Pediatric brainstem glioma is an incurable malignancy because of its inoperability. As a result of their extensive tropism toward cancer and the possibility of autologous transplantation, human adipose-derived mesenchymal stem cells (hAT-MSC) are attractive vehicles to deliver therapeutic genes to brainstem gliomas. In this study, in a good manufacturing practice (GMP) facility, we established clinically applicable hAT-MSCs expressing therapeutic genes and investigated their therapeutic efficacy against brainstem glioma in mice. For feasible clinical applications, (1) primary hAT-MSCs were cultured from human subcutaneous fat to make autologous transplantation possible, (2) hAT-MSCs were genetically engineered to express carboxyl esterase (CE) and (3) a secreted form of the tumor necrosis factor-related apoptosis-inducing ligand (sTRAIL) expression vector for synergistic effects was delivered by a gene transfer technology that did not result in genomic integration of the vector. (4) Human CE and sTRAIL sequences were utilized to avoid immunological side effects. The hAT-MSCs expressing CE±sTRAIL showed significant therapeutic effects against brainstem gliomas in vitro and in vivo. However, the simultaneous expression of CE and sTRAIL had no synergistic effects in vivo. The results indicate that non-viral transient single sTRAIL gene transfer to autologous hAT-MSCs is a clinically applicable stem cell-based gene therapy for brainstem gliomas in terms of therapeutic effects and safety.

The prognosis of medulloblastoma has improved significantly because of advances in multi-modal treatments; however, metastasis remains one of the prognostic factors for a poor outcome and is usually associated with tumor recurrence. We evaluated the migratory potential and therapeutic efficacy of genetically engineered human neural stem cells (NSCs) that encode a prodrug enzyme in the subdural medulloblastoma model. We genetically modified HB1.F3 (F3) immortalized human NSCs to express rabbit carboxylesterase (rCE) enzyme, which efficiently converts the prodrug CPT-11 (Irinotecan) into an active anti-cancer agent (SN-38). To simulate clinical metastatic medulloblastomas, we implanted human medulloblastoma cells into the subdural spaces of nude mice. rCE expressing NSCs (F3.rCE) were labeled with fluorescence magnetic nanoparticle for in vivo imaging. The therapeutic potential of F3.rCE was confirmed using a mouse subdural medulloblastoma model. The majority of intravenously (i.v.) injected, F3.rCE cells migrated to the subdural medulloblastoma site and a small number of F3.rCE cells were found in the lungs, pancreas, kidney and liver. Animals that received F3.rCE cells in combination with prodrug CPT-11 survived significantly longer (median survival: 142 days) than control mice that received F3.rCE cells only (median survival: 80 days, Po0.001) or CPT-11 only (median survival: 118 days, Po0.001). In conclusion, i.v. injected F3.rCE NSCs were able to target subdural medulloblastomas and demonstrate therapeutic efficacy. Our study provides data that supports further investigation of stem-cell-based gene therapy against metastatic medulloblastomas.

Objectives: To evaluate the effect of gadoxetic acid enhancement on the detection and characterisation of focal hepatic lesions on T 2 weighted and diffusion weighted (DW) images. Methods: A total of 63 consecutive patients underwent T 2 weighted and DW imaging before and after gadoxetic acid enhancement. Two blinded readers independently identified all of the focal lesions using a five-point confidence scale and characterised each lesion using a three-point scale: 1, non-solid; 2, indeterminate; and 3, solid. For both T 2 weighted and DW imaging, the accuracies for detecting focal lesions were compared using the free-response receiver operating characteristic analysis; the accuracies for lesion characterisation were compared using the McNemar test between non-enhanced and gadoxetic acid-enhanced image sets. For hepatic lesions >1 cm, the lesion-to-liver contrast-to-noise ratio (CNR) and the apparent diffusion coefficient (ADC) were compared in the non-enhanced and enhanced image sets using the generalised estimating equations. Results: For both T 2 weighted and DW images, the accuracies for detecting focal lesions (p>0.52) and those for lesion characterisation (p>0.63) did not differ significantly between the non-enhanced and enhanced image sets. The lesion-to-liver CNR was significantly higher on enhanced DW images than on non-enhanced DW images (p50.02), although the difference was not significant for T 2 weighted imaging (p50.65). The mean ADC values of lesions did not differ significantly on enhanced and non-enhanced DW imaging (p50.75). Conclusion: The acquisition of T 2 weighted and DW images after administration of gadoxetic acid has no significant effect on the detection or characterisation of focal hepatic lesions, although it improves the lesion-to-liver CNR on DW images. Various contrast agents have been developed and utilised for MRI of the liver in order to facilitate the detection and characterisation of focal hepatic lesions. Gadoxetic acid (gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid, PrimovistH; Bayer Schering Pharma, Berlin, Germany) is a recently developed, liverspecific contrast agent. As it has combined extracellular and hepatocyte-specific properties, gadoxetic acid can provide functional information regarding the cellular composition of focal hepatic lesions on hepatobiliary phase imaging as well as haemodynamic information on dynamic MRI following bolus injection. These properties of gadoxetic acid have been reported to improve the accuracy of liver MRI for lesion detection and characterisation [1][2][3][4][5][6][7].By contrast, these advantages of gadoxetic acidenhanced liver MRI are obtained with increased examination time, as delayed scanning approximately 20 min after contrast administration is necessary for optimal hepatobiliary phase imaging [4,5,[7][8][9]. Among the pulse sequences commonly acquired for clinical liver MRI, T 2 weighted and diffusion weighted (DW) imaging are frequently performed using a respiratory-triggered method in order to improve image quality...