Innovative Strategy for 3D Transfection of Primary Human Stem Cells with BMP-2 Expressing Plasmid DNA: A Clinically Translatable Strategy for Ex Vivo Gene Therapy

Selective hydrophobic interaction chromatography for high purity of supercoiled DNA plasmids

High purity of plasmid DNA (pDNA), particularly in supercoiled isoform (SC), is used for various biopharmaceutical applications, such as a transfecting agent for production of gene therapy viral vectors, for pDNA vaccines, or as a precursor for linearized form that serves as a template for mRNA synthesis. In clinical manufacturing, pDNA is commonly extracted from Escherichia coli cells with alkaline lysis followed by anion exchange chromatography or tangential flow filtration as a capture step for pDNA. Both methods remove a high degree of host cell contaminants but are unable to generically discriminate between SC and open-circular (OC) pDNA isoforms, as well as other DNA impurities, such as genomic DNA (gDNA). Hydrophobic interaction chromatography (HIC) is commonly used as polishing purification for pDNA. We developed HIC-based polishing purification methodology that is highly selective for enrichment of SC pDNA. It is generic with respect to plasmid size, scalable, and GMP compatible. The technique uses ammonium sulfate, a kosmotropic salt, at a concentration selective for SC pDNA binding to a butyl monolith column, while OC pDNA and gDNA are removed in flow-through. The approach is validated on multiple adeno-associated virus- and mRNA-encoding plasmids ranging from 3 to 12 kbp. We show good scalability to at least 300 mg of >95% SC pDNA, thus paving the way to increase the quality of genomic medicines that utilize pDNA as a key raw material.

Developing hydrogels for gene therapy and tissue engineering

Hydrogels are a class of highly absorbent and easily modified polymer materials suitable for use as slow-release carriers for drugs. Gene therapy is highly specific and can overcome the limitations of traditional tissue engineering techniques and has significant advantages in tissue repair. However, therapeutic genes are often affected by cellular barriers and enzyme sensitivity, and carrier loading of therapeutic genes is essential. Therapeutic gene hydrogels can well overcome these difficulties. Moreover, gene-therapeutic hydrogels have made considerable progress. This review summarizes the recent research on carrier gene hydrogels for the treatment of tissue damage through a summary of the most current research frontiers. We initially introduce the classification of hydrogels and their cross-linking methods, followed by a detailed overview of the types and modifications of therapeutic genes, a detailed discussion on the loading of therapeutic genes in hydrogels and their characterization features, a summary of the design of hydrogels for therapeutic gene release, and an overview of their applications in tissue engineering. Finally, we provide comments and look forward to the shortcomings and future directions of hydrogels for gene therapy. We hope that this article will provide researchers in related fields with more comprehensive and systematic strategies for tissue engineering repair and further promote the development of the field of hydrogels for gene therapy.

Comparison ofin-situversusex-situdelivery of polyethylenimine-BMP-2 polyplexes for rat calvarial defect repair via intraoperative bioprinting

Gene therapeutic applications combined with bio- and nano-materials have been used to address current shortcomings in bone tissue engineering due to their feasibility, safety and potential capability for clinical translation. Delivery of non-viral vectors can be altered using gene-activated matrices to improve their efficacy to repair bone defects.Ex-situandin-situdelivery strategies are the most used methods for bone therapy, which have never been directly compared for their potency to repair critical-sized bone defects. In this regard, we first time explore the delivery of polyethylenimine (PEI) complexed plasmid DNA encoding bone morphogenetic protein-2 (PEI-pBMP-2) using the two delivery strategies,ex-situandin-situdelivery. To realize these gene delivery strategies, we employed intraoperative bioprinting (IOB), enabling us to 3D bioprint bone tissue constructs directly into defect sites in a surgical setting. Here, we demonstrated IOB of an osteogenic bioink loaded with PEI-pBMP-2 for thein-situdelivery approach, and PEI-pBMP-2 transfected rat bone marrow mesenchymal stem cells laden bioink for theex-situdelivery approach as alternative delivery strategies. We found thatin-situdelivery of PEI-pBMP-2 significantly improved bone tissue formation compared toex-situdelivery. Despite debates amongst individual advantages and disadvantages ofex-situandin-situdelivery strategies, our results ruled in favor of thein-situdelivery strategy, which could be desirable to use for future clinical applications.

Cell-Based HIF1α Gene Therapy Reduces Myocardial Scar and Enhances Angiopoietic Proteome, Transcriptomic and miRNA Expression in Experimental Chronic Left Ventricular Dysfunction

Recent preclinical investigations and clinical trials with stem cells mostly studied bone-marrow-derived mononuclear cells (BM-MNCs), which so far failed to meet clinically significant functional study endpoints. BM-MNCs containing small proportions of stem cells provide little regenerative potential, while mesenchymal stem cells (MSCs) promise effective therapy via paracrine impact. Genetic engineering for rationally enhancing paracrine effects of implanted stem cells is an attractive option for further development of therapeutic cardiac repair strategies. Non-viral, efficient transfection methods promise improved clinical translation, longevity and a high level of gene delivery. Hypoxia-induced factor 1α is responsible for pro-angiogenic, anti-apoptotic and anti-remodeling mechanisms. Here we aimed to apply a cellular gene therapy model in chronic ischemic heart failure in pigs. A non-viral circular minicircle DNA vector (MiCi) was used for in vitro transfection of porcine MSCs (pMSC) with HIF1α (pMSC-MiCi-HIF-1α). pMSCs-MiCi-HIF-1α were injected endomyocardially into the border zone of an anterior myocardial infarction one month post-reperfused-infarct. Cell injection was guided via 3D-guided NOGA electro-magnetic catheter delivery system. pMSC-MiCi-HIF-1α delivery improved cardiac output and reduced myocardial scar size. Abundances of pro-angiogenic proteins were analyzed 12, 24 h and 1 month after the delivery of the regenerative substances. In a protein array, the significantly increased angiogenesis proteins were Activin A, Angiopoietin, Artemin, Endothelin-1, MCP-1; and remodeling factors ADAMTS1, FGFs, TGFb1, MMPs, and Serpins. In a qPCR analysis, increased levels of angiopeptin, CXCL12, HIF-1α and miR-132 were found 24 h after cell-based gene delivery, compared to those in untreated animals with infarction and in control animals. Expression of angiopeptin increased already 12 h after treatment, and miR-1 expression was reduced at that time point. In total, pMSC overexpressing HIF-1α showed beneficial effects for treatment of ischemic injury, mediated by stimulation of angiogenesis.

Injectable Natural Polymer Hydrogels for Treatment of Knee Osteoarthritis

Osteoarthritis (OA) is a serious chronic and degenerative disease that increasingly occurs in the aged population. Its current clinical treatments are limited to symptom relief and cannot regenerate cartilage. Although a better understanding of OA pathophysiology has been facilitating the development of novel therapeutic regimen, delivery of therapeutics to target sites with minimal invasiveness, high retention, and minimal side effects remains a challenge. Biocompatible hydrogels have been recognized to be highly promising for controlled delivery and release of therapeutics and biologics for tissue repair. In this review, the current approaches and the challenges in OA treatment, and unique properties of injectable natural polymer hydrogels as delivery system to overcome the challenges are presented. The common methods for fabrication of injectable polysaccharide-based hydrogels and the effects of their composition and properties on the OA treatment are detailed. The strategies of the use of hydrogels for loading and release cargos are also covered. Finally, recent efforts on the development of injectable polysaccharide-based hydrogels for OA treatment are highlighted, and their current limitations are discussed.

Investigation of the potential therapeutic effect of cationic lipoplex mediated fibroblast growth factor-2 encoding plasmid DNA delivery on wound healing

BACKGROUND

Developing an alternative and efficient therapy for wound healing has been an important research topic for pharmaceutical sciences. A straightforward but effective system for delivering fibroblast growth factor-2 (FGF-2) encoding plasmid DNA (pFGF-2) for wound healing therapy was aimed to develop in this study.

METHODS

In order to provide the delivery of pFGF-2, a delivery vector, namely, cationic lipid nanoparticle (cLN) was developed by the melt-emulsification process, complexed with pFGF-2 to form a lipoplex system and further characterized. The pFGF-2 binding and protecting ability of lipoplexes were evaluated. The cytotoxicity and transfection efficiency of the lipoplexes, FGF-2 expression levels, and in vitro wound healing ability have been investigated on the L929 fibroblast cell line.

RESULTS

The obtained lipoplex system has a particle size of 88.53 nm with a low PDI (0.185), and zeta potential values of 27.8 mV with a spherical shape. The ability of cLNs to bind pFGF-2 and protect against nucleases was demonstrated by gel retardation assay. Furthermore, the developed FGF-2 carrying lipoplexes system showed significant transfection and FGF-2 expression ability comparing naked plasmid. Finally, scratch assay revealed that the developed system is able to promote in vitro cell proliferation/migration in 48 h.

CONCLUSION

Promising results have been achieved with the use of lipoplexes carrying pFGF-2, and this approach could be considered as a potentially applicable concept for the future gene-based wound healing therapies.

Redox responsive Pluronic micelle mediated delivery of functional siRNA: a modular nano-assembly for targeted delivery

There is an unmet need to develop strategies that allow site-specific delivery of short interfering RNA (siRNA) without any associated toxicity. To address this challenge, we have developed a novel siRNA delivery platform using chemically modified pluronic F108 as an amphiphilic polymer with a releasable bioactive disulfide functionality. The micelles exhibited thermoresponsive properties and showed a hydrodynamic size of ∼291 nm in DLS and ∼200-250 nm in SEM at 37 °C. The grafting of free disulfide pyridyl groups enhanced the transfection efficiency and was successfully demonstrated in human colon carcinoma (HCT116; 88%) and glioma cell lines (U87; 90%), non-cancerous human dermal fibroblast (HDF; 90%) cells as well as in mouse embryonic stem (mES; 54%) cells. To demonstrate the versatility of our modular nanocarrier design, we conjugated the MDGI receptor targeting COOP peptide on the particle surface that allowed the targeted delivery of the cargo molecules to human patent-derived primary BT-13 gliospheres. Transfection experiments with this design resulted in ∼65% silencing of STAT3 mRNA in BT-13 gliospheres, while only ∼20% of gene silencing was observed in the absence of the peptide. We believe that our delivery method solves current problems related to the targeted delivery of RNAi drugs for potential in vivo applications.

Polyplex-Loaded Hydrogels for Local Gene Delivery to Human Dermal Fibroblasts

Impaired cutaneous healing leading to chronic wounds affects between 2 and 6% of the total population in most developed countries and it places a substantial burden on healthcare budgets. Current treatments involving antibiotic dressings and mechanical debridement are often not effective, causing severe pain, emotional distress, and social isolation in patients for years or even decades, ultimately resulting in limb amputation. Alternatively, gene therapy (such as mRNA therapies) has emerged as a viable option to promote wound healing through modulation of gene expression. However, protecting the genetic cargo from degradation and efficient transfection into primary cells remain significant challenges in the push to clinical translation. Another limiting aspect of current therapies is the lack of sustained release of drugs to match the therapeutic window. Herein, we have developed an injectable, biodegradable and cytocompatible hydrogel-based wound dressing that delivers poly(β-amino ester)s (pBAEs) nanoparticles in a sustained manner over a range of therapeutic windows. We also demonstrate that pBAE nanoparticles, successfully used in previous in vivo studies, protect the mRNA load and efficiently transfect human dermal fibroblasts upon sustained release from the hydrogel wound dressing. This prototype wound dressing technology can enable the development of novel gene therapies for the treatment of chronic wounds.

Bone morphogenetic protein 2-enhanced osteogenic differentiation of stem cell spheres by regulation of Runx2 expression

Bone morphogenetic protein 2 (BMP-2) is a growth factor that is used to induce osteogenic differentiation in stem cells. The present study assessed the effects of BMP-2 on stem cell spheroid morphology, viability and osteogenic differentiation. Stem cell spheres were constructed and treated with BMP-2 at predetermined concentrations (0-100 ng/ml) using concave microwells. Cell viability was qualitatively and quantitatively analyzed via microscopy and a water-soluble tetrazolium salt assay kit, respectively. Alkaline phosphatase activity was assessed and an anthraquinone dye for calcium deposit evaluation was performed to determine osteogenic differentiation. The expressions of (runt-related transcription factor 2) and collagen 1 were also determined via quantitative PCR. Spherical shapes were formed using concave microwells on day 1, which were maintained up to day 21. On day 1, the relative cell viability of 0, 10 and 100 ng/ml BMP-2 treated cells was 100.0±1.9, 97.3±4.4 and 101.3±2.6%, respectively. Significantly higher values for alkaline phosphatase activity were determined in the 100 ng/ml treated group when compared with the control group. Additionally, Runx2 mRNA levels were significantly higher in the 100 ng/ml BMP-2 group compared with the control group, as determined via quantitative PCR. The results of the present study indicated that BMP-2 enhanced the differentiation of stem cell spheres, which was demonstrated by increased alkaline phosphatase activity and Runx2 expression.

Insights into siRNA Transfection in Suspension: Efficient Gene Silencing in Human Mesenchymal Stem Cells Encapsulated in Hyaluronic Acid Hydrogel

Small interfering RNAs (siRNAs) are powerful tools for post-transcriptional gene silencing, which offers enormous opportunities for tissue engineering applications. However, poor serum stability, inefficient intracellular delivery, and inevitable toxicity of transfection reagents are the key barriers for their clinical translation. Thus, innovative strategies that allow safe and efficient intracellular delivery of the nucleic acid drugs at the desired site is urgently needed for a smooth clinical translation of therapeutically appealing siRNA-based technology. In this regard, we have developed an innovative siRNA transfection protocol that employs a short incubation time of just 5 min. This allows easy transfection in suspension followed by transplantation of the cells in a hyaluronic acid (HA) hydrogel system. We also report here the unique ability of siRNA to bind HA that was quantified by siRNA release and rheological characterization of the HA-hydrogel. Such interactions also showed promising results to deliver functional siRNA in suspension transfection conditions within 30 min using native HA, although removal of excess HA by centrifugation seem to be essential. In the 2D experiments, suspension transfection of hMSCs with RNAiMAX resulted in ≈90% gene silencing (with or without removal of the excess reagent by centrifugation), while HA demonstrated a modest ≈40% gene silencing after removal of excess reagent after 30 min. Transplantation of such transfected cells in the HA-hydrogel system demonstrated an improved knockdown (≈90% and ≈60% with RNAiMAX and HA respectively after 48 h), with lower cytotoxicity (up to 5-days) as determined by PrestoBlue assay. The gene silencing efficiency in the 2D and 3D conditions were also confirmed at the protein levels by Western blot analysis. We postulate this novel transfection method could be applied for in vivo applications as it allows minimal manipulation of cells that are to be transplanted and reduce toxicity.