Autologous bone marrow stromal cell transplantation for repair of full-thickness articular cartilage defects in human patellae: two case reports

From ‘Blade Runner’ to ‘Stem-Cell Player’ and beyond

Modern athletes are constantly susceptible to performance-threatening injury as they push their bodies to greater limits and endure higher physical stresses. Loss of performance and training time can adversely and permanently affect a sportsperson’s career. Now more than ever with advancing medical technology the answer may lie in biologic therapy. We have been using peripheral blood stem cells (PBSC) clinically and have been able to demonstrate that stem cells differentiate into target cells to enable regenerative repair. The potential of this technique as a regenerative agent can be seen in three broad applications: 1) articular cartilage, 2) bone and 3) soft tissue. This article highlights the successful cases, among many, in all three of these applications.

Effective, safe nonviral gene transfer to preserve the chondrogenic differentiation potential of human mesenchymal stem cells

BACKGROUND

Genetic modification of mesenchymal stem cells (MSCs) comprises a promising tool to generate cell- and gene-based platforms for regenerative approaches of articular cartilage repair. In the present study, we systematically screened a panel of 15 nonviral compounds for their ability to promote safe, efficient and durable gene expression in human bone marrow-derived MSCs (hMSCS) without impeding their commitment towards chondrogenic differentiation.

METHODS

Primary hMSCs were transfected with plasmid vectors carrying sequences for the Photinus pyralis luciferase Escherichia coli β-galactosidase, or human insulin-like growth factor I via 15 nonviral formulations. Transgene expression and transfection efficiencies were monitored for each component in parallel with the effects on cell viability and cytotoxicity. Upon optimization, the most promising reagent was then evaluated for a possible influence on the chondrogenic potential of hMSCs.

RESULTS

Among all formulations tested, GeneJammer® gave the best results for transgene expression and transfection efficacy (25-14% from days 2-21 in monolayer cultures and 35% in 21-day aggregate cultures), allowing for high levels of viability (92-94%) and modest cytotoxicity (< 12%). Most notably, the application of this reagent did not affect the potential of the cells for chondrogenic differentiation when maintained in long-term (21 days) three-dimensional (aggregate) cultures.

CONCLUSIONS

The data indicate that safe, efficient transgene expression can be achieved in hMSCs over time using the nonviral GeneJammer® compound, showing promise for future therapeutic settings aiming to treat human articular cartilage disorders.

Clinical use of bone marrow, bone marrow concentrate, and expanded bone marrow mesenchymal stem cells in cartilage disease

Mesenchymal stem cells (MSCs) from bone marrow (BM) are widely used for bone and less for cartilage tissue regeneration due to their self-renewal and differentiating properties into osteogenic or chondrogenic lineages. This review considers the last decade of clinical trials involving a two-step procedure, by expanding in vitro MSCs from BM, or the so called "one-step" procedure, using BM in toto or BM concentrate, for the regeneration of cartilage and osteochondral tissue defects. The following conclusions were drawn: (1) Cartilage defects that can be repaired by the two-step technique are about twice the size as those where the one-step method is used; (2) the two-step procedure is especially used for the treatment of osteoarthritic lesions, whereas the one-step procedure is used for osteochondral defects; (3) the number of transplanted cells ranges between 3.8×10(6) and 11.2×10(6) cells/mL, and the period of cell culture expansion of implanted MSCs varies widely with regard to the two-step procedure; (4) hyaluronic or collagenic scaffolds are used in all the clinical studies analyzed for both techniques; (5) the follow-up of the two-step procedure is longer than that of the one-step method, despite having a lower number of patients; and, finally, (6) the mean age of the patients (about 39 years old) is similar in both procedures. Clinical results underline the safety and good and encouraging outcomes for the use of MSCs in clinics. Although more standardized procedures are required, the length of follow-up and the number of patients observed should be augmented, and the design of trials should be implemented to achieve evidence-based results.

Surface markers for chondrogenic determination: a highlight of synovium-derived stem cells

Cartilage tissue engineering is a promising field in regenerative medicine that can provide substantial relief to people suffering from degenerative cartilage disease. Current research shows the greatest chondrogenic potential for healthy articular cartilage growth with minimal hypertrophic differentiation to be from mesenchymal stem cells (MSCs) of synovial origin. These stem cells have the capacity for differentiation into multiple cell lineages related to mesenchymal tissue; however, evidence exists for cell surface markers that specify a greater potential for chondrogenesis than other differentiation fates. This review will examine relevant literature to summarize the chondrogenic differentiation capacities of tested synovium-derived stem cell (SDSC) surface markers, along with a discussion about various other markers that may hold potential, yet require further investigation. With this information, a potential clinical benefit exists to develop a screening system for SDSCs that will produce the healthiest articular cartilage possible.

A Novel, Minimally-Invasive Technique of Cartilage Repair in the Human Knee Using Arthroscopic Microfracture and Injections of Mesenchymal Stem Cells and Hyaluronic Acid—A Prospective Comparative Study on Safety and Short-Term Efficacy

Introduction: Most current cell-based cartilage repair techniques require some form of scaffolds and 2 separate surgical procedures. We propose a novel, scaffold-less technique of cartilage repair in the human knee that combines arthroscopic microfracture and outpatient intra-articular injections of autologous bone marrow-derived mesenchymal stem cells (MSCs) and hyaluronic acid (HA). Materials and Methods: Seventy matched (age, sex, lesion size) knees with symptomatic cartilage defects underwent cartilage repair with the proposed technique (n = 35) or an open technique (n = 35) in which the MSCs were implanted beneath a sutured periosteal patch over the defect. Prospective evaluation of both groups were performed using the International Cartilage Repair Society (ICRS) Cartilage Injury Evaluation Package, which included questions from the Short-Form (SF-36) Health Survey, International Knee Documentation Committee (IKDC) subjective knee evaluation form, Lysholm knee scale, and Tegner activity level scale. Postoperative magnetic resonance imaging (MRI) evaluation was also performed at 1 year for most patients. Results: There were no clinically significant adverse events reported through the course of our study. At the final follow-up (mean = 24.5 months), there was significant improvement in mean IKDC, Lysholm, SF-36 physical component score and visual analogue pain scores in both treatment groups. Conclusion: In the short term, the results of this novel technique are comparable to the open procedure with the added advantages of being minimally invasive and requiring only a single operation under general anaesthesia. Its safety has been validated and its efficacy is currently being evaluated in an ongoing randomised controlled trial. Key words: Chondral, Novel, Osteoarthritis, Regeneration

Mesenchymal stem cell therapy in the sports knee: where are we in 2011?

Background:

The relationship between biological tissue healing following knee injury or surgery and long-term clinical outcome has come to the forefront of sports medicine practice. This has led many knee surgeons to incorporate biologically mediated healing factors into the management of knee injuries. In particular, the clinical use of mesenchymal stem cells has opened new horizons.

Evidence Acquisition:

Relevant studies were identified through a search of PubMed from January 2000 to April 2011, combining the term mesenchymal stem cells with articular cartilage, anterior cruciate ligament, and meniscus. Relevant citations from the reference lists of selected studies were also reviewed.

Results:

Knee injury treatment with mesenchymal stem cells shows potential. Most reports represent animal model studies; few advances have been translated to human clinical applications.

Conclusion:

Mesenchymal stem cell use to promote healing following knee injury is likely to increase. There are scientific methodological concerns and ethical and legal issues regarding mesenchymal stem cell use for treating knee injuries.

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.

Indian hedgehog gene transfer is a chondrogenic inducer of human mesenchymal stem cells

Introduction

To date, no single most-appropriate factor or delivery method has been identified for the purpose of mesenchymal stem cell (MSC)-based treatment of cartilage injury. Therefore, in this study we tested whether gene delivery of the growth factor Indian hedgehog (IHH) was able to induce chondrogenesis in human primary MSCs, and whether it was possible by such an approach to modulate the appearance of chondrogenic hypertrophy in pellet cultures in vitro.

Methods

First-generation adenoviral vectors encoding the cDNA of the human IHH gene were created by cre-lox recombination and used alone or in combination with adenoviral vectors, bone morphogenetic protein-2 (Ad.BMP-2), or transforming growth factor beta-1 (Ad.TGF-β1) to transduce human bone-marrow derived MSCs at 5 × 10² infectious particles/cell. Thereafter, 3 × 10⁵ cells were seeded into aggregates and cultured for 3 weeks in serum-free medium, with untransduced or marker gene transduced cultures as controls. Transgene expressions were determined by ELISA, and aggregates were analysed histologically, immunohistochemically, biochemically and by RT-PCR for chondrogenesis and hypertrophy.

Results

IHH, TGF-β1 and BMP-2 genes were equipotent inducers of chondrogenesis in primary MSCs, as evidenced by strong staining for proteoglycans, collagen type II, increased levels of glycosaminoglycan synthesis, and expression of mRNAs associated with chondrogenesis. IHH-modified aggregates, alone or in combination, also showed a tendency to progress towards hypertrophy, as judged by the expression of alkaline phosphatase and stainings for collagen type X and Annexin 5.

Conclusion

As this study provides evidence for chondrogenic induction of MSC aggregates in vitro via IHH gene delivery, this technology may be efficiently employed for generating cartilaginous repair tissues in vivo.

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.

Magnetic resonance imaging of ferumoxide-labeled mesenchymal stem cells in cartilage defects: in vitro and in vivo investigations

The purpose of this study was to (1) compare three different techniques for ferumoxide labeling of mesenchymal stem cells (MSCs), (2) evaluate if ferumoxide labeling allows in vivo tracking of matrix-associated stem cell implants (MASIs) in an animal model, and (3) compare the magnetic resonance imaging (MRI) characteristics of ferumoxide-labeled viable and apoptotic MSCs. MSCs labeled with ferumoxide by simple incubation, protamine transfection, or Lipofectin transfection were evaluated with MRI and histopathology. Ferumoxide-labeled and unlabeled viable and apoptotic MSCs in osteochondral defects of rat knee joints were evaluated over 12 weeks with MRI. Signal to noise ratios (SNRs) of viable and apoptotic labeled MASIs were tested for significant differences using t-tests. A simple incubation labeling protocol demonstrated the best compromise between significant magnetic resonance signal effects and preserved cell viability and potential for immediate clinical translation. Labeled viable and apoptotic MASIs did not show significant differences in SNR. Labeled viable but not apoptotic MSCs demonstrated an increasing area of T2 signal loss over time, which correlated to stem cell proliferation at the transplantation site. Histopathology confirmed successful engraftment of viable MSCs. The engraftment of iron oxide-labeled MASIs by simple incubation can be monitored over several weeks with MRI. Viable and apoptotic MASIs can be distinguished via imaging signs of cell proliferation at the transplantation site.

Same or not the same? Comparison of adipose tissue-derived versus bone marrow-derived mesenchymal stem and stromal cells

Mesenchymal stem/stromal cells (MSCs) comprise a heterogeneous population of cells with multilineage differentiation potential, the ability to modulate oxidative stress, and secrete various cytokines and growth factors that can have immunomodulatory, angiogenic, anti-inflammatory and anti-apoptotic effects. Recent data indicate that these paracrine factors may play a key role in MSC-mediated effects in modulating various acute and chronic pathological conditions. MSCs are found in virtually all organs of the body. Bone marrow-derived MSCs (BM-MSCs) were discovered first, and the bone marrow was considered the main source of MSCs for clinical application. Subsequently, MSCs have been isolated from various other sources with the adipose tissue, serving as one of the alternatives to bone marrow. Adipose tissue-derived MSCs (ASCs) can be more easily isolated; this approach is safer, and also, considerably larger amounts of ASCs can be obtained compared with the bone marrow. ASCs and BM-MSCs share many biological characteristics; however, there are some differences in their immunophenotype, differentiation potential, transcriptome, proteome, and immunomodulatory activity. Some of these differences may represent specific features of BM-MSCs and ASCs, while others are suggestive of the inherent heterogeneity of both BM-MSC and ASC populations. Still other differences may simply be related to different isolation and culture protocols. Most importantly, despite the minor differences between these MSC populations, ASCs seem to be as effective as BM-MSCs in clinical application, and, in some cases, may be better suited than BM-MSCs. In this review, we will examine in detail the ontology, biology, preclinical, and clinical application of BM-MSCs versus ASCs.

Interaction between adipose tissue-derived mesenchymal stem cells and regulatory T-cells

Mesenchymal stem cells (MSCs) exhibit immunosuppressive capabilities, which have evoked interest in their application as cell therapy in transplant patients. So far it has been unclear whether allogeneic MSCs and host regulatory T-cells (Tregs) functionally influence each other. We investigated the interaction between both cell types using perirenal adipose tissue-derived MSCs (ASCs) from kidney donors and Tregs from blood bank donors or kidney recipients 6 months after transplantation. The immunomodulatory capacity of ASCs was not prejudiced by both Tregs from healthy donors and Tregs from graft recipients, indicating that ASCs were not targeted by the inhibitory effects of Tregs and vice versa. In addition, Tregs supported ASC function, as they did not alter the secretion of IFN-γ by immune cells and hence contributed to ASC activation and efficiency. ASCs exerted their suppressive role by expressing IDO, reducing levels of TNF-α, and by inducing the production of IL-10 in effector cells and Tregs. In conclusion, this study presents evidence that donor ASCs and acceptor Tregs do not impair each other's function and therefore encourages the use of MSC therapy for the prevention of graft rejection in solid organ transplantation.

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.

BMPs are mediators in tissue crosstalk of the regenerating musculoskeletal system

The musculoskeletal system is a tight network of many tissues. Coordinated interplay at a biochemical level between tissues is essential for development and repair. Traumatic injury usually affects several tissues and represents a large challenge in clinical settings. The current demand for potent growth factors in such applications thus accompanies the keen interest in molecular mechanisms and orchestration of tissue formation. Of special interest are multitasking growth factors that act as signals in a variety of cell types, both in a paracrine and in an autocrine manner, thereby inducing cell differentiation and coordinating not only tissue assembly at specific sites but also maturation and homeostasis. We concentrate here on bone morphogenetic proteins (BMPs), which are important crosstalk mediators known for their irreplaceable roles in vertebrate development. The molecular crosstalk during embryonic musculoskeletal tissue formation is recapitulated in adult repair. BMPs act at different levels from the initiation to maturation of newly formed tissue. Interestingly, this is influenced by the spatiotemporal expression of different BMPs, their receptors and co-factors at the site of repair. Thus, the regenerative potential of BMPs needs to be evaluated in the context of highly connected tissues such as muscle and bone and might indeed be different in more poorly connected tissues such as cartilage. This highlights the need for an understanding of BMP signaling across tissues in order to eventually improve BMP regenerative potential in clinical applications. In this review, the distinct members of the BMP family and their individual contribution to musculoskeletal tissue repair are summarized by focusing on their paracrine and autocrine functions.

Comparative analysis of protein expression of three stem cell populations: models of cytokine delivery system in vivo

Several mechanisms mediate the regenerative and reparative capacity of stem cells, including cytokine secretion; therefore these cells can act as delivery systems of therapeutic molecules. Here we begin to address the molecular and cellular basis of their regenerative potential by characterizing the proteomic profile of human embryonic stem cells (hESCs), mesenchymal stem cells (hMSCs) and marrow isolated adult multilineage inducible (MIAMI) cells, followed by analysis of the secretory profile of the latter stem cell population. Proteomic analysis establishes the closer relationship between hMSCs and MIAMI cells, while hESCs are more divergent. However, MIAMI cells appear to have more proteins in common with hESCs than hMSCs. Proteins characteristic of hMSCs include transgelin-2, phosphatidylethanolamine-binding protein 1 (PEBP1), Heat-Shock 20 kDa protein (HSP20/HSPβ6), and programmed cell death 6-interacting protein (PDC6I) among others. MIAMI cells are characterized by the high level expression of ubiquitin carboxyl-terminal hydrolase isoenzyme L1 (UCHL1), 14-3-3 zeta, HSP27 (HSPβ1), and tropomyosin 4 and 3. For hESC, elongation factor Tu (EFTu), isocitrate dehydrogenase (IDH1) and the peroxiredoxins 1, 2, and 6 (PRDX1, PRDX2, and PRDX6) were the most characteristic. Secretome analysis indicates that MIAMI cells secrete higher levels of vascular endothelial growth factor (VEGF), Fractalkine, Interleukin-6, interlukin-8, and growth related oncogene (GRO), compared to hMSCs. These soluble mediators are known to play key roles in angiogenesis, arteriogenesis, atheroprotection, immunomodulation, neuroprotection, axonal growth, progenitor cell migration, and prevention of apoptosis. All these roles are consistent with a reparative pro-survival secretory phenotype. We further discuss the potential of these cells as therapeutic vehicles.

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.

General principles for the regeneration of bone and cartilage

For the regeneration of bone and cartilage, mesenchymal stem cells are currently used invitro and in-vivo. For bone, the existence of viable cells, scaffolds, mechanical environment, growth factors and vascularization are of paramount importance. Mesenchymal stem cells can be harvested from the bone marrow using minimally invasive techniques. Centrifugation can increase the number of transplanted cells per volume. The use of cell therapy is under current clinical investigation and the benefit from these systems has to be proven in level I studies. For cartilage, current techniques recruiting stem cells from the subchondral bone have been demonstrated to be nearly as effective as autologous chondrocyte transplantation, requiring less invasive surgery. The efficacy of mesenchymal stem cell concentrates remains to be proven. There is high potential for tissue engineered joint surfaces to become an option for joint surface defects and degeneration.

Human stromal (mesenchymal) stem cells: basic biology and current clinical use for tissue regeneration

Human stromal (mesenchymal) stem cells (hMSC) represent a group of non-hematopoietic stem cells present in the bone marrow stroma and the stroma of other organs including subcutaneous adipose tissue, placenta, and muscles. They exhibit the characteristics of somatic stem cells of self-renewal and multi-lineage differentiation into mesoderm-type of cells, e.g., to osteoblasts, adipocytes, chondrocytes and possibly other cell types including hepatocytes and astrocytes. Due to their ease of culture and multipotentiality, hMSC are increasingly employed as a source for cells suitable for a number of clinical applications, e.g., non-healing bone fractures and defects and also non-skeletal degenerative diseases like heart failure. Currently, the numbers of clinical trials that employ MSC are increasing. However, several biological and biotechnological challenges need to be overcome to benefit from the full potential of hMSC. In this current review, we present some of the most important and recent advances in understanding of the biology of hMSC and their current and potential use in therapy.

Fibrin glue as the cell-delivery vehicle for mesenchymal stromal cells in regenerative medicine

The use of tissue-engineering techniques such as stem-cell therapy to renew injured tissues is a promising strategy in regenerative medicine. As a cell-delivery vehicle, fibrin glues (FG) facilitate cell attachment, growth and differentiation and, ultimately, tissue formation and organization by its three-dimensional structure. Numerous studies have provided evidence that stromal cells derived from bone marrow (bone marrow stromal cells; BMSC) and adipose tissue (adipose-derived stromal cells; ADSC) contain a population of adult multipotent mesenchymal stromal cells (MSC) and endothelial progenitor cells that can differentiate into several lineages. By combining MSC with FG, the implantation could take advantage of the mutual benefits. Researchers and physicians have pinned their hopes on stem cells for developing novel approaches in regenerative medicine. This review focuses on the therapeutic potential of MSC with FG in bone defect reconstruction, cartilage and tendon injury repair, ligament, heart and nerve regeneration, and, furthermore, wound healing.

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.

Cartilage repair and joint preservation: medical and surgical treatment options

BACKGROUND

Articular cartilage defects are most often caused by trauma and osteoarthritis and less commonly by metabolic disorders of the subchondral bone, such as osteonecrosis and osteochondritis dissecans. Such defects do not heal spontaneously in adults and can lead to secondary osteoarthritis. Medications are indicated for symptomatic relief. Slow-acting drugs in osteoarthritis (SADOA), such as glucosamine and chondroitin, are thought to prevent cartilage degeneration. Reconstructive surgical treatment strategies aim to form a repair tissue or to unload compartments of the joint with articular cartilage damage.

METHODS

In this article, we selectively review the pertinent literature, focusing on original publications of the past 5 years and older standard texts. Particular attention is paid to guidelines and clinical studies with a high level of evidence, along with review articles, clinical trials, and book chapters.

RESULTS

There have been only a few randomized trials of medical versus surgical treatments. Pharmacological therapies are now available that are intended to treat the cartilage defect per se, rather than the associated symptoms, yet none of them has yet been shown to slow or reverse the progression of cartilage destruction. Surgical débridement of cartilage does not prevent the progression of osteoarthritis and is thus not recommended as the sole treatment. Marrow-stimulating procedures and osteochondral grafts are indicated for small focal articular cartilage defects, while autologous chondrocyte implantationis mainly indicated for larger cartilage defects. These surgical reconstructive techniques play a lesser role in the treatment of osteoarthritis. Osteotomy near the knee joint is indicated for axial realignment when unilateral osteoarthritis of the knee causes axis deviation.

CONCLUSION

Surgical reconstructive techniques can improve joint function and thereby postpone the need for replacement of the articular surface with an artificial joint.

Mesenchymal stem cells and articular cartilage repair: clinical studies and future direction

Cartilage is frequently injured but shows little capacity for repair. Current treatment options include the use of procedures that stimulate repair through the stimulation of subchondral bone marrow and result in the formation of fibrocartilage. There is considerable interest in the use of cell-based treatment strategies and there are limited studies describing the use of mesenchymal stem cells for cartilage repair with promising early results. This paper reviews the current treatment strategies for articular cartilage, describes use of mesenchymal stem cells for articular cartilage repair along with the results of clinical studies, and describes the future direction that these strategies are likely to take.

Mesenchymal stem cells and articular cartilage repair: clinical studies and future direction

Cartilage is frequently injured but shows little capacity for repair. Current treatment options include the use of procedures that stimulate repair through the stimulation of subchondral bone marrow and result in the formation of fibrocartilage. There is considerable interest in the use of cell-based treatment strategies and there are limited studies describing the use of mesenchymal stem cells for cartilage repair with promising early results. This paper reviews the current treatment strategies for articular cartilage, describes use of mesenchymal stem cells for articular cartilage repair along with the results of clinical studies, and describes the future direction that these strategies are likely to take.

Epigenetic regulation of mesenchymal stem cells: a focus on osteogenic and adipogenic differentiation

Stem cells are characterized by their capability to self-renew and terminally differentiate into multiple cell types. Somatic or adult stem cells have a finite self-renewal capacity and are lineage-restricted. The use of adult stem cells for therapeutic purposes has been a topic of recent interest given the ethical considerations associated with embryonic stem (ES) cells. Mesenchymal stem cells (MSCs) are adult stem cells that can differentiate into osteogenic, adipogenic, chondrogenic, or myogenic lineages. Owing to their ease of isolation and unique characteristics, MSCs have been widely regarded as potential candidates for tissue engineering and repair. While various signaling molecules important to MSC differentiation have been identified, our complete understanding of this process is lacking. Recent investigations focused on the role of epigenetic regulation in lineage-specific differentiation of MSCs have shown that unique patterns of DNA methylation and histone modifications play an important role in the induction of MSC differentiation toward specific lineages. Nevertheless, MSC epigenetic profiles reflect a more restricted differentiation potential as compared to ES cells. Here we review the effect of epigenetic modifications on MSC multipotency and differentiation, with a focus on osteogenic and adipogenic differentiation. We also highlight clinical applications of MSC epigenetics and nuclear reprogramming.

Terminal differentiation is not a major determinant for the success of stem cell therapy - cross-talk between muscle-derived stem cells and host cells

We have found that when muscle-derived stem cells (MDSCs) are implanted into a variety of tissues only a small fraction of the donor cells can be found within the regenerated tissues and the vast majority of cells are host derived. This observation has also been documented by other investigators using a variety of different stem cell types. It is speculated that the transplanted stem cells release factors that modulate repair indirectly by mobilizing the host's cells and attracting them to the injury site in a paracrine manner. This process is loosely called a 'paracrine mechanism', but its effects are not necessarily restricted to the injury site. In support of this speculation, it has been reported that increasing angiogenesis leads to an improvement of cardiac function, while inhibiting angiogenesis reduces the regeneration capacity of the stem cells in the injured vascularized tissues. This observation supports the finding that most of the cells that contribute to the repair process are indeed chemo-attracted to the injury site, potentially through host neo-angiogenesis. Since it has recently been observed that cells residing within the walls of blood vessels (endothelial cells and pericytes) appear to represent an origin for post-natal stem cells, it is tempting to hypothesize that the promotion of tissue repair, via neo-angiogenesis, involves these blood vessel-derived stem cells. For non-vascularized tissues, such as articular cartilage, the regenerative property of the injected stem cells still promotes a paracrine, or bystander, effect, which involves the resident cells found within the injured microenvironment, albeit not through the promotion of angiogenesis. In this paper, we review the current knowledge of post-natal stem cell therapy and demonstrate the influence that implanted stem cells have on the tissue regeneration and repair process. We argue that the terminal differentiation capacity of implanted stem cells is not the major determinant of the cells regenerative potential and that the paracrine effect imparted by the transplanted cells plays a greater role in the regeneration process.

Stem cell use in musculoskeletal disorders

Human stem cells derived from bone marrow are currently used in clinical medicine for bone and cartilage repair for injuries such as meniscal tears. New clinical stem cell studies underway include the treatment of patients with spinal cord injuries. Rapid advances in stem cell science are opening new avenues for drug discovery and may lead to new uses of stem cells for other musculoskeletal disorders.

Hydrogels for the repair of articular cartilage defects

The repair of articular cartilage defects remains a significant challenge in orthopedic medicine. Hydrogels, three-dimensional polymer networks swollen in water, offer a unique opportunity to generate a functional cartilage substitute. Hydrogels can exhibit similar mechanical, swelling, and lubricating behavior to articular cartilage, and promote the chondrogenic phenotype by encapsulated cells. Hydrogels have been prepared from naturally derived and synthetic polymers, as cell-free implants and as tissue engineering scaffolds, and with controlled degradation profiles and release of stimulatory growth factors. Using hydrogels, cartilage tissue has been engineered in vitro that has similar mechanical properties to native cartilage. This review summarizes the advancements that have been made in determining the potential of hydrogels to replace damaged cartilage or support new tissue formation as a function of specific design parameters, such as the type of polymer, degradation profile, mechanical properties and loading regimen, source of cells, cell-seeding density, controlled release of growth factors, and strategies to cause integration with surrounding tissue. Some key challenges for clinical translation remain, including limited information on the mechanical properties of hydrogel implants or engineered tissue that are necessary to restore joint function, and the lack of emphasis on the ability of an implant to integrate in a stable way with the surrounding tissue. Future studies should address the factors that affect these issues, while using clinically relevant cell sources and rigorous models of repair.

Current strategies for osteochondral regeneration: from stem cells to pre-clinical approaches

Damaged cartilage tissue has no functional replacement alternatives and current therapies for bone injury treatment are far from being the ideal solutions emphasizing an urgent need for alternative therapeutic approaches for osteochondral (OC) regeneration. The tissue engineering field provides new possibilities for therapeutics and regeneration in rheumatology and orthopaedics, holding the potential for improving the quality of life of millions of patients by exploring new strategies towards the development of biological substitutes to maintain, repair and improve OC tissue function. Numerous studies have focused on the development of distinct tissue engineering strategies that could result in promising solutions for this delicate interface. In order to outperform currently used methods, novel tissue engineering approaches propose, for example, the design of multi-layered scaffolds, the use of stem cells, bioreactors or the combination of clinical techniques.

Safety of autologous bone marrow-derived mesenchymal stem cell transplantation for cartilage repair in 41 patients with 45 joints followed for up to 11 years and 5 months

Among autologous somatic stem cells, bone marrow-derived mesenchymal stem cells (BMSCs) are the most widely used worldwide to repair not only mesenchymal tissues (bone, cartilage) but also many other kinds of tissues, including heart, skin, and liver. Autologous BMSCs are thought to be safe because of the absence of immunological reaction and disease transmission. However, it is possible that they will form tumours during long-term follow-up. In 1988, we transplanted autologous BMSCs to repair articular cartilage, which was the first such trial ever reported. Subsequently we performed this procedure in about 40 patients. Demonstration that neither partial infections nor tumours appeared in these patients provided strong evidence for the safety of autologous BMSC transplantation. Thus, in this study we checked these patients for tumour development and infections. Between January 1998 and November 2008, 41 patients received 45 transplantations. We checked their records until their last visit. We telephoned or mailed the patients who had not visited the clinics recently to establish whether there were any abnormalities in the operated joints. Neither tumours nor infections were observed between 5 and 137 (mean 75) months of follow-up. Autologous BMSC transplantation is a safe procedure and will be widely used around the world.

Mesenchymal-stem-cell-based experimental and clinical trials: current status and open questions

INTRODUCTION

Mesenchymal stem cells (MSCs) possess remarkable self-renewal ability and are able to differentiate into various cell lineages. MSCs can also enhance tissue repair and angiogenesis through a paracrine mechanism. It has been recognized that these cells hold great promise for tissue regeneration and treatment of immune-related diseases.

AREAS COVERED

This review aims at discussing the mechanisms of MSC-mediated immunomodulation and tissue repair and the related clinical trials, with special emphasis on factors that influence the efficiency of MSC-based therapy, including the source of MSCs, cell passage, cell dose, timing and route of administration.

EXPERT OPINION

MSCs may facilitate tissue repair through cell replacement and/or improving the microenvironment by releasing growth factors. Some of these factors also mediate the immunomodulatory effects of MSCs. It is important to establish global guidelines, protocols and standards for production and clinical trials of MSCs, so that MSCs can become a therapeutic agent with a reliable efficacy and good safety.

Infiltration of plasma rich in growth factors for osteoarthritis of the knee short-term effects on function and quality of life

PURPOSE

Osteoarthritis (OA) is a highly prevalent, chronic, degenerative condition that generates a high expense. Alternative and co-adjuvant therapies to improve the quality of life and physical function of affected patients are currently being sought.

METHODS

A total of 808 patients with knee pathology were treated with PRGF (plasma rich in growth factors), 312 of them with OA of the knee (Outerbridge grades I-IV) and symptoms of >3 months duration met the inclusion criteria and were evaluated to obtain a sample of 261 patients, 109 women and 152 men, with an average age of 48.39. Three intra-articular injections of autologous PRGF were administered at 2-week intervals in outpatient surgery. The process of obtaining PRGF was carried out following the Anitua Technique. Participants were asked to fill out a questionnaire with personal data and the following assessment instruments: VAS, SF-36, WOMAC Index and Lequesne Index before the first infiltration of PRGF and 6 months after the last infiltration.

RESULTS

Statistically significant differences (P < 0.0001) between pre-treatment and follow-up values were found for pain, stiffness and functional capacity in the WOMAC Index; pain and total score, distance and daily life activities in the Lequesne Index; the VAS pain score; and the SF-36 physical health domain. There were no adverse effects related to PRGF infiltration.

CONCLUSION

At 6 months following intra-articular infiltration of PRGF in patients with OA of the knee, improvements in function and quality of life were documented by OA-specific and general clinical assessment instruments. These favourable findings point to consider PRGF as a therapy for OA.

Mesenchymal Progenitor Cells and Their Orthopedic Applications: Forging a Path towards Clinical Trials

Mesenchymal progenitor cells (MPCs) are nonhematopoietic multipotent cells capable of differentiating into mesenchymal and nonmesenchymal lineages. While they can be isolated from various tissues, MPCs isolated from the bone marrow are best characterized. These cells represent a subset of bone marrow stromal cells (BMSCs) which, in addition to their differentiation potential, are critical in supporting proliferation and differentiation of hematopoietic cells. They are of clinical interest because they can be easily isolated from bone marrow aspirates and expanded in vitro with minimal donor site morbidity. The BMSCs are also capable of altering disease pathophysiology by secreting modulating factors in a paracrine manner. Thus, engineering such cells to maximize therapeutic potential has been the focus of cell/gene therapy to date. Here, we discuss the path towards the development of clinical trials utilizing BMSCs for orthopaedic applications. Specifically, we will review the use of BMSCs in repairing critical-sized defects, fracture nonunions, cartilage and tendon injuries, as well as in metabolic bone diseases and osteonecrosis. A review of www.ClinicalTrials.gov of the United States National Institute of Health was performed, and ongoing clinical trials will be discussed in addition to the sentinel preclinical studies that paved the way for human investigations.

Ex vivo cartilage defect model for the evaluation of cartilage regeneration using mesenchymal stem cells

An ex vivo cartilage defect model for the evaluation of cartilage regeneration using mesenchymal stem cells (MSCs) was developed. Porcine chondrocytes and human MSCs were transplanted into cartilage defects created on the porcine osteochondral and chondral discs and cultivated for 3 weeks. Although the regeneration of cartilage-like tissues was observed after the transplantation of chondrocytes to defects on both of the osteochondral and chondral discs, the transplanted MSCs formed cartilage-like tissues only in the defect on the chondral disc, in which an in vivo cartilage-like structure was partly observed, and a degraded tissue was observed in the defect on the osteochondral disc. The effects of medium additives such as serum, transforming growth factor-β3 (TGF-β3), and fibroblast growth factor-2, and the transfection of TGF-β3 gene to MSCs could be clearly estimated using the cartilage defect model. In conclusion, a chondral disc with defects is useful for evaluating cartilage regeneration using MSCs.

Effect of self-assembling peptide, chondrogenic factors, and bone marrow-derived stromal cells on osteochondral repair

OBJECTIVE

The goal of this study was to test the ability of an injectable self-assembling peptide (KLD) hydrogel with or without chondrogenic factors (CF) and allogeneic bone marrow stromal cells (BMSCs) to stimulate cartilage regeneration in a full-thickness, critically-sized, rabbit cartilage defect model in vivo. We used CF treatments to test the hypotheses that CF would stimulate chondrogenesis and matrix production by cells migrating into acellular KLD (KLD+CF) or by BMSCs delivered in KLD (KLD+CF+BMSCs).

DESIGN

Three groups were tested against contralateral untreated controls: KLD, KLD+CF, and KLD+CF+BMSCs, n=6-7. Transforming growth factor-β1 (TGF-β1), dexamethasone, and insulin-like growth factor-1 (IGF-1) were used as CF pre-mixed with KLD and BMSCs before injection. Evaluations included gross, histological, immunohistochemical and radiographic analyses.

RESULTS

KLD without CF or BMSCs showed the greatest repair after 12 weeks with significantly higher Safranin-O, collagen II immunostaining, and cumulative histology scores than untreated contralateral controls. KLD+CF resulted in significantly higher aggrecan immunostaining than untreated contralateral controls. Including allogeneic BMSCs+CF markedly reduced the quality of repair and increased osteophyte formation compared to KLD-alone.

CONCLUSIONS

These data show that KLD can fill full-thickness osteochondral defects in situ and improve cartilage repair as shown by Safranin-O, collagen II immunostaining, and cumulative histology. In this small animal model, the full-thickness critically-sized defect provided access to the marrow, similar in concept to abrasion arthroplasty or spongialization in large animal models, and suggests that combining KLD with these techniques may improve current practice.

Transplant of Primary Human Hepatocytes Cocultured With Bone Marrow Stromal Cells to SCID Alb-uPA Mice

Hepatocytes are vulnerable to loss of function and viability in culture. Modified culture methods have been applied to maintain their functional status. Heterotypic interactions between hepatocytes and nonparenchymal neighbors in liver milieu are thought to modulate cell differentiation. Cocultivation of hepatocyte with various cell types has been applied to mimic the hepatic environment. Bone marrow stromal cells (BMSC) are plastic cell lines capable of transforming to other cell types. In this study hepatocyte coculture with BMSCs achieved long-term function of human hepatocytes in culture for 4 weeks. In vitro functional status of human hepatocytes in BMSC coculture was compared with fibroblast coculture and collagen culture by measuring albumin, human-α-1-antitrypsin (hAAT), urea secretion, CYP450 activity, and staining for intracellular albumin and glycogen. After 2 weeks in culture hepatocytes were retrieved and transplanted to severe combined immunodeficiency/albumin linked-urokinase type plasminogen activator (SCID Alb-uPA) mice and engraft-ment capacity was analyzed by human hepatic-specific function measured by hAAT levels in mouse serum, and Alu staining of mouse liver for human hepatocytes. Hepatocytes from BMSC coculture had significantly higher albumin, hAAT secretion, urea production, and cytochrome P450 (CYP450) activity than other culture groups. Staining confirmed the higher functional status in BMSC coculture. Transplantation of hepatocytes detached from BMSC cocultures showed significantly higher engraftment function than hepatocytes from other culture groups measured by hAAT levels in mouse serum. In conclusion, BMSC coculture has excellent potential for hepatocyte function preservation in vitro and in vivo after transplant. It is possible to use BMSC hepatocyte coculture as a supply of cell therapy in liver disease.