C. Toxicity studies: 
1 . Assessment of Transduction of Non Tumor Proliferative Tissues. 
Using the (3-galactosidase gene as a marker, brain tumors were injected with 
the GINaSvBg vector-producer cells. Organs were harvested and stained with X-Gal 
in order to estimate the frequency of vector expressing cells. Organs evaluated 
included the heart, lungs, liver, spleen, kidney, and small and large bowel. Organs were 
examined at various intervals following the intra-tumoral injection of the vector (days 5, 
9, and 14 after injection). Organs from rats in which control non-producer BAG cells 
were injected into their tumors served as controls. 
No X-Gal positive cells were seen in the heart and kidney. Occasional X-Gal 
positive cells were seen in the spleen, liver, and in the lungs, compatible with the 
distribution of normal macrophages. No difference was observed between the 
frequency of X-Gal positive cells in these organs between the rats injected with the 
vector producer cells and those injected with the non-producer cells. In normal bowel, 
there is a large number of X-Gal positive cells within the villi of both the small and large 
bowel. Again, no significant difference was observed between the non-producer and 
the producer treated rats. These findings are consistent with the histological findings 
suggesting that no significant spread of the vector takes place within normal brain. 
2. Assessment of HS-tk-producer toxicity in the peritoneal cavity and in the lung. 
We have injected HS-tk vector-producer and control non-producer cells IP 
into mice. 10 mice received 5x1 0 6 HS-tk vector-producer cells and 10 received 5x1 0 6 
BAG vector-producer cells. The mice were observed for 7 days during which no 
evidence of toxicity was observed in either group. Ganciclovir was then administered at 
a dose of 150mg/Kg BID for six days. During and after ganciclovir administration, no 
toxic side effects were observed. A few mice were sacrificed at different time points. No 
grossor microscopic pathology was seen in the various organs. The rest of the group is 
followed up with no long-term signs of toxicity. 
In a second group of mice, 5x1 0^ HS-tk vector-producer cells were injected 
IV via the lateral tail vein to evaluate possible toxicity to the lungs where the cells are 
trapped. IV injection of 5x1 0 5 BAG vector-producer cells were used in control mice. No 
evidence of toxicity was observed before, during and following ganciclovir 
administration. Review of micorscpoic slides of the lungs revealed no areas of necrosis 
or other pathology in comparison to the control group. 
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Recombinant DNA Research, Volume 15 
