Universal Method for the Purification of Recombinant AAV Vectors of Differing Serotypes

The generation of clinical good manufacturing practices (GMP)-grade adeno-associated virus (AAV) vectors requires purification strategies that support the generation of vectors of high purity, and that exhibit a good safety and efficacy profile. To date, most reported purification schemas are serotype dependent, requiring method development for each AAV gene therapy product. Here, we describe a platform purification process that is compatible with the purification of multiple AAV serotypes. The method generates vector preparations of high purity that are enriched for capsids with full vector genomes, and that minimizes the fractional content of empty capsids. The two-column purification method, a combination of affinity and ion exchange chromatographies, is compatible with a range of AAV serotypes generated by either the transient triple transfection method or the more scalable producer cell line platform. In summary, the adaptable purification method described can be used for the production of a variety of high-quality AAV vectors suitable for preclinical testing in animal models of diseases.

Magnetic resonance imaging of lipid deposits in human atheroma via a stimulated-echo diffusion-weighted technique

NMR images of subintimal lipid deposits within the vessel walls of atherosclerotic human aortas were obtained at 37 and 27 degrees C at 4.7 T. A combination of a stimulated-echo and pulsed-field gradients was used for suppressing the mobile tissue water relative to the less mobile tissue lipids. At 27 degrees C there was also a substantial reduction of the subintimal lipid signal intensity, which is consistent with the characteristic phase transition of cholesteryl esters in human atheroma. These results represent the first direct detection of lipid deposits in nonprotruding atherosclerotic lesions with NMR imaging.

Proton NMR microscopy of multicellular tumor spheroid morphology

We report proton NMR images obtained at microscopic (less than 30 microns) resolution of EMT6/Ro and HT1080 multicellular tumor spheroids 1.2-1.7 mm in diameter. T1-weighted images showed little contrast across a slice through the spheroid. There was also no difference between the inner and outer spheroid regions when signal intensity was measured as a function of the repetition time (TR), showing that T1 was the same across the spheroid. Conversely, T2-weighted and multi-echo images clearly revealed the central necrosis that occurs as the spheroids develop. Measurements of the thickness of the viable cell zone made on NMR images agreed with those made on standard histology sections for two different cell lines. The basis for the NMR discrimination of the necrotic region from the viable rim cells was found to be a shortened apparent T2 in the necrotic region (132 +/- 17 ms) with respect to that in the viable cells (173 +/- 9 ms). These results illustrate the applicability of NMR microscopy to assaying conditions inside intact tumor spheroids and suggest that this technology will allow the use of spheroids to investigate several important questions in tumor biology and pathophysiology.

9.4-T NMR microimaging studies of hepatic metastases of human colorectal tumors in nude mice

We have applied NMR microimaging at 9.4 T to detect metastatic deposits in the liver of nude mice noninvasively, using an animal model for metastatic colon cancer that mimics several aspects of the human disease. Images were obtained with a resolution of 100 x 100 x 900 microns and the tumor deposits were clearly distinguished from the normal liver tissue with excellent contrast. Comparison of NMR images with corresponding histologic sections indicates that lesions as small as 900 microns were detected.

9.4 T imaging studies of human tumor xenografts in nude mice

To evaluate the potential of 9.4 T imaging in distinguishing normal and neoplastic tissues, we examined the progressive growth of human colon and prostate adenocarcinoma xenografts in nude mice. Images were obtained with a resolution of 100 X 100 X 650 micron, and tumors were clearly distinguished from normal tissue with high contrast. These results demonstrate the feasibility of detecting small human tumors in live nude mice with microscopic resolution at 9.4 T.

Renal imaging studies at 1.5 and 9.4 T: effects of diuretics

We have studied the effects of two diuretics, selective for renal cortical (furosemide) and inner medullary (vasopressin antagonist) water handling, in rat kidney at 1.5 T and find that furosemide completely dissipates the cortical-inner medullary T2 gradient whereas the vasopressin antagonist has little effect. This phenomenon appears to be related to changes in luminal water content. We also demonstrate the feasibility of obtaining live mouse kidney images with a resolution of 100 x 100 x 700 micrometers at 9.4 T.

Nuclear magnetic resonance imaging of a single cell

Nuclear magnetic resonance (NMR) imaging is now an established tool in clinical imaging and competes favourably with conventional X-ray computerized tomography (CT) scanning. The drive behind NMR imaging has primarily been in the area of whole-body imaging, which has been limited clinically to fields of up to 1.5 T (60 MHz). It is recognized that there may be substantial advantages in obtaining images with sub-millimetre spatial resolution. Also, there may be benefits to imaging at higher fields, since the signal increases as the square of the magnetic field. Using a modified 9.5 T 89-mm-bore high-resolution NMR spectrometer, we have now obtained the first NMR images of a single cell, demonstrating the advent of the NMR imaging microscope. The NMR microscope is expected to have considerable impact in the areas of biology, medicine and materials science, and may serve as a precursor to obtaining such resolutions on human subjects.