Kristen Jensen-Pergakes | PubMed Health

PubMed2002

Enhanced phagemid particle gene transfer in camptothecin-treated carcinoma cells.

Engineered phage-based vectors are an attractive alternative strategy for gene delivery because they possess no natural mammalian cell tropism and can be genetically modified for specific applications. Genotoxic treatments that increase the transduction efficiency of single-stranded adeno-associated virus were tested on cells transfected by single-stranded phage. Indeed, green fluorescent protein transgene expression by epidermal growth factor-targeted phagemid particles increased with heat shock, UV irradiation, and camptothecin (CPT) treatment. CPT resulted in transduction efficiencies of 30-45% in certain human carcinoma cell lines and reduced the minimal dose needed to detect green fluorescent protein-expressing cells to as low as 1-10 particles/cell. Targeted phage transduction was effective in many tumor cell lines and in prostate tumor xenografts with CPT treatment. Taken together, these data suggest the feasibility of using phage-based vectors for therapeutic gene delivery to cancer cells.

Animals↗

PubMed2002

Evolving phage vectors for cell targeted gene delivery.

We adapted filamentous phage vectors for targeted gene delivery to mammalian cells by inserting a mammalian reporter gene expression cassette (GFP) into the vector backbone and fusing the pIII coat protein to a cell targeting ligand (i.e. FGF2, EGF). Like transfection with animal viral vectors, targeted phage gene delivery is concentration, time, and ligand dependent. Importantly, targeted phage particles are specific for the appropriate target cell surface receptor. Phage have distinct advantages over existing gene therapy vectors because they are simple, economical to produce at high titer, have no intrinsic tropism for mammalian cells, and are relatively simple to genetically modify and evolve. Initially transduction by targeted phage particles was low resulting in foreign gene expression in 1-2% of transfected cells. We increased transduction efficiency by modifying both the transfection protocol and vector design. For example, we stabilized the display of the targeting ligand to create multivalent phagemid-based vectors with transduction efficiencies of up to 45% in certain cell lines when combined with genotoxic treatment. Taken together, these studies establish that the efficiency of phage-mediated gene transfer can be significantly improved through genetic modification. We are currently evolving phage vectors with enhanced cell targeting, increased stability, reduced immunogenicity and other properties suitable for gene therapy.

Animals↗