Biscarbamate Cross-Linked Low-Molecular-Weight Polyethylenimine for Delivering Anti-chordin siRNA into Human Mesenchymal Stem Cells for Improving Bone Regeneration

Abstract

Small-interfering RNA (siRNA) provides a rapid solution for drug design and provides new methods to develop customizable medicines. Polyethyleneimine 25 kDa (PEI25kDa) is an effective transfection agent used in siRNA delivery. However, the lack of degradable linkage causes undesirable toxicity, hindering its clinical application. We designed a low-molecular-weight cross-linked polyethylenimine named PEI-Et (Mn:1220, Mw:2895) by using degradable ethylene biscarbamate linkage with lower cytotoxicity and higher knockdown efficiency than PEI25kDa in delivery Chordin siRNA to human bone mesenchymal stem cells (hBMSCs). Suppression of Chordin by using anti-Chordin siRNA delivered by PEI-Et improved bone regeneration in vitro and in vivo associated with the bone morphogenetic protein-2 (BMP-2) mediated smad1/5/8 signaling pathway. Results of this study suggest that Chordin siRNA can be potentially used to improve osteogenesis associated with the BMP-2-mediated Smad1/5/8 signaling pathway and biodegradable biscarbamate cross-linked low-molecular-weight polyethylenimine (PEI-Et) is a therapeutically feasible carrier material to deliver anti-Chordin siRNA to hBMSCs.

Microtissues from mesenchymal stem cells and siRNA-loaded cross-linked gelatin microparticles for bone regeneration

“…The BMP-2 antagonist chordin was chosen as a promising target for our system. We and others have shown before that silencing of chordin in combination with BMP-2 supplementation could enhance osteogenic differentiation and accelerate mineralization in osteogenic cultures of hMSC [ [13] , [14] , [15] , [16] ].…”

Designing biomaterials for the delivery of RNA therapeutics to stimulate bone healing

“…Chordin, Noggin and Gremlin are well-known antagonists of BMPs such as BMP-2 and BMP-7 ​and are therefore interesting targets to enhance bone regeneration [ 47 ]. Downregulating the expression of Chordin with siRNA was shown to increase osteogenic differentiation and bone regeneration in vitro and in vivo [ [61] , [62] , [63] ]. Similarly, silencing of Noggin using siRNA did promote osteogenic differentiation in vitro and in vivo [ [64] , [65] , [66] ].…”

“…This approach is most often adopted for hydrogels, where the RNA complexes are mixed into the polymer solution before cross-linking the gel. So far, most studies investigated hydrogels made of natural [ 49 , 97 , 98 ] or synthetic [ 62 , 64 , [99] , [100] , [101] , [102] ] polymers or a mixture thereof [ [103] , [104] , [105] , [106] ], but RNA complexes have also been successfully mixed into inorganic HA cements [ 107 ]. Compared to diffusional post-loading, where the complexes are loosely associated with the material, this method usually leads to stronger retention of RNA complexes and thus to release kinetics that depend on degradation of the polymer matrix.…”

Polymeric Nanoparticles Based on Tyrosine-Modified, Low Molecular Weight Polyethylenimines for siRNA Delivery

“…Still, further improvements are warranted and various approaches have been explored to optimize transfection efficacies of low molecular weight PEIs and/or to decrease the toxicity of high molecular weight PEIs. These include the covalent modification of PEI with polyethylene glycol (PEG) [25,26,27], the cross-linking of small PEIs with hydrolysable linkers, e.g., esters, ketals, or reductive cleavable disulfide groups leading to the reversible formation of higher molecular weights ([28,29,30,31]; see [32] for review), the copolymerization/grafting with other polymers like polycaprolactone (PCL), starch or polyvinylalcohol (PVA) [33,34,35], the modification with lipophilic molecules, e.g., fatty acids, alkanes or cholesterol ([36,37], see [38] for review), or the combination of PEI-based complexes with liposomes [39,40,41,42].…”