Direct transplantation of mesenchymal stem cells into the knee joints of Hartley strain guinea pigs with spontaneous osteoarthritis

Introduction

Mesenchymal stem cells (MSCs) can differentiate into various connective tissue cells. Several techniques have been used for the clinical application of MSCs in articular cartilage repair; however, there are many issues associated with the selection of the scaffold material, including its ability to support cell viability and differentiation and its retention and degradation in situ. The application of MSCs via a scaffold also requires a technically demanding surgical procedure. The aim of this study was to test the outcome of intra-articular transplantation of mesenchymal stem cells suspended in hyaluronic acid (HA) in the knee joints of Hartley strain guinea pigs with spontaneous osteoarthritis (OA).

Methods

Commercially available human MSCs were cultured, labeled with carboxyfluorescein diacetate succinimidyl ester (CFDA-SE), suspended in either PBS or HA, and injected into the knee joints of 7-month-old animals. The control animals were injected with either PBS or HA alone. The animals were sacrificed at 1, 3, and 5 weeks post transplantation, the knee joints harvested, and fluorescent microscopic analysis was performed. Histological and immunohistochemical analysis were performed at 5 weeks post transplantation.

Results

At 5 weeks post transplantation, partial cartilage repair was noted in the HA-MSC group but not in the other groups. Examination of CFDA-SE-labeled cells demonstrated migration, differentiation, and proliferation of MSC in the HA-MSC group. There was strong immunostaining for type II collagen around both residual chondrocytes and transplanted MSCs in the OA cartilage.

Conclusion

This scaffold-free and technically undemanding technique appears to result in the regeneration of articular cartilage in the spontaneous OA animal model. Although further examination of the long-term effects of transplantation is necessary, the findings suggest that intra-articular injection of HA-MSC mixture is potentially beneficial for OA.     

Mesenchymal stem cells in arthritic diseases

Mesenchymal stem cells (MSCs), the nonhematopoietic progenitor cells found in various adult tissues, are characterized by their ease of isolation and their rapid growth in vitro while maintaining their differentiation potential, allowing for extensive culture expansion to obtain large quantities suitable for therapeutic use. These properties make MSCs an ideal candidate cell type as building blocks for tissue engineering efforts to regenerate replacement tissues and repair damaged structures as encountered in various arthritic conditions. Osteoarthritis (OA) is the most common arthritic condition and, like rheumatoid arthritis (RA), presents an inflammatory environment with immunological involvement and this has been an enduring obstacle that can potentially limit the use of cartilage tissue engineering. Recent advances in our understanding of the functions of MSCs have shown that MSCs also possess potent immunosuppression and anti-inflammation effects. In addition, through secretion of various soluble factors, MSCs can influence the local tissue environment and exert protective effects with an end result of effectively stimulating regeneration in situ. This function of MSCs can be exploited for their therapeutic application in degenerative joint diseases such as RA and OA. This review surveys the advances made in the past decade which have led to our current understanding of stem cell biology as relevant to diseases of the joint. The potential involvement of MSCs in the pathophysiology of degenerative joint diseases will also be discussed. Specifically, we will explore the potential of MSC-based cell therapy of OA and RA by means of functional replacement of damaged cartilage via tissue engineering as well as their anti-inflammatory and immunosuppressive activities.     

Cytokine interplay among the diseased retina,inflammatory cells and mesenchymal stem cells - a clue to stem cell-based therapy

Retinal degenerative disorders, such as diabetic retinopathy, retinitis pigmentosa, age-related macular degeneration or glaucoma, represent the most common causes of loss of vision and blindness. In spite of intensive research, treatment options to prevent, stop or cure these diseases are limited. Newer therapeutic approaches are offered by stem cell-based therapy. To date, various types of stem cells have been evaluated in a range of models. Among them, mesenchymal stem/stromal cells (MSCs) derived from bone marrow or adipose tissue and used as autologous cells have been proposed to have the potential to attenuate the negative manifestations of retinal diseases. MSCs delivered to the vicinity of the diseased retina can exert local anti-inflammatory and repair-promoting/regenerative effects on retinal cells. However, MSCs also produce numerous factors that could have negative impacts on retinal regeneration. The secretory activity of MSCs is strongly influenced by the cytokine environment. Therefore, the interactions among the molecules produced by the diseased retina, cytokines secreted by inflammatory cells and factors produced by MSCs will decide the development and propagation of retinal diseases. Here we discuss the interactions among cytokines and other factors in the environment of the diseased retina treated by MSCs, and we present results supporting immunoregulatory and trophic roles of molecules secreted in the vicinity of the retina during MSC-based therapy.     

Mesenchymal stem cells for cartilage regeneration in dogs

Articular cartilage damage and osteoarthritis (OA) are common orthopedic diseases in both humans and dogs. Once damaged, the articular cartilage seldom undergoes spontaneous repair because of its avascular, aneural, and alymphatic state, and the damage progresses to a chronic and painful situation. Dogs have distinctive characteristics compared to other laboratory animal species in that they share an OA pathology with humans. Dogs can also require treatment for naturally developed OA;therefore, effective treatment methods for OA are desired in veterinary medicine as well as in human medicine. Recently, interest has grown in regenerative medicine that includes the use of mesenchymal stem cells (MSCs). In cartilage repair, MSCs are a promising therapeutic tool due to their self-renewal capacity, ability to differentiate into cartilage, potential for trophic factor production, and capacity for immunomodulation. The MSCs from dogs (canine MSCs;cMSCs) share various characteristics with MSCs from other animal species, but they show some deviations, particularly in their differentiation ability and surface epitope expression. In vivo studies of cMSCs have demonstrated that intraarticular cMSC injection into cartilage lesions results in excellent hyaline cartilage regeneration. In clinical situations, cMSCs have shown great therapeutic effects, including amelioration of pain and lameness in dogs suffering from OA. However, some issues remain, such as a lack of regulations or guidelines and a need for unified methods for the use of cMSCs. This review summarizes what is known about cMSCs, including their in vitro characteristics, their therapeutic effects in cartilage lesion treatment in preclinical in vivo studies, their clinical efficacy for treatment of naturally developed OA in dogs, and the current limitations of cMSC studies.     

Mesenchymal stem cells in regenerative medicine applied to rheumatic diseases: Role of secretome and exosomes

Over the last decades, mesenchymal stem cells (MSCs) have been extensively studied with regard to their potential applications in regenerative medicine. In rheumatic diseases, MSC-based therapy is the subject of great expectations for patients who are refractory to proposed treatments such as rheumatoid arthritis (RA), or display degenerative injuries without possible curative treatment, such as osteoarthritis (OA). The therapeutic potential of MSCs has been demonstrated in several pre-clinical models of OA or RA and both the safety and efficacy of MSC-based therapy is being evaluated in humans. The predominant mechanism by which MSCs participate to tissue repair is through a paracrine activity. Via the production of a multitude of trophic factors with various properties, MSCs can reduce tissue injury, protect tissue from further degradation and/or enhance tissue repair. However, a thorough in vivo examination of MSC-derived secretome and strategies to modulate it are still lacking. The present review discusses the current understanding of the MSC secretome as a therapeutic for treatment of inflammatory or degenerative pathologies focusing on rheumatic diseases. We provide insights on and perspectives for future development of the MSC secretome with respect to the release of extracellular vesicles that would have certain advantages over injection of living MSCs or administration of a single therapeutic factor or a combination of factors.     

Tissue transglutaminase_variant 2-transduced mesenchymal stem cells and their chondrogenic potential

As cartilage is incapable of self-healing upon severe degeneration because of the lack of blood vessels, cartilage tissue engineering is gaining importance in the treatment of cartilage defects. This study was designed to improve cartilage tissue regeneration by expressing tissue transglutaminase variant 2 (TGM2_v2) in mesenchymal stem cells (MSC) derived from bone marrow of rats. For this purpose, rat MSCs transduced with TGM2_v2 were grown and differentiated on three-dimensional polybutylene succinate (PBSu) and poly-l -lactide (PLLA) blend scaffolds. The transduced cells could not only successfully express the short form transglutaminase-2, but also deposited the protein onto the scaffolds. In addition, they could spontaneously produce cartilage-specific proteins without any chondrogenic induction, suggesting that TGM2_v2 expression provided the cells the ability of chondrogenic differentiation. PBSu:PLLA scaffolds loaded with TGM2_v2 expressing MSCs could be used in repair of articular cartilage defects.     

Mesenchymal stem cells in the treatment of articular cartilage degeneration: New biological insights for an old-timer cell

Osteoarthritis (OA) is a debilitating, degenerative joint disease characterized by progressive destruction of articular cartilage. Given the poor repair capacity of articular cartilage and the associated local destructive immune/inflammatory responses involving all joint structures, OA frequently ends up as a “whole joint failure” requiring prosthetic replacement. Current pharmacological efforts, belatedly started, mainly aim at symptomatic pain relief, underscoring the need for novel therapeutic schemes designed to modify the course of the disease. Mesenchymal stem cell (MSC)–based therapy has gained significant interest, sparking the design of multiple trials proving safety while providing promising preliminary efficacy results. MSCs possess ‘medicinal signaling cell’ properties related to their immunomodulatory and anti-inflammatory effects, which induce the establishment of a pro-regenerative microenvironment at the injured tissue. Those trophic effects are paralleled by the long-established chondroprogenitor capacity that can be harnessed to ex vivo fabricate engineered constructs to repair damaged articular cartilage. The present review focuses on these two aspects of the use of MSCs for articular cartilage damage, namely, cell therapy and tissue engineering, providing information on their use criteria, advancements, challenges and strategies to overcome them.     

Application of mesenchymal stem cell therapy for the treatment of osteoarthritis of the knee: A concise review

Osteoarthritis(OA) refers to a chronic joint disease characterized by degenerative changes of articular cartilage and secondary bone hyperplasia. Since articular cartilage has a special structure, namely the absence of blood vessels as well as the low conversion rate of chondrocytes in the cartilage matrix, the treatment faces numerous clinical challenges. Traditional OA treatment(e.g., arthroscopic debridement, microfracture, autologous or allogeneic cartilage transplantation,chondrocyte transplantation) is primarily symptomatic treatment and pain management, which cannot contribute to regenerating degenerated cartilage or reducing joint inflammation. Also, the generated mixed fibrous cartilage tissue is not the same as natural hyaline cartilage. Mesenchymal stem cells(MSCs) have turned into the most extensively explored new therapeutic drugs in cell-based OA treatment as a result of their ability to differentiate into chondrocytes and their immunomodulatory properties. In this study, the preliminary results of preclinical(OA animal model)/clinical trials regarding the effects of MSCs on cartilage repair of knee joints are briefly summarized, which lay a solid application basis for more and deeper clinical studies on cell-based OA treatment.     

Small animal models to understand pathogenesis of osteoarthritis and use of stem cell in cartilage regeneration

Osteoarthritis (OA) is one of the most common diseases, which affect the correct functionality of synovial joints and is characterized by articular cartilage degradation. Limitation in the treatment of OA is mostly due to the very limited regenerative characteristic of articular cartilage once is damaged. Small animal models are of particular importance for mechanistic analysis to understand the processes that affect cartilage degradation. Combination of joint injury techniques with the use of stem cells has been shown to be an important tool for understanding the processes of cartilage degradation and regeneration. Implementation of stem cells and small animal models are important tools to help researchers to find a solution that could ameliorate and prevent the symptoms of OA.     

Repair of injured articular and growth plate cartilage using mesenchymal stem cells and chondrogenic gene therapy

Injuries to the articular cartilage and growth plate are significant clinical problems due to their limited ability to regenerate themselves. Despite progress in orthopedic surgery and some success in development of chondrocyte transplantation treatment and in early tissue-engineering work, cartilage regeneration using a biological approach still remains a great challenge. In the last 15 years, researchers have made significant advances and tremendous progress in exploring the potentials of mesenchymal stem cells (MSCs) in cartilage repair. These include (a) identifying readily available sources of and devising appropriate techniques for isolation and culture expansion of MSCs that have good chondrogenic differentiation capability, (b) discovering appropriate growth factors (such as TGF-beta, IGF-I, BMPs, and FGF-2) that promote MSC chondrogenic differentiation, (c) identifying or engineering biological or artificial matrix scaffolds as carriers for MSCs and growth factors for their transplantation and defect filling. In addition, representing another new perspective for cartilage repair is the successful demonstration of gene therapy with chondrogenic growth factors or inflammatory inhibitors (either individually or in combination), either directly to the cartilage tissue or mediated through transducing and transplanting cultured chondrocytes, MSCs or other mesenchymal cells. However, despite these rapid pre-clinical advances and some success in engineering cartilage-like tissue and in repairing articular and growth plate cartilage, challenges of their clinical translation remain. To achieve clinical effectiveness, safety, and practicality of using MSCs for cartilage repair, one critical investigation will be to examine the optimal combination of MSC sources, growth factor cocktails, and supporting carrier matrixes. As more insights are acquired into the critical factors regulating MSC migration, proliferation and chondrogenic differentiation both ex vivo and in vivo, it will be possible clinically to orchestrate desirable repair of injured articular and growth plate cartilage, either by transplanting ex vivo expanded MSCs or MSCs with genetic modifications, or by mobilising endogenous MSCs from adjacent source tissues such as synovium, bone marrow, or trabecular bone.     

Intradiscal transplantation of synovial mesenchymal stem cells prevents intervertebral disc degeneration through suppression of matrix metalloproteinase-related genes in nucleus pulposus cells in rabbits

Introduction  

Synovial mesenchymal stem cells (MSCs) have high proliferative and chondrogenic potentials, and MSCs transplanted into the articular cartilage defect produce abundant extracellular matrix. Because of similarities between the articular cartilage and the intervertebral disc cartilage, synovial MSCs are a potential cell source for disc regeneration. Here, we examined the effect of intradiscal transplantation of synovial MSCs after aspiration of nucleus pulposus in rabbits.     

Engineered Co-culture Strategies Using Stem Cells for Facilitated Chondrogenic Differentiation and Cartilage Repair

Osteoarthritis (OA) is a chronic disease in elders and athletes due to limited regenerative capacities of cartilage tissues and subsequently insufficient recovery of damaged sites. Recent clinical treatments for OA have utilized progenitor cell-based therapies for cartilage tissue regeneration. Administration of a single type of cell population such as stem cells or chondrocytes does not guarantee a full recovery of cartilage defects. Therefore, current tissue engineering approaches using co-culture techniques have been developed to mimic complex and dynamic cellular interactions in native cartilage tissues and facilitate changes in cellular phenotypes into chondrogenesis. Therefore, this paper introduces recently developed co-culture systems using two major cell populations, mesenchymal stem cells (MSCs) and chondrocytes. Specifically, a series of examples to describe (1) synergistic in vitro activations of MSCs by paracrine signaling molecules from adult chondrocytes in co-culture systems and (2) functional in vivo tissue regeneration via co-administration of both cell types were reviewed. Based on these findings, it could be speculated that engineered co-culture systems using MSC/ chondrocyte is a promising and feasible cell-based OA therapy in clinical aspects.     

Enhancing survival,engraftment, and osteogenic potential of mesenchymal stem cells

Mesenchymal stem cells (MSCs) are promising candidates for bone regeneration therapies due to their plasticity and easiness of sourcing. MSC-based treatments are generally considered a safe procedure, however, the long-term results obtained up to now are far from satisfactory. The main causes of these therapeutic limitations are inefficient homing, engraftment, and osteogenic differentiation. Many studies have proposed modifications to improve MSC engraftment and osteogenic differentiation of the transplanted cells. Several strategies are aimed to improve cell resistance to the hostile microenvironment found in the recipient tissue and increase cell survival after transplantation. These strategies could range from a simple modification of the culture conditions, known as cell-preconditioning, to the genetic modification of the cells to avoid cellular senescence. Many efforts have also been done in order to enhance the osteogenic potential of the transplanted cells and induce bone formation, mainly by the use of bioactive or biomimetic scaffolds, although alternative approaches will also be discussed. This review aims to summarize several of the most recent approaches, providing an up-to-date view of the main developments in MSC-based regenerative techniques.     

Rheumatoid arthritis: From synovium biology to cell-based therapy

Rheumatoid arthritis (RA) is a chronic inflammatory disease that affects the synovial joints and, if not treated properly, can lead to multiple progressive articular and extra-articular damage. Its pathogenesis is primarily associated with an inadequate immune response and dysregulated cytokine production. However, RA is also linked to disruption in oxygen metabolism, impaired redox signaling, acidosis and aberrant intercellular communication. Even though treatment modalities have made RA a manageable disease, a significant number of patients still do not respond satisfactorily or suffer considerably from the adverse events of conventional therapy. In recent years, cell-based strategies, especially the administration of the mesenchymal/medicinal stem/signaling cells (MSCs), have been proposed as a novel and very promising therapeutic approach. RA patients may benefit from the potent anti-inflammatory and immunomodulatory properties and tissue-repair potential of MSCs. Furthermore, the satisfactory safety profile of MSC therapy has been already demonstrated in several clinical studies. This review summarizes current understanding of the pathomechanism behind RA at the molecular and cellular level and focuses on MSC-based clinical research and applications of MSCs for RA treatment.     

Tissue engineering through autologous mesenchymal stem cells

The regeneration of damaged cartilage in different pathological situations is a major goal for the future and could be achieved through cell and/or gene therapy. Mesenchymal stem cells (MSCs) are the progenitors of multiple lineages, including bone, cartilage, muscle, fat, and astrocytes. MSCs seem to be the best candidates for cell therapy to regenerate injured tissue, as they are easily isolated from bone marrow and can be rapidly amplified. Full healing is extremely demanding, however, and includes integration of the regenerated tissue within the surrounding host tissue and true differentiation through pathways involved in embryonic development. This goal might be reached through the combined use of scaffolds, MSC-mediated therapy and the expression of selective differentiating factors. The long-term behavior of MSCs associated with biomaterials and implanted in pathological joints remains to be investigated before clinical application in osteoarthritis or rheumatoid arthritis.     

Three-dimensional scaffold containing EGF incorporated biodegradable polymeric nanoparticles for stem cell based tissue engineering applications

Stem cell-based tissue engineering holds much hope for the development of multifunctional tissues to replace diseased organs. The attachment and survival of stem cells on a three-dimensional (3D) scaffold must be enhanced for faster progression of stem cell based tissue engineering. This study evaluate the stability of mesenchymal stem cells (MSCs) in 3D porous scaffolds composed of a collagen and chitosan blend impregnated with epidermal growth factor incorporated chitosan nanoparticles (EGF-CNP). The EGF-CNP scaffolds were characterized by transmission electron microscopy, which revealed that the nanoparticles were round in shape and 20 ∼ 50 nm in size. The scaffolds were prepared by freeze drying. A Fourier-transform infrared spectrum study revealed that the linkage between collagen and chitosan was through an ionic interaction. Thermal analysis and degradation studies showed that the scaffold could be used in tissue engineering application. MSCs proliferated well in the EGF-CNP impregnated scaffold. A scanning electron microscope study showed anchored and elongated MSCs on the EGF-CNP impregnated scaffold. A 3D biodegradable collagen chitosan scaffold impregnated with EGF-CNP is a promising transportable candidate for MSC-based tissue engineering, and this scaffold could be used as an in vitro model for subsequent clinical applications.     

Specific inhibition of FAK signaling attenuates subchondral bone deterioration and articular cartilage degeneration during osteoarthritis pathogenesis

Osteoarthritis (OA), a disease of the entire joint, is characterized by abnormal bone remodeling and coalescent degradation of articular cartilage. We have previously found that elevated levels of H-type vessels in subchondral bone correlate with OA and that focal adhesion kinase (FAK) is critical for H-type vessel formation in osteoporosis. However, the potential role of FAK in OA remains unexplored. Here, we demonstrate that the p-FAK level was dramatically elevated in subchondral bone following anterior cruciate ligament transection (ACLT) in rats. Specific inhibition of FAK signaling with Y15 in subchondral bone resulted in the suppression of subchondral bone deterioration and this effect was mediated by H-type vessel-induced ectopic bone formation. Further, articular cartilage degeneration was also alleviated after Y15 treatment. In vitro, the p-FAK level was significantly elevated in mesenchymal stem cells (MSCs) from vehicle-treated ACLT rats as compared to that in MSCs from sham controls and Y15-treated ACLT rats. Elevated p-FAK level in MSCs promoted vascular endothelial growth factor (VEGF) expression, as demonstrated from the high VEGF level in the blood, subchondral bone, and conditioned medium (CM) of MSCs from vehicle-treated ACLT rats. The CM of MSCs from vehicle-treated ACLT rats might promote the angiogenesis of endothelial cells and the catabolic response of chondrocytes through the FAK-growth factor receptor-bound protein 2-mitogen-activated protein kinase-mediated expression of VEGF. The effect of the CM from MSCs of Y15-treated ACLT rats or that treated with a VEGF-neutralizing antibody on vessel formation and the catabolic response was lowered. Thus, the specific inhibition of FAK signaling may be a promising avenue for the prevention or early treatment of OA.     

Vascular endothelial growth factor (VEGF) as a key therapeutic trophic factor in bone marrow mesenchymal stem cell-mediated cardiac repair

We recently demonstrated a novel effective therapeutic regimen for treating hamster heart failure based on injection of bone marrow mesenchymal stem cells (MSCs) or MSC-conditioned medium into the skeletal muscle. The work highlights an important cardiac repair mechanism mediated by the myriad of trophic factors derived from the injected MSCs and local musculature that can be explored for non-invasive stem cell therapy. While this therapeutic regimen provides the ultimate proof that MSC-based cardiac repair is mediated by the trophic actions independent of MSC differentiation or stemness, the trophic factors responsible for cardiac regeneration after MSC therapy remain largely undefined. Toward this aim, we took advantage of the finding that human and porcine MSCs exhibit species-related differences in expression of trophic factors. We demonstrate that human MSCs when compared to porcine MSCs express and secrete 5-fold less vascular endothelial growth factor (VEGF) in conditioned medium (40 ± 5 and 225 ± 17 pg/ml VEGF, respectively). This deficit in VEGF output was associated with compromised cardiac therapeutic efficacy of human MSC-conditioned medium. Over-expression of VEGF in human MSCs however completely restored the therapeutic potency of the conditioned medium. This finding indicates VEGF as a key therapeutic trophic factor in MSC-mediated myocardial regeneration, and demonstrates the feasibility of human MSC therapy using trophic factor-based cell-free strategies, which can eliminate the concern of potential stem cell transformation.