An innovative miR-activated scaffold for the delivery of a miR-221 inhibitor to enhance cartilage defect repair

The development of treatments to restore damaged cartilage that can provide functional recovery with minimal risk of revision surgery remains an unmet clinical need. Gene therapy shows increased promise as an innovative solution for enhanced tissue repair. Within this study a novel microRNA (miR)-activated scaffold is developed for enhanced mesenchymal stem/stromal cells (MSC) chondrogenesis and cartilage repair through the delivery of an inhibitor to microRNA-221 (miR-221), which is known to have a negative effect of chondrogenesis. To fabricate the miR-activated scaffolds, composite type II collagen-containing scaffolds designed specifically for cartilage repair are first manufactured by lyophilization and then functionalized with glycosaminoglycan-binding enhanced transduction (GET) system nanoparticles (NPs) encapsulating the miR-221 inhibitor. Subsequently, scaffolds are cultured with human-derived MSCs in vitro under chondrogenic conditions for 28 days. The miR-activated scaffolds successfully transfect human MSCs with the miR-221 cargo in a sustained and controlled manner up to 28 days. The silencing of miR-221 in human MSCs using the miR-activated scaffold promotes an improved and more robust cell-mediated chondrogenic response with repressed early-stage events related to MSC hypertrophy. Taken together, this innovative miR-activated scaffold for the delivery of a miR-221 inhibitor demonstrates capability to improve chondrogenesis with promise to enhance cartilage defect repair. </p

Highly versatile cell-penetrating peptide loaded scaffold for efficient and localised gene delivery to multiple cell types: from development to application in tissue engineering

Gene therapy has recently come of age with seven viral vector-based therapies gaining regulatory approval in recent years. In tissue engineering, non-viral vectors are preferred over viral vectors, however, lower transfection efficiencies and difficulties with delivery remain major limitations hampering clinical translation. This study describes the development of a novel multi-domain cell-penetrating peptide, GET, designed to enhance cell interaction and intracellular translocation of nucleic acids; combined with a series of porous collagen-based scaffolds with proven regenerative potential for different indications. GET was capable of transfecting cell types from all three germ layers, including stem cells, with an efficiency comparable to Lipofectamine® 3000, without inducing cytotoxicity. When implanted in vivo, GET gene-activated scaffolds allowed for host cell infiltration, transfection localized to the implantation site and sustained, but transient, changes in gene expression – demonstrating both the efficacy and safety of the approach. Finally, GET carrying osteogenic (pBMP-2) and angiogenic (pVEGF) genes were incorporated into collagen-hydroxyapatite scaffolds and with a single 2 μg dose of therapeutic pDNA, induced complete repair of critical-sized bone defects within 4 weeks. GET represents an exciting development in gene therapy and by combining it with a scaffold-based delivery system offers tissue engineering solutions for a myriad of regenerative indications