A novel Lipidoid-MicroRNA formulation promotes calvarial bone regeneration

Abstract

Specific microRNAs (miRs) and the Wnt signaling pathway play critical roles in regulating bone development and homeostasis. Our previous studies revealed the ability of miR-335-5p to promote osteogenic differentiation by downregulating Wnt antagonist Dickkopf-1 (DKK1). The purpose of this study was to use nano-materials to efficiently deliver miR-335-5p into osteogenic cells for tissue engineering applications. We synthesized and screened a library of 12 candidate nano-lipidoids，of which L8 was identified as the preferred biodegradable lipidoid for miRNA molecule delivery into cells. We then investigated whether a lipidoid-miRNA formulation of miR-335-5-p (LMF-335) could successfully deliver miR-335-5-p into cells to promote osteogenesis in vitro and calvarial bone healing in vivo. Transfection of C3H10T1/2 cells and bone marrow stromal cells (BMSCs) with LMF-335 led to decreased expression of DKK1 and increased expression of the key osteogenic genes. LMF-335 and LMF-335-transfected BMSCs were then used in combination with silk scaffolds to evaluate healing of critical-size calvarial bone defects in mice. The results revealed significant new bone formation in the defects in LMF-335 groups as compared with control groups. In conclusion, this first report supports the notion that lipidoid delivery of miRNA can be used to induce osteogenic differentiation of stem cells and bone regeneration.

Potential roles of miR‐335‐5p on pathogenesis of experimental periodontitis

“…miR‐335‐5p, a crucial post‐transcriptional regulator in Wnt signaling, has been proven positive for bone formation in our laboratory . In addition, miR‐335‐5p has also been emerging negatively coordinated with inflammatory diseases .…”

“…The aberrant miRNA expression reacting to pathologic products, in turn, affects periodontitis . In our previous studies, it has been shown that microRNA‐335‐5p (miR‐335‐5p) could promote osteoblast differentiation and bone regeneration in vitro and in miR‐335‐5p transgenic (335‐Tg) mice via inhibiting DKK1, a Wnt pathway antagonist, which have been well‐characterized . Besides, several studies have reported the inhibitive effects of miR‐335‐5p on bone‐related disorders.…”

The Therapeutic Potential of MicroRNAs as Orthobiologics for Skeletal Fractures

“…Another study generated transgenic mice overexpressing miR‐355‐5p, and when BMSCs from these mice were incorporated in a silk fibroin scaffold and implanted in a mouse critical‐sized calvarial defect, significant increases were observed in bone volume compared with those using wild‐type BMSCs . The same laboratory also used a lipidoid‐miRNA formulation of miR‐335‐5‐p to demonstrate increased repair of a mouse critical‐sized calvarial defect . Finally, Hu et al used a miR‐210‐3p/poly‐L‐lactic acid (PLLA)/BMSCs construct to induce ectopic bone formation.…”

“…Recently, though, we have seen increases in transfection efficiencies with the use of lipid‐based carriers, polymeric‐based carriers, nanoparticles, peptides, inorganic materials, etc . Lastly, engineering stem cells with high levels of miRNA expression may be yet another approach of local delivery as was demonstrated by studies described above . Clearly, we have a variety of options that can be used to successfully and effectively deliver miRNA‐based therapeutics locally and safely.…”

Regional difference in microRNA regulation in the skull vault

“…Recently, micro ribonucleic acids (miRNAs) have been reported to play regulatory roles in the skeletal homeostasis . MiRNA‐378 can fuel osteogenesis‐angiogenesis for bone regeneration, and miR‐335‐5p can down‐regulate DKK1to boost osteogenic differentiation, and the modification of miR‐335‐5p was sufficient to enhance calvarial bone regeneration and minimize bone defects . Therefore, miRNAs can be potential therapeutic targets to treat the skeletal disorders, but the potential miRNAs in the frontal bone and parietal bone are still illusive.…”