Biodistribution and Tolerability of AAV-PHP.B-CBh-SMN1 in Wistar Han Rats and Cynomolgus Macaques Reveal Different Toxicologic Profiles.

Recombinant adeno-associated viruses (AAVs) have emerged as promising vectors for human gene therapy, but some variants have induced severe toxicity in Rhesus monkeys and piglets following high-dose intravenous (IV) administration. To characterize biodistribution, transduction, and toxicity among common preclinical species, an AAV9 neurotropic variant expressing the survival motor neuron 1 (SMN1) transgene (AAV-PHP.B-CBh-SMN1) was administered by IV bolus injection to Wistar Han rats and cynomolgus monkeys at doses of 2 × 1013, 5 × 1013, or 1 × 1014 vg/kg. A dose-dependent degeneration/necrosis of neurons without clinical manifestations occurred in dorsal root ganglia (DRGs) and sympathetic thoracic ganglia in rats, while liver injury was not observed in rats. In monkeys, one male at 5 × 1013 vg/kg was found dead on day 4. Clinical pathology data on days 3 and/or 4 at all doses suggested liver dysfunction and coagulation disorders, which led to study termination. Histologic evaluation of the liver in monkeys showed hepatocyte degeneration and necrosis without inflammatory cell infiltrates or intravascular thrombi, suggesting that hepatocyte injury is a direct effect of the vector following hepatocyte transduction. In situ hybridization demonstrated a dose-dependent expression of SMN1 transgene mRNA in the cytoplasm and DNA in the nucleus of periportal to panlobular hepatocytes, while quantitative polymerase chain reaction confirmed the dose-dependent presence of SMN1 transgene mRNA and DNA in monkeys. Monkeys produced a much greater amount of transgene mRNA compared with rats. In DRGs, neuronal degeneration/necrosis and accompanying findings were observed in monkeys as early as 4 days after test article administration. The present results show sensory neuron toxicity following IV delivery of AAV vectors at high doses with an early onset in Macaca fascicularis and after 1 month in rats, and suggest adding the autonomic system in the watch list for preclinical and clinical studies. Our data also suggest that the rat may be useful for evaluating the potential DRG toxicity of AAV vectors, while acute hepatic toxicity associated with coagulation disorders appears to be highly species-dependent.

Leptin-adiponectin ratio in pre-diabetic patients undergoing percutaneous coronary intervention.

BACKGROUND: The obesity-related hormones leptin and adiponectin are independently and oppositely associated with insulin resistance, which is an important risk factor for coronary artery disease (CAD) and restenosis after coronary intervention. In this report, we set out to determine the role of the leptin-adiponectin ratio (LAR) in non-diabetic patients with or without impaired glucose tolerance undergoing a percutaneous coronary intervention. METHODS: 300 PCI patients were enrolled in this prospective single-centre study. Patients with known diagnosis of diabetes (n = 50) and newly diagnosed diabetes (2h OGTT > 200 mg/dL, n = 25) were excluded. In both stable and acute subjects, assessment was done on the day of discharge and included a fasting glucose level, leptin, adiponectin and an oral glucose tolerance test (OGTT). RESULTS: LAR was significantly higher in diabetic (7.2 ± 0.7) than in non-diabetic patients (3.9 ± 0.3, P = 0.001), and even higher in newly diagnosed diabetics (9.8 ± 1.5, P < 0.001). Likewise, among non-diabetic patients, LAR was significantly higher in patients with impaired glucose tolerance. LAR was significantly higher in pre-diabetic (4.57 ± 0.48) versus normoglycaemic patients (3.45 ± 0.33, P = 0.05). LAR was found to be numerically higher in pre-diabetic versus normoglycaemic patients with two- and three-vessel disease (VD), but not in patients with single VD. In pre-diabetic patients, LAR was found to be significantly increased with more advanced CAD (P = 0.021), independent of stable versus unstable presentation. CONCLUSIONS: LAR is related to the extent of CAD in pre-diabetic patients but not in normoglycaemic patients. This finding might in part explain the poorer outcome in revascularized patients with impaired glucose tolerance compared to normoglycaemic patients.

A multiple time-scale computational model of a tumor and its micro environment.

Experimental evidence suggests that a tumor's environment may be critical to designing successful therapeutic protocols: Modeling interactions between a tumor and its environment could improve our understanding of tumor growth and inform approaches to treatment. This paper describes an efficient, flexible, hybrid cellular automaton-based implementation of numerical solutions to multiple time-scale reaction-diffusion equations, applied to a model of tumor proliferation. The growth and maintenance of cells in our simulation depend on the rate of cellular energy (ATP) metabolized from nearby nutrients such as glucose and oxygen. Nutrient consumption rates are functions of local pH as well as local concentrations of oxygen and other fuels. The diffusion of these nutrients is modeled using a novel variation of random-walk techniques. Furthermore, we detail the effects of three boundary update rules on simulations, describing their effects on computational efficiency and biological realism. Qualitative and quantitative results from simulations provide insight on how tumor growth is affected by various environmental changes such as micro-vessel density or lower pH, both of high interest in current cancer research.

Effect of dynamic loading on the transport of solutes into agarose hydrogels.

In functional tissue engineering, the application of dynamic loading has been shown to improve the mechanical properties of chondrocyte-seeded agarose hydrogels relative to unloaded free swelling controls. The goal of this study is to determine the effect of dynamic loading on the transport of nutrients in tissue-engineered constructs. To eliminate confounding effects, such as nutrient consumption in cell-laden disks, this study examines the response of solute transport due to loading using a model system of acellular agarose disks and dextran in phosphate-buffered saline (3 and 70 kDa). An examination of the passive diffusion response of dextran in agarose confirms the applicability of Fick's law of diffusion in describing the behavior of dextran. Under static loading, the application of compressive strain decreased the total interstitial volume available for the 70 kDa dextran, compared to free swelling. Dynamic loading significantly enhanced the rate of solute uptake into agarose disks, relative to static loading. Moreover, the steady-state concentration under dynamic loading was found to be significantly greater than under static loading, for larger-molecular-mass dextran (70 kDa). This experimental finding confirms recent theoretical predictions that mechanical pumping of a porous tissue may actively transport solutes into the disk against their concentration gradient. The results of this study support the hypothesis that the application of dynamic loading in the presence of growth factors of large molecular weight may result in both a mechanically and chemically stimulating environment for tissue growth.

Large capture-range of a single-beam gradient optical trap.

We have observed long-range trapping with a single-beam gradient force optical trap. 6 to 10 microm polystyrene beads that are initially approximately 100 microm away from the trap-center can be pulled into the trap-center. Particle-tracking enables us to determine the trajectory of a bead as it moves towards the trap-center and map out a capture zone inside which trapping can occur.