[Show abstract][Hide abstract] ABSTRACT: Objective:
Clostridium difficile is a major cause of nosocomial infectious diarrhoea. Treatment of C. difficile infection (CDI) depends on disease severity. A combination of vancomycin and metronidazole is often recommended in severe cases. The aim of this study was to examine, in a murine model of CDI, if mice treated with a combination of vancomycin and metronidazole had a better clinical outcome than mice treated with vancomycin or metronidazole alone.
C57BL/6J mice pretreated with an antimicrobial mixture were challenged with C. difficile VPI 10463 or phosphate-buffered saline by oral gavage. After the challenge, the mice were treated with placebo, vancomycin, metronidazole or a combination of vancomycin and metronidazole for 10 days. The mice were monitored for 20 days with weight and a clinical score. Stool samples were examined for C. difficile spore load and presence of C. difficile toxins.
None of the mice in the vancomycin-treated group died during the treatment phase compared to a mortality of 17%, 33% and 55% in the combination, metronidazole and infected control group, respectively. Mice treated with vancomycin alone or in combination with metronidazole recovered from CDI faster than mice treated with metronidazole alone. However, after discontinuation of treatment, vancomycin-treated and combination-treated mice succumbed to clinical and bacteriological relapse.
Mice treated with vancomycin alone had a better clinical outcome in the treatment phase of CDI than mice treated with metronidazole alone. A combination of vancomycin and metronidazole did not improve the clinical outcome when compared to treatment with vancomycin alone.
Trial registration number:
The trial registration number from the Danish Experimental Animal Inspectorate is J number 2012-15-2934-00422.
[Show abstract][Hide abstract] ABSTRACT: Skin is an easily accessible organ, and therapeutic gene transfer to skin remains an attractive alternative for treatment of skin diseases. Although we have previously documented potent lentiviral gene delivery to human skin, vectors based on adeno-associated virus (AAV) rank among the most promising gene delivery tools for in vivo purposes. Thus, we compared the potential usefulness of various serotypes of recombinant AAV vectors and lentiviral vectors for gene transfer to human skin in a xenotransplanted mouse model. Vector constructs encoding firefly luciferase were packaged in AAV capsids of serotype 1, 2, 5, 6, 8, and 9 and separately administered by intradermal injection in human skin transplants. For all serotypes, live bioimaging demonstrated low levels of transgene expression in the human skin graft, and firefly luciferase expression was observed primarily in neighboring tissue outside of the graft. In contrast, gene delivery by intradermally injected lentiviral vectors was efficient and led to extensive and persistent firefly luciferase expression within the human skin graft only. The study demonstrates limited capacity of single-stranded AAV vectors of six commonly used serotypes for gene delivery to human skin in vivo.
[Show abstract][Hide abstract] ABSTRACT: Erythropoietin, Epo, is a 30.4 kDa glycoprotein hormone produced primarily by the fetal liver and the adult kidney. Epo exerts its haematopoietic effects by stimulating the proliferation and differentiation of erythrocytes with subsequent improved tissue oxygenation. Epo receptors are furthermore expressed in non-haematopoietic tissue and today, Epo is recognised as a cytokine with many pleiotropic effects. We hypothesize that hydrodynamic gene therapy with Epo can restore haemoglobin levels in anaemic transgenic mice and that this will attenuate the extracellular matrix accumulation in the kidneys. The experiment is conducted by hydrodynamic gene transfer of a plasmid encoding murine Epo in a transgenic mouse model that overexpresses TGF-β1 locally in the kidneys. This model develops anaemia due to chronic kidney disease characterised by thickening of the glomerular basement membrane, deposition of mesangial matrix and mild interstitial fibrosis. A group of age matched wildtype littermates are treated accordingly. After a single hydrodynamic administration of plasmid DNA containing murine EPO gene, sustained high haemoglobin levels are observed in both transgenic and wildtype mice from 7.5 ± 0.6 mmol/L to 9.4 ± 1.2 mmol/L and 10.7 ± 0.3 mmol/L to 15.5 ± 0.5 mmol/L, respectively. We did not observe any effects in the thickness of glomerular or tubular basement membrane, on the expression of different collagen types in the kidneys or in kidney function after prolonged treatment with Epo. Thus, Epo treatment in this model of chronic kidney disease normalises haemoglobin levels but has no effect on kidney fibrosis or function.
PLoS ONE 06/2015; 10(6):e0128367. DOI:10.1371/journal.pone.0128367 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Bacterial biofilms causing implant-associated osteomyelitis is a severe complication with limited antimicrobial therapy options. We designed an animal model, in which implant associated osteomyelitis arise from a Staphylococcus aureus biofilm on a tibia implant. Two bioluminescently engineered (luxA-E transformed), strains of S. aureus were utilized, Xen29 and Xen31. Biofilm formation was assessed with epifluorescence microscopy. Quantitative measurements were performed day 4, 6, 8, 11 and 15 post-surgery. Bacteria were extracted from the biofilm by sonication and the bacterial load quantified by culturing. Biofilm formation was evident from day 6 post-implantation. Mean bacterial load from implants was ∼1×104 CFU/implant, while mean bacterial load from infected tibias were 1×106 CFU/bone. Bioluminesence imaging revealed decreasing activity throughout the 15-day observation period, with signal intensity for both strains reaching that of the negative control by day 15 while there was no significant reduction in bacterial load. The model is suitable for testing antimicrobial treatment options for implant associated OM, as treatment efficacy on both biofilm and viable counts can be assessed.
PLoS ONE 10/2014; 9(10):e103688. DOI:10.1371/journal.pone.0103688 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: RNAi-based strategies provide a great therapeutic potential for treatment of various human diseases including kidney disorders, but face the challenge of in vivo delivery and specific targeting. The chitosan delivery system has previously been shown to target siRNA specifically to the kidneys in mice when administered intravenously. Here we confirm by 2D and 3D bioimaging that chitosan formulated siRNA is retained in the kidney for more than 48 hours where it accumulates in proximal tubule epithelial cells (PTECs), a process that was strongly dependent on the molecular weight of chitosan. Chitosan/siRNA nanoparticles, administered to chimeric mice with conditional knockout of the megalin gene, distributed almost exclusively in cells that expressed megalin, implying that the chitosan/siRNA particle uptake was mediated by a megalin-dependent endocytotic pathway. Knockdown of the water channel aquaporin 1 (AQP1) by up to 50% in PTECs was achieved utilizing the systemic i.v. delivery of chitosan/AQP1 siRNA in mice. In conclusion, specific targeting PTECs with the chitosan nanoparticle system may prove to be a useful strategy for knockdown of specific genes in PTECs, and provides a potential therapeutic strategy for treating various kidney diseases.
[Show abstract][Hide abstract] ABSTRACT: MicroRNAs (miRNAs) play a critical role in many biological processes and are aberrantly expressed in human cancers. Particular miRNAs function either as tumor suppressors or oncogenes and appear to have diagnostic and prognostic significance. Although numerous miRNAs are dys-regulated in colorectal cancer (CRC) only a small fraction has been characterized functionally. Using high-throughput functional screening and miRNA profiling of clinical samples the present study aims at identifying miRNAs important for the control of cellular growth and/or apoptosis in CRC. The high-throughput functional screening was carried out in six CRC cell lines transfected with a pre-miR library including 319 synthetic human pre-miRs. Phenotypic alterations were evaluated by immunostaining of cleaved cPARP (apoptosis) or MKI67 (proliferation). Additionally, TaqMan Human MicroRNA Array Set v2.0 was used to profile the expression of 667 miRNAs in 14 normal colon mucosa and 46 microsatellite stable stage II CRC patients. Among the miRNAs that induced growth arrest and apoptosis in the CRC cell lines, and at same time were dys-regulated in the clinical samples, miR-375 was selected for further analysis. Independent in vitro analysis of transient and stable transfected CRC cell lines confirmed that miR-375 reduces cell viability through the induction of apoptotic death. We identified YAP1 as a direct miR-375 target in CRC and show that HELLS and NOLC1 are down-stream targets. Knock-down of YAP1 mimicked the phenotype induced by miR-375 over-expression indicating that miR-375 most likely exerts its pro-apoptotic role through YAP1 and its anti-apoptotic down-stream targets BIRC5 and BCL2L1. Finally, in vivo analysis of mouse xenograft tumors showed that miR-375 expression significantly reduced tumor growth. We conclude that the high-throughput screening successfully identified miRNAs that induce apoptosis and/or inhibit proliferation in CRC cells. Finally, combining the functional screening with profiling of CRC tissue samples we identified clinically relevant miRNAs and miRNA targets in CRC.
PLoS ONE 06/2014; 9(6):e96767. DOI:10.1371/journal.pone.0096767 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Atherosclerosis can be achieved in animals by germline genetic engineering leading to hypercholesterolemia, but such models are constrained to few species and strains and they are difficult to combine with other powerful techniques involving genetic manipulation or variation.
To develop a method for induction of atherosclerosis without germline genetic engineering.
Recombinant adeno-associated viral vectors (rAAV) were engineered to encode gain-of-function proprotein convertase subtilisin/kexin type 9 (PCSK9) mutants, and mice were given a single intravenous vector injection followed by high-fat diet feeding. Plasma PCSK9 and total cholesterol increased rapidly and were maintained at high levels, and after 12 weeks, mice had atherosclerotic lesions in the aorta. Histology of the aortic root showed progression of lesions to the fibroatheromatous stage. To demonstrate the applicability of this method for rapid analysis of the atherosclerosis susceptibility of a mouse strain and for providing temporal control over disease induction, we demonstrated the accelerated atherosclerosis of mature diabetic Akita mice. Furthermore, the versatility of this approach for creating atherosclerosis models also in non-murine species was demonstrated by inducing hypercholesterolemia and early atherosclerosis in Golden Syrian hamsters.
Single injections of PCSK9-encoding rAAV vectors is a rapid and versatile method to induce atherosclerosis in animals. This method should prove useful for experiments that are high-throughput or involves genetic techniques, strains, or species that do not combine well with current genetically engineered models.
Circulation Research 03/2014; 114(11). DOI:10.1161/CIRCRESAHA.114.302937 · 11.02 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background Bone destruction in the joints of patients with rheumatoid arthritis (RA) is the result of a combined bone resorption by osteoclasts and bone formation by osteoblasts. However, most knowledge about this process comes from in vitro studies, whereas only few studies have addressed the importance of the osteoclasts and osteoblasts using histological methods, and none has used 3D stereological estimators. Therefore, stereology may provide important knowledge about bone formation and resorption in RA.
Objectives To study the in vivo effect of bone resorption and bone formation in the paws of SKG mice using 3D stereological estimators.
Methods Twenty one 9–12-weeks-old female SKG mice were randomised to either i.p. injection with mannan (11 mice) or PBS (10 mice). Arthritis was scored twice weekly by an observer blinded for group distribution. The fluorescent label tetracycline was injected 8 days before termination of the study at the end of week 6.
Right hind paws were fixed in alcohol and embedded undecalcified in methylmethacrylate. Tissue sections of 7 μm were cut exhaustively according to the principles of vertical sectioning. Systematic sampling was used to obtain approximately 12 sections from 10 levels. Using newCAST stereological software, intercepts between a line grid and the tissue of interest were counted by an observer blinded for group distribution. Osteoclast-covered bone surfaces (Oc.S) and eroded surfaces (ES) were estimated on TRAP-stained sections and mineralising surfaces (MS) were estimated on unstained sections. All parameters were assessed in the tarsus on the periosteal and endosteal surfaces, and the presence of adjacent inflammatory tissue was evaluated for each intersection. The relevant reference bone surface (BS) was estimated for all parameters, presenting the results as relative values (MS/BS, ES/BS, and Oc.S/BS).
Results At the end of week 1 and until termination, there was a significant difference in arthritis score (p<0.01).
MS/BS, ES/BS, and Oc.S/BS were elevated in arthritic paws compared to normal paws both at the endosteal surface and the periosteal surface (p<0.001). On endosteal as well as periosteal surfaces MS/BS were elevated on surfaces without inflammation in arthritic mice compared to normal mice (p<0.001).
In arthritic mice the ES/BS and Oc.S/BS on endosteal as well as periosteal surfaces were larger on surfaces adjacent to inflammation compared with the surfaces without inflammation (p<0.01). However, the difference between MS/BS at surfaces with and without inflammation on either periosteal or endosteal surfaces did not reach the level of statistical significance.
Conclusions The study demonstrates that arthritis caused bone formation to occur on more bone surfaces, irrespectively of the adjacent tissue being inflamed. However, bone degradation was present almost exclusively at surfaces with adjacent inflammation. Therefore, arthritic bone degradation is likely to be explained by an imbalance of erosion and formation of bone rather than a general down-regulation of bone formation. The present study is the first to apply 3D stereological estimators to quantify bone formation and degradation in a model of RA.
Disclosure of Interest None Declared
Annals of the Rheumatic Diseases 01/2014; 71(Suppl 3):647-647. DOI:10.1136/annrheumdis-2012-eular.170 · 10.38 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In patients with acute kidney injury (AKI) mortality remains high, despite the fact that the patients are treated with continuous renal replacement therapy. The interaction between the kidney and the immune system might explain the high mortality observed in AKI. In order to elucidate the interaction between the kidney and immune system we developed a two-hit model of AKI and endotoxemia. Our hypothesis was that ischemia/reperfusion (I/R) of the kidney simultaneously with endotoxemia would generate a more extensive inflammatory response compared to I/R of the hind legs. Our expectation was that elevated levels of cytokines would be found in both blood and in organs distant to the kidneys. Forty mice were divided into five groups. The mice were subjected to the following operations: A: Sham only, no lipopolysaccharide (LPS); B: I/R of both kidneys + LPS; C: LPS only; D: Nephrectomy + LPS; E: I/R of both hind legs + LPS. In groups B and E, I/R times were identical. All mice were kept alive for 24 h and then sacrificed. Levels of interleukin (IL)-1β, IL-6, IL-10, and tumor necrosis factor-α were measured in the blood. The activity of myeloperoxidase (MPO) in lungs, kidneys, and liver was evaluated as an indirect measurement of accumulation of granulocytes. In this study, significantly higher amount of IL-6 and IL-10 in the plasma was observed following renal I/R compared to hind leg I/R. The elevated levels of cytokine in plasma were observed following nephrectomy and endotoxemia. The neutrophil infiltration of distant organs measured by the levels of MPO in the lung and liver also showed a significantly higher level in renal I/R compared to hind leg I/R. Renal I/R is associated with a more pronounced inflammatory response in blood and distant organs. The high cytokine levels measured following nephrectomy might be explained by compromised elimination of cytokines by the kidney in AKI.
[Show abstract][Hide abstract] ABSTRACT: We describe a simple method for bone engineering using biodegradable scaffolds with mesenchymal stem cells derived from human induced-pluripotent stem cells (hiPS-MSCs). The hiPS-MSCs expressed mesenchymal markers (CD90, CD73, and CD105), possessed multipotency characterized by tri-lineages differentiation: osteogenic, adipogenic, and chondrogenic, and lost pluripotency - as seen with the loss of markers OCT3/4 and TRA-1-81 - and tumorigenicity. However, these iPS-MSCs are still positive for marker NANOG. We further explored the osteogenic potential of the hiPS-MSCs in synthetic polymer polycaprolactone (PCL) scaffolds or PCL scaffolds functionalized with natural polymer hyaluronan and ceramic TCP (PHT) both in vitro and in vivo. Our results showed that these iPS-MSCs are functionally compatible with the two 3D scaffolds tested and formed typically calcified structure in the scaffolds. Overall, our results suggest the iPS-MSCs derived by this simple method retain fully osteogenic function and provide a new solution towards personalized orthopedic therapy in the future.
[Show abstract][Hide abstract] ABSTRACT: Background:
The tyrosine kinase receptor HER4 is a member of the epidermal growth factor receptor (EGFR) family. It plays diverse roles in cancer development and cancer progression and can both exert oncogenic and tumour-suppressive activities. Alternatively spliced isoforms of HER4 are critical to the different signalling possibilities of HER4.
We use a splice-switching oligonucleotide (SSO) to direct the alternative splicing of HER4 from the CYT1 to the CYT2 isoform in HER4-expressing breast cancer cells.
Treatment with a target-specific SSO was accompanied by a decreased growth of the cells (P<0.0001). In addition, the SSO treatment induced a decreased activity of Akt. We confirmed the SSO-dependent switching of the HER4 isoform CYT1 to CYT2 expression in a xenografted mouse tumour model driven by subcutaneously injected MCF7 cells. We hence demonstrated the feasibility of SSO-directed splice-switching activity in vivo. Furthermore, the SSO treatment efficiently decreased the growth of the xenografted tumour (P=0.0014).
An SSO directing the splicing of HER4 towards the CYT2 isoform has an inhibitory effect of cancer cell growth in vitro and in vivo. These results may pave the way for the development of new anticancer drugs in HER4-deregulated cancers in humans.
British Journal of Cancer 05/2013; 108(11). DOI:10.1038/bjc.2013.247 · 4.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Harnessing the RNA interference pathway offers a new therapeutic modality; however, solutions to overcome biological barriers to small interfering RNA (siRNA) delivery are required for clinical translation. This work demonstrates, by direct northern and quantitative PCR (qPCR) detection, stability, gastrointestinal (GI) deposition, and translocation into peripheral tissue of nonmodified siRNA after oral gavage of chitosan/siRNA nanoparticles in mice. In contrast to naked siRNA, retained structural integrity and deposition in the stomach, proximal and distal small intestine, and colon was observed at 1 and 5 hours for siRNA within nanoparticles. Furthermore, histological detection of fluorescent siRNA at the apical regions of the intestinal epithelium suggests mucoadhesion provided by chitosan. Detection of intact siRNA in the liver, spleen, and kidney was observed 1 hour after oral gavage, with an organ distribution pattern influenced by nanoparticle N:P ratio that could reflect differences in particle stability. This proof-of-concept work presents an oral delivery platform that could have the potential to treat local and systemic disorders by siRNA.Molecular Therapy - Nucleic Acids (2013) 2, e76; doi:10.1038/mtna.2013.2; published online 5 March 2013.
[Show abstract][Hide abstract] ABSTRACT: Some of the main concerns with in vivo application of naked small interfering RNA are rapid degradation and urinary excretion resulting in a short plasma half-life. In this study we investigated how conjugation of polyethylene glycol (PEG) with variable chain length affects siRNA pharmacokinetics and biodistribution.
The PEG chains were conjugated to chemically stabilized siRNA at the 5' terminal end of the passenger strand using click chemistry. The siRNA conjugate remained functionally active and showed significantly prolonged circulation in the blood stream after intravenous injection. siRNA conjugated with 20kDa PEG (PEG20k-siRNA) was most persistent, approximately 50% PEG20k-siRNA remained 1h post-injection, while the uncoupled siRNA was rapidly removed >90% at 15min. In vivo fluorescent imaging of the living animal showed increased concentration of siRNA in peripheral tissue and delayed urine excretion when coupled to PEG 20k. Biodistribution studies by northern blotting revealed equal distribution of conjugated siRNA in liver, kidney, spleen and lung without significant degradation 24 h post-injection. Our study demonstrates that PEG conjugated siRNA can be applied as a delivery system to improve siRNA bioavailability in vivo and may potentially increase the efficiency of siRNA in therapeutic applications.
[Show abstract][Hide abstract] ABSTRACT: Mitochondria, the powerhouses of our cells, are remnants of a eubacterial endosymbiont. Notwithstanding the evolutionary time that has passed since the initial endosymbiotic event, mitochondria have retained many hallmarks of their eubacterial origin. Recent studies have indicated that during perturbations of normal homeostasis, such as following acute trauma leading to massive necrosis and release of mitochondria, the immune system might mistake symbiont for enemy and initiate an inappropriate immune response. The innate immune system is the first line of defense against invading microbial pathogens, and as such is the primary suspect in the recognition of mitochondria-derived danger-associated molecular patterns (DAMPs) and initiation of an aberrant response. Conversely, innate immune mechanisms are also central to non-inflammatory clearance of innocuous agents. Here we investigated the role of a central humoral component of innate immunity, the lectin pathway of complement, in recognition of mitochondria in vitro and in vivo. We found that the soluble pattern-recognition molecules (PRMs), mannan-binding lectin (MBL), L-ficolin and M-ficolin were able to recognize mitochondria. Furthermore, MBL in complex with MBL-associated serine protease 2 (MASP-2) was able to activate the lectin pathway and deposit C4 onto mitochondria, suggesting that these molecules are either involved in homeostatic clearance of mitochondria or induction of untoward inflammatory reactions. We found that following mitochondrial challenge, C3 was consumed in vivo in the absence of overt inflammation, indicating a potential role of complement in non-inflammatory clearance of mitochondria. Thus, we report here the first indication of involvement of the lectin pathway in mitochondrial immune handling.
[Show abstract][Hide abstract] ABSTRACT: Circulating mannan-binding lectin (MBL) levels are elevated in type 1 diabetes. Further, high MBL levels are associated with the development of diabetic nephropathy. In animals, a direct effect of MBL on diabetic kidney changes is observed. We hypothesized that MBL levels and detrimental complement activation increase as a consequence of diabetes. We measured plasma MBL before and seven weeks after inducing diabetes by streptozotocin. Mice have two MBLs, MBL-A and MBL-C. Diabetes-induction led to an increase in MBL-C concentration whereas no change during the study was found in the control group. The increase in MBL-C was associated with the increasing plasma glucose levels. In accordance with the observed changes in circulating MBL levels, liver expression of Mbl2 mRNA (encoding MBL-C) was increased in diabetes. Mbl1 expression (encoding MBL-A) did not differ between diabetic and control animals. The estimated half-life of recombinant human MBL was significantly prolonged in mice with diabetes compared with control mice. Complement activation in plasma and glomeruli did not differ between groups. We demonstrate for the first time that MBL levels increase after induction of diabetes and in parallel with increasing plasma glucose. Our findings support the previous clinical observations of increased MBL in type 1 diabetes. This change may be explained by alternations both in MBL production and turnover.
[Show abstract][Hide abstract] ABSTRACT: Arthritic bone loss in the joints of patients with rheumatoid arthritis is the result of a combination of osteoclastic bone resorption and osteoblastic bone formation. This process is not completely understood, and especially the importance of local inflammation needs further investigation. We evaluated how bone formation and bone resorption are altered in experimental autoimmune arthritis.
Twenty-one female SKG mice were randomized to either an arthritis group or a control group. Tetracycline was used to identify mineralizing surfaces. After six weeks the right hind paws were embedded undecalcified in methylmethacrylate. The paws were cut exhaustively according to the principles of vertical sectioning and systematic sampling. 3D design-based methods were used to estimate the total number of osteoclasts, mineralizing surfaces, eroded surfaces, and osteoclast-covered bone surfaces. In addition the presence of adjacent inflammation was ascertained.
The total number of osteoclasts, mineralizing surfaces, eroded surfaces, and osteoclast covered surfaces were elevated in arthritic paws compared to normal paws. Mineralizing surfaces were elevated adjacent to as well as not adjacent to inflammation in arthritic mice compared to normal mice. In arthritic mice, eroded surfaces and osteoclast covered surfaces were larger on bone surfaces adjacent to inflammation than on bone surfaces without adjacent inflammation. However, we found no difference between mineralizing surfaces at bone surfaces with or without inflammation in arthritic mice.
Inflammation induced an increase in resorptive bone surfaces as well as formative bone surfaces. The bone formative response may be more general, since formative bone surfaces were also increased when not associated with inflammation. Thus, the bone loss may be the result of a substantial local bone resorption, which cannot be compensated by the increased local bone formation. These findings may be valuable for the development of new osteoblast targeting drugs in RA.
PLoS ONE 12/2012; 7(12):e53034. DOI:10.1371/journal.pone.0053034 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Gene electrotransfer is an effective non-viral technique for delivery of plasmid DNA into tissues. From a clinical perspective muscle is an attractive target tissue as long-term high-level transgenic expression can be achieved. Spatial distribution of the transgenic protein following gene electrotransfer to muscle in a large animal model has not yet been investigated. In this study 17 different doses of plasmid DNA (1-1500 µg firefly luciferase pCMV-Luc) were delivered in vivo to porcine gluteal muscle using electroporation. Forty-eight hours post treatment several biopsies were obtained from each transfection site in order to examine the spatial distribution of the transgenic product. We found a significantly higher luciferase activity in biopsies from the center of the transfection site compared to biopsies taken adjacent to the center 1 and 2 cm along muscle fibre orientation (p<0.05 and p<0.0001, respectively). On average, 43 % of the total luciferase activity was localized in the center biopsy. In conclusion, we found that gene electrotransfer to muscle in a large animal model led to localized gene expression corresponding to the area delineated by the electrodes. High doses of plasmid DNA did not lead to a larger area of the muscle expressing the transgenic protein.
[Show abstract][Hide abstract] ABSTRACT: Targeted transgenesis using site-specific recombinases is an attractive method to create genetically modified animals as it allows for integration of the transgene in a pre-selected transcriptionally active genomic site. Here we describe the application of recombinase-mediated cassette exchange (RMCE) in cells from a Göttingen minipig with four RMCE acceptor loci, each containing a green fluorescence protein (GFP) marker gene driven by a human UbiC promoter. The four RMCE acceptor loci segregated independent of each other, and expression profiles could be determined in various tissues. Using minicircles in RMCE in fibroblasts with all four acceptor loci and followed by SCNT, we produced piglets with a single copy of a transgene incorporated into one of the transcriptionally active acceptor loci. The transgene, consisting of a cDNA of the Alzheimer’s disease-causing gene PSEN1M146I driven by an enhanced human UbiC promoter, had an expression profile in various tissues similar to that of the GFP marker gene. The results show that RMCE can be done in a pre-selected transcriptionally active acceptor locus for targeted transgenesis in pigs.
Electronic supplementary material
The online version of this article (doi:10.1007/s11248-012-9671-6) contains supplementary material, which is available to authorized users.
Transgenic Research 10/2012; 22(4). DOI:10.1007/s11248-012-9671-6 · 2.32 Impact Factor