Noninvasive optical imaging of firefly luciferase reporter gene expression in skeletal muscles of living mice

Establishment of a visualized mouse orthotopic xenograft model of nasopharyngeal carcinoma

Mouse orthotopic xenograft tumor models are commonly employed in studies investigating the mechanisms underlying the development and progression of tumors and their preclinical treatment. However, the unavailability of mature and visualized orthotopic xenograft models of nasopharyngeal carcinoma limits the development of treatment strategies for this cancer. The aim of this study was to provide a simple and reliable method for building an orthotopic xenograft model of nasopharyngeal carcinoma. Human nasopharyngeal carcinoma (C666-1-luc) cells, stably expressing the firefly luciferase gene, were injected subcutaneously into the right axilla of BALB/C nude mice. Four weeks later, the resulting subcutaneous tumors were cut into small blocks and grafted into the nasopharynx of immunodeficient BALB/C nude mice to induce tumor formation. Tumor growth was monitored by bioluminescence imaging and small animal magnetic resonance imaging (MRI). The expression of histological and immunological antigens associated with orthotopic xenograft nasopharyngeal carcinoma was analyzed by tissue section analysis and immunohistochemistry (IHC). A visualized orthotopic xenograft nasopharyngeal carcinoma model was successfully developed in this study. Luminescence signal detection, micro-MRI, and hematoxylin and eosin staining revealed the successful growth of tumors in the nasopharynx of the nude mice. Moreover, IHC analysis detected cytokeratin (CK), CK5/6, P40, and P63 expression in the orthotopic tumors, consistent with the reported expression of these antigens in human nasopharyngeal tumors. This study established a reproducible, visual, and less lethal orthotopic xenograft model of nasopharyngeal carcinoma, providing a platform for preclinical research.

In Vivo Bioluminescence Imaging of Tumor Progression in the Lewis Lung Carcinoma Orthotopic Mouse Model: A Comparison Between the Tail Vein Injection and Intranasal Instillation Methods

Metastasis remains a leading cause of cancer-related mortality, yet its study has been constrained by the lack of reliable animal models that faithfully replicate this complex process. Syngeneic models for studying lung cancer metastasis are limited, with the Lewis lung carcinoma (LLC) model being the most commonly employed. The conventional LLC orthotopic model involves injecting LLC cells intravenously (i.v.) via the tail vein into syngeneic C57BL/6 mice. However, this model has significant drawbacks, such as tumor development in multiple anatomical sites, incomplete lung tumor penetrance, and challenges in monitoring lung tumor growth. This article highlights the advantages of using luciferase-expressing LLC cells combined with bioluminescence imaging (BLI) to quantify tumor progression in live animals. We demonstrate that both white- and black-furred C57BL/6 mice can be used for BLI. Finally, we propose that intranasal (i.n.) instillation of LLC cells offers a valuable alternative to the traditional i.v. tail vein injection method, particularly for its simplicity and improved reproducibility. Although the LLC i.n. model does not recapitulate the metastasis process via the blood vascular route, it is an effective model for studying tumor seeding within the lungs and is particularly useful for analyzing the impact of the lung microenvironment on tumor initiation and progression. © 2024 Wiley Periodicals LLC. Basic Protocol 1: Lewis lung carcinoma intravenous injection method Support Protocol: In vivo bioluminescence imaging Basic Protocol 2: Lewis lung carcinoma intranasal instillation method.

Peak transgene expression after intramuscular immunization of mice with adenovirus 26-based vector vaccines correlates with transgene-specific adaptive immune responses

Non-replicating adenovirus-based vectors have been broadly used for the development of prophylactic vaccines in humans and are licensed for COVID-19 and Ebola virus disease prevention. Adenovirus-based vectored vaccines encode for one or more disease specific transgenes with the aim to induce protective immunity against the target disease. The magnitude and duration of transgene expression of adenovirus 5- based vectors (human type C) in the host are key factors influencing antigen presentation and adaptive immune responses. Here we characterize the magnitude, duration, and organ biodistribution of transgene expression after single intramuscular administration of adenovirus 26-based vector vaccines in mice and evaluate the differences with adenovirus 5-based vector vaccine to understand if this is universally applicable across serotypes. We demonstrate a correlation between peak transgene expression early after adenovirus 26-based vaccination and transgene-specific cellular and humoral immune responses for a model antigen and SARS-CoV-2 spike protein, independent of innate immune activation. Notably, the memory immune response was similar in mice immunized with adenovirus 26-based vaccine and adenovirus 5-based vaccine, despite the latter inducing a higher peak of transgene expression early after immunization and a longer duration of transgene expression. Together these results provide further insights into the mode of action of adenovirus 26-based vector vaccines.

Current advances in the development of bioluminescent probes toward spatiotemporal trans-scale imaging

Bioluminescence imaging has recently attracted great attention as a highly sensitive and non-invasive analytical method. However, weak signal and low chemical stability of the luciferin are conventional drawbacks of bioluminescence imaging. In this review article, we describe the recent progress on the development and applications of bioluminescent probes for overcoming the aforementioned limitations, thereby enabling spatiotemporal trans-scale imaging. The detailed molecular design for manipulation of their luminescent properties and functions enabled a variety of applications, including in vivo deep tissue imaging, long-term imaging, and chemical sensor.

Inducing Angiogenesis in the Nucleus Pulposus

Bone morphogenetic protein (BMP) gene delivery to Lewis rat lumbar intervertebral discs (IVDs) drives bone formation anterior and external to the IVD, suggesting the IVD is inhospitable to osteogenesis. This study was designed to determine if IVD destruction with a proteoglycanase, and/or generating an IVD blood supply by gene delivery of an angiogenic growth factor, could render the IVD permissive to intra-discal BMP-driven osteogenesis and fusion. Surgical intra-discal delivery of naïve or gene-programmed cells (BMP2/BMP7 co-expressing or VEGF165 expressing) +/- purified chondroitinase-ABC (chABC) in all permutations was performed between lumbar 4/5 and L5/6 vertebrae, and radiographic, histology, and biomechanics endpoints were collected. Follow-up anti-sFlt Western blotting was performed. BMP and VEGF/BMP treatments had the highest stiffness, bone production and fusion. Bone was induced anterior to the IVD, and was not intra-discal from any treatment. chABC impaired BMP-driven osteogenesis, decreased histological staining for IVD proteoglycans, and made the IVD permissive to angiogenesis. A soluble fragment of VEGF Receptor-1 (sFlt) was liberated from the IVD matrix by incubation with chABC, suggesting dysregulation of the sFlt matrix attachment is a possible mechanism for the chABC-mediated IVD angiogenesis we observed. Based on these results, the IVD can be manipulated to foster vascular invasion, and by extension, possibly osteogenesis.

Tracking of Extracellular Vesicles' Biodistribution: New Methods and Approaches

Extracellular vesicles (EVs) are nanosized lipid bilayer vesicles that are released by almost all cell types. They range in diameter from 30 nm to several micrometres and have the ability to carry biologically active molecules such as proteins, lipids, RNA, and DNA. EVs are natural vectors and play an important role in many physiological and pathological processes. The amount and composition of EVs in human biological fluids serve as biomarkers and are used for diagnosing diseases and monitoring the effectiveness of treatment. EVs are promising for use as therapeutic agents and as natural vectors for drug delivery. However, the successful use of EVs in clinical practice requires an understanding of their biodistribution in an organism. Numerous studies conducted so far on the biodistribution of EVs show that, after intravenous administration, EVs are mostly localized in organs rich in blood vessels and organs associated with the reticuloendothelial system, such as the liver, lungs, spleen, and kidneys. In order to improve resolution, new dyes and labels are being developed and detection methods are being optimized. In this work, we review all available modern methods and approaches used to assess the biodistribution of EVs, as well as discuss their advantages and limitations.

The Establishment of a Noninvasive Bioluminescence-Specific Viral Encephalitis Model by Pseudorabies Virus-Infected NF-κBp-Luciferase Mice

Encephalitis is a rare brain inflammation that is most commonly caused by a viral infection. In this study, we first use an in vivo imaging system (IVIS) to determine whether NF-κBp-luciferase expression could be detected in the brain of pseudorabies virus (PRV)-infected NF-κBp-luciferase mice and to evaluate proinflammatory mediators in a well-described mouse model of PRV encephalitis. In in vitro studies, we used murine microglia (BV-2) cells to demonstrate the PRV-induced encephalitis model entailing the activation of microglia cells. The results indicate that PRV-induced neuroinflammation responses through the induction of IL-6, TNF-α, COX-2, and iNOS expression occurred via the regulation of NF-κB expression in BV-2 cells. In in vivo studies, compared with MOCK controls, the mice infected with neurovirulent PRV exhibited significantly elevated NF-κB transcription factor activity and luciferase protein expression only in the brain by IVIS. Mild focal necrosis was also observed in the brain. Further examination revealed biomarkers of inflammation, including inducible cyclooxygenase (COX)-2, inducible nitric oxide synthase (iNOS), and tumor necrosis factor (TNF)-α and interleukin (IL)-6, both of which constituted proinflammatory cytokines. PRV infection stimulated inflammation and COX-2 and iNOS expression of IL-6 and TNF-α. The presented results herein suggest that PRV induces iNOS and COX-2 expression in the brain of NF-κBp–luciferase mice via NF-κB activation. In conclusion, we used NF-κBp-luciferase mice to establish a specific virus-induced encephalitis model via PRV intranasal infection. In the future, this in vivo model will provide potential targets for the development of new therapeutic strategies focusing on NF-κB inflammatory biomarkers and the development of drugs for viral inflammatory diseases.

A Series of Furimazine Derivatives for Sustained Live-Cell Bioluminescence Imaging and Application to the Monitoring of Myogenesis at the Single-Cell Level

Bioluminescence (BL) imaging, which utilizes light emitted through the enzymatic reaction of luciferase oxidizing its substrate luciferin, enables sensitive and noninvasive monitoring of life phenomena. Herein, we developed a series of caged furimazine (FMZ) derivatives by introducing a protective group at the C-3 position and a hydroxy group at the C-6 phenyl ring to realize long-term live-cell BL imaging based on the NanoLuc (NLuc)/NanoKAZ (NKAZ)-FMZ system. The membrane permeability and cytotoxicity of the substrates were evaluated and related to their hydrophobicity. Among the series, the derivative with the bulkiest protective group (adamantanecarbonyl group) and a hydroxy substituent (named Ad-FMZ-OH) showed significantly prolonged and constant BL signal in cells expressing NLuc compared to the native FMZ substrate. This derivative enabled continuous BL imaging at the single-cell level for 24 h. Furthermore, we applied Ad-FMZ-OH to BL imaging of myocyte fusion and succeeded in the consecutive and sensitive monitoring at a single-cell level over a day. In summary, NLuc/NKAZ-caged FMZ derivatives have the potential to be applied to live-cell BL imaging of various life phenomena that require long-term observation.

Molecular modelling of the FOXO4-TP53 interaction to design senolytic peptides for the elimination of senescent cancer cells

BACKGROUND

Senescent cells accumulate in tissues over time as part of the natural ageing process and the removal of senescent cells has shown promise for alleviating many different age-related diseases in mice. Cancer is an age-associated disease and there are numerous mechanisms driving cellular senescence in cancer that can be detrimental to recovery. Thus, it would be beneficial to develop a senolytic that acts not only on ageing cells but also senescent cancer cells to prevent cancer recurrence or progression.

METHODS

We used molecular modelling to develop a series of rationally designed peptides to mimic and target FOXO4 disrupting the FOXO4-TP53 interaction and releasing TP53 to induce apoptosis. We then tested these peptides as senolytic agents for the elimination of senescent cells both in cell culture and in vivo.

FINDINGS

Here we show that these peptides can act as senolytics for eliminating senescent human cancer cells both in cell culture and in orthotopic mouse models. We then further characterized one peptide, ES2, showing that it disrupts FOXO4-TP53 foci, activates TP53 mediated apoptosis and preferentially binds FOXO4 compared to TP53. Next, we show that intratumoural delivery of ES2 plus a BRAF inhibitor results in a significant increase in apoptosis and a survival advantage in mouse models of melanoma. Finally, we show that repeated systemic delivery of ES2 to older mice results in reduced senescent cell numbers in the liver with minimal toxicity.

INTERPRETATION

Taken together, our results reveal that peptides can be generated to specifically target and eliminate FOXO4+ senescent cancer cells, which has implications for eradicating residual disease and as a combination therapy for frontline treatment of cancer.

FUNDING

This work was supported by the Cancer Early Detection Advanced Research Center at Oregon Health & Science University.

In vivo targeting of lentiviral vectors pseudotyped with the Tupaia paramyxovirus H glycoprotein bearing a cell-specific ligand

Despite their exceptional capacity for transgene delivery ex vivo, lentiviral (LV) vectors have been slow to demonstrate clinical utility in the context of in vivo applications. Unresolved safety concerns related to broad LV vector tropism have limited LV vectors to ex vivo applications. Here, we report on a novel LV vector-pseudotyping strategy involving envelope glycoproteins of Tupaia paramyxovirus (TPMV) engineered to specifically target human cell-surface receptors. LV vectors pseudotyped with the TPMV hemagglutinin (H) protein bearing the interleukin (IL)-13 ligand in concert with the TPMV fusion (F) protein allowed efficient transduction of cells expressing the human IL-13 receptor alpha 2 (IL-13Rα2). Immunodeficient mice bearing orthotopically implanted human IL-13Rα2 expressing NCI-H1299 non-small cell lung cancer cells were injected intravenously with a single dose of LV vector pseudotyped with the TPMV H-IL-13 glycoprotein. Vector biodistribution was monitored using bioluminescence imaging of firefly luciferase transgene expression, revealing specific transduction of tumor tissue. A quantitative droplet digital PCR (ddPCR) analysis of lung tissue samples revealed a >15-fold increase in the tumor transduction in mice treated with LV vectors displaying IL-13 relative to those without IL-13. Our results show that TPMV envelope glycoproteins can be equipped with ligands to develop targeted LV vectors for in vivo applications.

In vivo biodistribution analysis of transmission competent and defective RNA virus-based episomal vector

RNA virus-based episomal vector (REVec) is an emerging viral vector system that mediates long-term stable gene expression in variety of cell types in vitro. However, little is known about its tissue tropism and persistence of gene expression in vivo. Here, to evaluate the feasibility of REVec for in vivo gene delivery, we conducted biodistribution analysis of transmission competent REVec and transmission defective ΔG-REVec in Lewis rats. Following intracranial administration of REVec, transgene expression was detected in various tissues. In contrast, transgene expression was only observed in the brain after ΔG-REVec administration. Low levels of vector shedding in the feces and blood and of neutralizing antibody in the serum were detected after REVec injection. In the brain, microglia, astrocytes and neurons were susceptible to REVec-mediated transduction. However, the animals administered with REVec, but not with ΔG-REVec showed a significant decrease in body weight compared to mock treated animals. Additionally, CD8 T cell infiltration was observed in the brain of these animals. In summary, we demonstrated that REVec promotes long-term transgene expression in vivo without causing high vector shedding or neutralizing antibody production; however, suggests the need to attenuate vector associated pathogenicity in the future.

Continual Conscious Bioluminescent Imaging in Freely Moving Mice

In vivo bioluminescent imaging allows the detection of reporter gene expression in rodents in real time. Here we describe a novel technology whereby we can generate somatotransgenic rodents with the use of a viral vector carrying a luciferase transgene. We are able to achieve long term luciferase expression by a single injection of lentiviral or adeno-associated virus vectors to newborn mice. Further, we describe whole body bioluminescence imaging of conscious mice in a noninvasive manner, thus enforcing the 3R's (replacement, reduction, and refinement) of biomedical animal research.

Using Bioengineered Bioluminescence to Track Stem Cell Transplantation In Vivo

Bioluminescence imaging enables the real-time detection and tracking of engrafted cells in vivo noninvasively and dynamically. By detecting and quantifying the photons released from the oxidation of luciferin catalyzed by luciferase enzymes, this approach has proven effective in tracking engrafted stem cell survival and retention, making it a powerful tool to monitor cell fate after transplantation without animal sacrifice. Here we describe a protocol that allows luciferase-labeled stem cells to be imaged and tracked in vivo by bioluminescent imaging via an IVIS spectrum imaging system.

miR-15a/-16 Inhibit Angiogenesis by Targeting the Tie2 Coding Sequence: Therapeutic Potential of a miR-15a/16 Decoy System in Limb Ischemia

MicroRNA-15a (miR-15a) and miR-16, which are transcribed from the miR-15a/miR-16-1 cluster, inhibit post-ischemic angiogenesis. MicroRNA (miRNA) binding to mRNA coding sequences (CDSs) is a newly emerging mechanism of gene expression regulation. We aimed to (1) identify new mediators of the anti-angiogenic action of miR-15a and -16, (2) develop an adenovirus (Ad)-based miR-15a/16 decoy system carrying a luciferase reporter (Luc) to both sense and inhibit miR-15a/16 activity, and (3) investigate Ad.Luc-Decoy-15a/16 therapeutic potential in a mouse limb ischemia (LI) model. LI increased miR-15a and -16 expression in mouse muscular endothelial cells (ECs). The miRNAs also increased in cultured human umbilical vein ECs (HUVECs) exposed to serum starvation, but not hypoxia. Using bioinformatic tools and luciferase activity assays, we characterized miR-15a and -16 binding to Tie2 CDS. In HUVECs, miR-15a or -16 overexpression reduced Tie2 at the protein, but not the mRNA, level. Conversely, miR-15a or -16 inhibition improved angiogenesis in a Tie2-dependent manner. Local Ad.Luc-Decoy-15a/16 delivery increased Tie2 levels in ischemic skeletal muscle and improved post-LI angiogenesis and perfusion recovery, with reduced toe necrosis. Bioluminescent imaging (in vivo imaging system [IVIS]) provided evidence that the Ad.Luc-Decoy-15a/16 system responds to miR-15a/16 increases. In conclusion, we have provided novel mechanistic evidence of the therapeutic potential of local miR-15a/16 inhibition in LI.

Luminescence- and Fluorescence-Based Complementation Assays to Screen for GPCR Oligomerization: Current State of the Art

G protein-coupled receptors (GPCRs) have the propensity to form homo- and heterodimers. Dysfunction of these dimers has been associated with multiple diseases, e.g., pre-eclampsia, schizophrenia, and depression, among others. Over the past two decades, considerable efforts have been made towards the development of screening assays for studying these GPCR dimer complexes in living cells. As a first step, a robust in vitro assay in an overexpression system is essential to identify and characterize specific GPCR–GPCR interactions, followed by methodologies to demonstrate association at endogenous levels and eventually in vivo. This review focuses on protein complementation assays (PCAs) which have been utilized to study GPCR oligomerization. These approaches are typically fluorescence- and luminescence-based, making identification and localization of protein–protein interactions feasible. The GPCRs of interest are fused to complementary fluorescent or luminescent fragments that, upon GPCR di- or oligomerization, may reconstitute to a functional reporter, of which the activity can be measured. Various protein complementation assays have the disadvantage that the interaction between the reconstituted split fragments is irreversible, which can lead to false positive read-outs. Reversible systems offer several advantages, as they do not only allow to follow the kinetics of GPCR–GPCR interactions, but also allow evaluation of receptor complex modulation by ligands (either agonists or antagonists). Protein complementation assays may be used for high throughput screenings as well, which is highly relevant given the growing interest and effort to identify small molecule drugs that could potentially target disease-relevant dimers. In addition to providing an overview on how PCAs have allowed to gain better insights into GPCR–GPCR interactions, this review also aims at providing practical guidance on how to perform PCA-based assays.

Genomic and protein structure analysis of the luciferase from the Iranian bioluminescent beetle, Luciola sp

To date, two Iranian luciferase genes from the Lampyris turkestanicus and Lampyroidea maculata have been carefully studied. Here, we report the cloning and characterization of the gene and protein of luciferase enzyme from the beetle of an Iranian lampyrid species, Luciola sp. (Coleoptera-Lampyridae). In this study, a Luciola sp. firefly was collected from the Yasouj area of Iran and its luciferase gene sequence was cloned and characterized. The genomic DNA length for this luciferase was the 1950 bp that combined of seven exons and separated by six introns. The results of multiple sequence alignment show that this gene has the most similarity with DNA gene luciferase from the Hotaria unmunsana species. Further analysis determined accurately the location of these introns in the luciferase gene. However, the deduced amino acid sequences of the luciferase gene (548 residues) showed that this luciferase had 97.8% resemblance to luciferase from Lampyroidea maculata species. By in silico modeling of firefly luciferase in an I-TASSER server, the 3D structure of this enzyme was evaluated. The results of phylogenetic tree analysis display the close evolutionary relationship of this luciferase gene and luciferase gene from the Lampyroidea maculata and Hotaria unmunsana.

Ex vivo evaluation of intravitreal mesenchymal stromal cell viability using bioluminescence imaging

Background

Bone marrow-derived mesenchymal stromal cell (MSC) therapy is a promising treatment for several degenerative ocular diseases; however, no reproducible method of monitoring these cells into the eye has been established. The aim of this study was to describe successful bioluminescence imaging (BLI) to detect viable luciferase-expressing MSC in the eye.

Methods

Human donor MSC in culture were transduced with 50 μl luciferase lentiviral vector (three viral particles/cell) prior to intraocular injection. Twenty-one right eyes of 21 rabbits were evaluated through BLI after receiving 1 × 10⁶ luciferase-expressing MSC intravitreally. Contralateral eyes were injected with vehicle (phosphate-buffered saline (PBS)) and were used as controls. At seven different time points (1 h to 60 days), d-luciferin (40 mg/ml, 300 μl PBS) was injected in subsets of six enucleated eyes for evaluation of radiance decay through BLI analysis. CD90 and CD73 immunofluorescence was studied in selected eyes.

Results

Eyes injected with MSC showed high BLI radiance immediately after d-luciferin injection and progressive decay until 60 days. Mean BLI radiance measures from eyes with luciferase-expressing MSC were significantly higher than controls from 8 h to 30 days. At the thirtieth day, positive CD90- and CD73-expressing cells were observed only in the vitreous cavity of eyes injected with MSC.

Conclusions

Viable MSC were identified in the vitreous cavity 1 month after a single injection. Our results confirmed BLI as a useful and reliable method to detect MSC injected into the eye globe.

Bioluminescence Monitoring of Promoter Activity In Vitro and In Vivo

The application of luciferase reporter genes to provide quantitative outputs for the activation of promoters is a well-established technique in molecular biology. Luciferase catalyzes an enzymatic reaction, which in the presence of the substrate luciferin produces photons of light relative to its molar concentration. The luciferase transgene can be genetically inserted at the first intron of a target gene to act as a surrogate for the gene's endogenous expression in cells and transgenic mice. Alternatively, promoter sequences can be excised and/or amplified from genomic sources or constructed de novo and cloned upstream of luciferase in an expression cassette transfected into cells. More recently, the development of synthetic promoters where the essential components of an RNA polymerase binding site and transcriptional start site are fused with various upstream regulatory sequences are being applied to drive reporter gene expression. We have developed a high-throughput cloning strategy to develop lentiviral luciferase reporters driven by transcription factor activated synthetic promoters. Lentiviruses integrate their payload cassette into the host cell genome, thereby facilitating the study of gene expression not only in the transduced cells but also within all subsequent daughter cells. In this manuscript we describe the design, vector construction, lentiviral transduction, and luciferase quantitation of transcription factor activated reporters (TFARs) in vitro and in vivo.

Hepa1-6-FLuc cell line with the stable expression of firefly luciferase retains its primary properties with promising bioluminescence imaging ability

Reliable animal models are required for the in vivo study of the molecular mechanisms and effects of chemotherapeutic drugs in hepatocarcinoma. In vivo tracing techniques based on firefly luciferase (FLuc) may optimize the non-invasive monitoring of experimental animals. The present study established a murine Hepa1-6-FLuc cell line that stably expressed a retrovirus-delivered FLuc protein gene. The cell morphology, proliferation, migration and invasion ability of Hepa1-6-FLuc cells were the same as that of the Hepa1-6 cells, and thus is suitable to replace Hepa1-6 cells in the construction of hepatocarcinoma animal models. No differences in subcutaneous tumor mass and its pathomorphology from implanted Hepa1-6-FLuc cells were observed compared with Hepa1-6 control tumors. Bioluminescence imaging indicated that the Luc signal of the Hepa1-6-FLuc cells was consistently strengthened with increases in tumor mass; however, the Luc signal of Hepa1-6-AdFLuc became weaker and eventually disappeared during tumor development. Therefore, compared with the transient expression by adenovirus, stable expression of the FLuc gene in Hepa1-6 cells may better reflect cell proliferation and survival in vivo, and provide a reliable source for the establishment of hepatocarcinoma models.

Effects of Panax notoginseng saponins on severe acute pancreatitis through the regulation of mTOR/Akt and caspase-3 signaling pathway by upregulating miR-181b expression in rats

BACKGROUND

In China, Panax notoginseng has been used to treat oxidative stress-related diseases for a long time. Panax notoginseng saponins is an extract from Panax notoginseng Ledeb. Its therapeutic potential is related to antioxidant activity, but related mechanisms are still unclear. The study aims to assess the protection effects of Panax notoginseng saponins in the taurocholate-induced rat model of acute pancreatitis (AP) and explore underlying mechanisms.

METHODS

A rat model of severe acute pancreatitis (SAP) was established in rats induced with taurocholate. Panax notoginseng saponins was firstly administered in the treatment group via intravenous injection. After 2 h, taurocholate administration was performed. After 24 h, the expression levels of miR-181b, Beclin1, LC3-II, Akt and mTOR from pancreas tissues were measured by Western Blotting and RT-PCR. Then the expression levels of Caspase-3 and Blc-2 were determined by immunohistochemistry. Apoptosis was assessed by the TUNEL assay. Amylase and lipase in serum were determined by ELISA and pancreatic water contents in pancreatic tissue were measured. After eosin and hematoxylin staining, the histologic analysis was performed.

RESULTS

After SAP induction by taurocholate and the treatment with Panax notoginseng saponins for 24 h, we detected the up-regulated miR-181b, the reduced Bcl-2 expression, the increased activity of mTOR/Akt, the blocked Beclin1 and LC3-II expressions, and the enhanced Caspase-3 expression. Serum lipase and amylase levels were significantly decreased in the treatment group of Panax notoginseng saponins compared to the control group. Histological analysis results verified the attenuation effects of Panax notoginseng saponins on taurocholate-induced pancreas injury, apoptosis, and autophagy.

CONCLUSION

By up-regulating the miR-181b expression level, Panax notoginseng saponins significantly reduced taurocholate-induced pancreas injury and autophagy and increased apoptosis. The significant protection effects of Panax notoginseng saponins suggested its potential in treating taurocholate induced-acute pancreatitis.

Brief Report: External Beam Radiation Therapy for the Treatment of Human Pluripotent Stem Cell-Derived Teratomas

Human pluripotent stem cells, including human embryonic stem cells (hESCs) and human induced PSCs (hiPSCs), have great potential as an unlimited donor source for cell-based therapeutics. The risk of teratoma formation from residual undifferentiated cells, however, remains a critical barrier to the clinical application of these cells. Herein, we describe external beam radiation therapy (EBRT) as an attractive option for the treatment of this iatrogenic growth. We present evidence that EBRT is effective in arresting growth of hESC-derived teratomas in vivo at day 28 post-implantation by using a microCT irradiator capable of targeted treatment in small animals. Within several days of irradiation, teratomas derived from injection of undifferentiated hESCs and hiPSCs demonstrated complete growth arrest lasting several months. In addition, EBRT reduced reseeding potential of teratoma cells during serial transplantation experiments, requiring irradiated teratomas to be seeded at 1 × 10³ higher doses to form new teratomas. We demonstrate that irradiation induces teratoma cell apoptosis, senescence, and growth arrest, similar to established radiobiology mechanisms. Taken together, these results provide proof of concept for the use of EBRT in the treatment of existing teratomas and highlight a strategy to increase the safety of stem cell-based therapies. Stem Cells 2017;35:1994-2000.

Application of hairless mouse strain to bioluminescence imaging of Arc expression in mouse brain

BACKGROUND

Bioluminescence imaging (BLI) is a powerful technique for monitoring the temporal and spatial dynamics of gene expression in the mouse brain. However, the black fur, skin pigmentation and hair regrowth after depilation of mouse interfere with BLI during developmental and daily examination. The aim of this study was to extend the application of Arc-Luc transgenic (Tg) mice to the BLI of neuronal activity in the mouse brain by introducing the hairless (HL) gene and to examine Arc-Luc expression at various developmental stages without interference from black fur, skin pigmentation, and hair regrowth.

RESULTS

The Arc-Luc Tg HL mice were established by crossing the Tg C57BL/6 mouse strain with the HL mouse strain. Under physiological and pathological conditions, BLI was performed to detect the signal intensity changes at various developmental stages and at an interval of <7 days. The established Arc-Luc Tg HL mice exhibited clear and stable photon signals from the brain without interference during development. After surgical monocular deprivation during visual-critical period, large signal intensity changes in bioluminescence were observed in the mouse visual cortex. Exposure of mice to a novel object changed the photon distribution in the caudal and rostral cerebral areas. The temporal pattern of kainic-acid-induced Arc-Luc expression showed biphasic changes in signal intensity over 24 h.

CONCLUSIONS

This study showed the advantages of using the mutant HL gene in BLI of Arc expression in the mouse brain at various developmental stages. Thus, the use of the Arc-Luc Tg HL mice enabled the tracking of neuronal-activity-dependent processes over a wide range from a focal area to the entire brain area with various time windows.

Hepatocellular Carcinoma Cells Carrying a Multimodality Reporter Gene for Fluorescence, Bioluminescence, and Magnetic Resonance Imaging In Vitro and In Vivo

RATIONALE AND OBJECTIVES

The study aimed to evaluate the feasibility of imaging or tracking hepatocellular carcinoma cells by modifying these cells to carry a multimodality reporter gene, enabling fluorescence, bioluminescence, and magnetic resonance imaging (MRI) in vitro and in vivo.

MATERIALS AND METHODS

HepG2 cells were labeled with the enhanced green fluorescent protein (EGFP)/luciferase2/ferritin-the multimodality reporter gene (labeled HepG2 cells). The labeled and unlabeled HepG2 cells were cultured in vitro and then injected subcutaneously into mice as a hepatoma model in vivo. The expressions of EGFP, luciferase2, and ferritin in HepG2 cell suspensions and hepatoma model were investigated using fluorescence, bioluminescence, and MRI.

RESULTS

Individual HepG2 cells expressing EGFP were identified under blue laser excitation. The linear coefficient between the optical signal intensity of luciferase2 and the number of labeled cells was 0.993. MRI was used to distinguish the T2* signal of 2 × 10⁷ cells/mL between the labeled (6.67 ± 1.88 ms) and unlabeled cells (10.66 ± 2.22 ms) (P = 0.034). In vivo, individual HepG2 cells expressing EGFP in frozen sections were observed. Labeled cells expressing luciferase2 have been detected since the second day after injection, and the bioluminescence increased with the tumor size. The T2* signal was significantly different between the labeled (6.04 ± 1.60 ms) and unlabeled cells (17.06 ± 2.17 ms) (P <0.001).

CONCLUSIONS

A multimodality reporter gene consisting of EGFP, luciferase2, and ferritin was successfully integrated into the HepG2 cell genome via a lentiviral vector and was highly expressed in the daughter cells. These cells could be detected by fluorescence, bioluminescence, and MRI in vitro and in vivo.

TIP60 inhibits metastasis by ablating DNMT1-SNAIL2-driven epithelial-mesenchymal transition program

HIV-Tat-interacting protein of 60 kDa (TIP60) is a lysine acetyltransferase and known to be downregulated in multiple cancers. Among various signalling pathways, TIP60 is implicated in regulating epithelial-mesenchymal transition (EMT). Here, we show that TIP60 expression abrogates cell migration and metastatic potential of breast cancer cells using in vitro and in vivo models. Mechanistically, we show that this is through its ability to destabilize DNMT1 and inhibit SNAIL2 function (SNAIL2-mediated EMT/cell migration). Depletion of TIP60 stabilizes DNMT1 and increases SNAIL2 levels, resulting in EMT. Recruitment of DNMT1 to the SNAIL2 targets in the absence of TIP60 increases DNA methylation on their promoter region and further represses the expression of epithelial markers. In pathophysiological scenario, we find TIP60 to be significantly downregulated in breast cancer patients with poor overall survival and disease-free survival prognoses. These data suggest that levels of TIP60 can be a prognostic marker of breast cancer progression and stabilization of TIP60 could be a promising strategy to treat cancers.

A molecular imaging biosensor detects in vivo protein folding and misfolding

Aberrant protein folding represents the molecular basis of many important human diseases. Although the discovery of new anti-misfolding drugs is a major priority in molecular therapeutics, there is currently no generalizable protein folding assay for use in cell-based high throughput screening (HTS) of chemical libraries, or for in vivo imaging. We molecularly engineered a bioluminescence-based biosensor composed of rationally split Firefly luciferase reporter fragments flanking a test protein, and used this in a protein-fragment complementation assay to quantitatively measure folding of the test protein. We comprehensively validated this biosensor in vitro, in cells, and by optically imaging protein folding and misfolding in living mice using several test proteins including enhanced green fluorescent protein, Renilla luciferase, Gaussia luciferase, and SIRT1. Applications of this novel biosensor are potentially far-reaching in both cell-based HTS approaches to discover new anti-misfolding drugs, and when using the same biosensor in validation studies of drug candidates in small animal models.

KEY MESSAGES

Novel anti-misfolding drugs are needed as molecular therapeutics for many diseases. We developed first in vivo imaging protein folding biosensor to aid drug discovery. Biosensor created by flanking a test protein with rationally split Firefly luciferase. Biosensor validated by detecting folding of test proteins EGFP, Rluc, Gluc, and SIRT1. Generalizable molecular biosensor for translational applications in drug screening.

The Expanding Toolbox of In Vivo Bioluminescent Imaging

In vivo bioluminescent imaging (BLI) permits the visualization of engineered bioluminescence from living cells and tissues to provide a unique perspective toward the understanding of biological processes as they occur within the framework of an authentic in vivo environment. The toolbox of in vivo BLI includes an inventory of luciferase compounds capable of generating bioluminescent light signals along with sophisticated and powerful instrumentation designed to detect and quantify these light signals non-invasively as they emit from the living subject. The information acquired reveals the dynamics of a wide range of biological functions that play key roles in the physiological and pathological control of disease and its therapeutic management. This mini review provides an overview of the tools and applications central to the evolution of in vivo BLI as a core technology in the preclinical imaging disciplines.

Multimodality Molecular Imaging of Cardiac Cell Transplantation: Part I. Reporter Gene Design, Characterization, and Optical in Vivo Imaging of Bone Marrow Stromal Cells after Myocardial Infarction

Purpose To use multimodality reporter-gene imaging to assess the serial survival of marrow stromal cells (MSC) after therapy for myocardial infarction (MI) and to determine if the requisite preclinical imaging end point was met prior to a follow-up large-animal MSC imaging study. Materials and Methods Animal studies were approved by the Institutional Administrative Panel on Laboratory Animal Care. Mice (n = 19) that had experienced MI were injected with bone marrow-derived MSC that expressed a multimodality triple fusion (TF) reporter gene. The TF reporter gene (fluc2-egfp-sr39ttk) consisted of a human promoter, ubiquitin, driving firefly luciferase 2 (fluc2), enhanced green fluorescent protein (egfp), and the sr39tk positron emission tomography reporter gene. Serial bioluminescence imaging of MSC-TF and ex vivo luciferase assays were performed. Correlations were analyzed with the Pearson product-moment correlation, and serial imaging results were analyzed with a mixed-effects regression model. Results Analysis of the MSC-TF after cardiac cell therapy showed significantly lower signal on days 8 and 14 than on day 2 (P = .011 and P = .001, respectively). MSC-TF with MI demonstrated significantly higher signal than MSC-TF without MI at days 4, 8, and 14 (P = .016). Ex vivo luciferase activity assay confirmed the presence of MSC-TF on days 8 and 14 after MI. Conclusion Multimodality reporter-gene imaging was successfully used to assess serial MSC survival after therapy for MI, and it was determined that the requisite preclinical imaging end point, 14 days of MSC survival, was met prior to a follow-up large-animal MSC study. (©) RSNA, 2016 Online supplemental material is available for this article.

Salmonella-Mediated Cancer Therapy: Roles and Potential

The use of bacteria for cancer therapy, which was proposed many years ago, was not recognized as a potential therapeutic strategy until recently. Technological advances and updated knowledge have enabled the genetic engineering of bacteria for their safe and effective application in the treatment of cancer. The efficacy of radiotherapy depends mainly on tissue oxygen levels, and low oxygen concentrations in necrotic and hypoxic regions are a common cause of treatment failure. In addition, the distribution of a drug is important for the therapeutic effect of chemotherapy, and the poor vasculature in tumors impairs drug delivery, limiting the efficacy of a drug, especially in necrotic and hypoxic regions. Bacteria-mediated cancer therapy (BMCT) relies on facultative anaerobes that can survive in well or poorly oxygenated regions, and it therefore improves the therapeutic efficacy drug distribution throughout the tumor mass. Since the mid-1990s, the number of published bacterial therapy papers has increased rapidly, with a doubling time of 2.5 years in which the use of Salmonella increased significantly. BMCT is being reevaluated to overcome some of the drawbacks of conventional therapies. This review focuses on Salmonella-mediated cancer therapy as the most widely used type of BMCT.2.

Automated high-content morphological analysis of muscle fiber histology

In the search for a cure for many muscular disorders it is often necessary to analyze muscle fibers under a microscope. For this morphological analysis, we developed an image processing approach to automatically analyze and quantify muscle fiber images so as to replace today's less accurate and time-consuming manual method. Muscular disorders, that include cardiomyopathy, muscular dystrophies, and diseases of nerves that affect muscles such as neuropathy and myasthenia gravis, affect a large percentage of the population and, therefore, are an area of active research for new treatments. In research, the morphological features of muscle fibers play an important role as they are often used as biomarkers to evaluate the progress of underlying diseases and the effects of potential treatments. Such analysis involves assessing histopathological changes of muscle fibers as indicators for disease severity and also as a criterion in evaluating whether or not potential treatments work. However, quantifying morphological features is time-consuming, as it is usually performed manually, and error-prone. To replace this standard method, we developed an image processing approach to automatically detect and measure the cross-sections of muscle fibers observed under microscopy that produces faster and more objective results. As such, it is well-suited to processing the large number of muscle fiber images acquired in typical experiments, such as those from studies with pre-clinical models that often create many images. Tests on real images showed that the approach can segment and detect muscle fiber membranes and extract morphological features from highly complex images to generate quantitative results that are readily available for statistical analysis.

In vivo bioluminescence imaging for prolonged survival of transplanted human neural stem cells using 3D biocompatible scaffold in corticectomized rat model

Stem cell-based treatment of traumatic brain injury has been limited in its capacity to bring about complete functional recovery, because of the poor survival rate of the implanted stem cells. It is known that biocompatible biomaterials play a critical role in enhancing survival and proliferation of transplanted stem cells via provision of mechanical support. In this study, we noninvasively monitored in vivo behavior of implanted neural stem cells embedded within poly-l-lactic acid (PLLA) scaffold, and showed that they survived over prolonged periods in corticectomized rat model. Corticectomized rat models were established by motor-cortex ablation of the rat. F3 cells expressing enhanced firefly luciferase (F3-effLuc) were established through retroviral infection. The F3-effLuc within PLLA was monitored using IVIS-100 imaging system 7 days after corticectomized surgery. F3-effLuc within PLLA robustly adhered, and gradually increased luciferase signals of F3-effLuc within PLLA were detected in a day dependent manner. The implantation of F3-effLuc cells/PLLA complex into corticectomized rats showed longer-lasting luciferase activity than F3-effLuc cells alone. The bioluminescence signals from the PLLA-encapsulated cells were maintained for 14 days, compared with 8 days for the non-encapsulated cells. Immunostaining results revealed expression of the early neuronal marker, Tuj-1, in PLLA-F3-effLuc cells in the motor-cortex-ablated area. We observed noninvasively that the mechanical support by PLLA scaffold increased the survival of implanted neural stem cells in the corticectomized rat. The image-guided approach easily proved that scaffolds could provide supportive effect to implanted cells, increasing their viability in terms of enhancing therapeutic efficacy of stem-cell therapy.

Polymeric vector-mediated gene transfection of MSCs for dual bioluminescent and MRI tracking in vivo

MSC's transplantation is a promising cell-based therapy for injuries in regenerative medicine, and in vivo visualization of transplanted MSCs with noninvasive technique is essential for the tracking of cell infusion and homing. A new cationic polymer, poly(ethylene glycol)-block-poly(l-aspartic acid)-grafted polyethylenimine functionalized with superparamagnetic iron oxide nanoparticles (PAI/SPION), was constructed as a magnetic resonance imaging (MRI)-visible non-viral vector for the delivery of plasmids DNA (pDNA) encoding for luciferase and red fluorescence protein (RFP) as reporter genes into MSCs. As a result, the MSCs were labeled with SPION and reporter genes. The PAI/SPION complexes exhibited high transfection efficiency in transferring pDNA into MSCs, which resulted in efficient luciferase and RFP co-expression. Furthermore, the complexes did not significantly affect the viability and multilineage differentiation capacity of MSCs. After the labeled MSCs were transplanted into the rats with acute liver injury via the superior mesenteric vein (SMV) injection, the migration behavior and organ-specific accumulation of the cells could be effectively monitored using the in vivo imaging system (IVIS) and MRI, respectively. The immunohistochemical analysis further confirmed that the transplanted MSCs were predominantly distributed in the liver parenchyma. Our results indicate that the PAI/SPION is a MRI-visible gene delivery agent which can effectively label MSCs to provide the basis for bimodal bioluminescence and MRI tracking in vivo.

AEG-1 promoter-mediated imaging of prostate cancer

We describe a new imaging method for detecting prostate cancer, whether localized or disseminated and metastatic to soft tissues and bone. The method relies on the use of imaging reporter genes under the control of the promoter of AEG-1 (MTDH), which is selectively active only in malignant cells. Through a systemic, nanoparticle-based delivery of the imaging construct, lesions can be identified through bioluminescence imaging and single-photon emission computed tomography in the PC3-ML murine model of prostate cancer at high sensitivity. This approach is applicable for the detection of prostate cancer metastases, including bone lesions for which there is no current reliable agent for noninvasive clinical imaging. Furthermore, the approach compares favorably with accepted and emerging clinical standards, including PET with [(18)F]fluorodeoxyglucose and [(18)F]sodium fluoride. Our results offer a preclinical proof of concept that rationalizes clinical evaluation in patients with advanced prostate cancer.

In vitro and in vivo direct monitoring of miRNA-22 expression in isoproterenol-induced cardiac hypertrophy by bioluminescence imaging

PURPOSE

Growing evidence suggests that microRNAs (miRNAs) play key roles in cardiac hypertrophy. To measure the expression of endogenous miRNAs is very conducive to understanding the importance of miRNAs in cardiac hypertrophy. However, current methods to monitor endogenous miRNA levels, such as Northern blotting, quantitative real-time polymerase chain reaction (qRT-PCR), and microarrays cannot provide real-time information on miRNA biogenesis in vivo.

METHODS

We constructed a miRNA reporter imaging system to monitor miR-22 expression in isoproterenol-induced cardiac hypertrophy repetitively and noninvasively. There were three copies of the antisense of miR-22 (3×PT_miR-22) cloned into the 3' untranslated region (UTR) of the Gaussia luciferase (Gluc) reporter genes under the control of the cytomegalovirus (CMV) promoter in this miRNA reporter system (CMV/Gluc/3×PT_miR-22). CMV/firefly luciferase (Fluc) was used as a positive control for imaging of miR-22 expression. Meanwhile, quantifications of miR-22 in cardiomyocyte hypertrophy and in mouse cardiac hypertrophy induced by isoproterenol stimulation were measured by qRT-PCR. Furthermore, we used this miRNA reporter imaging system to appraise the antihypertrophic effect of antagomir-22 in vitro and in vivo.

RESULTS

The bioluminescence signals of the CMV/Gluc/3×PT_miR-22 were gradually decreased with prolongation of isoproterenol intervention in vitro and in vivo. Overexpression of miR-22 was observed in cardiac hypertrophy, and markedly administration of antagomir-22 could reverse the upregulation of miR-22 and its prohypertrophic effects. Furthermore, knockdown of miR-22 by antagomir-22 could markedly reverse the repressed Gluc activities in vitro and in vivo. However, the Fluc activity of CMV/Fluc was not affected with isoproterenol treatment.

CONCLUSION

This study elucidates the feasibility of using our constructed miRNA reporter imaging system to monitor the location and magnitude of expression levels of miR-22 in cardiac hypertrophy in vitro and in vivo.

Red-shifting the optical response of firefly oxyluciferin with group 15/16 substitutions

A range of firefly oxyluciferin analogues symmetrically substituted with group 15 and 16 elements have been found to have red-shifted first excitation energies with the heaviest derivative investigated (As/Se) displaying a shift of −0.69 eV.

Optical imaging as an expansion of nuclear medicine: Cerenkov-based luminescence vs fluorescence-based luminescence

Integration of optical imaging technologies can further strengthen the field of radioguided surgery. Rather than using two separate chemical entities to achieve this extension, hybrid imaging agents can be used that contain both radionuclear and optical properties. Two types of such hybrid imaging agents are available: (1) hybrid imaging agents generated by Cerenkov luminescence imaging (CLI) of β-emitters and (2) hybrid imaging agents that contain both a radioactive moiety and a fluorescent dye. One major challenge clinicians are now facing is to determine the potential value of these approaches. With this tutorial review we intend to clarify the differences between the two approaches and highlight the clinical potential of hybrid imaging during image-guided surgery applications.

Tracking stem cells for cellular therapy in stroke

Stem cell transplantation has emerged as a promising treatment strategy for stroke. The development of effective ways to monitor transplanted stem cells is essential to understand how stem cell transplantation enhances stroke recovery and ultimately will be an indispensable tool for advancing stem cell therapy to the clinic. In this review, we describe existing methods of tracking transplanted stem cells in vivo, including optical imaging, magnetic resonance imaging (MRI), and positron emission tomography (PET), with emphasis on the benefits and drawbacks of each imaging approach. Key considerations such as the potential impact of each tracking system on stem cell function, as well as its relative applicability to humans are discussed. Finally, we describe multi-modal imaging strategies as a more comprehensive method to track transplanted stem cells in the stroke-injured brain.

Cellular bioenergetics is an important determinant of the molecular imaging signal derived from luciferase and the sodium-iodide symporter

RATIONALE

Molecular imaging is useful for longitudinal assessment of engraftment. However, it is not known which factors, other than cell number, can influence the molecular imaging signal obtained from reporter genes.

OBJECTIVE

The effects of cell dissociation/suspension on cellular bioenergetics and the signal obtained by firefly luciferase and human sodium-iodide symporter labeling of cardiosphere-derived cells were investigated.

METHODS AND RESULTS

(18)Fluorodeoxyglucose uptake, ATP levels, (99m)Tc-pertechnetate uptake, and bioluminescence were measured in vitro in adherent and suspended cardiosphere-derived cells. In vivo dual-isotope single-photon emission computed tomography/computed tomography imaging or bioluminescence imaging (BLI) was performed 1 hour and 24 hours after cardiosphere-derived cell transplantation. Single-photon emission computed tomography quantification was performed using a phantom for signal calibration. Cell loss between 1 hour and 24 hours after transplantation was quantified by quantitative polymerase chain reaction and ex vivo luciferase assay. Cell dissociation followed by suspension for 1 hour resulted in decreased glucose uptake, cellular ATP, (99m)Tc uptake, and BLI signal by 82%, 43%, 42%, and 44%, respectively, compared with adherent cells, in vitro. In vivo (99m)Tc uptake was significantly lower at 1 hour compared with 24 hours after cell transplantation in the noninfarct (P<0.001; n=3) and infarct (P<0.001; n=4) models, despite significant cell loss during this period. The in vivo BLI signal was significantly higher at 1 hour than at 24 hours (P<0.01), with the BLI signal being higher when cardiosphere-derived cells were suspended in glucose-containing medium compared with saline (PBS).

CONCLUSIONS

Adhesion is an important determinant of cellular bioenergetics, (99m)Tc-pertechnetate uptake, and BLI signal. BLI and sodium-iodide symporter imaging may be useful for in vivo optimization of bioenergetics in transplanted cells.

Spatial distribution and survival of human and goat mesenchymal stromal cells on hydroxyapatite and β-tricalcium phosphate

The combination of scaffolds and mesenchymal stromal cells (MSCs) is a promising approach in bone tissue engineering (BTE). Knowledge on the survival, outgrowth and bone-forming capacity of MSCs in vivo is limited. Bioluminescence imaging (BLI), histomorphometry and immunohistochemistry were combined to study the fate of gene-marked goat and human MSCs (gMSCs, hMSCs) on scaffolds with different osteoinductive properties. Luciferase-GFP-labelled MSCs were seeded on hydroxyapatite (HA) or β-tricalcium phosphate (TCP), cultured for 7 days in vitro in osteogenic medium, implanted subcutaneously in immunodeficient mice and monitored with BLI for 6 weeks. The constructs were retrieved and processed for histomorphometry and detection of luciferase-positive cells (LPCs). For gMSCs, BLI revealed doubling of signal after 1 week, declining to 60% of input after 3 weeks and remaining constant until week 6. hMSCs showed a constant decrease of BLI signal to 25% of input, indicating no further expansion. Bone formation of gMSCs was two-fold higher on TCP than HA. hMSCs and gMSCs control samples produced equal amounts of bone on TCP. Upon transduction, there was a four-fold reduction in bone formation compared with untransduced hMSCs, and no bone was formed on HA. LPCs were detected at day 14, but were much less frequent at day 42. Striking differences were observed in spatial distribution. MSCs in TCP were found to be aligned and interconnected on the surface but were scattered in an unstructured fashion in HA. In conclusion, the spatial distribution of MSCs on the scaffold is critical for cell-scaffold-based BTE.

Bioluminescence based in vivo screening technologies

Bioluminescence is the biologically active luminescence light producing event encountered in nature. In recent years several new screening methods utilizing bioluminescent cell-based biosensors have been designed demonstrating their utility towards dynamic monitoring of a variety of cellular functions. Because luciferase is unnatural to mammalian physiology, assays utilizing specific substrates to yield a luminescent signal are attractive and serve the purpose with high sensitivity and specificity. Often genetic or chemical modifications in different luciferase-substrate system in use have afforded new functionalities making these assays even more robust. Finally, in the evolving paradigm of molecular imaging, in vivo bioluminescence imaging (BLI) has evolved as a very attractive tool for interrogating human cellular biology in rodent models. In this short review we explore various bioluminescence screening strategies developed and analyze their scope in future drug screening processes.

Control and augmentation of long-term plasmid transgene expression in vivo in murine muscle tissue and ex vivo in patient mesenchymal tissue

Purpose. In vivo gene therapy directed at tissues of mesenchymal origin could potentially augment healing. We aimed to assess the duration and magnitude of transene expression in vivo in mice and ex vivo in human tissues. Methods. Using bioluminescence imaging, plasmid and adenoviral vector-based transgene expression in murine quadriceps in vivo was examined. Temporal control was assessed using a doxycycline-inducible system. An ex vivo model was developed and optimised using murine tissue, and applied in ex vivo human tissue. Results. In vivo plasmid-based transgene expression did not silence in murine muscle, unlike in liver. Although maximum luciferase expression was higher in muscle with adenoviral delivery compared with plasmid, expression reduced over time. The inducible promoter cassette successfully regulated gene expression with maximum levels a factor of 11 greater than baseline. Expression was re-induced to a similar level on a temporal basis. Luciferase expression was readily detected ex vivo in human muscle and tendon. Conclusions. Plasmid constructs resulted in long-term in vivo gene expression in skeletal muscle, in a controllable fashion utilising an inducible promoter in combination with oral agents. Successful plasmid gene transfection in human ex vivo mesenchymal tissue was demonstrated for the first time.

A gantry-based tri-modality system for bioluminescence tomography

A gantry-based tri-modality system that combines bioluminescence (BLT), diffuse optical (DOT), and x-ray computed tomography (XCT) into the same setting is presented here. The purpose of this system is to perform bioluminescence tomography using a multi-modality imaging approach. As parts of this hybrid system, XCT and DOT provide anatomical information and background optical property maps. This structural and functional a priori information is used to guide and restrain bioluminescence reconstruction algorithm and ultimately improve the BLT results. The performance of the combined system is evaluated using multi-modality phantoms. In particular, a cylindrical heterogeneous multi-modality phantom that contains regions with higher optical absorption and x-ray attenuation is constructed. We showed that a 1.5 mm diameter bioluminescence inclusion can be localized accurately with the functional a priori information while its source strength can be recovered more accurately using both structural and the functional a priori information.

Normalisation to blood activity is required for the accurate quantification of Na/I symporter ectopic expression by SPECT/CT in individual subjects

The utilisation of the Na/I symporter (NIS) and associated radiotracers as a reporter system for imaging gene expression is now reaching the clinical setting in cancer gene therapy applications. However, a formal assessment of the methodology in terms of normalisation of the data still remains to be performed, particularly in the context of the assessment of activities in individual subjects in longitudinal studies. In this context, we administered to mice a recombinant, replication-incompetent adenovirus encoding rat NIS, or a human colorectal carcinoma cell line (HT29) encoding mouse NIS. We used (99m)Tc pertechnetate as a radiotracer for SPECT/CT imaging to determine the pattern of ectopic NIS expression in longitudinal kinetic studies. Some animals of the cohort were culled and NIS expression was measured by quantitative RT-PCR and immunohistochemistry. The radioactive content of some liver biopsies was also measured ex vivo. Our results show that in longitudinal studies involving datasets taken from individual mice, the presentation of non-normalised data (activity expressed as %ID/g or %ID/cc) leads to 'noisy', and sometimes incoherent, results. This variability is due to the fact that the blood pertechnetate concentration can vary up to three-fold from day to day. Normalisation of these data with blood activities corrects for these inconsistencies. We advocate that, blood pertechnetate activity should be determined and used to normalise the activity measured in the organ/region of interest that expresses NIS ectopically. Considering that NIS imaging has already reached the clinical setting in the context of cancer gene therapy, this normalisation may be essential in order to obtain accurate and predictive information in future longitudinal clinical studies in biotherapy.

Choice of surrogate and physiological markers for prenatal gene therapy

Surrogate genetically encoded markers have been utilized in order to analyze gene transfer efficacy, location, and persistence. These marker genes have greatly accelerated the development of gene transfer vectors for the ultimate application of gene therapy using therapeutic genes. They have also been used in many other applications, such as gene marking in order to study developmental cell lineages, to track cell migration, and to study tumor growth and metastasis. This chapter aims to describe the analysis of several commonly used marker genes: green fluorescent protein (GFP), β-galactosidase, firefly luciferase, human factor IX, and alkaline phosphatase. The merits and disadvantages of each are briefly discussed. In addition a few short examples are provided for continual and endpoint analysis in different disease models including hemophilia, cystic fibrosis, ornithine transcarbamylase deficiency and Gaucher disease.