A dual-functioning adenoviral vector encoding both transforming growth factor-β3 and shRNA silencing type I collagen: Construction and controlled release for chondrogenesis

Harnessing Nanomedicine for Cartilage Repair: Design Considerations and Recent Advances in Biomaterials

Cartilage injuries are escalating worldwide, particularly in aging society. Given its limited self-healing ability, the repair and regeneration of damaged articular cartilage remain formidable challenges. To address this issue, nanomaterials are leveraged to achieve desirable repair outcomes by enhancing mechanical properties, optimizing drug loading and bioavailability, enabling site-specific and targeted delivery, and orchestrating cell activities at the nanoscale. This review presents a comprehensive survey of recent research in nanomedicine for cartilage repair, with a primary focus on biomaterial design considerations and recent advances. The review commences with an introductory overview of the intricate cartilage microenvironment and further delves into key biomaterial design parameters crucial for treating cartilage damage, including microstructure, surface charge, and active targeting. The focal point of this review lies in recent advances in nano drug delivery systems and nanotechnology-enabled 3D matrices for cartilage repair. We discuss the compositions and properties of these nanomaterials and elucidate how these materials impact the regeneration of damaged cartilage. This review underscores the pivotal role of nanotechnology in improving the efficacy of biomaterials utilized for the treatment of cartilage damage.

A comparative study of chondroitin sulfate and heparan sulfate for directing three-dimensional chondrogenesis of mesenchymal stem cells

Background

Mesenchymal stem cells (MSCs) hold great promise for cartilage repair given their relative abundance, ease of isolation, and chondrogenic potential. To enhance MSC chondrogenesis, extracellular matrix components can be incorporated into three-dimensional (3D) scaffolds as an artificial cell niche. Chondroitin sulfate (CS)-containing hydrogels have been shown to support 3D chondrogenesis, but the effects of varying CS concentration and hydrogel stiffness on 3D MSC chondrogenesis remains elusive. Heparan sulfate (HS) is commonly used as a growth factor reservoir due to its ability to sequester growth factors; however, how it compares to CS in supporting 3D MSC chondrogenesis remains unknown.

Methods

We fabricated photocrosslinkable hydrogels containing physiologically relevant concentrations (0–10%) of CS or HS with two stiffnesses (~7.5 kPa and ~ 36 kPa) as a 3D niche for MSC chondrogenesis.

Results

CS is a more potent factor in enhancing MSC chondrogenesis, especially in soft hydrogels (~ 7.5 kPa). A moderate dosage of CS (5%) led to the highest amount of neocartilage deposition. Stiff hydrogels (~ 36 kPa) generally inhibited neocartilage formation regardless of the biochemical cues.

Conclusions

Taken together, the results from this study demonstrated that CS-containing hydrogels at low mechanical stiffness can provide a promising scaffold for enhancing MSC-based cartilage tissue regeneration.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0728-6) contains supplementary material, which is available to authorized users.

Hypoxia inducible factor 1 alpha down-regulates type i collagen through Sp3 transcription factor in human chondrocytes

Cartilage engineering is one challenging issue in regenerative medicine. Low oxygen tension or hypoxia inducible factor-1 (HIF-1α) gene therapy are promising strategies in the field of cartilage repair. Previously, we showed that hypoxia and its mediator HIF-1 regulate matrix genes expression (collagens and aggrecan). Here, we investigated the molecular mechanism involved in the regulation of type I collagen (COL1A1) by HIF-1 in human articular chondrocytes. We show that HIF-1α reduces COL1A1 transcription, through a distal promoter (-2300 to -1816 bp upstream transcription initiation site), containing two GC boxes that bind Sp transcription factors (Sp1/Sp3). Sp1 acts as a positive regulator but is not induced by HIF-1. COL1A1 inhibition caused by HIF-1 implies only Sp3, which accumulates and competes Sp1 binding on COL1A1 promoter. Additionally, Sp3 ectopic expression inhibits COL1A1, while Sp3 knockdown counteracts the downregulation of COL1A1 induced by HIF-1. In conclusion, we established a new regulatory model of COL1A1 regulation by HIF-1, and bring out its relationship with Sp3 transcription factor. In a fundamental level, these findings give insights in the mechanisms controlling COL1A1 gene expression. This may be helpful to improve strategies to impair type I collagen expression during chondrocyte differentiation for cartilage engineering. © 2016 IUBMB Life, 68(9):756-763, 2016.

Gene Transfer and Gene Silencing in Stem Cells to Promote Chondrogenesis

In stem cell-based chondrogenesis for articular cartilage regeneration, TGF-β3 is dosed to the stem cells to drive differentiation into chondrocytic cells. Meanwhile, type I collagen, which is endogenously expressed in some stem cells (e.g., synovium-derived mesenchymal stem cells) and upregulated by TGF-β3, poses a threat to chondrogenesis, as type I collagen may alter the components and stiffness of articular cartilage. Therefore, a wiser strategy would be to feed the cells with TGF-β3 while at the same time silencing the expression of type I collagen. In this chapter, methods for construction of adenoviral vectors and lentiviral vectors having both of the above functions are given. Their transduction into synovium-derived mesenchymal stem cells for articular cartilage engineering and following characterizations are also described.

Demineralized bone matrix combined bone marrow mesenchymal stem cells, bone morphogenetic protein-2 and transforming growth factor-β3 gene promoted pig cartilage defect repair

Objectives

To investigate whether a combination of demineralized bone matrix (DBM) and bone marrow mesenchymal stem cells (BMSCs) infected with adenovirus-mediated- bone morphogenetic protein (Ad-BMP-2) and transforming growth factor-β3 (Ad-TGF-β3) promotes the repair of the full-thickness cartilage lesions in pig model.

Methods

BMSCs isolated from pig were cultured and infected with Ad-BMP-2(B group), Ad-TGF-β3 (T group), Ad-BMP-2 + Ad-TGF-β3(BT group), cells infected with empty Ad served as a negative group(N group), the expression of the BMP-2 and TGF-β3 were confirmed by immunofluorescence, PCR, and ELISA, the expression of SOX-9, type II collagen(COL-2A), aggrecan (ACAN) in each group were evaluated by real-time PCR at 1w, 2w, 3w, respectively. The chondrogenic differentiation of BMSCs was evaluated by type II collagen at 21d with immunohistochemical staining. The third-passage BMSCs infected with Ad-BMP-2 and Ad-TGF-β3 were suspended and cultured with DBM for 6 days to construct a new type of tissue engineering scaffold to repair full-thickness cartilage lesions in the femur condyles of pig knee, the regenerated tissue was evaluated at 1,2 and 3 months after surgery by gross appearance, H&E, safranin O staining and O'driscoll score.

Results

Ad-BMP-2 and Ad-TGF-β3 (BT group) infected cells acquired strong type II collagen staining compared with Ad-BMP-2 (B group) and Ad-TGF-β3 (T group) along. The Ad-BMP-2 and Ad-TGF-β3 infected BMSCs adhered and propagated well in DBM and the new type of tissue engineering scaffold produced hyaline cartilage morphology containing a stronger type II collagen and safranin O staining, the O'driscoll score was higher than other groups.

Conclusions

The DBM compound with Ad-BMP-2 and Ad-TGF-β3 infected BMSCs scaffold has a good biocompatibility and could well induce cartilage regeneration to repair the defects of joint cartilage. This technology may be efficiently employed for cartilage lesions repair in vivo.

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.

Gene modification of mesenchymal stem cells and articular chondrocytes to enhance chondrogenesis

Current cell based treatment for articular cartilage and osteochondral defects are hampered by issues such as cellular dedifferentiation and hypertrophy of the resident or transplanted cells. The reduced expression of chondrogenic signalling molecules and transcription factors is a major contributing factor to changes in cell phenotype. Gene modification of chondrocytes may be one approach to redirect cells to their primary phenotype and recent advances in nonviral and viral gene delivery technologies have enabled the expression of these lost factors at high efficiency and specificity to regain chondrocyte function. This review focuses on the various candidate genes that encode signalling molecules and transcription factors that are specific for the enhancement of the chondrogenic phenotype and also how epigenetic regulators of chondrogenesis in the form of microRNA may also play an important role.

Antheraea pernyi silk fibroin-coated PEI/DNA complexes for targeted gene delivery in HEK 293 and HCT 116 cells

Polyethylenimine (PEI) has attracted much attention as a DNA condenser, but its toxicity and non-specific targeting limit its potential. To overcome these limitations, Antheraea pernyi silk fibroin (ASF), a natural protein rich in arginyl-glycyl-aspartic acid (RGD) peptides that contains negative surface charges in a neutral aqueous solution, was used to coat PEI/DNA complexes to form ASF/PEI/DNA ternary complexes. Coating these complexes with ASF caused fewer surface charges and greater size compared with the PEI/DNA complexes alone. In vitro transfection studies revealed that incorporation of ASF led to greater transfection efficiencies in both HEK (human embryonic kidney) 293 and HCT (human colorectal carcinoma) 116 cells, albeit with less electrostatic binding affinity for the cells. Moreover, the transfection efficiency in the HCT 116 cells was higher than that in the HEK 293 cells under the same conditions, which may be due to the target bonding affinity of the RGD peptides in ASF for integrins on the HCT 116 cell surface. This result indicated that the RGD binding affinity in ASF for integrins can enhance the specific targeting affinity to compensate for the reduction in electrostatic binding between ASF-coated PEI carriers and cells. Cell viability measurements showed higher cell viability after transfection of ASF/PEI/DNA ternary complexes than after transfection of PEI/DNA binary complexes alone. Lactate dehydrogenase (LDH) release studies further confirmed the improvement in the targeting effect of ASF/PEI/DNA ternary complexes to cells. These results suggest that ASF-coated PEI is a preferred transfection reagent and useful for improving both the transfection efficiency and cell viability of PEI-based nonviral vectors.

Cartilage tissue engineering: molecular control of chondrocyte differentiation for proper cartilage matrix reconstruction

BACKGROUND

Articular cartilage defects are a veritable therapeutic problem because therapeutic options are very scarce. Due to the poor self-regeneration capacity of cartilage, minor cartilage defects often lead to osteoarthritis. Several surgical strategies have been developed to repair damaged cartilage. Autologous chondrocyte implantation (ACI) gives encouraging results, but this cell-based therapy involves a step of chondrocyte expansion in a monolayer, which results in the loss in the differentiated phenotype. Thus, despite improvement in the quality of life for patients, reconstructed cartilage is in fact fibrocartilage. Successful ACI, according to the particular physiology of chondrocytes in vitro, requires active and phenotypically stabilized chondrocytes.

SCOPE OF REVIEW

This review describes the unique physiology of cartilage, with the factors involved in its formation, stabilization and degradation. Then, we focus on some of the most recent advances in cell therapy and tissue engineering that open up interesting perspectives for maintaining or obtaining the chondrogenic character of cells in order to treat cartilage lesions.

MAJOR CONCLUSIONS

Current research involves the use of chondrocytes or progenitor stem cells, associated with "smart" biomaterials and growth factors. Other influential factors, such as cell sources, oxygen pressure and mechanical strain are considered, as are recent developments in gene therapy to control the chondrocyte differentiation/dedifferentiation process.

GENERAL SIGNIFICANCE

This review provides new information on the mechanisms regulating the state of differentiation of chondrocytes and the chondrogenesis of mesenchymal stem cells that will lead to the development of new restorative cell therapy approaches in humans. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.

Gradient-regulated hydrogel for interface tissue engineering: steering simultaneous osteo/chondrogenesis of stem cells on a chip

Injury to articular cartilage, especially the defects induced by degenerative diseases has presented insurmountable challenges. Elaborating a replacement of articular cartilage using biomimic tissue-engineering strategies provides a promising remedy. However, none of the previous osteo/chondrogenic methodologies can not only simultaneously induce osteo/chondrogenesis of stem cells in one scaffolding niche, but also generate a biomimic interface between the formed osteogenic and chondrogenic zones. We report here an innovative method using biomicrofluidic techniques to simultaneously steer distinct specialized differentiation of stem cells into chondrocytes and osteoblasts in one hydrogel slab. Importantly, a gradient that mimics the interface of bone-to-cartilage was generated in the middle of the hydrogel slab. We compared this format with the conventional method for osteochondrogenesis; this format using the gradient-generating microfluidic device indicated outstanding superiorities in stem cell culture and differentiation. Our findings will have a major impact on the design of versatile biomicrofluidic devices for interfacial tissue regeneration.

A mixed co-culture of mesenchymal stem cells and transgenic chondrocytes in alginate hydrogel for cartilage tissue engineering

To regenerate articular cartilage tissue from degeneration and trauma, synovial mesenchymal stem cells (SMSCs) were used in this study as therapeutic progenitor cells to induce therapeutic chondrogenesis. To accomplish this, chondrocytes pre-transduced with adenoviral vectors carrying the transforming growth factor (TGF) β3 gene were selected as transgenic companion cells and co-cultured side-by-side with SMSCs in a 3D environment to provide chondrogenic growth factors in situ. We adopted a mixed co-culture strategy for this purpose. Transgenic delivery of TGF-β3 in chondrocytes was performed via recombinant adenoviral vectors. The mixed co-culture of SMSCs and transgenic chondrocytes was produced in alginate gel constructs. Gene expression in both SMSCs and chondrocytes were characterized. Biochemical assays in vitro and in vivo showed that release of TGF-ß3 from transgenic chondrocytes not only induced SMSC differentiation into chondrocytic cells but also preserved the chondrocytic phenotype of chondrocytes from suspected dedifferentiation. As a result, this mixed co-culture strategy in conjunction with TGF-ß3 gene delivery could be a promising approach in cartilage tissue engineering.

Adenovirus and miRNAs

Adenovirus infection has a tremendous impact on the cellular silencing machinery. Adenoviruses express high amounts of non-coding virus associated (VA) RNAs able to saturate key factors of the RNA interference (RNAi) processing pathway, such as Exportin 5 and Dicer. Furthermore, a proportion of VA RNAs is cleaved by Dicer into viral microRNAs (mivaRNAs) that can saturate Argonaute, an essential protein for miRNA function. Thus, processing and function of cellular miRNAs is blocked in adenoviral-infected cells. However, viral miRNAs actively target the expression of cellular genes involved in relevant functions such as cell proliferation, DNA repair or RNA regulation. Interestingly, the cellular silencing machinery is active at early times post-infection and can be used to control the adenovirus cell cycle. This is relevant for therapeutic purposes against adenoviral infections or when recombinant adenoviruses are used as vectors for gene therapy. Manipulation of the viral genome allows the use of adenoviral vectors to express therapeutic miRNAs or to be silenced by the RNAi machinery leading to safer vectors with a specific tropism. This article is part of a "Special Issue entitled:MicroRNAs in viral gene regulation".

Continuous supply of TGFβ3 via adenoviral vector promotes type I collagen and viability of fibroblasts in alginate hydrogel

In recent years, transforming growth factor-β3 (TGFβ3) has interested more and more researchers with its competence in engineered histogenesis. In the present study we employed recombinant adenoviral vectors to deliver the constitutively active TGFβ3 gene to human dermal fibroblasts, which could maintain the continuous secretion of TGFβ3 from the cells. The expression of type I collagen in the Ad-TGFβ3 group increased significantly in comparison with other three groups: Neg (cells without treatment of the adenovirus), Ad-null (cells with treatment of the adenovirus, without the inserted gene) and Ad-shRNA (cells with treatment of the adenovirus encoding shRNA specific for type I collagen). Additionally, we demonstrated that TGFβ3 enhanced the expression of Smad4 while inhibiting that of MMP-9, thus promoting the collagen transcription via the Smad signal transduction pathway and restraining collagen degradation by MMP-9, which contributed to the increasing type I collagen expression level. As type I collagen mediates cell-material interactions by providing anchorage, the viability of encapsulated fibroblasts in Ad-TGFβ3 group was significantly higher than that in other three groups. Accordingly, this approach forms an effective way to improve the compatibility of non-adhesive hydrogels containing anchorage-dependent cells.

Therapeutic potential of adenoviral vectors for delivery of expressed RNAi activators

IMPORTANCE OF THE FIELD

Harnessing RNA interference (RNAi) to silence pathology-causing genes has shown promise as a mode of therapy. The sustained gene inhibition that may be achieved with expressed sequences is potentially useful for treatment of chronic viral infections, but efficient and safe delivery of these sequences remains a challenge. It is generally recognized that there is no ideal vector for all therapeutic RNAi applications, but recombinant adenovirus vectors are well suited to hepatic delivery of expressed RNAi activators.

AREAS COVERED IN THIS REVIEW

Adenoviruses are hepatotropic after systemic administration, and this is useful for delivering expressed RNAi activators that silence pathology-causing genes in the liver. However, drawbacks of adenoviruses are toxicity and diminished efficacy, which result from induction of innate and adaptive immune responses. In this review, the advantages and hurdles facing therapeutic application of adenoviral vectors for liver delivery of RNAi effectors are covered.

WHAT THE READER WILL GAIN

Insights into adenovirus vectorology and the methods that have been used to make these vectors safer for advancing clinical application of RNAi-based therapy.

TAKE HOME MESSAGE

Adenoviruses are very powerful hepatotropic vectors. To make adenoviruses more effective for clinical use, polymer conjugation and deletion of viral vector sequences have been used successfully. However, further modifications to attenuate immunostimulation as well as improvements in large-scale production are necessary before the therapeutic potential of adenovirus-mediated delivery of RNAi activators is realized.