There exists a dire need for improved therapeutics to achieve predictable bone regeneration. Gene therapy using non-viral vectors that are safe and efficient at transfecting target cells is a promising approach to overcoming the drawbacks of protein delivery of growth factors. Here, we investigated the transfection efficiency, cytotoxicity, osteogenic potential and in vivo bone regenerative capacity of chemically modified ribonucleic acid (cmRNA) (encoding BMP-2) complexed with polyethylenimine (PEI) and made comparisons with PEI complexed with conventional plasmid DNA (encoding BMP-2). The polyplexes were fabricated at an amine (N) to phosphate (P) ratio of 10 and characterized for transfection efficiency using human bone marrow stromal cells (BMSCs). The osteogenic potential of BMSCs treated with these polyplexes was validated by determining the expression of bone-specific genes, osteocalcin and alkaline phosphatase as well as through the detection of bone matrix deposition. Using a calvarial bone defect model in rats it was shown that PEI-cmRNA (encoding BMP-2)-activated matrices promoted significantly enhanced bone regeneration compared to PEI-plasmid DNA (BMP-2)-activated matrices. Our proof of concept study suggests that scaffolds loaded with non-viral vectors harboring cmRNA encoding osteogenic proteins may be a powerful tool for stimulating bone regeneration with significant potential for clinical translation.

In vivo genome editing using nuclease-encoding mRNA corrects SP-B deficiency (2015) Nature Biotechnology, 33 (6), pp. 584-586.In vivo genome editing using nuclease-encoding mRNA corrects SP-B deficiencyTo the Editor:Nuclease-mediated genome editing holds great potential to knock out or repair diseasecausing genes. An ideal nuclease delivery vehicle is short-lived, does not integrate into the genome, and can enter target cells efficiently. These requirements have not yet been achieved simultaneously by any nuclease delivery vector. We and others have used modified mRNA, which is non-integrating and provides a transient pulse of protein expression, as an alternative to traditional viral vectors [1][2][3][4][5] . This approach allowed us to deliver therapeutic proteins in mouse models of Surfactant Protein B (SP-B) deficiency 3 and experimental asthma 4 . Here we apply it to deliver site-specific nucleases, demonstrating the value of nuclease-encoding chemically modified (nec) mRNA as a tool for in vivo genome editing. We chose a well-established transgenic mouse model of SP-B deficiency 6 in which SP-B cDNA is under the control of a tetracycline-inducible promoter 7 . Administration of doxycycline drives SP-B expression levels similar to those in wild-type mice (Supplementary Fig. 1), whereas cessation of doxycycline leads to phenotypic changes similar to those of the human disease, including thickened alveolar walls, heavy cellular infiltration, increased macrophages and neutrophils, interstitial edema, augmented cytokines in the lavage, a decline in lung function, and fatal respiratory distress leading to death within days 8,9 . We inserted a constitutive CAG promoter immediately upstream of the SP-B cDNA to allow doxycycline-independent expression and prolonged life in treated mice.First, we customized a panel of ZFNs and TALENs targeting the transgenic SP-B cassette ( Fig. 1a and Supplementary Fig. 2). We chose TALEN #1 (T1) and ZFN #3 (Z3) owing to their high activity and proximity to the desired site of promoter integration (Figs. 1a,b; amino acid sequences in Supplementary Fig. 4) and compared delivery by plasmid 1 DNA and mRNA. mRNA delivery resulted in higher levels of double-strand break (DSB)-induction ( Fig. 1c and Supplementary Fig. 3; P < 0.05) and homology-directed repair (HDR) ( Fig. 1d, P < 0.05). As Z3 mRNA was more efficient than T1 mRNA in both cases, Z3 was chosen for further experimentation. Comparison with a Z3-encoding AAV serotype 6 vector (AAV6) ("Z3 AAV") shows the relatively transient expression of Z3 mRNA (Fig. 1e), limiting the time during which off-target cleavage activity could occur.To optimize Z3 expression in the mouse lung, we administered a panel of 3xFLAG-tagged Z3 mRNAs with various modification schemes 2,5,10 , with or without complexation to biocompatible, biodegradable nanoparticles (NPs) made of chitosan-coated poly (lactic-coglycolic) acid (chit-PLGA) 11,12 . Following intratracheal (i.t.) delivery, NP-complexation significantly increased mRNA expression levels ( Supplem...

Employing cost-effective biomaterials to deliver chemically modified ribonucleic acid (cmRNA) in a controlled manner addresses the high cost, safety concerns and lower transfection efficiency that exist with protein and gene therapeutic approaches. By eliminating the need for nuclear entry, cmRNA therapeutics can potentially overcome the lower transfection efficiencies associated with non-viral gene delivery systems. Here, we investigated the osteogenic potential of cmRNA encoding BMP-9, in comparison to cmRNA encoding BMP-2. Polyethylenimine (PEI) was used as a vector to increase in vitro transfection efficacy. Complexes of PEI-cmRNA (encoding BMP-2 or BMP-9) were fabricated at an amine (N) to phosphate (P) ratio of 10 and characterized for transfection efficacy in vitro using human bone marrow stromal cells (BMSCs). The osteogenic potential of BMSCs treated with these complexes was determined by evaluating the expression of bone-specific genes as well as through the detection of bone matrix deposition. It was found that alkaline phosphatase (ALP) expression 3 days post transfection in the group treated with BMP-9-cmRNA was significantly higher than the group that received BMP-2-cmRNA treatment. Alizarin red staining and atomic absorption spectroscopy demonstrated enhanced osteogenic differentiation as evidenced by increased bone matrix production by the BMSCs treated with BMP-9-cmRNA when compared to cells treated with BMP-2-cmRNA. In vivo studies showed increased bone formation in calvarial defects treated with the BMP-9-cmRNA and BMP-2-cmRNA collagen scaffolds when compared to empty defects. The connectivity density of the regenerated bone was higher (2-fold-higher) in the group that received BMP-9-cmRNA compared to BMP-2-cmRNA. Together, these findings suggest that cmRNA activated matrix encoding osteogenic molecules can provide a powerful strategy for bone regeneration with significant clinical translational potential.

Gene therapy has always been a promising therapeutic approach for Cystic Fibrosis (CF). However, numerous trials using DNA or viral vectors encoding the correct protein resulted in a general low efficacy. In the last years, chemically modified messenger RNA (cmRNA) has been proven to be a highly potent, pulmonary drug. Consequently, we first explored the expression, function and immunogenicity of human (h)CFTR encoded by cmRNAhCFTR in vitro and ex vivo, quantified the expression by flow cytometry, determined its function using a YFP based assay and checked the immune response in human whole blood. Similarly, we examined the function of cmRNAhCFTR in vivo after intratracheal (i.t.) or intravenous (i.v.) injection of the assembled cmRNAhCFTR together with Chitosan-coated PLGA (poly-D, L-lactide-co-glycolide 75:25 (Resomer RG 752 H)) nanoparticles (NPs) by FlexiVent. The amount of expression of human hCFTR encoded by cmRNAhCFTR was quantified by hCFTR ELISA, and cmRNAhCFTR values were assessed by RT-qPCR. Thereby, we observed a significant improvement of lung function, especially in regards to FEV0.1, suggesting NP-cmRNAhCFTR as promising therapeutic option for CF patients independent of their CFTR genotype.

Bispecific antibodies such as MT110 might be used to intensify the antitumoural effect of γδ T cells in context of adoptive immune cell transfer. Optimised immunotherapeutic strategies might therefore improve the outcome of high risk hepatoblastoma and hepatocellular carcinoma.