Attachment II - Pg. 6 
any contaminating material (DNA, proteins, etc.) or contaminat- 
ing viruses or other organisms in the cells or serum. 
(2) Describe any other material to be used in preparation of the mate- 
rial to be given to the patient. For example, if a viral vector is 
proposed, what is the nature of the helper virus or cell line? If 
carrier particles are to be used, what Is the nature of these? 
c. Describe tissue culture and animal studies that have been used to char- 
acterize the efficiency and safety of the delivery system. 
(1) Delivery System. 
(a) What cells are the intended recipients of gene therapy? What is 
the theoretical and practical basis for assuming that only the 
target cells will act as recipients? If recipient cells are to 
be treated in vitro and returned to the patient, how will the 
cells be characterized before and after treatment? 
(b) Is the delivery system efficient in that it should result in the 
insertion of the desired unrearranged DNA sequences in an ade- 
quate number of the patient's cells? How is the structure moni- 
tored and what is the sensitivity of analysis? Is it extra- 
chromosomal or Integrated? How many copies per cell? How sta- 
ble is the Inserted DNA both In terms of its continued presence 
and Its structural stability? 
(2) Expression. 
Is the inserted gene expressed? To what extent is expression only 
from the desired gene (and not from the surrounding DNA)? In what 
percentage of cells Is expression occurring? Is the product biolog- 
ically active? What percentage of normal activity results from the 
inserted gene? 
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