Magnetic Targeted Delivery of Induced Pluripotent Stem Cells Promotes Articular Cartilage Repair

iPSCs chondrogenic differentiation for personalized regenerative medicine: a literature review

Cartilage, an important connective tissue, provides structural support to other body tissues, and serves as a cushion against impacts throughout the body. Found at the end of the bones, cartilage decreases friction and averts bone-on-bone contact during joint movement. Therefore, defects of cartilage can result from natural wear and tear, or from traumatic events, such as injuries or sudden changes in direction during sports activities. Overtime, these cartilage defects which do not always produce immediate symptoms, could lead to severe clinical pathologies. The emergence of induced pluripotent stem cells (iPSCs) has revolutionized the field of regenerative medicine, providing a promising platform for generating various cell types for therapeutic applications. Thus, chondrocytes differentiated from iPSCs become a promising avenue for non-invasive clinical interventions for cartilage injuries and diseases. In this review, we aim to highlight the current strategies used for in vitro chondrogenic differentiation of iPSCs and to explore their multifaceted applications in disease modeling, drug screening, and personalized regenerative medicine. Achieving abundant functional iPSC-derived chondrocytes requires optimization of culture conditions, incorporating specific growth factors, and precise temporal control. Continual improvements in differentiation methods and integration of emerging genome editing, organoids, and 3D bioprinting technologies will enhance the translational applications of iPSC-derived chondrocytes. Finally, to unlock the benefits for patients suffering from cartilage diseases through iPSCs-derived technologies in chondrogenesis, automatic cell therapy manufacturing systems will not only reduce human intervention and ensure sterile processes within isolator-like platforms to minimize contamination risks, but also provide customized production processes with enhanced scalability and efficiency.

Use of human induced pluripotent stem cells for cartilage regeneration in vitro and within chondral defect models of knee joint cartilage in vivo: a Preferred Reporting Items for Systematic Reviews and Meta-Analyses systematic literature review

BACKGROUND AIMS

Articular cartilage has limited regenerative ability when damaged through trauma or disease. Failure to treat focal chondral lesions results in changes that inevitably progress to osteoarthritis. Osteoarthritis is a major contributor to disability globally, which results in significant medical costs and lost wages every year. Human induced pluripotent stem cells (hiPSCs) have long been considered a potential autologous therapeutic option for the treatment of focal chondral lesions. Although there are significant advantages to hiPSCs over other stem cell options, such as mesenchymal and embryonic stem cells, there are concerns regarding their ability to form bona fide cartilage and their tumorgenicity in vivo.

METHODS

The authors carried out a systematic literature review on the use of hiPSCs to produce differentiated progeny capable of producing high-quality cartilage in vitro and regenerate cartilage in osteochondral defects in vivo in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Eight studies were included in the review that used hiPSCs or their derived progeny in xenogeneic transplants in animal models to regenerate cartilage in osteochondral defects of the knee joint. The in vitro-differentiated, hiPSC-derived and in vivo defect repair ability of the hiPSC-derived progeny transplants were assessed.

RESULTS

Most studies reported the generation of high-quality cartilage-producing progeny that were able to successfully repair cartilage defects in vivo. No tumorigenicity was observed.

CONCLUSIONS

The authors conclude that hiPSCs offer a valuable source of cartilage-producing progeny that show promise as an effective cell-based therapy in treating focal chondral lesions.

Research Progress on Stem Cell Therapies for Articular Cartilage Regeneration

Injury of articular cartilage can cause osteoarthritis and seriously affect the physical and mental health of patients. Unfortunately, current surgical treatment techniques that are commonly used in the clinic cannot regenerate articular cartilage. Regenerative medicine involving stem cells has entered a new stage and is considered the most promising way to regenerate articular cartilage. In terms of theories on the mechanism, it was thought that stem cell-mediated articular cartilage regeneration was achieved through the directional differentiation of stem cells into chondrocytes. However, recent evidence has shown that the stem cell secretome plays an important role in biological processes such as the immune response, inflammation regulation, and drug delivery. At the same time, the stem cell secretome can effectively mediate the process of tissue regeneration. This new theory has attributed the therapeutic effect of stem cells to their paracrine effects. The application of stem cells is not limited to exogenous stem cell transplantation. Endogenous stem cell homing and in situ regeneration strategies have received extensive attention. The application of stem cell derivatives, such as conditioned media, extracellular vesicles, and extracellular matrix, is an extension of stem cell paracrine theory. On the other hand, stem cell pretreatment strategies have also shown promising therapeutic effects. This article will systematically review the latest developments in these areas, summarize challenges in articular cartilage regeneration strategies involving stem cells, and describe prospects for future development.

Recent progress of animal transplantation studies for treating articular cartilage damage using pluripotent stem cells

Focal articular cartilage damage can eventually lead to the onset of osteoarthritis with degradation around healthy articular cartilage. Currently, there are no drugs available that effectively repair articular cartilage damage. Several surgical techniques exist and are expected to prevent progression to osteoarthritis, but they do not offer a long-term clinical solution. Recently, regenerative medicine approaches using human pluripotent stem cells (PSCs) have gained attention as new cell sources for therapeutic products. To translate PSCs to clinical application, appropriate cultures that produce large amounts of chondrocytes and hyaline cartilage are needed. So too are assays for the safety and efficacy of the cellular materials in preclinical studies including animal transplantation models. To confirm safety and efficacy, transplantation into the subcutaneous space and articular cartilage defects have been performed in animal models. All but one study we reviewed that transplanted PSC-derived cellular products into articular cartilage defects found safe and effective recovery. However, for most of those studies, the quality of the PSCs was not verified, and the evaluations were done with small animals over short observation periods. Large animals and longer observation times are preferred. We will discuss the recent progress and future direction of the animal transplantation studies for the treatment of focal articular cartilage damages using PSCs.

Cartilage Repair by Mesenchymal Stem Cell-Derived Exosomes: Preclinical and Clinical Trial Update and Perspectives

Osteoarthritis (OA) and other degenerative joint diseases are characterized by articular cartilage destruction, synovial inflammation, sclerosis of subchondral bone, and loss of extracellular matrix (ECM). Worldwide, these diseases are major causes of disability. Cell therapies have been considered to be the best therapeutic strategies for long-term treatment of articular cartilage diseases. It has been suggested that the mechanism of stem cell-based therapy is related to paracrine secretion of extracellular vesicles (EVs), which are recognized as the main secretion factors of stem cells. EVs, and in particular the subclass exosomes (Exos), are novel therapeutic approaches for treatment of cartilage lesions and OA. The results of recent studies have shown that EVs isolated from mesenchymal stem cells (MSCs) could inhibit OA progression. EVs isolated from various stem cell sources, such as MSCs, may contribute to tissue regeneration of the limbs, skin, heart, and other tissues. Here, we summarize recent findings of preclinical and clinical studies on different MSC-derived EVs and their effectiveness as a treatment for damaged cartilage. The Exos isolation techniques in OA treatment are also highlighted.

Versatility of Induced Pluripotent Stem Cells (iPSCs) for Improving the Knowledge on Musculoskeletal Diseases

Induced pluripotent stem cells (iPSCs) represent an unlimited source of pluripotent cells capable of differentiating into any cell type of the body. Several studies have demonstrated the valuable use of iPSCs as a tool for studying the molecular and cellular mechanisms underlying disorders affecting bone, cartilage and muscle, as well as their potential for tissue repair. Musculoskeletal diseases are one of the major causes of disability worldwide and impose an important socio-economic burden. To date there is neither cure nor proven approach for effectively treating most of these conditions and therefore new strategies involving the use of cells have been increasingly investigated in the recent years. Nevertheless, some limitations related to the safety and differentiation protocols among others remain, which humpers the translational application of these strategies. Nonetheless, the potential is indisputable and iPSCs are likely to be a source of different types of cells useful in the musculoskeletal field, for either disease modeling or regenerative medicine. In this review, we aim to illustrate the great potential of iPSCs by summarizing and discussing the in vitro tissue regeneration preclinical studies that have been carried out in the musculoskeletal field by using iPSCs.

Magnetically Actuated Manipulation and Its Applications for Cartilage Defects: Characteristics and Advanced Therapeutic Strategies

For the fact that articular cartilage is a highly organized and avascular tissue, cartilage defects are limited to spontaneously heal, which would subsequently progress to osteoarthritis. Many methods have been developed to enhance the ability for cartilage regeneration, among which magnetically actuated manipulation has attracted interests due to its biocompatibility and non-invasive manipulation. Magnetically actuated manipulation that can be achieved by introducing magnetic nanoparticles and magnetic field. This review summarizes the cutting-edge research on the chondrogenic enhancements via magnetically actuated manipulation, including cell labeling, cell targeting, cell assembly, magnetic seeding and tissue engineering strategies.

Platelet-Derived Microparticles Mediate the Intra-Articular Homing of Mesenchymal Stem Cells in Early-Stage Cartilage Lesions

After intra-articular injection, synovium-derived mesenchymal stem cells (SMSCs) can adhere to damaged cartilage (a process called homing) and then repair the cartilage defect. Nonetheless, the main obstacle of the current method is the insufficient homing ratio of SMSCs, which fails to meet the requirements for cartilage repair and thereby greatly limits the therapeutic effect. In this study, the optimal homing time of SMSCs was determined by evaluating the SMSC homing efficiency at 1, 3, 7, 14, and 28 days after injury using a rat cartilage defect model. The ability of platelet-derived microparticles (PMPs) to promote SMSC homing was evaluated by cartilage/subchondral bone cell adhesion, transmembrane migration, and intra-articular cell distribution assays. SMSCs had an optimal homing efficiency in the very early stage (1 day) after cartilage injury. We found that PMPs, which were abundant in the synovial fluid at this early stage, were responsible for this augmented SMSC homing. An ex vivo cell adhesion assay revealed that the coincubation of SMSCs with PMPs at a 1:50 ratio markedly enhanced cell adhesion to cartilage and the subchondral bone surface. The transmembrane cell migration assay yielded similar results. Further in vivo homing assays revealed that PMPs possess excellent homing capacity, which they transferred, to some extent, to SMSCs by coating the cell surface. We measured the expression of homing-related genes in SMSCs exposed to PMPs and identified several upregulated genes. Moreover, platelet-specific adhesion molecules, particularly GPIIb/IIIa, CXCR4, ITGβ1, and ITGα2, were determined to play a critical role in the homing of SMSC/PMP complexes. This improvement in SMSC homing increased the volume of regenerated tissue in the cartilage defect. In conclusion, PMPs significantly promoted the homing of SMSCs to cartilage, which facilitated cartilage regeneration. These data suggest a safe and promising strategy for improving the outcome of stem cell therapy.

In vitro and in vivo potentialities for cartilage repair from human advanced knee osteoarthritis synovial fluid-derived mesenchymal stem cells

Background

Mesenchymal stem cells (MSCs) are found in synovial fluid (SF) and can easily be harvested during arthrocentesis or arthroscopy. However, SF-MSC characterization and chondrogenicity in collagen sponges have been poorly documented as well as their hypothetical in vivo chondroprotective properties with intra-articular injections during experimental osteoarthritis (OA).

Methods

SF-MSCs were isolated from human SF aspirates in patients suffering from advanced OA undergoing total knee joint replacements. SF-MSCs at passage 2 (P2) were characterized by flow cytometry for epitope profiling. SF-MSCs at P2 were subsequently cultured in vitro to assess their multilineage potentials. To assess their chondrogenicity, SF-MSCs at P4 were seeded in collagen sponges for 4 weeks under various oxygen tensions and growth factors combinations to estimate their gene profile and matrix production. Also, SF-MSCs were injected into the joints in a nude rat anterior cruciate ligament transection (ACLT) to macroscopically and histologically assess their possible chondroprotective properties,.

Results

We characterized the stemness (CD73+, CD90+, CD105+, CD34−, CD45−) and demonstrated the multilineage potency of SF-MSCs in vitro. Furthermore, the chondrogenic induction (TGF-ß1 ± BMP-2) of these SF-MSCs in collagen sponges demonstrated a good capacity of chondrogenic gene induction and extracellular matrix synthesis. Surprisingly, hypoxia did not enhance matrix synthesis, although it boosted chondrogenic gene expression (ACAN, SOX9, COL2A1). Besides, intra-articular injections of xenogenic SF-MSCs did exert neither chondroprotection nor inflammation in ACLT-induced OA in the rat knee.

Conclusions

Advanced OA SF-MSCs seem better candidates for cell-based constructs conceived for cartilage defects rather than intra-articular injections for diffuse OA.

Magnetic cell delivery for the regeneration of musculoskeletal and neural tissues

Magnetic targeting is a cell delivery system using the magnetic labeling of cells and the magnetic field; it has been developed for minimally invasive cell transplantation. Cell transplantation with both minimal invasiveness and high efficacy on tissue repair can be achieved by this system. Magnetic targeting has been applied for the transplantation of bone marrow mesenchymal stem cells, blood CD133-positive cells, neural progenitor cells, and induced pluripotent stem cells, and for the regeneration of bone, cartilage, skeletal muscles, and the spinal cord. It enhances the accumulation and adhesion of locally injected cells, resulting in the improvement of tissue regeneration. It is a promising technique for minimally invasive and effective cell transplantation therapy.