Human CMV immediate-early enhancer: a useful tool to enhance cell-type-specific expression from lentiviral vectors.
BACKGROUND
Lentiviral vectors are attractive delivery tools for gene therapy, especially in terminally differentiated target cells. While restriction of gene expression to specific cell populations is of particular importance, highly efficient cell-type-specific gene expression after viral gene transfer so far has been hampered by low levels of transgene expression.


METHODS
Addressing this problem, we have integrated the human cytomegalovirus (CMV) immediate-early enhancer into an 'advanced' generation lentiviral vector. Expression cassettes with the reporter gene green fluorescent protein (GFP), combined with the woodchuck hepatitis virus posttranscriptional regulatory element (WPRE) under control of a ubiquitous phosphoglycerate kinase (mouse PGK), cardiomyocyte- (human atrial natriuretic factor (ANF), human ventricular myosin light chain (MLC2v)), or type II alveolar epithelial cell (AT-2)-specific human surfactant protein C (SP-C) promoter, were introduced. As insertion of an enhancing element can interfere with the promoter's specificity, expression levels conferred by our enhancer/promoter constructs were evaluated in target and non-target cells.


RESULTS
Transduction of target cells with human CMV enhancer containing lentiviral vectors resulted in a multiple-log increase in GFP expression compared to corresponding vectors lacking the human CMV enhancer. In the case of the ANF, the MLC2v, and the SP-C promoters, tissue-specific reporter gene expression in cardiomyocytes and in lung AT-2 cells was maintained, as expression in non-target cells increased only up to 7-fold.


CONCLUSIONS
The results of this study indicate that lentiviral vectors with the human CMV enhancer conferring efficient cell-type-specific gene expression may be useful tools for gene therapy purposes or cell tracing, e.g. to analyze stem cell differentiation in transplantation and co-culture settings.
Gruh
Ina
I
Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Hannover Medical School, Hannover, Germany.
Wunderlich
Stephanie
S
Winkler
Monica
M
Schwanke
Kristin
K
Heinke
Jennifer
J
Blömer
Ulrike
U
Ruhparwar
Arjang
A
Rohde
Bettina
B
Li
Ren-Ke
RK
Haverich
Axel
A
Martin
Ulrich
U
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D003587:Cytomegalovirus / Q000235:genetics*; D004742:Enhancer Elements, Genetic / Q000235:genetics*; D005786:Gene Expression Regulation; D005822:Genetic Vectors / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D016086:Lentivirus / Q000235:genetics* / Q000502:physiology; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism; D009928:Organ Specificity; D011401:Promoter Regions, Genetic / Q000235:genetics; D037721:Pulmonary Surfactant-Associated Protein C / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D019076:Transgenes; D014771:Virion / Q000235:genetics; D019065:Virus Assembly
D037721:Pulmonary Surfactant-Associated Protein C; D012333:RNA, Messenger; D009320:Atrial Natriuretic Factor