Biomedical subjects

Andrew P Byrnes

Publications and source records attributed to Andrew P Byrnes.

5 recordsLinked to original sources

PubMed2006

Quality prediction of cell substrate using gene expression profiling.

Changes in cell culture conditions influence the metabolism of cells, which consequently affects the quality of the products that they produce, such as viral vectors, recombinant proteins, or vaccines. Currently there is no effective technique available to monitor global quality of cells in cell culture. Here we describe a new method using gene expression profiling by microarray to predict the quality of cell substrates. Human embryonic kidney 293 cells are a commonly used cell substrate in the production of biological products. We demonstrate that the yield of adenoviral vectors was lower in over-confluent 293 cells, compared to 40 or 90% confluent cells. Total RNA derived from these cells of different confluence states was reverse transcribed, labeled, and used to hybridize 10K cDNA arrays to determine biomarkers for confluence states. Phenotype scatter-plot analysis and cluster analysis were used for class discovery. Based on this approach, we identified genes that were either up-regulated or down-modulated in response to different cell confluence states. By multivariate predictive models we identified a set of 37 genes that were either down-regulated or up-regulated compared to 90% confluent cells as a predictor of cell confluence and quality of 293 cell cultures. The predictive accuracy of these models was assessed by the leave-one-out cross-validation method. The expression of selected gene predictors was validated by quantitative PCR analysis. Our results demonstrate that gene expression profiling can assess the quality of cell substrates prior to large-scale production of a biological product.

Adenoviridae↗

PubMed2005

Heparin-binding and patterns of virulence for two recombinant strains of Sindbis virus.

E2 is an important determinant of Sindbis virus neurovirulence. Increased heparan sulfate (HS) binding is associated with rapid clearance of viremia and usually with decreased virulence. However, substitution of histidine for arginine at E2-157 (R157H) or glutamate for lysine at E2-159 (K159E) produces viruses with decreases in heparin-Sepharose binding and increases in viremia but different levels of binding to HS-expressing cells and virulence phenotypes in newborn CD-1 mice (Byrnes, A.P., Griffin, D.E., 2000. Large-plaque mutants of Sindbis virus show reduced binding to heparan sulfate, heightened viremia and slower clearance from the circulation. J. Virol. 74, 644-651). To identify mechanisms of virulence, R157H and K159E were studied in newborn CD-1 and BALB/c mice. Subcutaneous inoculation of R157H caused 100% and K159E 60% mortality in 2-day-old CD-1 mice. R157H caused 25% and K159E no mortality in 2-day-old BALB/c mice. R157H and K159E replicated similarly at the site of inoculation with the same level of viremia, but clearance was slower in CD-1 than BALB/c mice. R157H replicated better than K159E in the central nervous system (CNS) after subcutaneous and intracerebral inoculation and in undifferentiated neurons. These studies show a genetic restriction of replication in newborn BALB/c mice, and that amino acid substitutions affecting binding to proteoglycans may differ in importance for CNS infection and viremia.

Alphavirus Infections↗

PubMed2005

Rapid Kupffer cell death after intravenous injection of adenovirus vectors.

When adenovirus vectors are injected intravenously, they are quickly taken up by Kupffer cells in the liver. We report that this causes rapid necrosis of Kupffer cells in mice at doses of 10(11) particles/kg or higher. By 10 min after intravenous vector injection, Kupffer cells were permeable to propidium iodide and trypan blue. This coincided with a sharp rise in serum lactate dehydrogenase. Ultrastructural examination showed degeneration of Kupffer cells, including complete disappearance of chromatin by 1 h. After an initial intravenous injection of vector, dead Kupffer cells were unable to take up a second dose of vector, and hepatic transgene expression from the second dose was augmented. Death of Kupffer cells did not affect serum levels of IL-6 or IL-12. There was no immediate change in the number of Kupffer cells in the liver, but a significant decline was found by 4 h after injection of vector. Interestingly, substantial numbers of vector-containing Kupffer cells were found in pulmonary capillaries, indicating that they had been swept out of the liver. Together these results show that an intravenous injection of adenovirus vector causes synchronous and surprisingly rapid Kupffer cell death.

Adenoviridae↗

PubMed2005

Challenges and future prospects in gene therapy.

Gene therapy is a promising technique for treating disease through the modification of gene expression. It is currently being tested not only for correcting genetic defects, but also for treating cancer and other acquired diseases. Although this field is still relatively young, evidence for clinical efficacy has been observed and continued progress seems assured, as clinical trials continue to yield insights into how gene therapy can be applied and improvements are made in gene therapy tools.

Animals↗

PubMed2004

Severe pulmonary pathology after intravenous administration of vectors in cirrhotic rats.

After an intravascular injection, adenoviral vectors are normally taken up by the reticuloendothelial system in the liver, where they rapidly trigger an innate response. However, we have previously found that the biodistribution of adenoviral vectors is altered in cirrhotic rats due to the presence of pulmonary intravascular macrophages, which cause a shift in vector uptake from the liver to the lungs. We now report that this is correlated with fatal pulmonary hemorrhagic edema in cirrhotic rats. In addition, cirrhotic rats reacted to vector with enormous increases in TNF-alpha and IL-6 and markedly prolonged coagulation times. Although we also saw fatal reactions to high doses of adenoviral vectors in normal rats, the time course and symptoms were very different, and pulmonary hemorrhagic edema was seen only in cirrhotic rats. Because abnormal pulmonary reticuloendothelial uptake is known to occur in humans during cirrhosis and other diseases, there is the potential that intravascular administration of adenoviral vectors might cause lung pathology in such patients.

Adenoviridae↗