Jung-Joon Min

Molecular Imaging of Cardiac Cell Transplantation in Living Animals Using Optical Bioluminescence and Positron Emission Tomography

Background—The current method of analyzing myocardial cell transplantation relies on postmortem histology. We sought to demonstrate the feasibility of monitoring transplanted cell survival in living animals using molecular imaging techniques. Methods and Results—For optical bioluminescence charged-coupled device imaging, rats (n=20) underwent intramyocardial injection of embryonic rat H9c2 cardiomyoblasts (3×106 to 5×105) expressing firefly luciferase (Fluc) reporter gene. Cardiac bioluminescence signals were present for more than 2 weeks with 3×106 cells: day 1 (627 000±15%), day 2 (346 100±21%), day 4 (112 800±20%), day 8 (78 860±24%), day 12 (67 780±12%), and day 16 (62 200±5% p · s−1 · cm2−1 · sr−1). For micro–positron emission tomography imaging, rats (n=20) received cardiomyoblasts (3×106) expressing mutant herpes simplex type 1 thymidine kinase (HSV1-sr39tk) reporter gene. Detailed tomography of transplanted cells is shown by 9-(4-[18F]-fluoro-3hydroxymethylbutyl)guanine ([18F]-FHBG) reporter probe and nitrogen-13 ammonia ([13N]-NH3) perfusion images. Within the transplanted region, there was a 4.48±0.71-fold increase of in vivo [18F]-FHBG activity and a 4.01±0.51-fold increase of ex vivo gamma counting compared with control animals. Finally, the in vivo images of cell survival were confirmed by ex vivo autoradiography, histology, immunohistochemistry, and reporter protein assays. Conclusions—The location(s), magnitude, and survival duration of embryonic cardiomyoblasts were monitored noninvasively. With further development, molecular imaging studies should add critical insights into cardiac cell transplantation biology.

Determination of the prognostic value of [18F]fluorodeoxyglucose uptake by using positron emission tomography in patients with non-small cell lung cancer

The aim of this study was to determine whether quantitative information obtained from [18F]fluorodeoxyglucose positron emission tomography (18F-FDG PET) has a prognostic significance for patients with non-small cell lung cancer (NSCLC). We investigated 18F-FDG PET imaging of 73 patients with NSCLC. The maximum standardized uptake value (SUVmax) was significantly different between the histopathological types of tumour (squamous cell carcinoma (n = 37, 12.4±5.1), adenocarcinoma (n = 30, 8.2±5.8), bronchioloalveolar carcinoma (n = 4, 2.6±1.7), P<0.01). In the univariate analysis of all patients, staging (P = 0.0001), tumour cell type (P = 0.013), and a SUVmax greater than 7 (P = 0.0011) was correlated with survival. However, a multivariate analysis identified staging and SUVmax greater than 7 were affected survival adversely. The mortality rate of patients with group I disease (stage I to stage IIIA) was 5.8 times lower than that of patients with group II disease (stage IIIB to stage IV). Patients with a high SUVmax (⩾7) had a 6.3 times higher mortality than those with a low SUVmax (<7). By multivariate analysis of patients with squamous cell carcinoma, only grouping affected survival (P = 0.008, relative risk = 4.3). In the case of adenocarcinoma, the SUVmax (>10) correlated exclusively with poorer survival (P = 0.031, relative risk = 11.152). 18F-FDG uptake correlated with survival in NSCLC. Especially in adenocarcinomas, the SUVmax was complementary to other known prognostic factors.

Quantitative bioluminescence imaging of tumor-targeting bacteria in living animals.

We describe a protocol for imaging bacterial luciferase (Lux)-expressing bacteria in small living animals. In this protocol, light emitted by Lux-expressing bacteria is detected and monitored by a cooled charge-coupled device detector. When these bacteria are administered to animals, it provides a potentially valuable approach to generate sensitive whole-body images with extremely low background. This imaging technology should enable the real-time monitoring of bacterial migration into both primary and metastatic tumors in several different mouse tumor models at a strong quantification power.

New paradigm for tumor theranostic methodology using bacteria-based microrobot.

We propose a bacteria-based microrobot (bacteriobot) based on a new fusion paradigm for theranostic activities against solid tumors. We develop a bacteriobot using the strong attachment of bacteria to Cy5.5-coated polystyrene microbeads due to the high-affinity interaction between biotin and streptavidin. The chemotactic responses of the bacteria and the bacteriobots to the concentration gradients of lysates or spheroids of solid tumors can be detected as the migration of the bacteria and/or the bacteriobots out of the central region toward the side regions in a chemotactic microfluidic chamber. The bacteriobots showed higher migration velocity toward tumor cell lysates or spheroids than toward normal cells. In addition, when only the bacteriobots were injected to the CT-26 tumor mouse model, Cy5.5 signal was detected from the tumor site of the mouse model. In-vitro and in-vivo tests verified that the bacteriobots had chemotactic motility and tumor targeting ability. The new microrobot paradigm in which bacteria act as microactuators and microsensors to deliver microstructures to tumors can be considered a new theranostic methodology for targeting and treating solid tumors.

Inverse agonist of estrogen-related receptor γ controls Salmonella typhimurium infection by modulating host iron homeostasis

In response to microbial infection, expression of the defensin-like peptide hepcidin (encoded by Hamp) is induced in hepatocytes to decrease iron release from macrophages. To elucidate the mechanism by which Salmonella enterica var. Typhimurium (S. typhimurium), an intramacrophage bacterium, alters host iron metabolism for its own survival, we examined the role of nuclear receptor family members belonging to the NR3B subfamily in mouse hepatocytes. Here, we report that estrogen-related receptor γ (ERRγ, encoded by Esrrg) modulates the intramacrophage proliferation of S. typhimurium by altering host iron homeostasis, and we demonstrate an antimicrobial effect of an ERRγ inverse agonist. Hepatic ERRγ expression was induced by S. typhimurium–stimulated interleukin-6 signaling, resulting in an induction of hepcidin and eventual hypoferremia in mice. Conversely, ablation of ERRγ mRNA expression in liver attenuated the S. typhimurium–mediated induction of hepcidin and normalized the hypoferremia caused by S. typhimurium infection. An inverse agonist of ERRγ ameliorated S. typhimurium–mediated hypoferremia through reduction of ERRγ–mediated hepcidin mRNA expression and exerted a potent antimicrobial effect on the S. typhimurium infection, thereby improving host survival. Taken together, these findings suggest an alternative approach to control multidrug-resistant intracellular bacteria by modulating host iron homeostasis.

Antitumor Activity of Novel Indirubin Derivatives in Rat Tumor Model

Purpose: The novel indirubin derivatives 5′-nitro-indirubinoxime, 5′-fluoro-indirubinoxime, and 5′-trimethylacetamino-indirubinoxime were designed and tested for antitumor activity both in vitro and in vivo using rat tumor model. Experimental Design: Three-week-old male Sprague-Dawley rats were inoculated s.c. on the left flank with 107 RK3E-ras rat kidney epithelial cells harboring k-ras gene. Alternatively, 5 × 106 RK3E-ras cells were injected into the oral mucosa. Indirubin derivative treatment began on the 3rd or 6th day after oral or s.c. cell injection, respectively. Indirubin derivatives were directly injected into the tumor every other day for a total of five times. Animals were monitored daily and tumor volume was measured by caliper. Results: Indirubin derivatives showed potent antiproliferative activity on various human cancer cells and oncogenic RK3E-ras rat kidney cells, with IC50 ranging from 1 to 12 μmol/L. Treatment with indirubin derivatives induced the activation of caspase-7 followed by apoptosis in RK3E-ras cells. Indirubin derivatives showed strong antitumor activity in rat solid and oral tumor models. Direct injection of indirubin derivatives every other day for 10 days induced significant inhibition of tumor growth in Sprague-Dawley rats bearing RK3E-ras-induced tumors. Histologically, treatment with indirubin derivatives caused significant inhibition of tumor formation with increased apoptosis and decreased tumor cell proliferation. Conclusions: Our data showed that novel indirubin derivatives 5′-nitro-indirubinoxime, 5′-fluoro-indirubinoxime, and 5′-trimethylacetamino-indirubinoxime effectively arrested the tumor growth by inhibiting cell proliferation and inducing apoptosis. These findings provide the potential value of indirubin derivatives as novel candidates for antitumor agents.

Prognostic significance of interim 18F-FDG PET/CT after three or four cycles of R-CHOP chemotherapy in the treatment of diffuse large B-cell lymphoma

PURPOSE (18)F-fluoro-2-dexoy-D-glucose-positron emission tomography (FDG-PET)/computerised tomography (CT) has been used for staging and monitoring responses to treatment in patients with diffuse large B cell lymphoma (DLBCL). The sequential interim PET/CT was prospectively investigated to determine whether it provided additional prognostic information and could be a positive predictable value within patients with the same international prognostic index (IPI) after the use of rituximab in DLBCL. METHODS One hundred and sixty-one patients with newly diagnosed DLBCL were enroled; the assessment of the PET/CT was performed at the time of diagnosis and mid-treatment of rituxibmab, cyclophosphamide, doxorubicin, vincristine and prednisolone (R-CHOP). RESULTS Sixty-seven patients (41.6%) presented with advanced stage disease and 27 (16.8%) had bulky lesions. Forty-three patients (26.7%) continued to have positive metabolic uptakes with a significantly high relapse rate (62.8%) compared to the patients with a negative interim PET/CT (12.1%) (P<0.01). After a median follow-up of 30.8months, the positivity of interim PET/CT was found to be a prognostic factor for both overall survival (OS) and progression-free survival (PFS), with a hazard ratio of 4.07 (2.62-6.32) and 5.46 (3.49-8.52), respectively. In the low-risk IPI group, the 3-year OS and PFS rates were significantly different in the patients with positive (53.3% and 52.5%) and negative (93.8% and 88.3%) interim PET/CT, respectively (P<0.01). These significant prognostic differences of interim PET/CT responses were consistent with the results of the patients with high-risk IPI group (P<0.01). CONCLUSIONS Interim PET/CT scanning had a significant predictive value for disease progression and survival of DLBCL in post-rituximab treatment; it might be the single most important determinant of clinical outcome in patients with the same IPI risk.

Inhibition of Tumor Growth and Metastasis by a Combination of Escherichia coli–mediated Cytolytic Therapy and Radiotherapy

We have reported that Escherichia coli K-12 colonizes hypoxic and necrotic tumor regions after intravenous injection into tumor-bearing mice. In this study, we established a novel strategy for cancer therapy using engineered bacteria to enhance the therapeutic effects of radiation. E. coli strain K-12 was engineered to produce cytolysin A (ClyA), and its effects on tumor growth in primary and metastatic tumor models were evaluated. A single treatment with E. coli-expressing ClyA significantly decreased tumor growth rates initially (9 days after treatment); however, the tumors tended to grow thereafter. With only radiotherapy (RT; 21 Gy), the tumor growth rates were retarded, but not the tumor sizes. A combination of therapy with E. coli-expressing ClyA and radiation [a total of 5 x 10(7) colony-forming units (CFU) and 21 Gy] resulted in significant tumor shrinkage and even complete disappearance of tumors in mice with tumors derived from murine CT26 colon cancer. Furthermore, treatment with E. coli-expressing ClyA markedly suppressed metastatic tumor growth and prolonged the survival time in mice. The results described here indicate that therapy with engineered E. coli could significantly improve the results of RT, and could exert a striking inhibitory effect on the development of lung metastasis.

Noninvasive Real-time Imaging of Tumors and Metastases Using Tumor-targeting Light-emitting Escherichia coli

PurposeA number of bacteria types are known to preferentially grow in tumors. We have taken advantage of this phenomenon to target luciferase-expressing Escherichia coli to tumors and metastases in mouse models to image them noninvasively.Methods and ResultsAfter intravenous injection of pLux-expressing E. coli (108 CFU), bioluminescence signals from the bacteria were detected exclusively in tumor tissue after 24 hours. The balanced-lethal host–vector system using the gene encoding aspartate β-semialdehyde dehydrogenase (asd) enabled stable maintenance of the pLux in the tumor-targeting E. coli. This phenomenon of selective tumor targeting and proliferation of E. coli was observed in a diverse range of tumors implanted in nude mice. More importantly, E. coli was capable of targeting both primary tumors and metastases, enabling them to be imaged noninvasively in both nude and immunocompetent mice.ConclusionsOur results suggest the potential clinical use of this technology for tumor targeting.

In vivo bioluminescence imaging of cord blood derived mesenchymal stem cell transplantation into rat myocardium

ObjectiveThe conventional method for the analysis of myocardial cell transplantation depends on postmortem histology. Here, we have sought to demonstrate the feasibility of a longitudinal monitoring of transplanted cell survival in living animals, accomplished with optical imaging techniques and pharmacological interventions.MethodsHuman cord blood (50 ml) was donated with parental consent. After getting cord blood derived mesenchymal stem cells (CBMSCs), cells were transfected (MOI = 100) overnight with adenovirus encoding firefly luciferase gene (Ad-CMV-Fluc). Our experimental Sprague-Dawley rats (n = 12) were given intramyocardial injections containing 1 × 106 CBMSCs, which had been made to express the firefly luciferase (Fluc) reporter gene. Optical bioluminescence imaging was then conducted using a cooled charged-coupled device (CCD) camera (Xenogen), beginning on the day after the transplantation (day 1). Groups of mice were intraperitoneally injected with cyclosporine (5 mg/kg) or tacrolimus (1 mg/kg), in an attempt to determine the degree to which cell survival had been prolonged, and these values were then compared with the cell survival values of the negative control group. The presence of transplanted CBMSCs on in vivo images confirmed by in situ hybridization for human specific Alu in the myocardium.ResultsCardiac bioluminescence signals were determined to be present for 6 days after transplantation: day 1 (97000 ± 9100 × 105 p/s/cm2/sr), day 3 (9600 ±1110 p/s/cm2/sr), and day 5 (3200 ± 550 p/s/cm2/sr). The six mice that received either cyclosporine or tacrolimus displayed cardiac bioluminescence signals for a period of 8 days after transplantation. We observed significant differences between the treated group and the non-treated group, beginning on day 3 (tacrolimus; 26500 ± 4340 p/s/cm2/sr, cyclosporine; 27200 ± 3340 p/s/cm2/sr, non-treated; 9630 ± 1180 p/s/cm2/sr, p < 0.01), and persisting until day 7 (tacrolimus; 12500 ± 2946 p/s/cm2/sr, cyclosporine; 7310 ±1258 p/s/cm2/sr, non-treated; 2460 ± 160 p/s/cm2/sr, p < 0.01). The human-derived CBMSCs were detected in the myocardium 3 days after transplantation by in situ hybridization.ConclusionsThe locations, magnitude, and survival duration of the CBMSCs were noninvasively monitored with a bioluminescence optical imaging system. We determined that optical molecular imaging expedites the fast throughput screening of pharmaceutical agents, allowing for the noninvasive tracking of cell survival within animals. In rat cardiac CBMSC transplant models, transient immunosuppressive treatment with tacrolimus or cyclosporine was shown to improve donor cell survival.