeutic effect.

In vitro Delivery of HIV-1 Nef-Vpr DNA Construct Using the Human Antimicrobial Peptide LL-37.

BACKGROUND AND OBJECTIVES: DNA-based therapeutic vaccines have been proposed as a promising strategy for the treatment of established HIV infections. However, these vaccines are often associated with certain shortcomings, such as poor immunogenicity and low transfection efficiency. In this study, we investigated the ability of LL-37 to deliver a potential immunogenic fusion construct comprising HIV-1 nef and vpr genes into a mammalian cell line. METHODS: First, the pEGFP-N1 eukaryotic expression vector harboring the HIV-1 nef-vpr fusion was produced free of endotoxin on a large scale. Then, DNA/LL-37 complexes were prepared by coincubation of pEGFP-nef-vpr with LL-37 for 45 minutes at different nitrogen to phosphate (N/P) ratios. The formation of DNA/peptide complexes was investigated by gel retardation assay. Next, the stability and morphological characteristics of the nanoparticles were evaluated. The toxicity of LL-37 and the nanoparticles in HEK-293T cells were assessed by MTT assay. The transfection efficiency of the DNA/LL-37 complexes was studied by fluorescence microscopy, flow cytometry, and western blot analysis. RESULTS: LL-37 formed stable complexes with pEGFP-nef-vpr (diameter of 150-200 nm) while providing good protection against nucleolytic and proteolytic degradation. The peptide significantly affected cell viability even at low concentrations. However, the LL-37/DNA complexes had no significant cytotoxic effect. Treatment of cells with pEGFP-N1/LL-37 and pEGFP-nef-vpr/LL-37 resulted in transfection of 36.32% ± 1.13 and 25.55% ± 2.07 of cells, respectively. CONCLUSION: Given these findings and the important immunomodulatory and antiviral activities of LL- 37, the use of this peptide can be further exploited in the development of novel gene delivery strategies and vaccine design.

Effect of Src tyrosine kinase on a rat model of asthma.

Src tyrosine kinase is a protein encoded by the Src gene. The present study aimed to determine the role of Src protein kinase in asthma using small interfering RNA (siRNA) technology. Several Src siRNAs were designed and the most effective siRNA pair was selected. A rat model of asthma was established using ovalbumin, and the rats were treated with Src siRNA, empty vector or phosphate-buffered saline (PBS). A non-asthmatic control group was also established. The rats were clinically observed and Src mRNA and protein levels were measured by reverse transcription-quantitative PCR and western blot analysis, respectively. Pathological observation of the lung tissue, counting of white blood cells (WBCs) and eosinophils (EOSs) and analysis of the concentrations of IL-5, IL-33 and IFN-γ in the bronchoalveolar lavage fluid were performed. The expression levels of Src mRNA in the control, PBS, empty vector and siRNA groups were 110±30.7x103, 253±55.4x103, 254±41.3x103 and 180±50.9x103, respectively. Histochemical analysis of the lung tissue of rats in the siRNA group exhibited a relatively complete lung structure and little damage to the alveolar cavity. Src protein expression and IL-5, IL-33 levels, WBC and EOS levels were positively correlated with Src mRNA expression, while the IFN-γ concentration was negatively correlated with Src mRNA expression. These results indicate that Src knockdown inhibits the release of tracheal inflammatory factors and significantly alleviates asthma in rats. In conclusion, the present study utilized a gene transfer technique to interfere with the expression of Src in rats, which decreased the levels of IL-5, IL-33, WBCs and EOSs and increased the level of IFN-γ; these changes effectively ameliorated the condition of the trachea in asthmatic rats.

Silencing SALL-4 Gene by Transfecting Small Interfering RNA with Targeted Aminoglycoside-Carboxyalkyl Polyethylenimine Nano-Polyplexes Reduced Migration of MCF-7 Breast Cancer Cells.

BACKGROUND: The application of non-viral systems for delivering genes to cells is becoming a very interesting issue, especially in the treatment of neoplasms such as Breast Cancer (BC). Polymer-based non-viral systems are safe and feasible gene carriers to be used in targeted cancer therapy. SALL4 gene encodes a transcription factor and is overexpressed in some cancers. METHODS: In this study, carboxyalkylated-PEI25 (25 kDa) was used to deliver plasmids expressing SALL4-siRNA into MCF-7 cells. DLS and AFM were applied to determine the size of nanoparticles. The MTT method was used to assess cytotoxicity, and the efficiency of transfection was confirmed both qualitatively and quantitatively. Finally, the effect of silencing SALL4 was investigated on the migration of MCF7 cells using the scratch test. RESULTS: The results showed that transferring the SALL4-siRNA using PEI25G10C50 reduced the expression of the corresponding transcription factor by 14 folds which attenuated the migration of MCF-7 cells by 58%. CONCLUSION: In conclusion, PEI25G10C50 can serve as an effective gene delivery system for treating BC by targeting SALL-4.

The challenging nature of primary T lymphocytes for transfection: Effect of protamine sulfate on the transfection efficiency of chemical transfection reagents.

BACKGROUND AND PURPOSE: The optimization of an effective non-viral gene delivery method for genetic manipulation of primary human T cells has been a major challenge in immunotherapy researches. Due to the poor transfection efficiency of conventional methods in T cells, there has been an effort to increase the transfection rate in these cells. Protamine is an FDA-approved compound with a documented safety profile that enhances DNA condensation for gene delivery. EXPERIMENTAL APPROACH: In this study, the effect of protamine sulfate on the transfection efficiency of standard transfection reagents, was evaluated to transfect primary human T cells. In this regard, pre-condensation of DNA was applied using protamine, and the value of the zeta potential of DNA/protamine/cargo complexes was determined. T cells were transfected with DNA/protamine/cargo complexes. The transfection efficiency rate was evaluated by flow cytometry. Also, the green fluorescent protein expression level and cytotoxicity of each complex were identified using real-time polymerase chain reaction and MTT assay, respectively. FINDINGS/RESULTS: Our results demonstrated that protamine efficiently increases the positive charge of DNA/cargo complex without any cytotoxic effect on the primary human T cells. We observed that the transfection efficiency in DNA/protamine/ Lipofectamine® 2000 and DNA/protamine/TurboFect™ was 87.2% and 78.9%, respectively, while transfection of T cells by Lipofectamine® 2000 and TurboFect™ would not result in sufficient transfection. CONCLUSION AND IMPLICATIONS: Protamine sulfate enhanced the transfection rate of T cells; and could be a promising non-viral gene delivery method to achieve a safe, rapid, cost-effective, and efficient system which will be further applied in gene therapy and T cells manipulation methods.

Synergism of wt-p53 and synthetic material in local nano-TAE gene therapy of hepatoma: comparison of four systems and the possible mechanism.

BACKGROUND: TAE-gene therapy for hepatoma, incorporating the tumor-targeted therapeutic efficacy of trans-arterial embolization, hydroxyapatite nanoparticles (nHAP) and anti-cancer wild-type p53 gene (wt-p53), was presented in our former studies (Int J Nanomedicine 8:3757-68, 2013, Liver Int 32:998-1007, 2012). However, the incompletely antitumoral effect entails defined guidelines on searching properer materials for this novel therapy. METHODS: Unmodified nHAP, Ca(2+) modified nHAP, poly-lysine modified nHAP and liposome were separately used to form U-nanoplex, Ca-nanoplex, Pll-nanoplex, L-nanoplex respectively with wt-p53 expressing plasmid. The four nanoplexs were then applied in vitro for human normal hepacyte L02 and hepatoma HePG2 cell line, and in vivo for rabbits with hepatic VX2 tumor by injection of nanoplexs/lipiodol emulsion into the hepatic artery in a tumor target manner. The distribution, superficial potential, physical structure, morphology and chemical compositions of nanoplexs were evaluated by TEM, SEM, EDS etc., with the objective of understanding their roles in hepatoma TAE-gene therapy. RESULTS: In vitro, L-nanoplex managed the highest gene transferring efficiency. Though with the second highest transfection activity, Pll-nanoplex showed the strongest tumor inhibition activity while maintaining safe to the normal hepacyte L02. In fact, only Pll-nanoplex can combine both the antitumoral effect to HePG2 and safe procedure to L02 among the four systems above. In vivo, being the only one with successful gene transference to hepatic VX2 tumor, Pll-nanoplex/lipiodol emulsion can target the tumor more specifically, which may explain its best therapeutic effect and hepatic biologic response. Further physical characterizations of the four nanoplexs suggested particle size and proper electronic organic surface may be crucial for nano-TAE gene therapy. CONCLUSION: Pll-nanoplex is the most proper system for the combined therapy due to its selectively retention in liver cancer cells, secondary to its morphological and physico-chemical properties of nanometric particle size, steady emulsion, proper organic and electronic surface.

Establishment of Stable Cell Lines from Primary Human Dental Pulp Stem Cells.

This protocol is for the isolation of primary human dental pulp stem cells (DPSCs) from adult extracted molars and for the generation of high-titer lentivirus for in vitro infection of the DPSCs. Stable cell lines of dental pulp stem cells are generated, maintained in culture, and used for subsequent experiments.

Synthesis, characterization and evaluation of transfection efficiency of dexamethasone conjugated poly(propyleneimine) nanocarriers for gene delivery#.

CONTEXT: Polypropylenimine (PPI), a cationic dendrimer with defined structure and positive surface charge, is a potent non-viral vector. Dexamethasone (Dexa) conveys to the nucleus through interaction with its intracellular receptor. OBJECTIVE: This study develops efficient and non-toxic gene carriers through conjugation of Dexa at various percentages (5, 10 and 20%) to the fourth and the fifth generation PPIs (PPIG4s and PPIG5s). MATERIALS AND METHODS: The 21-OH group of Dexa (0.536 mmol) was modified with methanesulfonyl chloride (0.644 mmol) to activate it (Dexa-mesylate), and then it was conjugated to PPIs using Traut's reagent. After dialysis (48 h) and lyophilization, the physicochemical characteristics of products (PPI-Dexa) including zeta potential, size, buffering capacity and DNA condensing capability were investigated and compared with unmodified PPIs. Moreover, the cytotoxicity and transfection activity of the Dexa-modified PPIs were assessed using Neuro2A cells. RESULTS: Transfection of PPIG4 was close to PEI 25 kDa. Although the addition of Dexa to PPIG4s did not improve their transfection, their cytotoxicity was improved; especially in the carrier to DNA weight ratios (C/P) of one and two. The Dexa conjugation to PPIG5s enhanced their transfection at C/P ratio of one in both 5% (1.3-fold) and 10% (1.6-fold) Dexa grafting, of which the best result was observed in PPIG5-Dexa 10% at C/P ratio of one. DISCUSSION AND CONCLUSIONS: The modification of PPIs with Dexa is a promising approach to improve their cytotoxicity and transfection. The higher optimization of physicochemical characteristics, the better cell transfection and toxicity will be achieved.

Changes of plasma miR-1470 expression in patients with diabetic retinopathy and its possible mechanism / 中华眼底病杂志

Objective To investigate the expression and mechanism of miR-1470 in plasma of diabetic retinopathy (DR) patients.Methods Thirty patients with DR (DR group),30 patients with diabetes (DM group) and 30 normal healthy subjects (normal group) were enrolled in the study.Three groups of subjects were taken 5 ml of venous blood,and total plasma RNA was extracted and purified.The differentially expressed miRNAs in the plasma of DR patients were screened by gene chip,and the results of gene chip detection were verified by reverse transcription polymerase chain reaction (RT-PCR).Bioinformatics was used to predict potential target genes for miRNA regulation,and miR-1470 and its target gene epidermal growth factor receptor (EGFR) were screened.Human retinal microvascular endothelial cells (hREC) were divided into normal group (sugar concentration 5.5 mmol/L) and high glucose group (sugar concentration 25.0 mmol/L).hREC was transfected into miR-1470 mimics to establish a miR-1470 high expression cell model,which was divided into blank control group,high expression group and negative control group.The expression of miR-1470 was detected by RT-PCR.The expression of EGFR protein was detected by Western blot.The measurement data of the two groups were compared using the independent sample t test.The comparison of the measurement data between the two groups was analyzed by ANOVA.The comparison between the measurement data of the groups was compared by multiple comparisons.Results The results of RT-PCR were consistent with those of the gene chip.The expression of miR-1470 in the plasma of the DR group,the DM group and the normal group was statistically significant (F=63.486,P=0.049).Compared with the DM group and the normal group,the expression of miR-1470 in the DR group was significantly decreased,and the difference was statistically significant (q=l 11.2,73.9;P＜0.05).The expression of miR-1470 in hREC in the high glucose group was significantly lower than that in the normal group (t=42.082,P=0.015).The expression of EGFR protein in hREC of high glucose group was significantly higher than that of normal group (t=-39.939,P=0.016).The expression of miR-1470 (F=637.069,P=0.000) and EGFR (F=122.908,P=0.000) protein expression in hREC of blank control group,negative control group and high expression group were statistically significant.Compared with the blank control group and the negative control group,the expression of miR-1470 in hREC of high expression group was significantly increased (q=329.7,328.8;P＜0.05),and the expression of EGFR protein was significantly decreased (q=242.5,234.6;P＜0.05).There was no significant difference in the expression of miR-1470 and EGFR protein in hREC between the negative control group and the blank control group (q=1.5,7.9;P＞0.05).Conclusion The expression ofmiR-1470 in the plasma of patients with DR is significantly down-regulated,and the increase of EGFR expression may be related to it.

Localized Optogenetic Targeting of Rotors in Atrial Cardiomyocyte Monolayers.

BACKGROUND: Recently, a new ablation strategy for atrial fibrillation has emerged, which involves the identification of rotors (ie, local drivers) followed by the localized targeting of their core region by ablation. However, this concept has been subject to debate because the mode of arrhythmia termination remains poorly understood, as dedicated models and research tools are lacking. We took a unique optogenetic approach to induce and locally target a rotor in atrial monolayers. METHODS AND RESULTS: Neonatal rat atrial cardiomyocyte monolayers expressing a depolarizing light-gated ion channel (Ca2+-translocating channelrhodopsin) were subjected to patterned illumination to induce single, stable, and centralized rotors by optical S1-S2 cross-field stimulation. Next, the core region of these rotors was specifically and precisely targeted by light to induce local conduction blocks of circular or linear shapes. Conduction blocks crossing the core region, but not reaching any unexcitable boundary, did not lead to termination. Instead, electric waves started to propagate along the circumference of block, thereby maintaining reentrant activity, although of lower frequency. If, however, core-spanning lines of block reached at least 1 unexcitable boundary, reentrant activity was consistently terminated by wave collision. Lines of block away from the core region resulted merely in rotor destabilization (ie, drifting). CONCLUSIONS: Localized optogenetic targeting of rotors in atrial monolayers could lead to both stabilization and destabilization of reentrant activity. For termination, however, a line of block is required reaching from the core region to at least 1 unexcitable boundary. These findings may improve our understanding of the mechanisms involved in rotor-guided ablation.

Targeting expression to megakaryocytes and platelets by lineage-specific lentiviral vectors.

Essentials Platelet phenotypes can be modified by lentiviral transduction of hematopoietic stem cells. Megakaryocyte-specific lentiviral vectors were tested in vitro and in vivo for restricted expression. The glycoprotein 6 vector expressed almost exclusively in megakaryocytes. The platelet factor 4 vector was the strongest but with activity in hematopoietic stem cells. SUMMARY: Background Lentiviral transduction and transplantation of hematopoietic stem cells (HSCs) can be utilized to modify the phenotype of megakaryocytes and platelets. As the genetic modification in HSCs is transmitted onto all hematopoietic progenies, transgene expression from the vector should be restricted to megakaryocytes to avoid un-physiologic effects by ectopic transgene expression. This can be achieved by lentiviral vectors that control expression by lineage-specific promoters. Methods In this study, we introduced promoters of megakaryocyte/platelet-specific genes, namely human glycoprotein 6 (hGP6) and hGP9, into third generation lentiviral vectors and analyzed their functionality in vitro and in vivo in bone marrow transplantation assays. Their specificity and efficiency of expression was compared with lentiviral vectors utilizing the promoters of murine platelet factor 4 (mPf4) and hGP1BA, both with strong activity in megakaryocytes (MKs) used in earlier studies, and the ubiquitously expressing phosphoglycerate kinase (hPGK) and spleen focus forming virus (SFFV) enhancer/promoters. Results Expression from the mPf4 vector in MKs and platelets was the strongest similar to expression from the viral SFFV promoter, however, the mPf4 vector, also exhibited considerable off-target expression in hematopoietic stem and progenitor cells. In contrast, the newly generated hGP6 vector was highly specific to megakaryocytes and platelets. The specificity was also retained when reducing the promoter size to 350 bp, making it a valuable new tool for lentiviral expression in MKs/platelets. Conclusion MK-specific vectors express preferentially in the megakaryocyte lineage. These vectors can be applied to develop murine models to study megakaryocyte and platelet function, or for gene therapy targeting proteins to platelets.

Adenoviral Vector-Mediated Delivery of p21WAF1/CIP1 Prevents Retinal Neovascularization in an Oxygen-Induced Retinopathy Model.

OBJECTIVE: To evaluate the inhibitory effect(s) of adenovirus (Ad) vector-mediated delivery of p21WAF1/CIP1 (Ad-p21) on retinal neovascularization (RNV) in an animal model of oxygen-induced retinopathy (OIR). METHODS: RNV was determined by examination of retinal fiat mounts and sections postnatal (P) day-17 (P17). Non-perfused retinal areas were analyzed using Image-Pro plus 6.0 software. Reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot analysis were used to measure mRNA and protein expression of p21 and cyclin-dependent kinase (CDK) 2. RESULTS: Compared with phosphate buffer saline (PBS) and Ad-NC group mice, non-perfused retinal areas, neovascularization, and number of endothelial cell nuclei breaking through the internal limiting membrane (ILM) in Ad-p21 group mice were significantly reduced. There were fewer non-perfused retinal areas in Ad-p21 mice than in either PBS or Ad-NC group mice, the differences being significant (F = 101.634; p < 0.05). Levels of p21 mRNA and protein in the Ad-p21 group had increased significantly compared with the other three groups (F = 839.664, 509.817; p < 0.05). Levels of CDK2 mRNA and protein in the Ad-p21 group decreased significantly (F = 301.858, 592.882; p < 0.05). CONCLUSIONS: Ad-p21 inhibits RNV in OIR. A potential underlying mechanism for this may be that overexpression of p21 arrests the cell cycle at the G1- to S-phase transition via inhibition of CDK2 activity.