Dr. Victor Krasnykh
The University of Texas MD Anderson Cancer Center
Department of Experimental Diagnostic Imaging
The main focus of my research efforts is the development of viral vectors for tumor-specific delivery and expression of therapeutic and imaging transgenes. The ultimate goal of these efforts is to enable both gene therapy of cancer and molecular-genetic imaging of tumors through the development of vectors capable of safe, efficient and selective delivery of these transgenes to tumors. To design such vectors we use adenoviruses of human and non-human origin as vector prototypes. This choice is supported by several advantages that adenoviruses offer as gene vectors. However, a number of serious challenges remain to be addressed. These could be illustrated using human adenovirus serotype 5 (Ad5), which has long been considered a gold standard in vector development. In particular, Ad5 has three major limitations preventing its use as a therapeutic or imaging agent in humans. First, owing to unfavorable expression of its natural receptor, the virus lacks specificity for tumor cells and thus tends to miss tumors upon system administration and transduce normal, healthy tissues instead. Second, this pattern of random in vivo gene transfer by Ad5 is further compromised by the virus' association with the blood coagulation factors and redirecting the virus to the liver, which efficiently eliminates the vector from the intended gene delivery scheme and also causes severe toxicity. Third, due to continuous circulation of Ad5 in human population, most humans have pre-existing immunity to the virus and cannot be efficiently treated with the Ad5-derived vectors. To overcome these challenges, our strategy is based on the use of those non-Ad5 serotypes of Ad to which there is no pre-existing immunity and whose virions do not transduce the liver. To make these viral vectors tumor-specific we modify their virions to incorporate protein ligands that are specific for major molecular markers found on the surface of tumors cells. These studies involve genetic re-engineering of Ad genes and genomes; development of cell lines capable of complementing essential viral functions for vector rescue and propagation; molecular characterization of the designed viruses; in vitro and in vivo validation of their modified tropism and gene delivery.
While doing a tutorial in my laboratory, a student might work on a vector targeting subproject and could learn numerous laboratory methods such as the isolation, purification and manipulation with nucleic acids; gene construction either with oligonucleotides, or restriction-ligation, or by polymerase chain reaction; transformation of bacteria and transfection of eukaryotic cells; gel electrophoresis of proteins and nucleic acids; western blotting; expression of recombinant proteins in bacteria and purification of proteins by chromatography; flow-cytometry; ELISA, cell culture methods; viral infections in vitro and in vivo, propagation of adenoviruses and their purification; titration of adenoviruses; establishing tumor xenografts in mice; bioluminescent imaging of reporter genes in live mice.
Office: MDA T8.3900 (Unit 59)
Title: Associate Professor
Ph.D. - Free University of Amsterdam - 1999