Mitochondrial Transplantation Ameliorates the Development and Progression of Osteoarthritis

Connecting the dots: Mitochondrial transfer in immunity, inflammation, and cancer

Mitochondria are more than mere energy generators; they are multifaceted organelles that integrate metabolic, signalling, and immune functions, making them indispensable players in maintaining cellular and systemic health. Mitochondrial transfer has recently garnered attention due to its potential role in several physiological and pathological processes. This process involves multiple mechanisms by which mitochondria, along with mitochondrial DNA and other components, are exchanged between cells. In this review, we examine the critical roles of mitochondrial transfer in health and disease, focusing on its impact on immune cell function, the resolution of inflammation, tissue repair, and regeneration. Additionally, we explore its implications in viral infections and cancer progression. We also provide insights into emerging therapeutic applications, emphasizing its potential to address unmet clinical needs.

Recent advances in omics and the integration of multi-omics in osteoarthritis research

Osteoarthritis (OA) is a complex disorder driven by the combination of environmental and genetic factors. Given its high global prevalence and heterogeneity, developing effective and personalized treatment methods is crucial. This requires identifying new disease mechanisms, drug targets, and biomarkers. Various omics approaches have been applied to identify OA-related genes, pathways, and biomarkers, including genomics, epigenomics, transcriptomics, proteomics, and metabolomics. These omics studies have generated vast datasets that are shaping the field of OA research. The emergence of high-resolution methodologies, such as single-cell and spatial omics techniques, further enhances our ability to dissect molecular complexities within the OA microenvironment. By integrating these multi-layered datasets, researchers can uncover central signaling hubs and disease mechanisms, ultimately facilitating the development of targeted therapies and precision medicine approaches for OA treatment.

New mesenchymal stem/stromal cell-based strategies for osteoarthritis treatment: targeting macrophage-mediated inflammation to restore joint homeostasis

Macrophages are pivotal in osteoarthritis (OA) pathogenesis, as their dysregulated polarization can contribute to chronic inflammatory processes. This review explores the molecular and metabolic mechanisms that influence macrophage polarization and identifies potential strategies for OA treatment. Currently, non-surgical treatments for OA focus only on symptom management, and their efficacy is limited; thus, mesenchymal stem/stromal cells (MSCs) have gained attention for their anti-inflammatory and immunomodulatory capabilities. Emerging evidence suggests that small extracellular vesicles (sEVs) derived from MSCs can modulate macrophage function, thus offering potential therapeutic benefits in OA. Additionally, the transfer of mitochondria from MSCs to macrophages has shown promise in enhancing mitochondrial functionality and steering macrophages toward an anti-inflammatory M2-like phenotype. While further research is needed to confirm these findings, MSC-based strategies, including the use of sEVs and mitochondrial transfer, hold great promise for the treatment of OA and other chronic inflammatory diseases.

Recent advances in mitochondrial transplantation to treat disease

Mitochondrial transplantation (MT), an innovative regenerative technique widely used to treat diseases caused by mitochondrial dysfunction, shows great promise for clinical application. This procedure can increase the number of mitochondria and improve the function of damaged mitochondria, resulting in increased adenosine triphosphate levels, decreased reactive oxygen species production, improved Ca2+ buffering capacity, modulated inflammatory response, and reduced apoptosis to protect cells, thus promoting tissue repair. In this review, we describe research advances in MT over the last five years, focusing on its application in treating various diseases, including ischaemic injuries (of the kidney, heart, lung, and liver), neurodegenerative disorders, spinal cord injury, sepsis, diabetes mellitus, stroke, and ultraviolet radiation injuries, as well as in procedures such as organ transplantation, focusing on instances where MT demonstrated good efficacy. We also cover the application of engineered mitochondria and mitochondrial combination therapies and present the latest advances in improving MT efficiency, as well as the current clinical applications and shortcomings of MT, aiming to provide a theoretical foundation for enhanced MT utilisation in the future.

Organelle-tuning condition robustly fabricates energetic mitochondria for cartilage regeneration

Mitochondria are vital organelles whose impairment leads to numerous metabolic disorders. Mitochondrial transplantation serves as a promising clinical therapy. However, its widespread application is hindered by the limited availability of healthy mitochondria, with the dose required reaching up to 109 mitochondria per injection/patient. This necessitates sustainable and tractable approaches for producing high-quality human mitochondria. In this study, we demonstrated a highly efficient mitochondria-producing strategy by manipulating mitobiogenesis and tuning organelle balance in human mesenchymal stem cells (MSCs). Utilizing an optimized culture medium (mito-condition) developed from our established formula, we achieved an 854-fold increase in mitochondria production compared to normal MSC culture within 15 days. These mitochondria were not only significantly expanded but also exhibited superior function both before and after isolation, with ATP production levels reaching 5.71 times that of normal mitochondria. Mechanistically, we revealed activation of the AMPK pathway and the establishment of a novel cellular state ideal for mitochondrial fabrication, characterized by enhanced proliferation and mitobiogenesis while suppressing other energy-consuming activities. Furthermore, the in vivo function of these mitochondria was validated in the mitotherapy in a mouse osteoarthritis model, resulting in significant cartilage regeneration over a 12-week period. Overall, this study presented a new strategy for the off-the-shelf fabrication of human mitochondria and provided insights into the molecular mechanisms governing organelle synthesis.

In Vivo and In Vitro Evaluation of the Feasibility and Safety Profiles of Intraarticular Transplantation of Mitochondria for Future Use as a Therapy for Osteoarthritis

Osteoarthritis (OA) is the most common rheumatologic disease and a major cause of pain and disability in older adults. No efficient treatment is currently available. Mitochondrial dysfunction in chondrocytes drives molecular dysregulation in OA pathogenesis. Recently, mitochondrial transfer to chondrocytes had been described, enabling transplant of mitochondria as a new avenue to modify the OA process, although evidence on its feasibility and safety remains limited.The primary objective of this study was to demonstrate the feasibility and safety of intra-articular mitochondrial transplantation. Mitochondria were isolated from liver using the procedure described by Preble and coworkers combined with magnetic beads coupled to anti-TOM22 antibodies. The organelles obtained were analyzed to determine their purity and viability. The safety and viability of the administration of the isolated mitochondria into articular tissues as well as the integration and distribution of the transplanted mitochondria within joint tissues were analyzed using both in vitro and in vivo models. We established an efficient, reproducible, effective, and rapid protocol for isolating mitochondria from liver. We obtained mitochondria with high viability, yield, and purity. The isolated mitochondria were injected into joint tissue using both in vitro and in vivo models. Functional mitochondria were detected in the extracellular matrix of the cartilage, menisci and synovium. Our results establish a safe and viable protocol for mitochondrial isolation and intra-articular injection. The methodology and findings presented here pave the way for future studies in osteoarthritis models to validate mitochondrial transplantation as a potentially effective treatment for OA.

Safety and efficacy of mesenchymal stromal cells mitochondria transplantation as a cell-free therapy for osteoarthritis

OBJECTIVE

The inflammatory responses from synovial fibroblasts and macrophages and the mitochondrial dysfunction in chondrocytes lead to oxidative stress, disrupt extracellular matrix (ECM) homeostasis, and accelerate the deterioration process of articular cartilage in osteoarthritis (OA). In recent years, it has been proposed that mesenchymal stromal cells (MSC) transfer their functional mitochondria to damaged cells in response to cellular stress, becoming one of the mechanisms underpinning their therapeutic effects. Therefore, we hypothesize that a novel cell-free treatment for OA could involve direct mitochondria transplantation, restoring both cellular and mitochondrial homeostasis.

METHODS

Mitochondria were isolated from Umbilical Cord (UC)-MSC (Mito-MSC) and characterized based on their morphology, phenotype, functions, and their ability to be internalized by different articular cells. Furthermore, the transcriptional changes following mitochondrial uptake by chondrocytes were evaluated using an Affymetrix analysis, Lastly, the dose dependence therapeutic efficacy, biodistribution and immunogenicity of Mito-MSC were assessed in vivo, through an intra-articular injection in male C57BL6 mice in a collagenase-induced OA (CIOA) model.

RESULTS

Our findings demonstrate the functional integrity of Mito-MSC and their ability to be efficiently transferred into chondrocytes, synovial macrophages, and synovial fibroblasts. Moreover, the transcriptomic analysis showed the upregulation of genes involved in stress such as DNA reparative machinery and inflammatory antiviral responses. Finally, Mito-MSC transplantation yielded significant reductions in joint mineralization, a hallmark of OA progression, as well as improvements in OA-related histological signs, with the lower dose exhibiting better therapeutic efficacy. Furthermore, Mito-MSC was detected within the knee joint for up to 24 h post-injection without eliciting an inflammatory response in CIOA mice.

CONCLUSION

Collectively, our results reveal that mitochondria derived from MSC are transferred to key articular cells and are retained in the joint without generating an inflammatory immune response mitigating articular cartilage degradation in OA, probably through a restorative effect triggered by the stress antiviral response within OA chondrocytes.

Autologous transplantation of mitochondria/rAAV IGF-I platforms in human osteoarthritic articular chondrocytes to treat osteoarthritis

Despite various available treatments, highly prevalent osteoarthritis (OA) cannot be cured in patients. In light of evidence showing mitochondria dysfunction during the disease progression, our goal was to develop a novel therapeutic concept based on the transplantation of mitochondria as a platform to deliver recombinant adeno-associated virus (rAAV) gene vectors with potency for OA. For the first time, to our best knowledge, we report the successful creation of a safe mitochondria/rAAV system effectively promoting the overexpression of a candidate insulin-like growth factor I (IGF-I) by administration to autologous human osteoarthritic articular chondrocytes versus control conditions (reporter mitochondria/rAAV lacZ system, rAAV-free system, absence of mitochondria transplantation; up to 8.4-fold difference). The candidate mitochondria/rAAV IGF-I system significantly improved key activities in the transplanted cells (proliferation/survival, extracellular matrix production, mitochondria functions) relative to the control conditions (up to a 9.5-fold difference), including when provided in a pluronic F127 (PF127) hydrogel for reinforced delivery (up to a 5.9-fold difference). Such effects were accompanied by increased levels of cartilage-specific SOX9 and Mfn-1 (mitochondria fusion) and decreased levels of Drp-1 (mitochondria fission) and proinflammatory tumor necrosis factor alpha (TNF-α; up to 4.5-fold difference). This study shows the potential of combining the use of mitochondria with rAAV as a promising approach for human OA.

From dysfunction to healing: advances in mitochondrial therapy for Osteoarthritis

Osteoarthritis (OA) is a chronic degenerative joint condition characterised by cartilage deterioration and changes in bone morphology, resulting in pain and impaired joint mobility. Investigation into the pathophysiological mechanisms underlying OA has highlighted the significance of mitochondrial dysfunction in its progression. Mitochondria, which are cellular organelles, play a crucial role in regulating energy metabolism, generating reactive oxygen species, and facilitating essential biological processes including apoptosis. In recent years, the utilisation of exogenous drugs and MT to improve mitochondrial function in chondrocytes has shown great promise in OA treatment. Numerous studies have investigated the potential of stem cells and extracellular vesicles in mitochondrial transfer. This review aims to explore the underlying mechanisms of mitochondrial dysfunction in OA and assess the progress in utilising mitochondrial transfer as a therapeutic approach for this disease.

KLF2 Inhibits Ferroptosis and Improves Mitochondrial Dysfunction in Chondrocyte Through SIRT1/GPX4 Signaling to Improve Osteoarthritis

Osteoarthritis (OA), a disease of articular joints, is the leading cause of disability in the elderly. Repressing ferroptosis and improving mitochondrial function can delay the progression of OA. Kruppel-like factor 2 (KLF2) exerts a protective effect on OA. However, whether KLF2 affects ferroptosis and mitochondrial function during OA remains unknown. The OA in vivo and in vitro models were constructed in this work. The structural damage of knee joint in OA mice was evaluated through Micro-CT scanning. H&E, SOFG, TB, and TUNEL staining were applied for pathological examination of cartilage tissues. ELISA was employed to examine the contents of inflammatory factors. Additionally, iron deposition in cartilage tissues was measured by Prussian blue staining, and the levels of proteins related to ferroptosis were assessed by immunoblotting. Besides, mitochondrial morphology and function were estimated using a transmission electron microscope and JC-1 staining. In interleukin (IL)-1β-treated C28/I2 cells, the levels of inflammatory factors, intracellular ROS, mitochondrial ROS, lipid ROS, and Fe2+ were measured. Mitochondrial function was evaluated by detecting the levels of mitochondrial membrane potential (MMP), ATP, mPTP, and OCR. KLF2 overexpression ameliorated the structural damage of knee cartilage in OA mice. KLF2 upregulation inhibited ferroptosis and alleviated mitochondrial damage in knee cartilage of OA mice and IL-1β-treated C28/I2 cells. Moreover, KLF2 overexpression activated SIRT1/GPX4 signaling in vivo and in vitro. EX527 addition blocked the influences of KLF2 upregulation on ferroptosis and mitochondrial dysfunction in IL-1β-treated C28/I2 cells. Altogether KLF2 inhibits ferroptosis and improves mitochondrial dysfunction in chondrocytes through SIRT1/GPX4 signaling to improve OA.

Mitochondrial transplantation: a promising strategy for treating degenerative joint diseases

The prevalence of age-related degenerative joint diseases, particularly intervertebral disc degeneration and osteoarthritis, is increasing, thereby posing significant challenges for the elderly population. Mitochondrial dysfunction is a critical factor in the etiology and progression of these disorders. Therapeutic interventions that incorporate mitochondrial transplantation exhibit considerable promise by increasing mitochondrial numbers and improving their functionality. Existing evidence suggests that exogenous mitochondrial therapy improves clinical outcomes for patients with degenerative joint diseases. This review elucidates the mitochondrial abnormalities associated with degenerative joint diseases and examines the mechanisms of mitochondrial intercellular transfer and artificial mitochondrial transplantation. Furthermore, therapeutic strategies for mitochondrial transplantation in degenerative joint diseases are synthesized, and the concept of engineered mitochondrial transplantation is proposed.

Mitochondrial transfer balances cell redox, energy and metabolic homeostasis in the osteoarthritic chondrocyte preserving cartilage integrity

Osteoarthrosis (OA) is a leading cause of disability and early mortality, with no disease modifying treatment. Mitochondrial (MT) dysfunction and changes in energy metabolism, leading to oxidative stress and apoptosis, are main drivers of disease. In reaction to stress, mesenchymal stromal/stem cells (MSCs) donate their MT to damaged tissues. Methods: To evaluate the capacity of clinically validated MSCs to spontaneously transfer their MT to human OA chondrocytes (OA-Ch), primary cultured Ch isolated from the articular cartilage of OA patients were co-cultured with MT-labeled MSCs. MT transfer (MitoT) was evidenced by flow cytometry and confocal microscopy of MitoTracker-stained and YFP-tagged MT protein. MT persistence and metabolic analysis on target cells were assessed by direct transfer of MSC-derived MT to OA-Chs (Mitoception), through SNP-qPCR analysis, ATP measurements and Seahorse technology. The effects of MitoT on MT dynamics, oxidative stress and cell viability were gauged by western blot of fusion/fission proteins, confocal image analysis, ROS levels, Annexin V/7AAD and TUNEL assays. Intra-articular injection of MSC-derived MT was tested in a collagenase-induced murine model of OA. Results: Dose-dependent cell-to-cell MitoT from MSCs to cultured OA-Chs was detected starting at 4 hours of co-culture, with increasing MT-fluorescence levels at higher MSC:Ch ratios. PCR analysis confirmed the presence of exogenous MSC-MT within MitoT+ OA-Chs up to 9 days post Mitoception. MitoT from MSCs to OA-Ch restores energetic status, with a higher ATP production and metabolic OXPHOS/Glycolisis ratio. Significant changes in the expression of MT network regulators, increased MFN2 and decreased p-DRP1, reveal that MitoT promotes MT fusion restoring the MT dynamics in the OA-Ch. Additionally, MitoT increases SOD2 transcripts, protein, and activity levels, and reduces ROS levels, confering resistance to oxidative stress and enhancing resistance to apoptosis. Intra-articular injection of MSC-derived MT improves histologic scores and bone density of the affected joints in the OA mouse model, demonstrating a protective effect of MT transplantation on cartilage degradation. Conclusion: The Mitochondria transfer of MSC-derived MT induced reversal of the metabolic dysfunction by restoring the energetic status and mitochondrial dynamics in the OA chondrocyte, while conferring resistance to oxidative stress and apoptosis. Intra-articular injection of MT improved the disease in collagenase-induced OA mouse model. The restoration of the cellular homeostasis and the preclinical benefit of the intra-articular MT treatment offer a new approach for the treatment of OA.

Autophagy and the pancreas: Healthy and disease states

Macroautophagy/autophagy is an intracellular degradation pathway that has an important effect on both healthy and diseased pancreases. It protects the structure and function of the pancreas by maintaining organelle homeostasis and removing damaged organelles. A variety of pancreas-related diseases, such as diabetes, pancreatitis, and pancreatic cancer, are closely associated with autophagy. Genetic studies that address autophagy confirm this view. Loss of autophagy homeostasis (lack or overactivation) can lead to a series of adverse reactions, such as oxidative accumulation, increased inflammation, and cell death. There is growing evidence that stimulating or inhibiting autophagy is a potential therapeutic strategy for various pancreatic diseases. In this review, we discuss the multiple roles of autophagy in physiological and pathological conditions of the pancreas, including its role as a protective or pathogenic factor.

Stroke studies in large animals: Prospects of mitochondrial transplantation and enhancing efficiency using hydrogels and nanoparticle-assisted delivery

One of the most frequent reasons for mortality and disability today is acute ischemic stroke, which occurs by an abrupt disruption of cerebral circulation. The intricate damage mechanism involves several factors, such as inflammatory response, disturbance of ion balance, loss of energy production, excessive reactive oxygen species and glutamate release, and finally, neuronal death. Stroke research is now carried out using several experimental models and potential therapeutics. Furthermore, studies are being conducted to address the shortcomings of clinical care. A great deal of research is being done on novel pharmacological drugs, mitochondria targeting compounds, and different approaches including brain cooling and new technologies. Still, there are many unanswered questions about disease modeling and treatment strategies. Before these new approaches may be used in therapeutic settings, they must first be tested on large animals, as most of them have been done on rodents. However, there are several limitations to large animal stroke models used for research. In this review, the damage mechanisms in acute ischemic stroke and experimental acute ischemic stroke models are addressed. The current treatment approaches and promising experimental methods such as mitochondrial transplantation, hydrogel-based interventions, and strategies like mitochondria encapsulation and chemical modification, are also examined in this work.

The common link between sleep apnea syndrome and osteoarthritis: a literature review

Patients with Osteoarthritis (OA) often also suffer from Sleep Apnea Syndrome (SAS), and many scholars have started to notice this link, although the relationship between the two is still unclear. In this review, we aim to summarize the current literature on these two diseases, integrate evidence of the OA and OSA connection, explore and discuss their potential common mechanisms, and thus identify effective treatment methods for patients with both OA and SAS. Some shared characteristics of the two conditions have been identified, notably aging and obesity as mutual risk factors. Both diseases are associated with various biological processes or molecular pathways, including mitochondrial dysfunction, reactive oxygen species production, the NF-kB pathway, HIF, IL-6, and IL-8. SAS serves as a risk factor for OA, and conversely, OA may influence the progression of SAS. The effects of OA on SAS are underreported in the literature and require more investigation. To effectively manage these patients, timely intervention for SAS is necessary while treating OA, with weight reduction being a primary requirement, alongside combined treatments such as Continuous positive airway pressure (CPAP) and medications. Additionally, numerous studies in drug development are now aimed at inhibiting or clearing certain molecular pathways, including ROS, NF-KB, IL-6, and IL-8. Improving mitochondrial function might represent a viable new strategy, with further research into mitochondrial updates or transplants being essential.

Effects of mitochondrial transplantation on chronic pressure wound healing in a human patient

BACKGROUND AIMS

Wound healing is a multistage process that requires a concerted effort of various cell types. The intricate processes involved in the healing of wounds result in high energy requirements. Furthermore, mitochondria play a crucial role in the healing process because of their involvement in neo angiogenesis, growth factor synthesis, and cell differentiation. It is unclear how mitochondria transplantation, a promising new approach, influences wound healing.

METHODS

In this study, healthy autologous mitochondria obtained from skeletal muscle were injected into chronic pressure wounds as an intervention to promote wound healing.

RESULTS

Mitochondrial transplantation accelerated wound healing by reducing wound size, increasing granulation tissue, and hastening epithelialization.

CONCLUSIONS

This study is the first to demonstrate the therapeutic efficacy of mitochondrial transplantation in wound healing.

Mitochondrial dysfunction: mechanisms and advances in therapy

Mitochondria, with their intricate networks of functions and information processing, are pivotal in both health regulation and disease progression. Particularly, mitochondrial dysfunctions are identified in many common pathologies, including cardiovascular diseases, neurodegeneration, metabolic syndrome, and cancer. However, the multifaceted nature and elusive phenotypic threshold of mitochondrial dysfunction complicate our understanding of their contributions to diseases. Nonetheless, these complexities do not prevent mitochondria from being among the most important therapeutic targets. In recent years, strategies targeting mitochondrial dysfunction have continuously emerged and transitioned to clinical trials. Advanced intervention such as using healthy mitochondria to replenish or replace damaged mitochondria, has shown promise in preclinical trials of various diseases. Mitochondrial components, including mtDNA, mitochondria-located microRNA, and associated proteins can be potential therapeutic agents to augment mitochondrial function in immunometabolic diseases and tissue injuries. Here, we review current knowledge of mitochondrial pathophysiology in concrete examples of common diseases. We also summarize current strategies to treat mitochondrial dysfunction from the perspective of dietary supplements and targeted therapies, as well as the clinical translational situation of related pharmacology agents. Finally, this review discusses the innovations and potential applications of mitochondrial transplantation as an advanced and promising treatment.

Mitochondria as secretory organelles and therapeutic cargos

Mitochondria have been primarily considered intracellular organelles that are responsible for generating energy for cell survival. However, accumulating evidence suggests that mitochondria are secreted into the extracellular space under physiological and pathological conditions, and these secreted mitochondria play diverse roles by regulating metabolism, the immune response, or the differentiation/maturation in target cells. Furthermore, increasing amount of research shows the therapeutic effects of local or systemic administration of mitochondria in various disease models. These findings have led to growing interest in exploring mitochondria as potential therapeutic agents. Here, we discuss the emerging roles of mitochondria as extracellularly secreted organelles to shed light on their functions beyond energy production. Additionally, we provide information on therapeutic outcomes of mitochondrial transplantation in animal models of diseases and an update on ongoing clinical trials, underscoring the potential of using mitochondria as a novel therapeutic intervention.

Fusogenic liposomes encapsulating mitochondria as a promising delivery system for osteoarthritis therapy

Many attempts have been made to use mitochondria (MT) to treat human diseases; however, MT are large, making them difficult to deliver effectively. Therefore, a transfer strategy based on membrane fusion was established. Fusogenic mitochondrial capsules (FMCs) comprising a neutral lipid (PE), a cationic lipid (DOTAP), an aromatic lipid (Liss Rhod PE), and three types of liposome (FMC0, FMC1, and FMC2), were designed and synthesized. The amount of DOTAP, which affects membrane fusion efficiency, differed between FMC preparations. The characteristics of these FMCs were analyzed by DLS, TEM, and AFM, and the encapsulation and fusion efficiency between FMC-MT and FMC-chondrocytes were confirmed by FRET, mtDNA copy number, and CLSM, respectively. Compared with naked MT, delivery of FMCs to chondrocytes was faster and more efficient. Moreover, fusion was a more stable delivery method than endocytosis, as evidenced by reduced induction of mitophagy. In vitro and in vivo experiments revealed that FMCs reduced expression of inflammatory cytokines and MMP13, increased expression of extracellular matrix components, and promoted cartilage regeneration. These findings suggest that FMCs are a highly effective and promising strategy for delivery of MT to promote cartilage regeneration, and highlight their potential as a novel platform for MT transfer therapy.

Mitochondrial transplantation and transfer: The promising method for diseases

Mitochondria are organelles that serve as the powerhouses for cellular bioenergetics in eukaryotic cells. It is responsible for mitochondrial adenosine triphosphate (ATP) generation, cell signaling and activity, calcium balance, cell survival, proliferation, apoptosis, and autophagy. Mitochondrial transplantation is a promising disease therapy that involves the recovery of mitochondrial dysfunction using isolated functioning mitochondria. The objective of the present article is to provide current knowledge on natural mitochondrial transfer processes, in vitro and in vivo applications of mitochondrial transplantation, clinical trials, and challenges associated with mitochondrial transplantation.

Failure of cartilage regeneration: emerging hypotheses and related therapeutic strategies

Osteoarthritis (OA) is a disabling condition that affects billions of people worldwide and places a considerable burden on patients and on society owing to its prevalence and economic cost. As cartilage injuries are generally associated with the progressive onset of OA, robustly effective approaches for cartilage regeneration are necessary. Despite extensive research, technical development and clinical experimentation, no current surgery-based, material-based, cell-based or drug-based treatment can reliably restore the structure and function of hyaline cartilage. This paucity of effective treatment is partly caused by a lack of fundamental understanding of why articular cartilage fails to spontaneously regenerate. Thus, research studies that investigate the mechanisms behind the cartilage regeneration processes and the failure of these processes are critical to instruct decisions about patient treatment or to support the development of next-generation therapies for cartilage repair and OA prevention. This Review provides a synoptic and structured analysis of the current hypotheses about failure in cartilage regeneration, and the accompanying therapeutic strategies to overcome these hurdles, including some current or potential approaches to OA therapy.

Mitochondrial transplantation as a possible therapeutic option for sarcopenia

With advancing age, the skeletal muscle phenotype is characterized by a progressive loss of mass, strength, and quality. This phenomenon, known as sarcopenia, has a negative impact on quality of life and increases the risk of morbidity and mortality in older adults. Accumulating evidence suggests that damaged and dysfunctional mitochondria play a critical role in the pathogenesis of sarcopenia. Lifestyle modifications, such as physical activity, exercise, and nutrition, as well as medical interventions with therapeutic agents, are effective in the management of sarcopenia and offer solutions to maintain and improve skeletal muscle health. Although a great deal of effort has been devoted to the identification of the best treatment option, these strategies are not sufficient to overcome sarcopenia. Recently, it has been reported that mitochondrial transplantation may be a possible therapeutic approach for the treatment of mitochondria-related pathological conditions such as ischemia, liver toxicity, kidney injury, cancer, and non-alcoholic fatty liver disease. Given the role of mitochondria in the function and metabolism of skeletal muscle, mitochondrial transplantation may be a possible option for the treatment of sarcopenia. In this review, we summarize the definition and characteristics of sarcopenia and molecular mechanisms associated with mitochondria that are known to contribute to sarcopenia. We also discuss mitochondrial transplantation as a possible option. Despite the progress made in the field of mitochondrial transplantation, further studies are needed to elucidate the role of mitochondrial transplantation in sarcopenia. KEY MESSAGES: Sarcopenia is the progressive loss of skeletal muscle mass, strength, and quality. Although the specific mechanisms that lead to sarcopenia are not fully understood, mitochondria have been identified as a key factor in the development of sarcopenia. Damaged and dysfunctional mitochondria initiate various cellular mediators and signaling pathways, which largely contribute to the age-related loss of skeletal muscle mass and strength. Mitochondrial transplantation has been reported to be a possible option for the treatment/prevention of several diseases. Mitochondrial transplantation may be a possible therapeutic option for improving skeletal muscle health and treating sarcopenia. Mitochondrial transplantation as a possible treatment option for sarcopenia.

Effects of mitochondrial dysfunction on bone metabolism and related diseases: a scientometric study from 2003 to 2022

Background

In recent years, mitochondrial dysfunction has been extensively studied and published, but research on the effects of mitochondrial dysfunction on bone metabolism and related diseases is only just beginning. Furthermore, no studies have been carried out to systematically illustrate this area from a scientometric point of view. The goal of this research is to review existing knowledge and identify new trends and possible hotspots in this area.

Methods

All publications related to the relationship between mitochondrial dysfunction and bone metabolism and related diseases from 2003 to 2022 were searched at the Web of Science Core Collection (WoSCC) on May 7, 2022. Four different analytical tools: VOSviewer 1.6.18, CiteSpace V 6.1, HistorCite (12.03.07), and Excel 2021 were used for the scientometric research.

Results

The final analysis included 555 valid records in total. Journal of Biological Chemistry (Co-citations = 916) is the most famous journal in this field. China (Percentage = 37%), the United States (Percentage = 24%), and Korea (Percentage = 12%) are the most productive countries. Blanco FJ and Choi EM are the main researchers with significant academic influence. Current research hotspots are basic research on mitochondrial dysfunction and the prevention or treatment of bone metabolism-related diseases.

Conclusion

The study of the consequences of mitochondrial dysfunction on bone metabolism and associated diseases is advancing rapidly. Several prominent researchers have published extensive literature and are widely cited. Future research in this area will focus on oxidative stress, aging, gene expression, and the pathogenesis of bone metabolism-related diseases.