Osteogenic Programming of Human Mesenchymal Stem Cells with Highly Efficient Intracellular Delivery of RUNX2

Long noncoding RNA lncAIS downregulation in mesenchymal stem cells is implicated in the pathogenesis of adolescent idiopathic scoliosis

Adolescent idiopathic scoliosis (AIS) is a complex, three dimensional deformity of the spine that commonly occurs in pubescent girls. Abnormal osteogenic differentiation of mesenchymal stem cells (MSCs) is implicated in the pathogenesis of AIS. However, the biological roles of long noncoding RNAs (lncRNAs) in the regulation of osteogenic differentiation of MSCs are unknown. Through microarray analyses of bone marrow (BM) MSCs from healthy donors and AIS patients, we identified 1483 differentially expressed lncRNAs in AIS BM-MSCs. We defined a novel lncAIS (gene symbol: ENST00000453347) is dramatically downregulated in AIS BM-MSCs. In normal BM-MSCs, lncAIS interacts with NF90 to promote HOXD8 mRNA stability that enhances RUNX2 transcription in BM-MSCs, leading to osteogenic differentiation of normal BM-MSCs. By contrast, lncAIS downregualtion in AIS BM-MSCs cannot recruit NF90 and abrogates HOXD8 mRNA stability, which impedes RUNX2 transcription for osteogenic differentiation. Thereby lncAIS downregualtion in BM-MSCs suppresses osteogenic differentiation that is implicated in the pathogenesis of AIS.

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.

Padina pavonica Extract Promotes In Vitro Differentiation and Functionality of Human Primary Osteoblasts

Marine algae have gained much importance in the development of nutraceutical products due to their high content of bioactive compounds. In this work, we investigated the activity of Padina pavonica with the aim to demonstrate the pro-osteogenic ability of its extract on human primary osteoblast (HOb). Our data indicated that the acetonic extract of P. pavonica (EPP) is a safe product as it did not show any effect on osteoblast viability. At the same time, EPP showed to possess a beneficial effect on HOb functionality, triggering their differentiation and mineralization abilities. In particular EPP enhanced the expression of the earlier differentiation stage markers: a 5.4-fold increase in collagen type I alpha 1 chain (COL1A1), and a 2.3-fold increase in alkaline phosphatase (ALPL), as well as those involved in the late differentiation stage: a 3.7-fold increase in osteocalcin (BGLAP) expression and a 2.8-fold in osteoprotegerin (TNFRSF11B). These findings were corroborated by the enhancement in ALPL enzymatic activity (1.7-fold increase) and by the reduction of receptor activator of nuclear factor-κB ligand (RANKL) and osteoprotegerin (OPG) ratio (0.6-fold decrease). Moreover, EPP demonstrated the capacity to enhance the bone nodules formation by 3.2-fold in 4 weeks treated HOb. Therefore, EPP showed a significant capability of promoting osteoblast phenotype. Given its positive effect on bone homeostasis, EPP could be used as a useful nutraceutical product that, in addition to a healthy lifestyle and diet, can be able to contrast and prevent bone diseases, especially those connected with ageing, such as osteoporosis (OP).

Human mesenchymal stem cells differentiate into an osteogenic lineage in presence of strontium containing bioactive glass nanoparticles

While bioactive glass and ions released during its dissolution are known to stimulate osteoblast cells, the effect bioactive glass has on human stem cells is not clear. Here, we show that spherical monodispersed strontium containing bioactive nanoparticles (Sr-BGNPs) of composition 90.6 mol% SiO₂, 5.0 mol% CaO, 4.4% mol% SrO (4.4%Sr-BGNPs) and 88.8 mol% SiO₂, 1.8 mol% CaO, and 9.4 mol% SrO (9.4%Sr-BGNPs) stimulate bone marrow derived human stem cell (hMSC) differentiation down an osteogenic pathway without osteogenic supplements. The particles were synthesised using a modified Stӧber process and had diameters of 90 ± 10 nm. Previous work on similar particles that did not contain Sr (80 mol% SiO₂, 20 mol% CaO) showed stem cells did not differentiate when exposed to the particles. Here, both compositions of the Sr-BGNPs (up to concentration of 250 μg/mL) stimulated the early-, mid-, and late-stage markers of osteogenic differentiation and accelerated mineralisation in the absence of osteogenic supplements. Sr ions play a key role in osteogenic stem cell differentiation. Sr-BGNP dissolution products did not adversely affect hMSC viability and no significant differences in viability were measured between each particle composition. Confocal and transmission electron microscopy (TEM) demonstrated that monodispersed Sr-BGNPs were internalised and localised within vesicles in the cytoplasm of hMSCs. Degradation of particles inside the cells was observed, whilst maintaining effective cations (Ca and Sr) in their silica network after 24 h in culture. The uptake of Sr-BGNPs by hMSCs was reduced by inhibitors of specific routes of endocytosis, indicating that the Sr-BGNPs uptake by hMSCs was probably via mixed endocytosis mechanisms. Sr-BGNPs have potential as injectable therapeutic devices for bone regeneration or treatment of conditions such as osteoporosis, because of their ability deliver a sustained release of osteogenic inorganic cations, e.g. calcium (Ca) or and strontium (Sr), through particle degradation locally to cells. STATEMENT OF SIGNIFICANCE: Here, we show that 90 nm spherical strontium containing bioactive nanoparticles of stimulate bone marrow derived human stem cell (hMSC) differentiation down an osteogenic pathway without the use of osteogenic supplements. While bioactive glass and its dissolution products are known to promote excellent bone regeneration in vivo and to stimulate osteoblast cells to produce bone matrix in vitro, their effect on human stem cells is not clear. Previously our nanoparticles that contained only SiO₂ and CaO did not provoke human bone marrow or adipose derived stem cell differentiation.

A Novel Gene Delivery Approach Using Metal Organic Frameworks in Human Islet-Derived Progenitor Cells

The ability to regenerate insulin-producing β cells is the ultimate goal for treatment of type 1 diabetes. Several sources of stem cells have been investigated by studying their differential potential to form insulin-producing β cells that can be used for replacement therapy. Progenitor cells derived from human islets that are lineage committed have been shown to be better alternatives with regard to their differentiation capabilities for the generation of insulin-producing β-like cells. Controlling the differentiation of progenitor cells is a vital approach in exploiting cellular expansion, mesenchymal transition and β-cell generation. One of the most powerful and useful methods involve the intracellular delivery of biomolecules like genes, miRNAs, siRNAs, proteins, and peptides. However, the delivery vehicle used for such approaches is the most significant factor that determines the in vivo efficacy. Current delivery systems, although promising, are deterred by issues like toxicity, sustained release, loading capacity, and cost-effectiveness. In this chapter, we show an alternative nanomaterial called metal organic frameworks (MOFs) as gene delivery systems in human islet-derived progenitor cells (hIPCs). Based on our results, we believe that nanoscale MOFs can function as controlled cellular delivery agents that deliver, protect, and maintain functional activity of genes or other bioactive molecules into the cytoplasm or nucleus of progenitor cells. Here, we describe the details for the synthesis, characterization, and transfection of selected, biocompatible MOFs in hIPCs.

In Vitro Long-Term Expansion and High Osteogenic Potential of Periodontal Ligament Stem Cells: More Than a Mirage

The periodontal ligament displays a reservoir of mesenchymal stem cells which can account for periodontal regeneration. Despite the numerous studies directed at the definition of optimal culture conditions for long-term expansion of periodontal ligament stem cells (PDLSCs), no consensus has been reached as to what is the ideal protocol. The aim of the present study was to determine the optimal medium formulation for long-term expansion and stemness maintenance of PDLSCs, in order to obtain a sufficient number of cells for therapeutic approaches. For this purpose, the effects of three different culture medium formulations were evaluated on PDLSCs obtained from three periodontal ligament samples of the same patient: minimum essential medium Eagle, alpha modification (α-MEM), Dulbecco's modified Eagle's medium (DMEM), both supplemented with 10% fetal bovine serum (FBS), and a new medium formulation, Ham's F12 medium, supplemented with 10% FBS, heparin 0.5 U/ml, epidermal growth factor (EGF) 50 ng/ml, fibroblast growth factor (FGF) 25 ng/ml, and bovine serum albumin (BSA) 1% (enriched Ham's F12 medium; EHFM). PDLSCs grown in EHFM displayed a higher PE-CD73 mean fluorescence intensity compared with cells maintained in α-MEM and DMEM, even at later passages. Cells maintained in EHFM displayed an increased population doubling and a reduced population doubling time compared with cells grown in DMEM or α-MEM. α-MEM, DMEM and EHFM with added dexamethasone, 2-phospho-L-ascorbic acid, and β-glycerophosphate were all able to promote alkaline phosphatase activity; however, no calcium deposition was detected in PDLSCs cultured in EHFM-differentiation medium. When EHFM-, α-MEM- and DMEM-expanded PDLSCs were transferred to a commercial culture medium for the osteogenesis, mineralization became much more evident in confluent monolayers of EHFM-expanded PDLSCs compared with DMEM and α-MEM. The results suggest EHFM is the optimal medium formulation for growth and stemness maintenance of primary PDLSCs. Moreover, EHFM confers higher osteogenic potential to PDLSCs compared with cells maintained in the other culture media. Overall, the results of the present work confirmed the advantages of using EHFM for long-term expansion of mesenchymal cells in vitro and the preservation of high osteogenic potential.

PEGylated enhanced cell penetrating peptide nanoparticles for lung gene therapy

The lung remains an attractive target for the gene therapy of monogenetic diseases such as cystic fibrosis (CF). Despite over 27 clinical trials, there are still very few gene therapy vectors that have shown any improvement in lung function; highlighting the need to develop formulations with improved gene transfer potency and the desirable physiochemical characteristics for efficacious therapy. Herein, we introduce a novel cell penetrating peptide (CPP)-based non-viral vector that utilises glycosaminoglycan (GAG)-binding enhanced transduction (GET) for highly efficient gene transfer. GET peptides couple directly with DNA through electrostatic interactions to form nanoparticles (NPs). In order to adapt the GET peptide for efficient in vivo delivery, we engineered PEGylated versions of the peptide and employed a strategy to form DNA NPs with different densities of PEG coatings. We were able to identify candidate formulations (PEGylation rates ≥40%) that shielded the positively charged surface of particles, maintained colloidal stability in bronchoalveolar lavage fluid (BALF) and retained gene transfer activity in human bronchial epithelial cell lines and precision cut lung slices (PCLS) in vitro. Using multiple particle tracking (MPT) technology, we demonstrated that PEG-GET complexes were able to navigate the mucus mesh and diffuse rapidly through patient CF sputum samples ex vivo. When tested in mouse lung models in vivo, PEGylated particles demonstrated superior biodistribution, improved safety profiles and efficient gene transfer of a reporter luciferase plasmid compared to non-PEGylated complexes. Furthermore, gene expression was significantly enhanced in comparison to polyethylenimine (PEI), a non-viral gene carrier that has been widely tested in pre-clinical settings. This work describes an innovative approach that combines novel GET peptides for enhanced transfection with a tuneable PEG coating for efficacious lung gene therapy.

Epigallocatechin-3-Gallate Ameliorates Glucocorticoid-Induced Osteoporosis of Rats in Vivo and in Vitro

Background: Prolonged administration of overdoses of glucocorticoids results in increased bone remodeling, leading to glucocorticoid-induced osteoporosis (GIO), which is primarily due to the dysfunction and apoptosis of osteoblasts. The present study investigated the therapeutic effect and molecular mechanism of action of epigallocatechin-3-gallate (EGCG), a bioactive catechin in green tea, in high-dose dexamethasone-induced osteoblast differentiation in vivo and in vitro. Methods: The anti-dexamethasone (DEX) effects of EGCG on primary osteoblasts were determined on the basis of cell viability and alkaline phosphatase (ALP) and total cellular superoxide dismutase (SOD) activities. Flow cytometry and Western blot analysis were also used to evaluate the expression of related biomarkers in vitro, and bone microarchitecture was also extensively examined in a rat model in vivo. Results: The results showed that EGCG pretreatment significantly increased osteoblast viability and ALP and SOD activities when cells were exposed to DEX. Alizarin red staining indicated that there was more mineralization with EGCG pretreatment, countering DEX effects. EGCG reduced DEX-induced reactive oxygen species at both the mitochondrial and cellular levels in osteoblasts by activating the nuclear factor erythroid-derived 2-like-2 (Nrf2) pathway. In addition, EGCG protected osteoblasts from apoptosis. EGCG also regulated the formation of active glucocorticoid by 11β-hydroxysteroid dehydrogenase activity. Furthermore, femoral micro-computed tomography scans revealed that EGCG improved bone microstructure and mitigated DEX-induced deterioration of bone quality. Conclusion: These findings suggested that EGCG reversed GIO in rats by protecting osteoblasts by activating the Nrf2 signaling pathway.