Effects of combinational adenoviral vector-mediated TGFβ3 transgene and shRNA silencing type I collagen on articular chondrogenesis of synovium-derived mesenchymal stem cells

TGF-β1 overexpressing human MSCs generated using gene editing show robust therapeutic potential for treating collagen-induced arthritis

Transforming growth factor β (TGF-β) plays a pivotal role in cartilage differentiation and other functions of mesenchymal stem cells (MSCs). In this study, we investigated the therapeutic potential of TGF-β1 overexpressing amniotic MSCs (AMMs) generated using gene editing in a mouse model of damaged cartilage. The TGF-β1 gene was inserted into a safe harbor genomic locus in AMMs using transcription activator-like effector nucleases. The chondrogenic properties of TGF-β1-overexpressing AMMs (AMM/T) were characterized using reverse transcription polymerase chain reaction (RT-PCR), quantitative RT-PCR, and histological analysis, and their therapeutic effects were evaluated in mouse model of collagen-induced arthritis (CIA). AMM/T expressed cartilage-specific genes and showed intense Safranin O and Alcian blue staining. Furthermore, injecting AMM/T attenuated CIA progression compared with AMM injection, and increased the regulatory T (Treg) cell population, while suppressing T helper (Th)17 cell activation in CIA mice. Proinflammatory factors, such as interleukin-1β (IL-1β), IL-6, monocyte chemoattractant protein-1, and tumor necrosis factor-α were significantly decreased in AMM/T injected CIA mice compared with their AMM injected counterparts. In conclusion, genome-edited AMMs overexpressing TGF-β1 may be a novel and alternative therapeutic option for protecting cartilage and treating inflammatory joint arthritis.

Effects of TGF-β Overexpression via rAAV Gene Transfer on the Early Repair Processes in an Osteochondral Defect Model in Minipigs

BACKGROUND

Application of the chondrogenic transforming growth factor beta (TGF-β) is an attractive approach to enhance the intrinsic biological activities in damaged articular cartilage, especially when using direct gene transfer strategies based on the clinically relevant recombinant adeno-associated viral (rAAV) vectors.

PURPOSE

To evaluate the ability of an rAAV-TGF-β construct to modulate the early repair processes in sites of focal cartilage injury in minipigs in vivo relative to control (reporter lacZ gene) vector treatment.

STUDY DESIGN

Controlled laboratory study.

METHODS

Direct administration of the candidate rAAV-human TGF-β (hTGF-β) vector was performed in osteochondral defects created in the knee joint of adult minipigs for macroscopic, histological, immunohistochemical, histomorphometric, and micro-computed tomography analyses after 4 weeks relative to control (rAAV- lacZ) gene transfer.

RESULTS

Successful overexpression of TGF-β via rAAV at this time point and in the conditions applied here triggered the cellular and metabolic activities within the lesions relative to lacZ gene transfer but, at the same time, led to a noticeable production of type I and X collagen without further buildup on the subchondral bone.

CONCLUSION

Gene therapy via direct, local rAAV-hTGF-β injection stimulates the early reparative activities in focal cartilage lesions in vivo.

CLINICAL RELEVANCE

Local delivery of therapeutic (TGF-β) rAAV vectors in focal defects may provide new, off-the-shelf treatments for cartilage repair in patients in the near future.

Enhanced chondrogenesis of bone marrow-derived stem cells by using a combinatory cell therapy strategy with BMP-2/TGF-β1, hypoxia, and COL1A1/HtrA1 siRNAs

Mesenchymal stem cells (MSCs) hold promise for cartilage engineering. Here, we aimed to determine the best culture conditions to induce chondrogenesis of MSCs isolated from bone marrow (BM) of aged osteoarthritis (OA) patients. We showed that these BM-MSCs proliferate slowly, are not uniformly positive for stem cell markers, and maintain their multilineage potential throughout multiple passages. The chondrogenic lineage of BM-MSCs was induced in collagen scaffolds, under normoxia or hypoxia, by BMP-2 and/or TGF-β1. The best chondrogenic induction, with the least hypertrophic induction, was obtained with the combination of BMP-2 and TGF-β1 under hypoxia. Differentiated BM-MSCs were then transfected with siRNAs targeting two markers overexpressed in OA chondrocytes, type I collagen and/or HtrA1 protease. siRNAs significantly decreased mRNA and protein levels of type I collagen and HtrA1, resulting in a more typical chondrocyte phenotype, but with frequent calcification of the subcutaneously implanted constructs in a nude mouse model. Our 3D culture model with BMP-2/TGF-β1 and COL1A1/HtrA1 siRNAs was not effective in producing a cartilage-like matrix in vivo. Further optimization is needed to stabilize the chondrocyte phenotype of differentiated BM-MSCs. Nevertheless, this study offers the opportunity to develop a combinatory cellular therapy strategy for cartilage tissue engineering.

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.

Cartilage Tissue Engineering: What Have We Learned in Practice?

Many technologies that underpin tissue engineering as a research field were developed with the aim of producing functional human cartilage in vitro. Much of our practical experience with three-dimensional cultures, tissue bioreactors, scaffold materials, stem cells, and differentiation protocols was gained using cartilage as a model system. Despite these advances, however, generation of engineered cartilage matrix with the composition, structure, and mechanical properties of mature articular cartilage has not yet been achieved. Currently, the major obstacles to synthesis of clinically useful cartilage constructs are our inability to control differentiation to the extent needed, and the failure of engineered and host tissues to integrate after construct implantation. The aim of this chapter is to distil from the large available body of literature the seminal approaches and experimental techniques developed for cartilage tissue engineering and to identify those specific areas requiring further research effort.

Overexpression of TGF-β1 enhances chondrogenic differentiation and proliferation of human synovium-derived stem cells

Transforming growth factor-beta (TGF-β) superfamily proteins play a critical role in proliferation, differentiation, and other functions of mesenchymal stem cells (MSCs). During chondrogenic differentiation of MSCs, TGF-β up-regulates chondrogenic gene expression by enhancing the expression of the transcription factor SRY (sex-determining region Y)-box9 (Sox9). In this study, we investigated the effect of continuous TGF-β1 overexpression in human synovium-derived MSCs (hSD-MSCs) on immunophenotype, differentiation potential, and proliferation rate. hSD-MSCs were transduced with recombinant retroviruses (rRV) encoding TGF-β1. The results revealed that continuous overexpression of TGF-β1 did not affect their phenotype as evidenced by flow cytometry and reverse transcriptase PCR (RT-PCR). In addition, continuous TGF-β1 overexpression strongly enhanced cell proliferation of hSD-MSCs compared to the control groups. Also, induction of chondrogenesis was more effective in rRV-TGFB-transduced hSD-MSCs as shown by RT-PCR for chondrogenic markers, toluidine blue staining and glycosaminoglycan (GAG)/DNA ratio. Our data suggest that overexpression of TGF-β1 positively enhances the proliferation and chondrogenic potential of hSD-MSCs.

Evaluation of insulin medium or chondrogenic medium on proliferation and chondrogenesis of ATDC5 cells

Background. The ATDC5 cell line is regarded as an excellent cell model for chondrogenesis. In most studies with ATDC5 cells, insulin medium (IM) was used to induce chondrogenesis while chondrogenic medium (CM), which was usually applied in chondrogenesis of mesenchymal stem cells (MSCs), was rarely used for ATDC5 cells. This study was mainly designed to investigate the effect of IM, CM, and growth medium (GM) on chondrogenesis of ATDC5 cells. Methods. ATDC5 cells were, respectively, cultured in IM, CM, and GM for a certain time. Then the proliferation and the chondrogenesis progress of cells in these groups were analyzed. Results. Compared with CM and GM, IM promoted the proliferation of cells significantly. CM was effective for enhancement of cartilage specific markers, while IM induced the cells to express endochondral ossification related genes. Although GAG deposition per cell in CM group was significantly higher than that in IM and GM groups, the total GAG contents in IM group were the most. Conclusion. This study demonstrated that CM focused on induction of chondrogenic differentiation while IM was in favor of promoting proliferation and expression of endochondral ossification related genes. Combinational use of these two media would be more beneficial to bone/cartilage repair.

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.

Control of collagen production in mouse chondrocytes by using a combination of bone morphogenetic protein-2 and small interfering RNA targeting Col1a1 for hydrogel-based tissue-engineered cartilage

Because articular cartilage does not self-repair, tissue-engineering strategies should be considered to regenerate this tissue. Autologous chondrocyte implantation is already used for treatment of focal damage of articular cartilage. Unfortunately, this technique includes a step of cell amplification, which results in dedifferentiation of chondrocytes, with expression of type I collagen, a protein characteristic of fibrotic tissues. Therefore, the risk of producing a fibrocartilage exists. The aim of this study was to propose a new strategy for authorizing the recovery of the differentiated status of the chondrocytes after their amplification on plastic. Because the bone morphogenetic protein (BMP)-2 and the transforming growth factor (TGF)-β1 are cytokines both proposed as stimulants for cartilage repair, we undertook a detailed comparative analysis of their biological effects on chondrocytes. As a cellular model, we used mouse chondrocytes after their expansion on plastic and we tested the capability of BMP-2 or TGF-β1 to drive their redifferentiation, with special attention given to the nature of the proteins synthesized by the cells. To prevent any fibrotic character of the newly synthesized extracellular matrix, we silenced type I collagen by transfecting small interfering RNA (siRNA) into the chondrocytes, before their exposure to BMP-2 or TGF-β1. Our results showed that addition of siRNA targeting the mRNA encoded by the Col1a1 gene (Col1a1 siRNA) and BMP-2 represents the most efficient combination to control the production of cartilage-characteristic collagen proteins. To go one step further toward scaffold-based cartilage engineering, Col1a1 siRNA-transfected chondrocytes were encapsulated in agarose hydrogel and cultured in vitro for 1 week. The analysis of the chondrocyte-agarose constructs by using real-time polymerase chain reaction, Western-blotting, immunohistochemistry, and electron microscopy techniques demonstrated that the BMP-2/Col1a1 siRNA combination is effective in reinitializing correct production and assembly of the cartilage-characteristic matrix in agarose hydrogel, without production of type I collagen. Because agarose is known to favor long-term expression of the chondrocyte phenotype and agarose-based hydrogels are approved for clinical trials, this strategy appears very promising to repair hyaline cartilage.

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.

Chondrogenesis and cartilage tissue engineering: the longer road to technology development

Joint injury and disease are painful and debilitating conditions affecting a substantial proportion of the population. The idea that damaged cartilage in articulating joints might be replaced seamlessly with tissue-engineered cartilage is of obvious commercial interest because the market for such treatments is large. Recently, a wealth of new information about the complex biology of chondrogenesis and cartilage has emerged from stem cell research, including increasing evidence of the role of physical stimuli in directing differentiation. The challenge for the next generation of tissue engineers is to identify the key elements in this new body of knowledge that can be applied to overcome current limitations affecting cartilage synthesis in vitro. Here we review the status of cartilage tissue engineering and examine the contribution of stem cell research to technology development for cartilage production.