The use of adenoviral vectors for genetic manipulation and analysis of primitive hematopoietic cells

Highly efficient gene transfer into mobilized CD34+ hematopoietic cells using serotype-5 adenoviral vectors and BoosterExpress Reagent

OBJECTIVE

To optimize transduction efficiency of mobilized CD34(+) cells with serotype-5 adenoviruses (Ad5s), we investigated the activity of the chemical cocktail BoosterExpress Reagent in enhancing Ad5-mediated gene transfer into CD34(+) cells.

METHODS

Enriched CD34(+) cells were transduced with three different Ad5s at increasing multiplicity of infections (MOIs) in the presence and absence of BoosterExpress Reagent. Percentages of transduced cells and levels of transgene expression were quantified by flow cytometry. Propidium iodide staining and colony growth were used to assess the toxicity of the transduction protocol. Expression of adenovirus receptors was investigated by flow cytometry.

RESULTS

Irrespective of the Ad5 used, transduction with BoosterExpress Reagent using an MOI of 500 resulted in an average six- to seven-fold increase of transduction efficiencies and 1.5- to 2-fold increase of the levels of transgene expression, which could be detected up to 7 days post-transduction. Although BoosterExpress Reagent alone did not affect the plating efficiency of CD34(+) cells, adenovector transduction plus BoosterExpress Reagent significantly reduced the plating efficiency due to the marked increase of transduced cells. However, adenoviral transduction in the presence of BoosterExpress Reagent failed to significantly reduce the recovery of CD34(+) cells as compared with transduction in the absence of the compound. Coxsackievirus and adenovirus receptor as well as alpha(v)beta(3), alpha(v)beta(5), alpha(5), and beta(1) integrins were upregulated by BoosterExpress Reagent.

CONCLUSIONS

BoosterExpress Reagent allows high-levels of durable transgene expression, thus making CD34(+) cells a suitable target for Ad5-mediated gene transfer.

Advances in gene transfer into haematopoietic stem cells by adenoviral vectors

Until recently, the cells of haematopoietic origin were not considered good adenoviral (Adv) targets, primarily because they lacked the specific Adv receptors required for productive and efficient Adv infections. In addition, because of limitations inherent in Adv infections, such as short-term expression and a non-integrating nature, their application has been precluded from haematopoietic stem cell (HSC) and bone marrow transduction protocols where long-term expression has been required. Therefore, limited research utilising Adv-mediated gene transfer into haematopoietic cells had been conducted. With recent insights into the critical interactions between adenovirus (Adv) and cells, new Adv-mediated gene transduction strategies have now been reported that may overcome these limitations. These new strategies include Adv possessing synthetic polymer coatings, genetically modified capsid proteins or antibody-redirected fibres that can efficiently redirect and retarget Adv to transfer genes into HSC. Additionally, new hybrid Advs, engineered with both modified capsid proteins and novel cis-acting integration sequences, are also being developed which can efficiently deliver and integrate Adv delivered genes into HSC. This is an area of research that is now rapidly gaining momentum in terms of techniques and applications. Here we review the current status of adenovirus-based vectors as a means to achieve high-level gene transfer into haematopoietic cell types.