Mesenchymal stromal cells for articular cartilage repair: preclinical studies

Adipose Tissue-Derived Minimally Manipulated Products versus Platelet-Rich Plasma for the Treatment of Knee Osteoarthritis: A Systematic Review of Clinical Evidence and Meta-Analysis

The use of minimally manipulated adipose tissue (MM-AT) products is gaining increasing interest for the treatment of knee osteoarthritis (OA). MM-AT represents an easy way to exploit adipose tissue properties, although clinical evidence is still limited, as well as their benefits with respect to more documented orthobiologics like platelet-rich plasma (PRP). A systematic review and meta-analysis were performed to evaluate the safety and efficacy of MM-AT products for knee OA management. The risk of bias of the included studies was evaluated using the Dawns and Black checklist for all the included studies and RoB-2.0 for randomized controlled trials (RCTs). Thirty-three clinical studies were included in the qualitative analysis: 13 prospective case series, 10 retrospective case series, 7 RCTs, 2 retrospective comparative studies, and 1 prospective comparative study. An overall clinical improvement and few minor adverse events were observed. Five RCTs comparing MM-AT and PRP injections were meta-analyzed, showing comparable results. The analysis also highlighted the limits of the literature, with only a few high-level trials and an overall low quality. Even though the current literature is still limited, the available evidence suggests the safety and overall positive results of the intra-articular injections of MM-AT products for knee OA treatment.

Four-Arm Polymer-Guided Formation of Curcumin-Loaded Flower-Like Porous Microspheres as Injectable Cell Carriers for Diabetic Wound Healing

Stem cell injection is an effective approach for treating diabetic wounds; however, shear stress during injections can negatively affect their stemness and cell growth. Cell-laden porous microspheres can provide shelter for bone mesenchymal stem cells (BMSC). Herein, curcumin-loaded flower-like porous microspheres (CFPM) are designed by combining phase inversion emulsification with thermally induced phase separation-guided four-arm poly (l-lactic acid) (B-PLLA). Notably, the CFPM shows a well-defined surface topography and inner structure, ensuring a high surface area to enable the incorporation and delivery of a large amount of -BMSC and curcumin. The BMSC-carrying CFPM (BMSC@CFPM) maintains the proliferation, retention, and stemness of -BMSCs, which, in combination with their sustainable curcumin release, facilitates the endogenous production of growth/proangiogenic factors and offers a local anti-inflammatory function. An in vivo bioluminescence assay demonstrates that BMSC@CFPM can significantly increase the retention and survival of BMSC in wound sites. Accordingly, BMSC@CFPM, with no significant systemic toxicity, could significantly accelerate diabetic wound healing by promoting angiogenesis, collagen reconstruction, and M2 macrophage polarization. RNA sequencing further unveils the mechanisms by which BMSC@CFPM promotes diabetic wound healing by increasing -growth factors and enhancing angiogenesis through the JAK/STAT pathway. Overall, BMSC@CFPM represents a potential therapeutic tool for diabetic wound healing.

Treatment with Mesenchymal Stem Cell-Derived Nanovesicle-Containing Gelatin Methacryloyl Hydrogels Alleviates Osteoarthritis by Modulating Chondrogenesis and Macrophage Polarization

Osteoarthritis is a degenerative disorder that can severely affect joints, and new treatment strategies are urgently needed. Administration of mesenchymal stem cell (MSC)-derived exosomes is a promising therapeutic strategy in osteoarthritis treatment. However, the poor yield of exosomes is an obstacle to the use of this modality in the clinic. Herein, a promising strategy is developed to fabricate high-yield exosome-mimicking MSC-derived nanovesicles (MSC-NVs) with enhanced regenerative and anti-inflammatory capabilities. MSC-NVs are prepared using an extrusion approach and are found to increase chondrocyte and human bone marrow MSC differentiation, proliferation, and migration, in addition to inducing M2 macrophage polarization. Furthermore, gelatin methacryloyl (GelMA) hydrogels loaded with MSC-NVs (GelMA-NVs) are formulated, which exhibit sustained release of MSC-NVs and are shown to be biocompatible with excellent mechanical properties. In a mouse osteoarthritis model constructed by surgical destabilization of the medial meniscus (DMM), GelMA-NVs effectively ameliorate osteoarthritis severity, reduce the secretion of catabolic factors, and enhance matrix synthesis. Furthermore, GelMA-NVs induce M2 macrophage polarization and inflammatory response inhibition in vivo. The findings demonstrate that GelMA-NVs hold promise for osteoarthritis treatment through modulation of chondrogenesis and macrophage polarization.

Conditioned Medium - Is it an Undervalued Lab Waste with the Potential for Osteoarthritis Management?

BACKGROUND

The approaches currently used in osteoarthritis (OA) are mainly short-term solutions with unsatisfactory outcomes. Cell-based therapies are still controversial (in terms of the sources of cells and the results) and require strict culture protocol, quality control, and may have side-effects. A distinct population of stromal cells has an interesting secretome composition that is underrated and commonly ends up as biological waste. Their unique properties could be used to improve the existing techniques due to protective and anti-ageing properties.

SCOPE OF REVIEW

In this review, we seek to outline the advantages of the use of conditioned media (CM) and exosomes, which render them superior to other cell-based methods, and to summarise current information on the composition of CM and their effect on chondrocytes.

MAJOR CONCLUSIONS

CM are obtainable from a variety of mesenchymal stromal cell (MSC) sources, such as adipose tissue, bone marrow and umbilical cord, which is significant to their composition. The components present in CMs include proteins, cytokines, growth factors, chemokines, lipids and ncRNA with a variety of functions. In most in vitro and in vivo studies CM from MSCs had a beneficial effect in enhance processes associated with chondrocyte OA pathomechanism.

GENERAL SIGNIFICANCE

This review summarises the information available in the literature on the function of components most commonly detected in MSC-conditioned media, as well as the effect of CM on OA chondrocytes in in vitro culture. It also highlights the need to standardise protocols for obtaining CM, and to conduct clinical trials to transfer the effects obtained in vitro to human subjects.

A bionic composite hydrogel with dual regulatory functions for the osteochondral repair

Due to the avascular nature of cartilage, it is difficult to heal and regenerate spontaneously after injury. At present, tissue engineering has become a promising strategy for repairing damaged cartilage, but the use of seed cells and growth factors is limited. In addition, the importance of mechanical compatibility of scaffold materials is often ignored. In this study, osteochondral scaffold was designed as a bilayer structure with a dense γ-Polyglutamic acid/carboxymethyl chitosan/bacterial cellulose (PGA/CMCS/BC) hydrogel cartilage layer and a porous nano HA-containing PGA/CMCS/BC hydrogel osteogenic layer. In addition, bioactive ions were introduced into the hydrogel scaffold to adjust the mechanical and swelling properties of the material to match the mechanical properties of natural articular cartilage. At the same time, based on the structural characteristics of bone and cartilage, magnesium and copper ions were introduced into the double-layer hydrogel scaffold, respectively, to prepare the cartilage layer and the bone layer, which endowed the material with excellent antibacterial properties and achieved the purpose of the integrated repair of bone and cartilage. The results showed that, after adding magnesium ions, the tensile breaking strength of material was increased from 0.66 MPa to 1.37 MPa，the corresponding compression modulus of the material (strain 0-12%) increased from 0.15 MPa to 0.58 MPa whilst the maximum mass swelling rate decreased from 155% to 75%. The results of in vivo experiments show that the group with bioactive ions had a much better effect on the repair of osteochondral defects, compared with group without bioactive ions, demonstrating such double ion regulation strategy is a very practical strategy for the treatment of osteochondral defects.

An improved diagnostic tool to predict cartilage formation in an osteoarthritic joint environment

Osteoarthritis (OA) is a degenerative joint disease with progressive articular cartilage loss. Due to the chondrogenic potential of human mesenchymal stromal cells (MSCs), MSC-based therapies are promising treatment strategies for cartilage loss. However, the local joint microenvironment has a great impact on the success of cartilage formation by MSCs. This local joint environment is different between patients and therefore the outcome of MSC therapies is uncertain. We previously developed gene promoter-based reporter assays as a novel tool to predict the effect of a patient's OA joint microenvironment on the success of MSC-based cartilage formation. Here we describe an improved version of this molecular tool with increased prediction accuracy. For this, we generated fourteen stable cell lines using transcription factor (TF) binding elements (AP1, ARE, CRE, GRE, ISRE, NFAT5, NFκB, PPRE, SBE, SIE, SOX9, SRE, SRF, TCF/LEF) to drive luciferase reporter gene expression, and evaluated the cell lines for their responsiveness to an osteoarthritic microenvironment by stimulation with OA synovium-conditioned medium (OAs-cm; n=31). To study the effect of this OA microenvironment on MSC-based cartilage formation, MSCs were cultured in a three-dimensional pellet culture model while stimulated with OAs-cm. Cartilage formation was assessed histologically and by quantifying sulfated glycosaminoglycan (sGAG) production. Six TF reporters correlated significantly with the effect of OAs-cm on cartilage formation. We validated the predictive value of these TF reporters with an independent cohort of OAs-cm (n=22) and compared the prediction accuracy between our previous and the current new tool. Furthermore, we investigated which combination of reporters could predict the effect of the OA microenvironment on cartilage repair with the highest accuracy. A combination between the TF (NFκB) and the promoter-based (IL6) reporter proved to reach a more accurate prediction compared to the tools separately. These developments are an important step towards a diagnostic tool that can be used for personalized cartilage repair strategies for OA patients.

Vaspin promotes chondrogenic differentiation of BMSCs via Akt activation in osteoarthritis

Background

The aim of this study was to investigate the role of Vaspin on the chondrogenic differentiation of bone mesenchymal stem cells (BMSCs), and its effect on chondrocyte survival and ECM secretion. We also assessed whether the Akt activation participates in these processes.

Methods

In vivo, immunohistochemistry was used to examine the positive rate of the protein expressions of Akt in Wistar rat articular cartilage and subchondral bone after Vaspin intraperitoneal injection for 14 days. In vitro, we isolated and expanded BMSCs from Wistar rats, and further cultured BMSCs as pellets in a chondrogenic-differentiation medium supplemented with different concentrations of Vaspin. After 21 days, the pellets were processed for cell counting kit assay. The mRNA level of Akt, SOX9 and COL2A1 in the pellets were investigated using quantitative Real-Time polymerase chain reaction, and the protein level of COMP was detected using western blot.

Results

During the chondrogenic differentiation of BMSCs, Vaspin promoted the chondrogenic differentiation of BMSCs and chondrocyte survival by activating the Akt pathway. These effects were significantly reduced by treatment with an Akt inhibitor. Moreover, Vaspin promoted chondrogenic differentiation of BMSCs by increasing the expression of markers in cartilage formation and extracellular matrix secretion. Furthermore, our study also found that Vaspin could increase Akt expression in cartilage cavities and subchondral bone in vivo.

Conclusion

These findings demonstrate that Vaspin can promote the chondrogenic differentiation of BMSCs and chondrocyte survival via Akt activation. Our study provides new insights into the potential ability of Vaspin to ameliorate the chondrogenic differentiation of BMSCs and chondrocyte survival in OA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05295-9.

Bone marrow mesenchymal stem cell-derived exosomes inhibit chondrocyte apoptosis and the expression of MMPs by regulating Drp1-mediated mitophagy

Osteoarthritis (OA) is a joint degenerative disease commonly seen in the elderly. Bone marrow mesenchymal stem cell-exosomes (BMSC-exosomes) are closely associated with the progression of OA. Here, we investigated whether BMSC-exosomes can affect OA development by regulating mitophagy. Primary rat chondrocytes were treated with advanced glycation end products (AGEs) to induce cell damage. The results of flow cytometry showed that AGEs treatment significantly promoted apoptosis of chondrocytes. AGEs treatment also enhanced the expression of matrix metalloproteinases (MMPs), MMP-3 and MMP-13, and dynamin-related protein 1 (Drp1) in chondrocytes. To investigate the impact of BMSC-exosomes on chondrocytes, chondrocytes were treated with BMSC-exosomes. AGEs-mediated increase of apoptosis and up-regulation of MMP-3, MMP-13, and Drp1 in chondrocytes were abrogated by BMSC-exosomes. Western blot analysis of autophagy-related proteins and Mito-Keima assay revealed that BMSC-exosome treatment elevated the expression of autophagy-related proteins, LC3-II/LC3-I and Beclin-1, and promoted mitophagy in the AGEs-treated chondrocytes. Moreover, Drp1 overexpression repressed the expression of LC3-II/LC3-I and Beclin-1, and enhanced apoptosis and the expression of MMP-3 and MMP-13 in AGEs-treated chondrocytes. BMSC-exosomes reversed the impact of Drp1 overexpression on AGEs-treated chondrocytes. In conclusion, this work demonstrates that BMSC-exosomes inhibit chondrocyte apoptosis and the expression of MMPs, which attributes to regulate Drp1-mediated mitophagy. Thus, BMSC-exosomes may be a potential treatment for OA.

Simulated Microgravity Remodels Extracellular Matrix of Osteocommitted Mesenchymal Stromal Cells

The extracellular matrix (ECM) is the principal structure of bone tissue. Long-term spaceflights lead to osteopenia, which may be a result of the changes in composition as well as remodeling of the ECM by osteogenic cells. To elucidate the cellular effects of microgravity, human mesenchymal stromal cells (MSCs) and their osteocommitted progeny were exposed to simulated microgravity (SMG) for 10 days using random positioning machine (RPM). After RPM exposure, an imbalance of MSC collagen/non-collagen ratio at the expense of a decreased level of collagenous proteins was detected. At the same time, the secretion of proteases (cathepsin A, cathepsin D, MMP3) was increased. No significant effects of SMG on the expression of stromal markers and cell adhesion molecules on the MSC surface were noted. Upregulation of COL11A1, CTNND1, TIMP3, and TNC and downregulation of HAS1, ITGA3, ITGB1, LAMA3, MMP1, and MMP11 were detected in RPM exposed MSCs. ECM-associated transcriptomic changes were more pronounced in osteocommitted progeny. Thus, 10 days of SMG provokes a decrease in the collagenous components of ECM, probably due to the decrease in collagen synthesis and activation of proteases. The presented data demonstrate that ECM-associated molecules of both native and osteocommitted MSCs may be involved in bone matrix reorganization during spaceflight.

Immunomodulation of MSCs and MSC-Derived Extracellular Vesicles in Osteoarthritis

Osteoarthritis (OA) has become recognized as a low-grade inflammatory state. Inflammatory infiltration of the synovium by macrophages, T cells, B cells, and other immune cells is often observed in OA patients and plays a key role in the pathogenesis of OA. Hence, orchestrating the local inflammatory microenvironment and tissue regeneration microenvironment is important for the treatment of OA. Mesenchymal stem cells (MSCs) offer the potential for cartilage regeneration owing to their effective immunomodulatory properties and anti-inflammatory abilities. The paracrine effect, mediated by MSC-derived extracellular vehicles (EVs), has recently been suggested as a mechanism for their therapeutic properties. In this review, we summarize the interactions between MSCs or MSC-derived EVs and OA-related immune cells and discuss their therapeutic effects in OA. Additionally, we discuss the potential of MSC-derived EVs as a novel cell-free therapy approach for the clinical treatment of OA.