Regulation of Transgene Expression Using an Inducible System for Improved Safety of Intervertebral Disc Gene Therapy

Abstract

The transgene expressed by the transduced NPC was efficiently regulated by inclusion of tetracycline in culture media. The presence of tetracycline turns off the protein expression and the subsequent absence allows it to recover again, demonstrating the ability to control gene expression in NPCs. Therefore, we propose a Tet-off inducible system as an efficient tool for modulating the transgene expression to avoid the toxicity that could result from a missed injection.

Molecular Basis of Intervertebral Disc Degeneration and Herniations: What Are the Important Translational Questions?

“…Vectors can be developed containing a gene whose expression is initiated when the inducing agent such as tetracycline is delivered [96]. As such, with the removal of the induction agent, the protein production of the introduced gene ceases.…”

Developing a System for Regulating Expression of Human Hepatocyte Growth Factor Using Tetracycline in NRK52E Cells

“…Compared with other pharmacological control of gene expressions including the Pip on/off [29] , the antiprogestin-dependent [30] , ecdysone-dependent [31] and rapamycin-dependent [32] gene switch systems, the Teton system exhibits the best features for applications in patients because: (a) the inducer Dox is well tolerated in humans and has been widely used as an antibiotic, (b) Dox is liposoluble and has considerable tissue penetration, (c) it can be given orally and permits rapid gene induction/silencing switch in vivo in a dose-dependent manner, (d) the level of gene expression in individual cells correlates directly with the dose of inducer, allowing a graded transcriptional response [33] , and (e) this system has been studied in the context of numerous viral and nonviral vectors to regulate expression of various genes, and results are well documented [8,27] . Despite these advantages, a main drawback of this system is that the procedure is more complex than other gene expression systems.…”

“…A number of inducible gene expression systems have been developed in an attempt to meet the need for regulated gene expression [27] . Although some regulation has been achieved, these previous systems present a number of limitations, including basal leakiness, toxicity of the inducing agents and low levels of expression [27] . An additional disadvantage of these systems is the pleiotropic effects of the inducing agent.…”

Biologic Treatments in Intervertebral Disc Degeneration: Protein-Based and Cell-Based Therapies

“…In theory gene therapy would eliminate the need for repeated protein injections. However, gene therapy currently still has significant limitations given safety concerns of dosing, delivery method, and localization of injection 50 . Given these suboptimal safety concerns, the current body of clinical data pertaining to gene therapy is minimal.…”