Lentivirus-mediated knockdown of aggrecanase-1 and -2 promotes chondrocyte-engineered cartilage formation in vitro

APOE-knockout in rabbits causes loss of cells in nucleus pulposus and enhances the levels of inflammatory catabolic cytokines damaging the intervertebral disc matrix

Rabbits with naturally high levels of cholesterol ester transfer protein (CETP), unlike rodents, have become an interesting animal model for the study of lipid metabolism and atherosclerosis, as they have similarities to humans in lipid metabolism, cardiovascular physiology and susceptibility to develop atherosclerosis. Rodents, such as mice, are not prone to atherosclerosis as they lack the mass and activity of CETP, as a key player in lipoprotein metabolism. Recently, APOE-knockout in rabbits has been shown to promote atherosclerosis and associated premature IVD degeneration that mimic the symptoms of atherosclerosis and structural changes of IVDs in humans. Here we examined whether APOE-knockout promoted IVD degeneration in rabbits is associated with imbalanced inflammatory catabolic activities, as the underlying problem of biological deterioration that mimic the symptoms of advanced IVD degeneration in humans. We analysed in lumbar nucleus pulposus (NP) of APOE-knockout rabbits the cell viabilities and the intracellular levels of inflammatory, catabolic, anti-catabolic and anabolic proteins derogating IVD matrix. Grades of IVD degeneration were evaluated by magnetic resonance imaging. NP cells were isolated from homozygous APOE-knockout and wild-type New Zealand White rabbits of similar age. Three-dimensional cell culture with low-glucose was completed in alginate hydrogel. Cell proliferation and intracellular levels of target proteins were examined by MTT and ELISA assays. Alike human NP cells of different disc degeneration grades, NP cells of APOE-knockout and wild-type rabbits showed significantly different in vivo cell population densities (p<0.0001) and similar in vitro proliferation rates. Furthermore, they showed differences in overexpression of selective inflammatory and catabolic proteins (p<0.0001) similar to those found in human NP cells of different disc degeneration grades, such as IL-1β, TNF-α, ADAMTS-4, ADAMTS-5 and MMP-3. This study showed that premature IVD degeneration in APOE-knockout rabbits was promoted by the accumulation of selective inflammatory catabolic factors that enhanced imbalances between catabolic and anabolic factors mimicking the symptoms of advanced IVD degeneration in humans. Thus, APOE-knockout rabbits could be used as a promising model for therapeutic approaches of degenerative disc disorders.

Effects of human cyclooxygenase-2 gene silencing on synovial cells of rheumatoid arthritis mediated by lentivirus

The aim of the study is to screen the effective shRNA sequence which can silence the human COX-2 expression level in synovial cells of rheumatoid arthritis (RA) patient transfected by the lentivirus. Four pairs of hCOX-2 shRNA were designed and inserted into lentivirus to form pGPHI/GFP/Neo-shRNA vector. The reconstructed virus was transfected into synovial cells derived from RA patients, and then the expression level of hCOX-2 mRNA and the protein of the inflammatory factors including prostaglandin E2 (PGE2), vascular endothelial growth factor (VEGF), interleukin-1β (IL-1β) and tumour necrosis factor alpha (TNF-α) in the supernatants were examined with real-time PCR and ELISA, respectively. There was no obvious negative influence on cell growth and morphology after hCOX-2 shRNA gene transfection mediated by lentivirus. The hCOX-2 mRNA expression level, as well as the concentration of PGE2, VEGF, IL-1β and TNF-α, decreased significantly (p < .05). RNAi mediated by lentivirus can significantly inhibit hCOX-2 mRNA expression level in synovial cells of RA patients, so as to reduce the expression of inflammatory cytokines.

Cross-Coupling Effects of Silencing of Cyclooxygenase-2 (COX-2)/Aggrecanase-1 and Over-Expressed Insulin-Like Growth Factor 1 (IGF-1) in an Osteoarthritis Animal Model

BACKGROUND This study aimed to observe the effect of lentivirus-mediated cyclooxygenase-2 and aggrecanase-1 silencing and insulin-like growth factor-1 overexpression in human bone marrow mesenchymal stem cells after injection into model osteoarthritic knees. MATERIAL AND METHODS Using genetic recombination technique, the genes of cyclooxygenase-2, aggrecanase-1, and insulin-like growth factor-1 were recombined into the lentiviral vectors, and we transfected the human bone marrow stem cells in vitro. The BMSC transfected with lentivirus without genes served as a blank-virus group, and saline was used for another control group. One week later, the cytokines PGE2, aggrecanase-1, hIGF-1, and IL-1 were detected and compared between groups. RESULTS Compared with blank-virus group, the expression of COX-2 (85.81±5.12 ng/L) and aggrecanase1 (6.256±1.66) were decreased in the virus group (p<0.05), while the expression of hIGF-1 (17.46±1.86) was increased (p<0.05). The concentrations of PGE2 (85.81±5.12 ng/L), aggrecanase1 (51.34±5.463 ng/L), and IL-1 (82.31±4.321 ng/L) decreased (p<0.05) within the knee, but the concentration of hIGF-1 (44.33±0.7194 ng/L) increased (p<0.05). Compared with the other groups, the results of histological and immunohistochemical examinations demonstrated that the abrasion of articular cartilage was significantly improved and repaired. CONCLUSIONS Lentivirus-mediated RNAi can inhibit the expression of COX-2 mRNA and aggrecanase-1mRNA, and enhance the hIGF-1 mRNA expression, thereby influencing the concentration of cytokines in the early osteoarthritic model knee joints.

Emerging potential of gene silencing approaches targeting anti-chondrogenic factors for cell-based cartilage repair

The field of cartilage repair has exponentially been growing over the past decade. Here, we discuss the possibility to achieve satisfactory regeneration of articular cartilage by means of human mesenchymal stem cells (hMSCs) depleted of anti-chondrogenic factors and implanted in the site of injury. Different types of molecules including transcription factors, transcriptional co-regulators, secreted proteins, and microRNAs have recently been identified as negative modulators of chondroprogenitor differentiation and chondrocyte function. We review the current knowledge about these molecules as potential targets for gene knockdown strategies using RNA interference (RNAi) tools that allow the specific suppression of gene function. The critical issues regarding the optimization of the gene silencing approach as well as the delivery strategies are discussed. We anticipate that further development of these techniques will lead to the generation of implantable hMSCs with enhanced potential to regenerate articular cartilage damaged by injury, disease, or aging.

Gene therapy for human osteoarthritis: principles and clinical translation

INTRODUCTION

Osteoarthritis (OA) is the most prevalent chronic joint disease. Its key feature is a progressive articular cartilage loss. Gene therapy for OA aims at delivering gene-based therapeutic agents to the osteoarthritic cartilage, resulting in a controlled, site-specific, long-term presence to rebuild the damaged cartilage.

AREAS COVERED

An overview is provided of the principles of gene therapy for OA based on a PubMed literature search. Gene transfer to normal and osteoarthritic cartilage in vitro and in animal models in vivo is reviewed. Results from recent clinical gene therapy trials for OA are discussed and placed into perspective.

EXPERT OPINION

Recombinant adeno-associated viral (rAAV) vectors enable to directly transfer candidate sequences in human articular chondrocytes in situ, providing a potent tool to modulate the structure of osteoarthritic cartilage. However, few preclinical animal studies in OA models have been performed thus far. Noteworthy, several gene therapy clinical trials have been carried out in patients with end-stage knee OA based on the intraarticular injection of human juvenile allogeneic chondrocytes overexpressing a cDNA encoding transforming growth factor-beta-1 via retroviral vectors. In a recent placebo-controlled randomized trial, clinical scores were improved compared with placebo. These translational results provide sufficient reason to proceed with further clinical testing of gene transfer protocols for the treatment of OA.

Molecular targets in arthritis and recent trends in nanotherapy

Due to its severity and increasing epidemiology, arthritis needs no description. There are various forms of arthritis most of which are disabling, very painful, and common. In spite of breakthroughs in the field of drug discovery, there is no cure for arthritis that can eliminate the disease permanently and ease the pain. The present review focuses on some of the most successful drugs in arthritis therapy and their side effects. Potential new targets in arthritis therapy such as interleukin-1β, interleukin-17A, tumor necrosis factor alpha, osteopontin, and several others have been discussed here, which can lead to refinement of current therapeutic modalities. Mechanisms for different forms of arthritis have been discussed along with the molecules that act as potential biomarkers for arthritis. Due to the difficulty in monitoring the disease progression to detect the advanced manifestations of the diseases, drug-induced cytotoxicity, and problems with drug delivery; nanoparticle therapy has gained the attention of the researchers. The unique properties of nanoparticles make them highly attractive for the design of novel therapeutics or diagnostic agents for arthritis. The review also focuses on the recent trends in nanoformulation development used for arthritis therapy. This review is, therefore, important because it describes the relevance and need for more arthritis research, it brings forth a critical discussion of successful drugs in arthritis and analyses the key molecular targets. The review also identifies several knowledge gaps in the published research so far along with the proposal of new ideas and future directions in arthritis therapy.

Chondrogenic potential of Slug-depleted human mesenchymal stem cells

The use of short interfering RNA (siRNA) in combination with stem cells and biocompatible scaffolds is a promising strategy in regenerative medicine. Our experimental strategy was to explore the possibility of forcing or guiding the chondrogenic differentiation of human mesenchymal stem cells (hMSCs) by knocking down a negative regulator of chondrogenesis, Slug transcription factor (TF), thus altering cell behavior. We found that TGFβ-driven chondrogenic differentiation of hMSCs cultured onto a hyaluronan-based scaffold, HYAFF(®)-11, was strengthened after cell exposure to siRNA against Slug. Slug silencing was effective in promoting the expression of chondrogenic markers, including Col2A1, aggrecan, Sox9, LEF1, and TRPS1. In addition, we confirmed that HYAFF-11 is a good scaffold candidate for hMSC use in tissue engineering applications, and showed that it is effective in sustaining TGFβ3 treatment associated with a specific gene silencing. Interestingly, preliminary results from the experimental model described here suggested that, even in the absence of differentiation supplements, Slug silencing showed a pro-chondrogenic effect, highlighting both its potential use as an alternative to TGFβ treatment, and the critical role of the Slug TF in determining the fate of hMSCs.

Delivery of the Sox9 gene promotes chondrogenic differentiation of human umbilical cord blood-derived mesenchymal stem cells in an in vitro model

SRY-related high-mobility-group box 9 (Sox9) gene is a cartilage-specific transcription factor that plays essential roles in chondrocyte differentiation and cartilage formation. The aim of this study was to investigate the feasibility of genetic delivery of Sox9 to enhance chondrogenic differentiation of human umbilical cord blood-derived mesenchymal stem cells (hUC-MSCs). After they were isolated from human umbilical cord blood within 24 h after delivery of neonates, hUC-MSCs were untreated or transfected with a human Sox9-expressing plasmid or an empty vector. The cells were assessed for morphology and chondrogenic differentiation. The isolated cells with a fibroblast-like morphology in monolayer culture were positive for the MSC markers CD44, CD105, CD73, and CD90, but negative for the differentiation markers CD34, CD45, CD19, CD14, or major histocompatibility complex class II. Sox9 overexpression induced accumulation of sulfated proteoglycans, without altering the cellular morphology. Immunocytochemistry demonstrated that genetic delivery of Sox9 markedly enhanced the expression of aggrecan and type II collagen in hUC-MSCs compared with empty vector-transfected counterparts. Reverse transcription-polymerase chain reaction analysis further confirmed the elevation of aggrecan and type II collagen at the mRNA level in Sox9-transfected cells. Taken together, short-term Sox9 overexpression facilitates chondrogenesis of hUC-MSCs and may thus have potential implications in cartilage tissue engineering.

A combinatorial relative mass value evaluation of endogenous bioactive proteins in three-dimensional cultured nucleus pulposus cells of herniated intervertebral discs: identification of potential target proteins for gene therapeutic approaches

Painful degenerative disc diseases have been targeted by different biological treatment approaches. Nucleus pulposus (NP) cells play a central role in intervertebral disc (IVD) maintenance by orchestrating catabolic, anabolic and inflammatory factors that affect the extracellular matrix. IVD degeneration is associated with imbalances of these factors, resulting in a catabolic inflammatory metabolism. Therefore, accurate knowledge about their quantity and quality with regard to matrix synthesis is vital for a rational gene therapeutic approach. NP cells were isolated from 63 patients operated due to lumbar disc herniation (mean age 56 / range 29 - 84 years). Then, three-dimensional culture with low-glucose was completed in a collagen type I scaffold for four weeks. Subsequently cell proliferation evaluation was performed using 3-(4, 5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide and intracellular concentration of 28 endogenously expressed anabolic, catabolic, inflammatory factors and relevant matrix proteins was determined by enzyme-linked immunosorbent assay. Specimen-related grades of degeneration were confirmed by preoperative magnetic resonance imaging. Independent from gender, age and grade of degeneration proliferation rates remained similar in all groups of NP cells. Progressive grades of degeneration, however, showed a significant influence on accumulation of selective groups of factors such as disintegrin and metalloproteinase with thrombospondin motifs 4 and 5, matrix metalloproteinase 3, metalloproteinase inhibitor 1 and 2, interleukin-1β and interleukin-1 receptor. Along with these changes, the key NP matrix proteins aggrecan and collagen II decreased significantly. The concentration of anabolic factors bone morphogenetic proteins 2, 4, 6 and 7, insulin-like growth factor 1, transforming growth factor beta 1 and 3, however, remained below the minimal detectable quantities. These findings indicate that progressive degenerative changes in NP may be problematic with regard to biologic treatment strategies. Hence, gene therapeutic interventions regulating relevant bioactive factors identified in this work might contribute to the development of regenerative treatment approaches for degenerative disc diseases.

Lentivirus vector-mediated knockdown of erythropoietin-producing hepatocellular carcinoma receptors B4 inhibits laser-induced choroidal neovascularization

PURPOSE

To evaluate the efficacy of erythropoietin-producing hepatocellular carcinoma receptors B4 (EphB4) knockdown on the development of laser-induced choroidal neovascularization (CNV) in vivo.

METHODS

We constructed recombinant lentiviral vectors (Lv) Lv-shRNA-EphB4 to specifically knock down the expression of EphB4. The mRNA and protein expression of EphB4 was investigated by real-time reverse transcription-polymerase chain reaction (RT-PCR) and western blot. CNV was induced by laser photocoagulation in C57BL/6 mice. The mice were then randomly assigned to be intravitreally injected with phosphate-buffered saline (PBS), Lv-shRNA-EphB4 recombinant lentivirus, or an unrelated shRNA recombinant lentivirus (pFU LV-shRNA-NC). An uninjected group was used as the control. Fundus fluorescein angiography (FFA), histologic analysis, and choroidal flat mounts analysis were applied to evaluate the inhibition of CNV after an intravitreal injection.

RESULTS

Transfection of Lv-shRNA-EphB4 led to the knockdown of EphB4, and EphB4 mRNA was down-regulated by about 80%. FFA and histologic analysis revealed that the leakage areas and the mean thickness of CNV were much smaller in the Lv-shRNA-EphB4 group than in the PBS-treated, pFU Lv-shRNA-NC group and the non-injection group. Choroidal flat mounts showed significantly less leakage and smaller leakage areas in the Lv-shRNA-EphB4 group than those in other groups.

CONCLUSION

Knocking down the expression of EphB4 exerts an inhibitory effect on CNV in vivo. It may provide a potential strategy for the treatment of CNV.

Enhancing human nucleus pulposus cells for biological treatment approaches of degenerative intervertebral disc diseases: a systematic review

Intervertebral disc (IVD) degeneration has been described as an aberrant, cell-mediated, age- and genetics-dependent molecular degeneration process, which can be accelerated by nutritional, mechanical and toxic factors. Collective involvement of these factors can result in structural failures, which are often associated with pain. Current treatment approaches are restricted to symptomatic therapies, not addressing options of restoring structural or biological deterioration of the IVD as the underlying problem. Therapeutic potentials of IVD cell transplantation, biomaterials, inhibiting or activating bioactive factors, including gene-therapeutic approaches, have been shown in vitro or in small animal models. Since human degenerative IVD cells display distinctive features with regard to cell biology and regenerative potential, we attempted a systematic review, investigating the in vitro response of human nucleus pulposus cells to different stimuli. Therefore, we conducted an electronic database search on Medline through July 2011 to identify, compare and discuss publications concerning the effects of cell-cell stimulation, bioactive factors, biomaterials and combinations thereof in terms of cell isolation, proliferation, differentiation and matrix protein synthesis. This survey and discussion might serve as a source for designing future biological treatment strategies for the human IVD.

Enhanced cartilage formation by inhibiting cathepsin K expression in chondrocytes expanded in vitro

Although engineered cartilage has great potential in cartilage regeneration and reconstruction, dedifferentiation of chondrocytes during in vitro expansion remains a technical bottleneck in the clinical application. To overcome the problem, a gene modification approach was developed to knock-down the key gene involving dedifferentiation of human chondrocytes. A microarray assay revealed 84 up-regulated genes and 56 down-regulated genes in passage 4 (dedifferentiated) human chondrocytes compared to passage 1 cells. Among them, cathepsin K (CTSK) was the key gene (with 28 folds of increased gene expression), which was further confirmed by RT-PCR and Western-Blot. Furthermore, over-expression of CTSK led to reduced matrix production in cultured human chondrocytes in vitro and poor formation of engineered cartilage in vivo. In contrast, CTSK knock-down could better maintain the chondrogenic phenotype of in vitro expanded cells with increased gene and protein expression of collagen II and aggrecan when compared to control cells. More importantly, after 6 passages, the knock-down cells formed much better engineered cartilage than the control cells after in vivo implantation with 30% Pluronic F127 for 8 weeks as the experimental group formed much bigger sized cartilages with significantly increased weight and glycosaminoglycan content (p < 0.05) than the control group. Histologically, the knock-down cells formed a more homogenous cartilage structure with enhanced production of collagen II and proteoglycans. Overall, these results suggest that CTSK knock-down may provide a feasible way to expand functional human chondrocytes in vitro for engineering good quality human cartilage and thus may have its great potential in the clinical translation of engineered cartilage in the future, given the fact that biosafe RNA interference techniques are already available.