RNA interference and its application in bone-related diseases

Titanium Surfaces Functionalized with siMIR31HG Promote Osteogenic Differentiation of Bone Marrow Mesenchymal Stem Cells

Titanium (Ti) implants are widely used in the clinic as bone substitutes and dental implants, but further improvements are needed to obtain high osteogenic ability and consequent osseointegration. Knockdown of long noncoding RNA MIR31HG promotes osteogenic differentiation and bone formation. In this study, we fabricated a Ti surface functionalized with siRNA targeting MIR31HG (siMIR31HG) and accelerated osteogenesis of bone marrow mesenchymal stem cells (BMSCs). Chitosan/siRNA complex was loaded onto the thermal alkali-treated Ti surface to fabricate the siMIR31HG-functionalized Ti surface. The surface morphology, siRNA loading and release efficiency, and transfection efficacy were investigated, and the biological effects, such as cell proliferation, cell morphology, and osteogenic activity, were determined. The results showed that the siMIR31HG-functionalized Ti implant generated an ∼50% knockdown of MIR31HG, with no apparent cytotoxicity, which consequently enhanced osteogenic differentiation of BMSCs, as indicated by the increase of ALP production, extracellular matrix mineralization, osteogenic gene expression, and ectopic bone formation in vivo. The siMIR31HG biofunctionalization can be used to obtain better osseointegration of Ti implant in the clinic.

Future nanomedicine for the diagnosis and treatment of osteoarthritis

Current treatments for osteoarthritis (OA) are largely palliative until the joints become totally dysfunctional and prosthetic replacement becomes necessary. Effective methods are needed for diagnosing OA and monitoring its progression during its early stages, when the effects of therapeutic drugs or biological agents are most likely to be effective. Theranostic nanosomes and nanoparticles have the potential to noninvasively detect, track and treat the early stages of OA. As articular cartilage does not regenerate once it is degraded, cell-based treatments aided by superparamagnetic iron oxide nanoparticle tracking are attractive future treatment modalities for the later stages of OA progression, when significant cartilage replacement is needed. This article will describe the current and future translational approaches for the detection and noninvasive treatment of degenerative OA.

Chitosan/siCkip-1 biofunctionalized titanium implant for improved osseointegration in the osteoporotic condition

Biofunctionalization with siRNA targeting the key negative modulators of bone turnover involved in the molecular mechanism of osteoporosis, such as casein kinase-2 interacting protein-1 (Ckip-1), may lead to enhanced Ti osseointegration in the osteoporotic condition. In this study, even siRNA loading was accomplished by the thermal alkali (TA) treatment to make the Ti ultrahydrophilic and negatively charged to facilitate the physical adsorption of the positively charged CS/siR complex, designated as TA-CS/siR. The intracellular uptake of the CS/siR complex and the gene knockdown efficiency were assessed with bone marrow mesenchymal stem cells (MSCs) as well as the green fluorescent protein (GFP) expressing H1299 cells. In vitro osteogenic activity of TA-CS/siCkip-1 targeting Ckip-1 was assessed with MSCs. In vivo osseointegration of TA-CS/siCkip-1 was assessed in the osteoporotic rat model. TA-CS/siR showed excellent siRNA delivery efficiency and gene silencing effect. TA-CS/siCkip-1 significantly improved the in vitro osteogenic differentiation of MSCs in terms of the enhanced alkaline phosphatase and collagen product and extracellular matrix mineralization, and led to dramatically enhanced in vivo osseointegration in the osteoporostic rat model, showing promising clinical potential for the osteoporotic condition application. TA-CS/siR may constitute a general approach for developing the advanced Ti implants targeting specific molecular mechanism.

Spatial regulation of controlled bioactive factor delivery for bone tissue engineering

Limitations of current treatment options for critical size bone defects create a significant clinical need for tissue engineered bone strategies. This review describes how control over the spatiotemporal delivery of growth factors, nucleic acids, and drugs and small molecules may aid in recapitulating signals present in bone development and healing, regenerating interfaces of bone with other connective tissues, and enhancing vascularization of tissue engineered bone. State-of-the-art technologies used to create spatially controlled patterns of bioactive factors on the surfaces of materials, to build up 3D materials with patterns of signal presentation within their bulk, and to pattern bioactive factor delivery after scaffold fabrication are presented, highlighting their applications in bone tissue engineering. As these techniques improve in areas such as spatial resolution and speed of patterning, they will continue to grow in value as model systems for understanding cell responses to spatially regulated bioactive factor signal presentation in vitro, and as strategies to investigate the capacity of the defined spatial arrangement of these signals to drive bone regeneration in vivo.

Local delivery of small and large biomolecules in craniomaxillofacial bone

Current state of the art reconstruction of bony defects in the craniomaxillofacial (CMF) area involves transplantation of autogenous or allogenous bone grafts. However, the inherent drawbacks of this approach strongly urge clinicians and researchers to explore alternative treatment options. Currently, a wide interest exists in local delivery of biomolecules from synthetic biomaterials for CMF bone regeneration, in which small biomolecules are rapidly emerging in recent years as an interesting adjunct for upgrading the clinical treatment of CMF bone regeneration under compromised healing conditions. This review highlights recent advances in the local delivery small and large biomolecules for the clinical treatment of CMF bone defects. Further, it provides a perspective on the efficacy of biomolecule delivery in CMF bone regeneration by reviewing presently available reports of pre-clinical studies using various animal models.

Glucose transporter protein 1-targeted RNA interference inhibits growth and invasion of the osteosarcoma cell line MG63 in vitro

Malignant cells show increased glucose uptake, which is thought to be mediated by glucose transporters. Glucose transporter protein 1 (Glut-1) is critical for growth, proliferation, and migration of tumor cells and Glut-1 overexpression is associated with poor overall survival in osteosarcoma patients. The present study was designed to determine the role of Glut-1 in the growth and invasion of the osteosarcoma cell line MG63, using RNA interference technology in vitro. shRNA-expressing lentiviral vectors targeting the Glut-1 gene were constructed, which were stably expressed in MG63 cells. The level of Glut-1 mRNA was investigated using real-time reverse transcription-polymerase chain reaction, and the protein expression of Glut-1 mRNA was observed using western blotting. MG63 cellular glucose uptake, proliferation, and migration were detected by methyl thiazole tetrazolium assay and flow cytometry. A Glut-1-specific shRNA-expressing lentiviral vector was obtained, which could efficiently inhibit the mRNA and protein expression of Glut-1 to ∼82%-85% in MG63 cells. Downregulation of Glut-1 inhibited the cellular glucose uptake, growth, and invasion of MG63 cells in vitro. These results indicate that RNA interference targeting of Glut-1 could be an effective strategy for the treatment of osteoscarcoma patients.

Inhibitory effects of VEGF-siRNA mediated by adenovirus on osteosarcoma-bearing nude mice

As one of the blood-rich malignancies, the growth and metastasis of osteosarcoma both depend on its angiogenesis, a procedure in which vascular endothelial growth factor (VEGF) acts essentially. Although with the advent of neoadjuvant chemotherapy, more aggressive surgical excision and logical therapy strategy, the 5-year survival rate remains relatively stable at 70%, at best. However, antiangiogenic therapeutics, through gene silencing and targeting key sequences, probably brings an outlook to the conventional algorithm. In our current research, human-specific VEGF-siRNA (small interfering RNA) mediated by adenovirus was constructed and a cell line of MG63 was cultured and used to make an osteosarcoma-bearing nude mice model. The recombined adenovirus vector of Ad-VEGF-siRNA could successfully suppress VEGF expression and slow down the multiplication of MG63 cells in vivo; likewise, the down regulation of VEGF could be detected in vitro of the animal model. Inhibitory effects on osteosarcoma growth and blockage of pulmonary metastasis could be observed in the following oncotherapy procedure. The study demonstrates potent growth and pulmonary metastasis inhibitory effects of VEGF-siRNA on osteosarcoma in vivo and in vitro, which could potentially be applicable to the treatment of cancers as an antiangiogenic therapeutic in the near future.