Definitions

CD34+ Cells

Population of bone marrow cells that express the CD34 antigen on their surface. Hematopoietic stem cells, cells that can repopulate the entire hematopoietic system, are present in high numbers within the CD34+ population.

Electroporation

A transfection method of introducing DNA into cells by mixing the cells with the DNA and then passing an electric current through the mixture.

Episomal

A vector that does not integrate into chromosomal DNA but stays extra-chromosomal.

Exons

The segments of the gene that are retained after RNA processing (splicing) that contribute to the mature messenger RNA for that gene. Coding exons are those that are translated into the final protein product. Non-coding exons are those that are part of the messenger RNA but are not translated into protein.

Gene Transfer

The delivery of a transgene into a cell.

Infection

The introduction of nucleic acid into cells using a viral vector.

Introns

Intervening sequences in genes that are removed during RNA processing (splicing) so that they do not contribute to the mature messenger RNA for that gene.

LTR (Long terminal repeat)

An element that caps the ends of retroviruses and lentiviruses that serve as packaging elements for the virus but can also serve as promoter and enhancer elements for the packaged transgene.

Transduction

The introduction of nucleic acid into a cell by a virus. A transduced cell is one that has been infected by a virus.

Transfection

The introduction of DNA into cells via physical techniques: such as by cationic lipids or electroporation.

Transgene

The gene of interest that is incorporated into a gene therapy vector and delivered into the cell of interest. To treat sickle cell disease, for example, the transgene would be the α-globin gene. A transgene can either be the gene itself (including all the introns or exons) or a cDNA (containing only the exons) or some combination of exons and introns.

Vector

An element that delivers a transgene into a cell. Most vectors are derived from viruses. Sometimes naked DNA can be the vector for delivery.