Background: To date, the significant osteoinductive potential of bone morphogenetic protein
2 (BMP-2) non-viral gene therapy cannot be fully exploited therapeutically. This is mainly due to
weak gene delivery and brief expression peaks restricting the therapeutic effect.
Objective: Our objective was to test the application of minicircle DNA, allowing prolonged expression
potential. It offers notable advantages over conventional plasmid DNA. The lack of bacterial sequences
and the resulting reduction in size, enables safe usage and improved performance for tissue regeneration.
Methods: We inserted an optimized BMP-2 gene cassette with minicircle plasmid technology. BMP-2
minicircle plasmids were produced in E. coli yielding plasmids lacking bacterial backbone elements.
Comparative studies of these BMP-2 minicircles and conventional BMP-2 plasmids were performed
in vitro in cell systems, including bone marrow derived stem cells. Tests performed included gene expression
profiles and cell differentiation assays.
Results: A C2C12 cell line transfected with the BMP-2-Advanced minicircle showed significantly elevated
expression of osteocalcin, alkaline phosphatase (ALP) activity, and BMP-2 protein amount
when compared to cells transfected with conventional BMP-2-Advanced plasmid. Furthermore, the
plasmids show suitability for stem cell approaches by showing significantly higher levels of ALP activity
and mineralization when introduced into human bone marrow stem cells (BMSCs).
Conclusion: We have designed a highly bioactive BMP-2 minicircle plasmid with the potential to fulfil
clinical requirements for non-viral gene therapy in the field of bone regeneration.