Mesenchymal stem cell therapy for knee osteoarthritis. Preliminary report of four patients

SOX9 gene transfer via safe, stable, replication-defective recombinant adeno-associated virus vectors as a novel, powerful tool to enhance the chondrogenic potential of human mesenchymal stem cells

Introduction

Transplantation of genetically modified human bone marrow-derived mesenchymal stem cells (hMSCs) with an accurate potential for chondrogenic differentiation may be a powerful means to enhance the healing of articular cartilage lesions in patients. Here, we evaluated the benefits of delivering SOX9 (a key regulator of chondrocyte differentiation and cartilage formation) via safe, maintained, replication-defective recombinant adeno-associated virus (rAAV) vector on the capability of hMSCs to commit to an adequate chondrocyte phenotype compared with other mesenchymal lineages.

Methods

The rAAV-FLAG-hSOX9 vector was provided to both undifferentiated and lineage-induced MSCs freshly isolated from patients to determine the effects of the candidate construct on the viability, biosynthetic activities, and ability of the cells to enter chondrogenic, osteogenic, and adipogenic differentiation programs compared with control treatments (rAAV-lacZ or absence of vector administration).

Results

Marked, prolonged expression of the transcription factor was noted in undifferentiated and chondrogenically differentiated cells transduced with rAAV-FLAG-hSOX9, leading to increased synthesis of major extracellular matrix components compared with control treatments, but without effect on proliferative activities. Chondrogenic differentiation (SOX9, type II collagen, proteoglycan expression) was successfully achieved in all types of cells but strongly enhanced when the SOX9 vector was provided. Remarkably, rAAV-FLAG-hSOX9 delivery reduced the levels of markers of hypertrophy, terminal and osteogenic/adipogenic differentiation in hMSCs (type I and type X collagen, alkaline phosphatise (ALP), matrix metalloproteinase 13 (MMP13), and osteopontin (OP) with diminished expression of the osteoblast-related transcription factor runt-related transcription factor 2 (RUNX2); lipoprotein lipase (LPL), peroxisome proliferator-activated receptor gamma 2 (PPARG2)), as well as their ability to undergo proper osteo-/adipogenic differentiation. These effects were accompanied with decreased levels of β-catenin (a mediator of the Wnt signaling pathway for osteoblast lineage differentiation) and enhanced parathyroid hormone-related protein (PTHrP) expression (an inhibitor of hypertrophic maturation, calcification, and bone formation) via SOX9 treatment.

Conclusions

This study shows the potential benefits of rAAV-mediated SOX9 gene transfer to propagate hMSCs with an advantageous chondrocyte differentiation potential for future, indirect therapeutic approaches that aim at restoring articular cartilage defects in the human population.

New trends for knee cartilage regeneration: from cell-free scaffolds to mesenchymal stem cells

In the last decade, huge steps forward have been made in the field of cartilage regeneration. The most recent trend for treating chondral/osteochondral lesions is based on the application of smart biomaterials that could lead to "in situ" regeneration of not only cartilage, but also subchondral bone, preferably through a single step procedure to reduce the costs and the morbidity for the patient. This innovative approach is currently under investigation as several "scaffolds" have been proposed in clinical practice, with or without the aid of cells, with the opportunity, in the second case, of bypassing the strict limits imposed by cell manipulation regulations. Furthermore, the fascinating potential of mesenchymal stem cells has recently opened new paths of research to discover how and whether these powerful entities can really contribute to tissue regeneration. The first clinical trials have been published but further high quality research is needed to understand their mechanisms of action, their limits, and their clinical efficacy.

Platelet-rich plasma favors proliferation of canine adipose-derived mesenchymal stem cells in methacrylate-endcapped caprolactone porous scaffold niches

Osteoarticular pathologies very often require an implementation therapy to favor regeneration processes of bone, cartilage and/or tendons. Clinical approaches performed on osteoarticular complications in dogs constitute an ideal model for human clinical translational applications. The adipose-derived mesenchymal stem cells (ASCs) have already been used to accelerate and facilitate the regenerative process. ASCs can be maintained in vitro and they can be differentiated to osteocytes or chondrocytes offering a good tool for cell replacement therapies in human and veterinary medicine. Although ACSs can be easily obtained from adipose tissue, the amplification process is usually performed by a time consuming process of successive passages. In this work, we use canine ASCs obtained by using a Bioreactor device under GMP cell culture conditions that produces a minimum of 30 million cells within 2 weeks. This method provides a rapid and aseptic method for production of sufficient stem cells with potential further use in clinical applications. We show that plasma rich in growth factors (PRGF) treatment positively contributes to viability and proliferation of canine ASCs into caprolactone 2-(methacryloyloxy) ethyl ester (CLMA) scaffolds. This biomaterial does not need additional modifications for cASCs attachment and proliferation. Here we propose a framework based on a combination of approaches that may contribute to increase the therapeutical capability of stem cells by the use of PRGF and compatible biomaterials for bone and connective tissue regeneration.

Regenerative medicine in rheumatic disease-progress in tissue engineering

Joint destruction occurs in both osteoarthritis and rheumatoid arthritis. Even in the era of biologic agents, this destruction can be delayed but not averted. As cartilage has limited ability to self-regenerate, joint arthroplasty is required. Here, we outline current tissue engineering procedures (including autologous chondrocyte implantation and in situ mesenchymal stem cell recruitment) that are routinely applied for the regenerative treatment of injured or early osteoarthritic cartilage. Potential future regenerative therapies, including administration of multipotent or pluripotent stem cells, are also discussed. In the future, cell-free, material-based (for cartilage lesions) or cell-free, factor-based (for osteoarthritic cartilage) therapies to facilitate the recruitment of repair cells and improve cartilage metabolism are likely to become more important. Moreover, delivery of anti-inflammatory factors or immunomodulatory cells could be a regenerative treatment option for rheumatoid arthritis. Tissue engineering faces a crucial phase to translate products into clinical routine and the regulatory framework for cell-based products in particular is an important issue.

Mesenchymal stem cells for cartilage repair in osteoarthritis

Osteoarthritis (OA) is a degenerative disease of the connective tissue and progresses with age in the older population or develops in young athletes following sports-related injury. The articular cartilage is especially vulnerable to damage and has poor potential for regeneration because of the absence of vasculature within the tissue. Normal load-bearing capacity and biomechanical properties of thinning cartilage are severely compromised during the course of disease progression. Although surgical and pharmaceutical interventions are currently available for treating OA, restoration of normal cartilage function has been difficult to achieve. Since the tissue is composed primarily of chondrocytes distributed in a specialized extracellular matrix bed, bone marrow stromal cells (BMSCs), also known as bone marrow-derived 'mesenchymal stem cells' or 'mesenchymal stromal cells', with inherent chondrogenic differentiation potential appear to be ideally suited for therapeutic use in cartilage regeneration. BMSCs can be easily isolated and massively expanded in culture in an undifferentiated state for therapeutic use. Owing to their potential to modulate local microenvironment via anti-inflammatory and immunosuppressive functions, BMSCs have an additional advantage for allogeneic application. Moreover, by secreting various bioactive soluble factors, BMSCs can protect the cartilage from further tissue destruction and facilitate regeneration of the remaining progenitor cells in situ. This review broadly describes the advances made during the last several years in BMSCs and their therapeutic potential for repairing cartilage damage in OA.

Mesenchymal stem cells in osteoarticular pediatric diseases: an update

Cellular therapy has gained an increasing popularity in recent years. Mesenchymal stem cells (MSCs) have the potential to differentiate into bone, cartilage, or fat tissue. In recent studies, these cells have also shown healing capability by improving angiogenesis and preventing fibrosis, which could have a role in tissue repair and tissue regeneration. Preclinical and clinical orthopedic studies conducted in the adult population support the use of MSCs for bone-healing problems, early stages of osteonecrosis, and local bone defects. Only a few published studies support the use of MSCs in pediatric osteoarticular disorders, probably due to the unknown long-term results of cellular therapy. The purpose of this review is to explain the mechanism by which MSCs could exhibit a therapeutic role in pediatric osteoarticular disorders.

Concise review: the clinical application of mesenchymal stem cells for musculoskeletal regeneration: current status and perspectives

Regenerative therapies in the musculoskeletal system are based on the suitable application of cells, biomaterials, and/or factors. For an effective approach, numerous aspects have to be taken into consideration, including age, disease, target tissue, and several environmental factors. Significant research efforts have been undertaken in the last decade to develop specific cell-based therapies, and in particular adult multipotent mesenchymal stem cells hold great promise for such regenerative strategies. Clinical translation of such therapies, however, remains a work in progress. In the clinical arena, autologous cells have been harvested, processed, and readministered according to protocols distinct for the target application. As outlined in this review, such applications range from simple single-step approaches, such as direct injection of unprocessed or concentrated blood or bone marrow aspirates, to fabrication of engineered constructs by seeding of natural or synthetic scaffolds with cells, which were released from autologous tissues and propagated under good manufacturing practice conditions (for example, autologous chondrocyte implantation). However, only relatively few of these cell-based approaches have entered the clinic, and none of these treatments has become a "standard of care" treatment for an orthopaedic disease to date. The multifaceted reasons for the current status from the medical, research, and regulatory perspectives are discussed here. In summary, this review presents the scientific background, current state, and implications of clinical mesenchymal stem cell application in the musculoskeletal system and provides perspectives for future developments.

Autologous stromal vascular fraction therapy for rheumatoid arthritis: rationale and clinical safety

Advancements in rheumatoid arthritis (RA) treatment protocols and introduction of targeted biological therapies have markedly improved patient outcomes, despite this, up to 50% of patients still fail to achieve a significant clinical response. In veterinary medicine, stem cell therapy in the form of autologous stromal vascular fraction (SVF) is an accepted therapeutic modality for degenerative conditions with 80% improvement and no serious treatment associated adverse events reported. Clinical translation of SVF therapy relies on confirmation of veterinary findings in targeted patient populations. Here we describe the rationale and preclinical data supporting the use of autologous SVF in treatment of RA, as well as provide 1, 3, 6, and 13 month safety outcomes in 13 RA patients treated with this approach.

The potential of human fetal mesenchymal stem cells for off-the-shelf bone tissue engineering application

Mesenchymal stem cells (MSCs) have become one of the most promising cell sources for bone tissue engineering (BTE) applications. In this review, we first highlight recent progress in the understanding of MSC biology, their in vivo niche, multi-faceted contribution to fracture healing and bone re-modelling, and their role in BTE. A literature review from clinicaltrials.gov and Pubmed on clinical usage of MSC for both orthopedic and non-orthopedic indications suggests that translational use of MSC for BTE indications is likely to bear fruit in the ensuing decade. Last, we disscuss the profound influence of ontological and antomical origins of MSC on their proliferation and osteogenesis and demonstrated human fetal MSC (hfMSC) as a superior cellular candidate for off-the-shelf BTE applications. This relates to their superior proliferation capacity, more robust osteogenic potential and lower immunogenecity, as compared to MSC from perinatal and postnatal sources. Furthermore, we discuss our experience in developing a hfMSC based BTE strategy with the integrated use of bioreactor-based dynamic priming within macroporous scaffolds, now ready for evaluation in clinical trials. In conclusion, hfMSC is likely the most promising cell source for allogeneic based BTE application, with proven advantages compared to other MSC based ones.

Prospects for translational regenerative medicine

Translational medicine is an evolutional concept that encompasses the rapid translation of basic research for use in clinical disease diagnosis, prevention and treatment. It follows the idea "from bench to bedside and back", and hence relies on cooperation between laboratory research and clinical care. In the past decade, translational medicine has received unprecedented attention from scientists and clinicians and its fundamental principles have penetrated throughout biomedicine, offering a sign post that guides modern medical research toward a patient-centered focus. Translational regenerative medicine is still in its infancy, and significant basic research investment has not yet achieved satisfactory clinical outcomes for patients. In particular, there are many challenges associated with the use of cell- and tissue-based products for clinical therapies. This review summarizes the transformation and global progress in translational medicine over the past decade. The current obstacles and opportunities in translational regenerative medicine are outlined in the context of stem cell therapy and tissue engineering for the safe and effective regeneration of functional tissue. This review highlights the requirement for multi-disciplinary and inter-disciplinary cooperation to ensure the development of the best possible regenerative therapies within the shortest timeframe possible for the greatest patient benefit.

Mesenchymal stem cells in osteoarticular diseases

Multipotent mesenchymal stromal cells or mesenchymal stem cells (MSCs) are mainly isolated from bone marrow or fat tissue. Owing to their potential for multilineage differentiation towards bone, cartilage and fat tissue, they were initially evaluated in innovative strategies for tissue engineering. More recently, they have gained interest for their immunomodulatory properties and have been tested in various clinical trials that aim to modulate the host immune response in graft-versus-host disease or autoimmune diseases. MSC-mediated immunomodulation occurs through the secretion of soluble mediators. The clinical applications of MSCs for rheumatic diseases focus on their potential to promote tissue repair/regeneration and prevent inflammation. This article will focus on the mechanisms by which MSCs might exhibit a therapeutic potential in rheumatology. Special attention is given to their potential for innovative future strategies.