Globin vector regulatory elements are active in early hematopoietic progenitor cells.

Area of Science:

• Genetics and Molecular Biology
• Hematology
• Gene Therapy

Background:

• Globin genes are typically active only in red blood cell precursors.
• Locus control regions (LCRs) regulate globin gene expression.
• Lentiviral vectors using LCRs are used for treating beta-thalassemia and sickle cell disease.

Purpose of the Study:

• To investigate the non-erythroid activity of lentiviral LCR elements.
• To assess the risk of unintended gene activation by these vectors.
• To evaluate the efficacy of insulators in mitigating this risk.

Main Methods:

• Lentiviral vectors containing LCR elements (HS1, HS2) and a reporter gene were constructed.
• Vector activity was tested in early hematopoietic cells, including stem cells and myeloid progenitors.
• The effect of an insulator sequence on vector activity was examined.

Main Results:

• LCR elements (HS1, HS2) showed position-dependent activity in non-erythroid hematopoietic cells.
• This activity led to the transcriptional activation of a reporter gene in progenitor cells.
• An insulator sequence successfully blocked non-erythroid activity without compromising therapeutic globin expression.

Conclusions:

• Lentiviral vectors with LCR elements can activate genes in early hematopoietic cells.
• This poses a risk of trans-activating cancer-related genes.
• Insulators can mitigate this risk, enhancing the safety of gene therapy vectors.