Multilineage potential of adult human mesenchymal stem cells

Microglial polarization pathways and therapeutic drugs targeting activated microglia in traumatic brain injury

Traumatic brain injury can be categorized into primary and secondary injuries. Secondary injuries are the main cause of disability following traumatic brain injury, which involves a complex multicellular cascade. Microglia play an important role in secondary injury and can be activated in response to traumatic brain injury. In this article, we review the origin and classification of microglia as well as the dynamic changes of microglia in traumatic brain injury. We also clarify the microglial polarization pathways and the therapeutic drugs targeting activated microglia. We found that regulating the signaling pathways involved in pro-inflammatory and anti-inflammatory microglia, such as the Toll-like receptor 4 /nuclear factor-kappa B, mitogen-activated protein kinase, Janus kinase/signal transducer and activator of transcription, phosphoinositide 3-kinase/protein kinase B, Notch, and high mobility group box 1 pathways, can alleviate the inflammatory response triggered by microglia in traumatic brain injury, thereby exerting neuroprotective effects. We also reviewed the strategies developed on the basis of these pathways, such as drug and cell replacement therapies. Drugs that modulate inflammatory factors, such as rosuvastatin, have been shown to promote the polarization of anti-inflammatory microglia and reduce the inflammatory response caused by traumatic brain injury. Mesenchymal stem cells possess anti-inflammatory properties, and clinical studies have confirmed their significant efficacy and safety in patients with traumatic brain injury. Additionally, advancements in mesenchymal stem cell-delivery methods-such as combinations of novel biomaterials, genetic engineering, and mesenchymal stem cell exosome therapy-have greatly enhanced the efficiency and therapeutic effects of mesenchymal stem cells in animal models. However, numerous challenges in the application of drug and mesenchymal stem cell treatment strategies remain to be addressed. In the future, new technologies, such as single-cell RNA sequencing and transcriptome analysis, can facilitate further experimental studies. Moreover, research involving non-human primates can help translate these treatment strategies to clinical practice.

Atoh8 expression inhibition promoted osteogenic differentiation of ADSCs and inhibited cell proliferation in vitro and rat bone defect models

Stem cell-based bone tissue engineering offers a promising approach for treating oral and cranio-maxillofacial bone defects. This study investigated the role of Atoh8, a key regulator in various cells, in the osteogenic potential of adipose-derived stem cells (ADSCs). ADSCs transfected with small interfering RNA (siRNA) targeting Atoh8 were evaluated for proliferation, migration, adhesion, and osteogenic capacity. In vivo, 20 SD rats were used to assess bone regeneration using Atoh8-knockdown ADSC sheets, with new bone formation quantified via micro-CT and histological analysis. Atoh8 knockdown in vitro reduced ADSC proliferation and migration but enhanced osteogenic differentiation and upregulation of osteogenic-related factors. This approach improved bone healing in rat defect models, accelerating repair both in vitro and in vivo. The findings underscore the clinical potential of ADSCs in bone tissue engineering and elucidate Atoh8's regulatory role in ADSC osteogenesis, providing a novel therapeutic strategy for enhancing bone regeneration through targeted modulation of stem cell differentiation pathways.

Adipogenic dedifferentiation enhances survival of human umbilical cord-derived mesenchymal stem cells under oxidative stress

Mesenchymal stem cells (MSCs) serve as ideal candidates for a broad range of cell-based therapies. However, cell ageing caused by long-term in vitro expansion and poor survival after in vivo delivery greatly limits their success in preclinical and clinical applications. Dedifferentiation represents a potential strategy for enhancing the retention and function of MSCs in hostile environments. In this study, we evaluated the cell phenotype, proliferation, and differentiation potential, as well as the anti-oxidative stress ability of human umbilical cord-derived MSCs (hMSCs) manipulated with adipogenic priming and subsequent dedifferentiation. After an in vitro differentiation and dedifferentiation procedure, the resultant dedifferentiated hMSCs (De-hMSCs) displayed properties similar to their original counterparts, including immunophenotype and mesodermal potential. Upon re-induction, De-hMSCs exhibited a significantly higher adipogenic differentiation capability than unmanipulated hMSCs. Importantly, De-hMSCs showed a significantly enhanced ability to resist tert-butyl hydroperoxide (t-BHP) induced apoptosis compared to undifferentiated hMSCs. Mechanisms involving bcl-2 family proteins and autophagy may contribute to the demonstrated advantages of dedifferentiation-reprogrammed hMSCs. These results indicate that adipogenic dedifferentiation promotes adipogenesis and cell persistence, as well as preserves the stemness of human umbilical cord-derived MSCs that have been committed to the adipocytic lineage. As a unique stem cell population, dedifferentiated MSCs may represent an attractive and promising candidate for MSC-based therapy.

Effectiveness of intraglandular allogeneic mesenchymal stem cell administration for treating chronic vesicular adenitis in bulls

This study aimed to evaluate the effects of the application of allogeneic mesenchymal stem cells (MSCs) bilaterally and intraglandularly in the vesicular glands of bulls affected by seminal vesiculitis. Twelve bulls that presented chronic vesiculitis with two or more recurrences were selected at Semen Collection and Processing Centres, based on the presence of pus in the semen, leukocytes on the motility and vigour evaluation slide, reactive to the California Mastitis Test - CMT (one cross or more) and the presence of leukocytes on a slide stained by Diff Quik staining with more than 5 polymorphonuclear cells (PMN) per field. Ultrasound examination of the vesicular glands was performed, and the clinical signs were definitive for the diagnosis. The proposed method of the intraglandular injection of MSCs involved application through the ischiorectal fossa with a long needle measuring 30-35 cm and a guide measuring 25-30 cm in length directly into the affected vesicular glands. The MSCs were cultured and frozen in the Bio Cell Cellular Therapy® laboratory (Brasilia, Brazil) and prepared by washing and centrifugation for intraglandular injection on the day of application. In total, 3x106 MSCs were injected into each vesicular gland. Data were evaluated for normality of residuals using the Shapiro-Wilk test. When the normality of the test was significant (P < 0.05), the data were transformed or outliers were removed and reevaluated. The "T-Test" was applied to identify statistical differences between variables before and after treatment. The probability of P ≤ 0.05 was considered a significant difference. Data were presented as the mean ± standard error of the mean (S.E.M.). Improvements were observed in the initial percent motility from 60.09 ± 4.8 to 69.89 ± 4.6 (P < 0.05), as well as in the post-thawing percent motility from 26.26 ± 6.77 to 42.5 ± 5 0.99 (P < 0.05). The number of doses produced increased significantly after treatment with MSCs, from 95.61 ± 23.31 units to 337.84 ± 67.75 units (P < 0.05) per ejaculate. The number of leukocytes observed per field decreased from 5.83 ± 0.48 to zero, demonstrating the recovery of the inflamed vesicular glands. Based on the results presented, it was concluded that the application of 3x106 MSCs in the vesicular glands of bulls with vesiculitis is safe and efficient, as it improved several parameters evaluated in this research, mainly the production of semen doses per ejaculate.

3D Printed Bioelastomer Scaffold for Mandibular Defect Repair Based on Rapid Distraction Therapy

Mandibular distraction osteogenesis (MDO) is a widely recognized surgical method for treating mandibular hypoplasia. However, it still presents some limitations, including multiple hospital visits required by the long distraction period, and previous studies show that a shortened distraction period will easily lead to a non-union gap and suboptimal quality of the new bone. In this research, a 3D-printed customized PGS scaffold is constructed and combined it with rapid MDO to repair mandible defects. It not only accommodates the dynamically changing distraction gap but also meets the mandibular distraction model's high morphological requirements. The BMSCs-loaded PGS scaffolds also provide favorable osteogenic microenvironments. This approach helps shorten the distraction period and accelerates bone regeneration and osseointegration in the rapid distraction model of rabbit mandibles, showing promise for future clinical advancements in large-scale mandibular defect repair.

Effect of type 2 diabetes mellitus microenvironment on osteogenic capacity of bone marrow mesenchymal stem cells

Type 2 diabetes mellitus (T2DM) often leads to delayed bone regeneration such as slow healing of fractures and bone defects. The number, status and osteogenic differentiation capacity of bone marrow mesenchymal stem cells (BMSCs) are extremely important in bone healing and bone regeneration. The T2DM microenvironment can have irreversible negative effects on BMSCs. In this paper, we review the molecular expression and altered proliferation, migration, and osteogenic differentiation capacity of BMSCs in the microenvironment of T2DM, it provides a new perspective to restore the normal function of T2DM-BMSCs, so as to save the damaged bone regeneration capacity.

Amelioration of female menopausal syndrome by intravenous administration of autologous menstrual blood-derived stem cells

Introduction

Menopausal syndrome is characterized by a wide range of physical and psychological symptoms in women aged 40s-50s as a result of hormonal fluctuations and age-related decline. Various treatments have been used to manage the symptoms, including hormone replacement therapy, but no effective causal therapies have yet been identified. Regenerative medicine has gained considerable attention as a promising approach to age-related problems, and mesenchymal stem cell therapies have been extensively studied. Recently, menstrual blood has emerged as a novel cell source of stem cells, called menstrual blood-derived stem cells (MenSCs), due to its non-invasive, regular and consistent collection from women. In this study, we have investigated the therapeutic potential of intravenous administration of autologous MenSCs on female menopausal syndromes.

Methods

Menstrual blood was collected from 15 patients aged 30s-60s with ovarian dysfunction using a menstrual cup, and MenSCs were isolated, cultured and expanded. Patients received either 3 × 107 cells or 1 × 108 cells intravenously 1 to 5 times at intervals of more than 1 month. Patient-reported symptoms were assessed using the Simplified Menopausal Index at pre-treatment and after 1, 3, 6, and 12 months, and safety assessments were performed. Serum estradiol and follicle-stimulating hormone levels were also measured by immunoassay.

Results

Almost all patients who received MenSCs experienced a sharp reduction in menopausal symptoms, including vasomotor, neuropsychiatric, and motor symptoms, one month after the first administration, and these symptoms remained low for 6 months. The Simplified Menopausal Index score was significantly reduced after treatment. The reducing potency of 1 × 108 MenSCs was greater than that of 3 × 107 MenSCs. Patients who received a higher number of MenSCs showed an increasing trend in estradiol levels and a decreasing trend in follicle-stimulating hormone levels. When MenSCs were administered to postmenopausal patients, this trend was more pronounced. Overall, no apparent serious adverse events were observed during these treatments.

Conclusions

The present results suggest that the administration of MenSCs improved menopausal symptoms and regulated hormonal balance without any serious adverse events. This is the first report on the promising therapeutic potential of cell-based therapy using autologous MenSCs for female menopausal syndrome.

Recent advances in the delivery of microRNAs via exosomes derived from MSCs, and their role in regulation of ferroptosis

Mesenchymal stem cell (MSC) therapy, with its unique properties, has garnered interest in cancer treatment. Exosomes (EXOs)-derived from MSC retain the paracrine components of MSCs and demonstrate increased stability, minimal immunogenicity, and low risk of unintended tumorigenesis. Enhanced endocytosis methods make them versatile delivery vehicles for therapeutic cargo. MSC-EXOs can either promote or inhibit carcinogenesis, mediated by paracrine factors and various RNA molecules, particularly microRNAs (miRNAs). The prospect of using MSC-EXOs as a delivery tool for antitumor miRNAs in solid tumor therapy is promising. Exosomes' intrinsic tumor-targeting abilities and low immunogenicity make them ideal for delivering miRNAs, which have shown potential as cancer therapeutics. miRNAs within MSC-EXOs molecules can stimulate tumor growth or induce non-apoptotic cell death pathways, such as ferroptosis, depending on context. Ferroptosis is a kind of controlled cell death that is associated with the pathophysiology of several illnesses and includes iron metabolism. There is growing evidence that miRNAs carried by exosomes derived from MSCs may control ferroptosis in tumor cells by altering key genes related to antioxidant defense, lipid peroxidation, and iron metabolism. Understanding their complex mechanisms in the tumor microenvironment and optimizing their cargo are critical steps toward harnessing their full therapeutic potential. This review provides a comprehensive overview of MSC-EXOs and their role in cancer treatment. We also discuss the potential of MSC-EXOs as delivery vehicles for miRNAs to enhance therapeutic efficacy, as well as the role of exosomal miRNAs in the induction of ferroptosis.

Optimal dose of bone marrow mesenchymal stem cell transplantation for experimental ulcerative colitis

Objective

To investigate the optimal dose of bone marrow mesenchymal stem cell-transplantation for the ulcerative colitis rat.

Methods

The BMSC of SD rat were isolated, cultured and labelled with DAPI. SD rats were randomly distributed into 3 groups, Colitis was induced with immune-combined TNBS/ethanol in group A、B、C, 3 groups received caudal vein injection of 1 mL fluids, which contain cell number 1 × 106、5 × 106、1 × 107 separately. 5 rats in each group were sacrificed at day 7 and 14 after injection, Cryostat sections of gut, The number of BMSCs in colon and normal tissue surrounded was observed with fluorescent microscope.

Results

The DAPI marked BMSCs could been seen in the colic mucosa in each group on day 7、14, more cells in colon than the surrounding normal tissue, compared with 1 × 106 group, More cells in 5 × 106 group (P < 0.05), there were no significant difference (P > 0.05) between 5 × 106 group and 1 × 107 group. There were more cells in colon on 14 day than 7 day, and less in the surrounding normal tissue on 14 day than 7 day.

Conclusions

The density 5 × 106 is proper of bone mesenchymal stem cells for treatment of ulcerative colitis.

Monocytes/macrophages contamination disrupts functional and transcriptional characteristics of murine bone marrow- and bone-derived stromal cells

Stromal cells are critical regulators of hematopoietic stem/progenitor cells and skeletal homeostasis. Although precise systems for functional analysis are critical to investigate mechanistically bone and bone marrow (BM)-derived stromal cells, the establishment of reproducible, highly enriched ex vivo methods for stromal cell isolation, culture and evaluation have been challenging, leading to inconsistent data on stromal cell function. In this work, we carefully tested ex vivo culture of murine stromal cells from BM and bone and discovered abundant and persistent contamination of monocytes and macrophages. We succeeded in establishing highly enriched ex vivo culture system for stromal cells by eliminating persistent monocytes and macrophages using selection against the immunological markers F4/80, Ly6C, and CD45. Transcriptional and functional assays of enriched stromal cell culture revealed differential characteristics of stromal cells from different origins, a dormant signature for bone-derived cells and a highly proliferative progenitor-like signature for BM-derived cells. Monocyte and macrophage contamination reduced signatures of immature stromal cells such as expression levels of SOX9 and CD140a as well as the cells' ability to support hematopoietic stem and progenitor cells based on our growth factor-free co-culture system of hematopoietic cells and stromal cells followed by in vivo functional assays. The inhibitory effects of macrophages on stromal cells may be explained by their potent production of inflammatory cytokines such as CXCL2, CCL3, and complement factor (C1q) confirmed by protein immunoassay of culture supernatant, as well as the differential contribution of pre-osteoblasts to the stromal cell population. This study highlights the functional diversity of stromal cells depending on the microenvironment of origin while addressing a critical limitation of murine ex vivo systems. Our robust culture system enables the study of isolated stromal cells function as well as the impact of stromal cells-macrophage crosstalk.

Pericytes Are Odontoblast Progenitor Cells Depending on ER Stress

Odontoblasts are terminally differentiated cells that exhibit mechanosensitivity and mineralization capacity. Mechanosensitive ion channels such as Piezo1 are present in odontoblasts and are associated with their physiological functions via Ca2+ signaling. Both Ca2+ signals via Ca2+ influx from mechanosensitive ion channels and Ca2+ release from Ca2+ stores function as secondary messenger systems for various biological phenomena. The endoplasmic reticulum (ER) serves as an intracellular Ca2+ store that mobilizes intracellular Ca2+. Changes in Ca2+ concentration inside the ER are among the factors that cause ER stress. Perivascular cells are located around odontoblasts in the dental pulp. Although such formation indicates that perivascular cells interact with odontoblasts, their detailed profiles under developmental and pathological conditions remain unclear. In this study, we revealed that pericyte marker, neural/glial antigen 2 (NG2)-positive cells, in cell-rich zones (CZs) can differentiate into Piezo1-positive odontoblasts following genetic odontoblast depletion in mice, and modeled as odontoblast death after severe dentin injury and as reparative dentin formation. NG2-positive pericytes differentiated into odontoblasts faster than glial cells. To determine how NG2-positive cells differentiate into Piezo1-positive odontoblasts, we focused on the ER-stress sensor protein, activating transcription factor 6a (ATF6a). After genetic odontoblast depletion, NG2-positive cells regenerated in the odontoblast layer and were capable of acting as functional odontoblasts. In the presence of extracellular Ca2+, the application of a sarco/ER Ca2+-ATPase (SERCA) inhibitor, thapsigargin, known as an ER-stress inducer, increased the intracellular Ca2+ concentration in the odontoblast lineage cells (OLCs). The increase was significantly inhibited by the application of a pharmacologic Piezo1 inhibitor, indicating that ER stress by SERCA inhibition augmented Piezo1-induced responses in odontoblast progenitor cells. However, the physiological activation of Gq-coupled receptors by adenosine diphosphate did not induce Piezo1 activation. Gene silencing of ATF6a and/or NG2 impaired the mineralization of OLCs. Overall, ATF6a orchestrates the differentiation of NG2-positive pericytes into functional odontoblasts that act as sensory receptor cells and dentin-forming cells.

IFN-γ Synergizes with TNF-α to Induce RIPK1-Independent Necroptosis of Mesenchymal Stem/Stromal Cells

IFN-γ and TNF-α are two vital inflammatory factors elevated aberrantly in many diseases. Such an inflammatory microenvironment is detrimental to residual cells such as mesenchymal stem cells (MSCs), yet the precise mechanisms are not fully understood. IFN-γ and TNF-α have distinct effects on the immunoregulatory properties of MSCs, and they have been proposed as optimal priming factors to enhance the immunosuppressive capacity of engineered MSCs. Thus, the overall effects of IFN-γ and/or TNF-α exposure on MSCs needs to be elucidated. Here, it is found that IFN-γ and TNF-α synergistically induce cell death of MSCs via necroptosis. When MSCs are exposed to both IFN-γ and TNF-α, their morphological features and biological functions are impaired. Mechanistically revealed by RNA-Sequencing, the injured MSCs undergo a unique cell death process, namely necroptosis. Compared with controls, IFN-γ synergized with TNF-α to increase the expression of RIPK1, RIPK3, MLKL, and all other genes associated with necroptosis. Rescue experiments further demonstrate that this process can be reversed by RIPK3 and MLKL inhibitors but not by the RIPK1 inhibitor, suggesting a RIPK1-independent pathway. Collectively, this study discloses an inflammatory injury mechanism of MSCs, which may shed new light on revealing the MSCs deficits in many inflammatory diseases with expectations to inspire potential targeted therapies. In addition, inflammatory impairment should be taken into consideration when delivering cell therapy based on MSCs primed with IFN-γ and TNF-α.

METTL9 mediated N1-Histidine methylation of SLC39A7 confers ferroptosis resistance and inhibits adipogenic differentiation in mesenchymal stem cells

Osteoporosis is a prevalent systemic metabolic disease, and an imbalance in the adipogenic and osteogenic differentiation of mesenchymal stem cells (MSCs) plays a crucial role in its pathogenesis. Thus, elucidating the mechanisms that regulate MSC lineage allocation is urgently needed. METTL9 was recently characterized as a novel N1-histidine methyltransferase that performs a wide range of functions. however, the role of METTL9 in the imbalance of MSC differentiation in osteoporosis remains unclear. In this study, we found that METTL9 expression was downregulated in osteoporosis, and further adipogenic functional experiments revealed that METTL9 negatively regulated the adipogenic differentiation of MSCs both in vitro and in vivo. Mechanistically, METTL9 mediated methylation of SLC39A7 at the His45 and His49 residues suppressed ferroptosis through the endoplasmic reticulum (ER) stress regulatory protein kinase R-like endoplasmic reticulum kinase (PERK)/ATF4 signaling pathway and the downstream protein SLC7A11. Moreover, SLC7A11 transported cystine for intracellular glutathione synthesis, eliminating intracellular reactive oxygen species (ROS) and inhibiting MSC adipogenic differentiation. Additionally, METTL9 overexpression significantly alleviated bone loss in ovariectomy (OVX) model mice. In summary, our results suggest that the METTL9/SLC39A7 axis may be a promising diagnostic and therapeutic target for osteoporosis.

GPx3 marks adipocyte lineage commitment in bone marrow stromal cells

BACKGROUND

Bone marrow adipose tissue (BMAT) plays an essential role in skeletal health and systemic metabolism, particularly under conditions of ageing and osteoporosis. Despite increasing recognition of BMAT as an active endocrine organ, the molecular mechanisms underlying its formation and expansion remain incompletely understood.

METHODS

We conducted a transcriptomic re-analysis of publicly available datasets focused on the adipogenic differentiation of bone marrow stromal cells (BMSCs). Differential gene expression and pathway enrichment analyses were performed to identify key molecular changes. Validation was conducted at both the transcript and protein levels. Furthermore, re-analysis of single-cell RNA sequencing (scRNA-seq) data was employed to determine the cell type-specific expression of candidate genes within the bone marrow. Functional assays using RNA interference were carried out to investigate the role of glutathione peroxidase 3 (GPx3) in adipogenesis.

RESULTS

Our analysis revealed a consistent activation of oxidative stress-related pathways during adipogenic differentiation. Among the upregulated antioxidant enzymes, GPx3 was selectively increased during adipogenic-but not osteogenic-differentiation. This pattern was validated at both mRNA and protein levels in vitro. scRNA-seq analysis showed that GPx3 expression is predominantly localized in BMSCs and adipocytes, with reduced expression observed in aged mice, corresponding to elevated levels of adipocyte-related genes. In vitro functional experiments demonstrated that GPx3 knockdown significantly promoted adipogenic differentiation of BMSCs.

CONCLUSION

These findings indicate that GPx3 is closely associated with adipocyte lineage commitment within the bone marrow microenvironment and may serve as a key modulator of BMSC fate. This study underscores the potential role of antioxidant enzymes such as GPx3 in the regulation of age-related bone-fat imbalance and highlights their relevance in metabolic bone disorders.

Mesenchymal stem cells protect the integrity of the alveolar epithelial barrier through extracellular vesicles by inhibiting MAPK-mediated necroptosis

BACKGROUND

Alveolar‒capillary barrier disruption is a hallmark of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). The contribution of necroptosis to the compromised alveolar-barrier in ALI remains unclear. Mesenchymal stem cells (MSCs) may contribute to tissue repair in ALI and ARDS. Here we evaluated the efficacy and explored the molecular mechanisms of menstrual blood-derived endometrial stem cells (MenSCs) and MenSC-derived extracellular vesicles (MenSC-EVs) in ALI-induced alveolar epithelial barrier dysfunction.

METHODS

Human lung epithelial cells were stimulated with endotoxin and treated with MenSCs or MenSC-EVs, and their barrier properties were evaluated. Lipopolysaccharide (LPS)-injured mice were treated with MenSCs or MSC-EVs, and the degree of lung injury and the alveolar epithelial barrier of the lung tissue were assessed.

RESULTS

We found that MenSCs reduced lung injury and restored alveolar-barrier integrity in lung tissue. In vitro, MenSCs reduced paracellular permeability and restored barrier integrity in human lung epithelial cells. MenSC-EVs replicated all these MenSC-mediated changes. Mechanistic research revealed that MenSCs inhibited MAPK signaling and necroptosis. JNK inhibition SP600125, and ERK inhibition U0126 or inhibition of necroptosis with Nec-1 or GSK872 diminished the beneficial anti-epithelial barrier dysfunction effects of MenSCs or MenSC-EVs.

CONCLUSIONS

Our results suggest that human menstrual blood-derived endometrial stem cells mitigate lung injury and improve alveolar barrier properties by inhibiting MAPK-mediated necroptosis through extracellular vesicles, supporting the application of MenSCs or MenSC-derived extracellular vesicles to treat ALI or ARDS.

Mechano-metabolism on the rise

Cells respond to the physical and geometrical tissue properties by multiple mechanotransduction mechanisms that can profoundly influence cells' decision-making, extending to cell metabolism. This review incorporates the most recent findings on this topic, organized along the idea that the mechano-metabolic connection serves three main functions, namely to inform systemic metabolism on the general functioning of a tissue/organ, to tune cells' energy production with the mechanical requirements imposed by their surroundings, and to coordinate cell metabolism with cell fate choices induced in response to mechanical cues. This connection highlights the pervasive influence of mechanical cues on cell activity, opens interesting questions on its physiological and pathological roles, and lays the foundations for exploiting the mechano-metabolism axis to design new therapeutic approaches.

Progress of extracellular vesicles-based system for tumor therapy

The increasing number of new cancer cases and cancer-related deaths worldwide highlights the urgent need to develop novel anti-tumor treatment methods to alleviate the current challenging situation. Nearly all organisms are capable of secreting extracellular vesicles (EVs), and these nano-scale EVs carrying biological molecules play an important role in intercellular communication, further affecting various physiological and pathological processes. Notably, EVs from different sources have differences in their characteristics and functions. Consequently, diverse EVs have been utilized as drug or vaccine delivery carriers for improving anti-tumor treatment due to their good safety, ease of modification and unique properties, and achieved satisfactory results. Meanwhile, the clinical trials of EV-based platform for tumor therapy are also continuously being conducted. Therefore, in this review, we summarize the recent research progress of EV-based tumor treatment methods, including the introduction of main sources and unique functions of EVs, the application of EVs in tumor treatment as well as their prospects and challenges. Additionally, considering the unique advantages of artificial EVs over natural EVs, we also highlighted their characteristics and applications in tumor treatments. We believe that this review will help researchers develop novel EV-based anti-tumor platforms through a bottom-up design and accelerate the development in this field.

Roles for Exosomes from Various Cellular Sources in Spinal Cord Injury

Spinal cord injury (SCI) is a severe disorder characterized by regeneration challenges in the central nervous system (CNS), resulting in permanent paralysis, loss of sensation, and abnormal autonomic functions. The complex pathophysiology of SCI poses challenges to traditional treatments, highlighting the urgent need for novel treatment approaches. Exosomes have emerged as promising candidates for SCI therapy because of their ability to deliver a wide range of bioactive molecules, such as RNAs, proteins, and lipids, to target cells with minimal immunogenicity, which contribute to anti-inflammatory, anti-apoptotic, autophagic, angiogenic, neurogenic, and axon remodeling activities. In this study, we classified exosomes from different sources into four categories based on the characteristics of the donor cells (mesenchymal stem cells, neurogenic cells, immune cells, vascular-associated cells) and provided a detailed summary and discussion of the current research progress and future directions for each source. We also conducted an in-depth investigation into the applications of engineered exosomes in SCI therapy, focusing on their roles in drug delivery and combination with surface engineering technologies and tissue engineering strategies. Finally, the challenges and prospects of exosomal clinical applications in SCI repair are described.

Dual-regulation biomimetic composite nerve scaffold with oriented structure and conductive function for skin peripheral nerve injury repair

Skin peripheral nerve injury repair still faces significant clinical challenges. Although nerve tissue engineering scaffolds show potential, issues such as limited functionality and low repair efficiency persist. This study developed a dual-regulation biomimetic composite nerve scaffold with oriented structure and conductive function to promote nerve injury repair. The structural layer was a chitosan (CS)/polycaprolactone (PCL) oriented nanofiber membrane, which could promote cell adhesion and induce directional growth of cells. The functional layer was a CS/sodium alginate (SA) ionic conductive hydrogel, which could enhance endogenous electric fields to promote cell proliferation and differentiation. The two layers were combined through physical crosslinking, avoiding the use of chemical adhesives and preserving the surface morphology of the nanofibrous membrane and the porous structure of the hydrogel. The biomimetic composite nerve scaffold exhibited layered degradability, excellent orientation, conductivity, and biocompatibility. Cell experiments indicated that the scaffold effectively induced directional migration, growth, and differentiation of cells and enhanced cell activity, thereby providing a favorable microenvironment for nerve regeneration. This study not only overcomes the limitation of functional singularity in traditional nerve scaffolds but also aligns with the forefront trend in tissue engineering toward multifunctional and biomimetic materials. It demonstrates great potential for treating complex conditions such as traumatic nerve defects and post-surgical nerve regeneration and has broad application prospects in the field of neural tissue engineering.

Evaluation of Outgrowth Potential of Rat Pheochromocytoma Cells Supplied with Highly Purified Rapidly Expanding Clones and Potential Application to Trigeminal Nerve Regeneration

BACKGROUND

Mesenchymal stem/stromal cells (MSCs) are non-hematopoietic, plastic-adherent, and self-renewing cells capable of in vitro trilineage differentiation into fat, bone, and cartilage tissue. Suggestively, MSCs have additional plasticity, as demonstrated by their ability to differentiate in vitro into myocytes, neuron-like cells, and hepatocytes. MSCs are ideal for therapeutic application owing to their numerous advantages; they exhibit limited growth and differentiation abilities, leading to heterogeneous cell populations with inconsistent functions. However, highly purified MSCs, namely, rapidly expanding clones (RECs) that are isolated by single-cell sorting, display uniform functionality. RECs have the potential to offer many benefits, such as transplantable cells for treating several disorders of bone, heart, peripheral nerves, brain, and other organs. This study aimed to assess the effects of RECs on the pheochromocytoma (PC12) cell line, a well-known neuronal cell model.

METHODS

PC12 cells were cultured under the following conditions: co-culture with RECs, treatment with REC-derived conditioned medium (CM), or co-culture with RECs using Transwell inserts for 7 days. The cells were stained with anti-βIII-tubulin antibody; the lengths of neurites were measured by image analysis.

RESULTS

Regarding the co-culture with RECs, PC12's outgrowth was significantly increased. The RECs expressed nerve growth factor (NGF), a neurotrophic factor that could act on PC12 cells to trigger cellular differentiation.

CONCLUSIONS

Our findings suggest that RECs via direct culture, intercellular communication in Transwell culture, and RECs CM promoted PC12 cell survival and outgrowth via NGF signaling.

Cellular senescence in age-related musculoskeletal diseases

Aging is typically associated with decreased musculoskeletal function, leading to reduced mobility and increased frailty. As a hallmark of aging, cellular senescence plays a crucial role in various age-related musculoskeletal diseases, including osteoporosis, osteoarthritis, intervertebral disc degeneration, and sarcopenia. The detrimental effects of senescence are primarily due to impaired regenerative capacity of stem cells and the pro-inflammatory environment created by accumulated senescent cells. The secreted senescence-associated secretory phenotype (SASP) can induce senescence in neighboring cells, further amplifying senescent signals. Although the removal of senescent cells and the suppression of SASP factors have shown promise in alleviating disease progression and restoring musculoskeletal health in mouse models, clinical trials have yet to demonstrate significant efficacy. This review summarizes the mechanisms of cellular senescence in age-related musculoskeletal diseases and discusses potential therapeutic strategies targeting cellular senescence.

Bone marrow aspirate concentrate (BMAC) harvested in the axial and appendicular skeleton does not differ in progenitor cell count: A systematic review and meta-analysis

Introduction

Bone marrow aspirate concentrate (BMAC) is a reliable source of progenitor cells that facilitate healing, and it is typically harvested from the iliac crest. The purpose of this systematic review and meta-analysis was to compare total nucleated cell (TNC) count and the presence of colony-forming units (CFUs) in BMAC harvested from axial versus appendicular harvest sites.

Methods

In accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, PubMed, Embase, and Cochrane Library databases were searched in August 2024 for studies published after 2004. Studies were included if they evaluated cell counts within BMAC samples harvested from males and females of any age and were prospective. Studies that had no reported cell count within BMAC samples, had evaluations of biologic material other than BMAC, or were translational or cadaveric studies, as well as review articles or technical notes, were excluded. Patients were divided into two cohorts based on whether BMAC was harvested from their axial or appendicular skeleton.

Results

The initial search identified 2126 studies, of which 15 non-randomized prospective studies with a total of 583 patients were included. Each study had low risk of bias. In the axial skeleton, TNC counts ranged from 0.1-502 × 106 cells/mL, and CFU concentration ranged from 0 to 807 CFU/mL. In the appendicular skeleton, TNC counts ranged from 0.1-87 × 106 cells/mL and CFU counts ranged from 0 to 802.7 CFU/mL. No significant differences in TNC or CFU count in BMAC harvested from the axial versus appendicular skeleton were observed.

Conclusions

BMAC harvested from the axial and appendicular skeletons demonstrate significant variability in progenitor cell concentration. These findings suggest that harvesting at appendicular sites near the operative location allows the surgeon to extract sufficient quality BMAC as compared to harvest sites within the axial skeleton, such as the iliac crest.

Level of evidence

Level II, systematic review of level II studies.

Metabolic crosstalk between platelets and cancer: Mechanisms, functions, and therapeutic potential

Platelets, traditionally regarded as passive mediators of hemostasis, are now recognized as pivotal regulators in the tumor microenvironment, establishing metabolic feedback loops with tumor and immune cells. Tumor-derived signals trigger platelet activation, which induces rapid metabolic reprogramming, particularly glycolysis, to support activation-dependent functions such as granule secretion, morphological changes, and aggregation. Beyond self-regulation, platelets influence the metabolic processes of adjacent cells. Through direct mitochondrial transfer, platelets reprogram tumor and immune cells, promoting oxidative phosphorylation. Additionally, platelet-derived cytokines, granules, and extracellular vesicles drive metabolic alterations in immune cells, fostering suppressive phenotypes that facilitate tumor progression. This review examines three critical aspects: (1) the distinctive metabolic features of platelets, particularly under tumor-induced activation; (2) the metabolic crosstalk between activated platelets and other cellular components; and (3) the therapeutic potential of targeting platelet metabolism to disrupt tumor-promoting networks. By elucidating platelet metabolism, this review highlights its essential role in tumor biology and its therapeutic implications.

Identification of the crucial roles of BAXhigh NK cells in human derived mesenchymal stem cell therapy for chronic heart failure patients

Mesenchymal stem cells (MSCs) have demonstrated significant potential in heart failure (HF) treatment, but the exact mechanisms are still not fully understood. This research utilized single-cell RNA sequencing to examine alterations in peripheral blood mononuclear cells from heart failure patients pre- and post-MSC therapy. Moreover, we utilized Mendelian randomization (MR) analysis to identify causal genes linked to HF. Specifically, through scRNA-seq, we observed a progressive increase in Natural Killer (NK) cells within peripheral blood mononuclear cells (PBMCs) following MSC treatment. Furthermore, MR analysis identified the differentially expressed gene (DEG) BAX as a potential target gene for HF. Notably, the expression of BAX was significantly downregulated after MSC treatment, suggesting its potential as a therapeutic response biomarker. Cell-cell communication analysis revealed that BAXhigh NK cells displayed reduced cell-cell communication and increased apoptotic activity. Enrichment analysis indicated an association between BAXhigh NK cells and the "coagulant" pathway. Taken together, our findings suggest that BAX may contribute to the pathogenesis of HF by promoting coagulation and apoptotic pathways. In contrast, MSCs appear to suppress BAX expression, thereby inhibiting these pathways. MSC treatment increases the proportion of NK cells and reduces BAXhigh NK cells, ultimately improving NK cell function, and ameliorating HF.

Potential applications of mesenchymal stem cells in ocular surface immune-mediated disorders

We explore the interaction between corneal immunity and mesenchymal stem/stromal cells (MSCs) and their potential in treating corneal and ocular surface disorders. We outline the cornea's immune privilege mechanisms and the immunomodulatory substances involved. In this realm, MSCs are characterized by their immunomodulatory properties and regenerative potential, making them promising for therapeutic application. Therefore, we focus on the role of MSCs in immune-mediated corneal diseases such as dry eye disease, corneal transplantation rejection, limbal stem cell deficiency, and ocular graft-versus-host disease. Preclinical and clinical studies demonstrate MSCs' efficacy in promoting corneal healing and reducing inflammation in these conditions. Overall, we emphasize the potential of MSCs as innovative therapies in ophthalmology, offering promising solutions for managing various ocular surface pathologies.

Sonic Hedgehog potentiates BMP9-induced osteogenic differentiation of mesenchymal stem cells

Bone morphogenetic protein 9 (BMP9) has remarkable potential to induce the differentiation of mesenchymal stem cells (MSCs) towards the osteoblastic lineage. Additionally, research suggests that certain growth factors have the ability to potentiate BMP9-induced osteogenic differentiation of MSCs. Sonic Hedgehog (Shh) plays an indispensable role in the regulation of skeletal development. The objective of this research was to assess the potential influence of Shh on BMP9-induced osteogenic differentiation of MSCs. Our findings indicated that Shh effectively enhanced BMP9-induced early and late osteogenic differentiation of MSCs, and increased BMP9-induced expression/transcriptional activity of osteogenesis-related transcription factors. Besides, it was observed that Shh promoted BMP9-induced ectopic bone formation of MSCs in vivo. Moreover, BMP9 was able to facilitate the repair of bone defects in rats, while Shh further accelerated this reparative process. Mechanistically, Shh enhanced the activation of the Smad1/5/8 signaling pathway which was induced by BMP9. Furthermore, GANT-61, an inhibitor of Gli1 and Gli2, attenuated the enhancing effect of Shh on BMP9-induced osteogenic differentiation of MSCs. Collectively, the co-administration of BMP9 and Shh may present a promising therapeutic approach for the treatment of fracture nonunion, delayed fracture healing, and bone defects.

Therapeutic potential of stem cell-derived exosomes for bone tissue regeneration around prostheses

Artificial joint replacement is a widely recognized treatment for arthritis and other severe joint conditions. However, one of the primary causes of failure in joint replacements is the loosening of the prosthesis. After implantation, wear particles between the implant and the adjacent bone tissue are the principal contributors to this loosening. Recently, exosomes have garnered significant interest due to their low immunogenicity and effective membrane binding. They have shown potential in promoting bone regeneration via the paracrine pathway. This review examines the role and mechanisms of exosomes derived from mesenchymal stem cells (MSCs) in bone regeneration, their impact on the integration of various implants into surrounding bone tissue and current challenges and future directions for the clinical application of exosomes. The Translational Potential of this Article: Emerging evidence suggests that mesenchymal stem cell-derived exosomes may offer a promising therapeutic strategy for aseptic prosthesis loosening, potentially mediated through mechanisms such as modulation of inflammatory responses, suppression of osteoclastogenesis, enhancement of osteogenic differentiation and facilitation of bone regeneration. Preclinical studies further indicate that the therapeutic potential of these extracellular vesicles could be optimized through bioengineering strategies, including surface modification and cargo-loading techniques, warranting further investigation to advance their clinical translation.

Lack of IFN-γ response of human uterine myometrium-derived MSCs significantly improve multiple IBD parameters compared to bone marrow MSCs: Implications for anti-TNFα-refractory patients

The clinical efficacy of mesenchymal stem cell (MSC) therapy for inflammatory bowel disease (IBD) is inconsistent and often fails to match promising preclinical findings. To improve outcome, we compared MSCs isolated from human uterine myometrium (Ut), a readily-available tissue source from a unique immune niche, to bone marrow (BM) MSCs, the most common source, in a murine IBD model with mechanisms underlying differential effects. In this study, human BMMSCs and UtMSCs were intravenously administered to mice with dextran sulfate sodium-induced colitis and evaluated for disease activity, microbiome composition, and cellular immunity. Bioinformatics analyses including patient data were performed to further specify involved mechanisms with subsequent functional validation performed. We found that UtMSC but not BMMSC treatment significantly reversed disease parameters by improving microbiome and reducing mesenteric lymph node IFN-γ and IL-17A-secreting T cells. Transcriptomic analysis revealed UtMSCs had reduced MHC II pathway activation compared to BMMSCs. Functional validation confirmed UtMSCs compared to BMMSCs expressed lower IFN-γ receptors, prevent MHC II-mediated human unstimulated T cell activation, and modulated stimulated T helper (Th) cells away from effector phenotypes while increasing regulatory T cells (Tregs) and IL-10 levels. Bioinformatics from IBD patients resistant to non-T cell-specific therapies implicated persistent MHC II-mediated Th1/Th17 activation as key drivers of disease. Overall, UtMSCs outperformed BMMSCs in improving microbiota, avoiding IFN-γ responses, and modulating overall Th responses, suggesting this MSC source may offer more significant effectiveness for IBD and Th1/Th17-mediated conditions. Our findings also highlight that understanding MSC source-specific therapeutic mechanisms is crucial for optimizing clinical therapies.

Enhance the therapeutic efficacy of human umbilical cord-derived mesenchymal stem cells in prevention of acute graft-versus-host disease through CRISPLD2 modulation

BACKGROUND

Acute graft-versus-host disease (aGVHD) remains a major life-threatening complication of allogeneic haematopoietic cell transplantation (allo-HSCT), often limiting the therapeutic efficacy of allo-HSCT. Recent studies have suggested that mesenchymal stem cells (MSCs) may be beneficial for the treatment of aGVHD. However, the therapeutic potential of MSCs is often negatively impacted by their heterogeneity.

METHODS

To investigate MSCs heterogeneity, we conducted single-cell transcriptomic analysis of human umbilical cord-derived MSCs (HUC-MSCs) and identified key feature genes that distinguish MSCs subpopulations. The function of the newly discovered biomarker CRISPLD2 was also explored. We engineered human umbilical cord-derived MSCs (HUC-MSCs) to overexpress the CRISPLD2 gene using lentiviral vectors. The downstream regulatory effects of CRISPLD2 overexpression were assessed through bulk RNA sequencing. Additionally, we evaluated its impact on cellular senescence using Western blotting and β-galactosidase (SA-β-gal) staining. The immunoregulatory capability of HUC-MSCs was tested through coculture experiments with T cells and liver organoids in vitro. Mitochondrial function was analysed via flow cytometry and electron microscopy. The in vivo therapeutic effects of HUC-MSCs on aGVHD were evaluated using an aGVHD murine model. The graft-versus-leukaemia (GVL) effect was measured via the inoculation of luciferase-positive A20 cells, and tumour growth was monitored via bioluminescence imaging.

RESULTS

Our findings indicated that the CRISPLD2 gene is heterogeneously expressed in HUC-MSCs subsets characterized by stemness and immunosuppressive properties. Transcriptomic analysis revealed that CRISPLD2 overexpression suppressed calcium ion binding and G protein-coupled receptor signalling. In vitro studies demonstrated a marked increase in IL-10 secretion, which enhanced T-cell suppression in CRISPLD2-modified HUC-MSCs. The in vivo results demonstrated that transfusion of CRISPLD2-overexpressing HUC-MSCs ameliorated aGVHD while maintaining GVL activity. Mechanistically, CRISPLD2 overexpression overcomes the mitochondrial damage mediated by extracellular ATP and LPS in HUC-MSCs by inhibiting P2Y11 receptor signalling, thereby preserving their stemness and IL-10-mediated immunosuppressive functions.

CONCLUSIONS

Our study revealed that CRISPLD2 is a novel marker for identifying HUC-MSCs subpopulation with enhanced immunosuppressive functions. CRISPLD2 overexpression enhances the immunosuppressive function of HUC-MSCs by inhibiting P2Y11 receptor signalling. Targeting CRISPLD2 is a promising strategy to improve the therapeutic efficacy of HUC-MSCs in aGVHD while maintaining GVL activity.

Human stromal cell-based protocol to generate astrocytes: a straightforward in vitro predictive strategy in neurotoxicology

The inherent adaptability of human mesenchymal stromal cells (hMSCs) to differentiate into neural lineages provides a valuable resource for investigating potential neurotoxicity in humans. By harnessing the ability of hMSCs to transform into astrocytes, we can evaluate the effects of various agents on these vital cells. Our protocol employs hMSCs sourced from umbilical cord tissue, ensuring a readily available supply of high-quality cells. The hMSC-to-neural workflow encompasses six essential steps: hMSC culture, followed by the generation of embryoid bodies (EBs) from these cells on specialized surfaces. Next, EBs and cells are expanded in a growth-promoting medium, directing them toward neural lineages. Subsequent differentiation into immature astrocytes is achieved through the use of specific factors. The process continues with the maturation of EBs/cells into astrocyte-like cells (hALCs) under optimized conditions, culminating in the final development of hALCs in a specialized medium. This methodology yields cells that display astrocyte morphology and express characteristic markers such as GFAP and S100β. The protocol is efficient, requiring roughly 6 weeks to generate hALCs from primary hMSCs without genetic manipulation. The application of hMSCs in evaluating cell damage triggered by neurotoxicants like MeHg and MGO underscores their potential as a valuable component within a more extensive battery of neurotoxicity tests.

Promotion of bone-tendon healing after ACL reconstruction using scaffold-free constructs comprising ADSCs produced by a bio-3D printer in rabbit models

Background/Objective: This study evaluated the impact of adipose tissue-derived mesenchymal stromal cells (ADSCs) on bone-tendon healing in rabbit anterior cruciate ligament (ACL) reconstruction.

Methods

Nineteen mature male Japanese White rabbits underwent bilateral ACL reconstruction. ADSC constructs were implanted in the right femoral bone tunnel of each rabbit (implant group), while the left knee served as the control group without implantation. Nine rabbits were sacrificed at 3 and 6 weeks post-surgery, while the remaining were sacrificed immediately post-surgery. Biomechanical and micro computed tomography evaluations were conducted on six rabbits, while histological observation was performed on the remaining three.

Results

showed: (1) The implant group exhibited a significantly greater failure load than the control group at 3 weeks post-surgery. (2) Initially, the amount of new bone in the femoral tunnel was lower in the implant group at 3 weeks but surpassed that of the control group by 6 weeks. (3) Histological analysis indicated faster bone-tendon healing in the implant group than that of the control.

Conclusion

These findings suggest a positive effect of ADSC constructs on bone-tendon healing post-ACL reconstruction in rabbits. However, further studies using larger animal models must confirm these effects comprehensively.

The translational potential of this article

The method of transplanting a scaffold-free autologous ADSC construct is a technique that can safely and reliably transplant ADSCs to the tendon-bone tunnel interface without using foreign substances. It can be applied to bone-tendon healing in ACL reconstruction surgery and other areas, such as the rotator cuff and Achilles tendon attachment site.

Dysregulated circular RNAs in rheumatoid arthritis: Cellular roles and clinical prospects

Rheumatoid arthritis (RA) is still a healthcare challenge, although current therapeutic strategies have substantially improved its clinical outcomes. The development of novel biomarkers and treatments can increase the likelihood of identification and disease remission in RA patients, especially for patients with seronegative RA and difficult-to-treat RA (D2T RA). Circular RNAs (circRNAs), a novel non-coding RNA species, have been reported to play crucial roles in various biological process of RA. The mechanistic functions of the dysregulated circRNAs in RA are primarily associated with miRNA sponging and regulating transcription. CircRNAs acting as miRNA sponges are further summarized by cell types, including fibroblast-like synoviocytes (FLSs), lymphocytes, macrophages, chondrocytes, and mesenchymal stem cells (MSCs)-/plasma-secreted exosomes. Besides, a description of dysregulated circRNAs in blood, synovial tissue and cartilage tissue suggests their diagnostic potential for RA. In addition, some directions for future research are provided to open the possibility that dysregulated cell- and tissue- specific circRNAs constituting a fresh reservoir of therapeutic targets, and biomarkers for diagnosis, predicting response to therapy, drug selection or patient stratification for RA.

Evolution in Bone Tissue Regeneration: From Grafts to Innovative Biomaterials

Bone defects caused by various traumas and diseases such as osteoporosis, which affects bone density, and osteosarcoma, which affects the integrity of bone structure, are now well known. Given this situation, several innovative research projects have been reported to improve orthopedic methods and technologies that positively contribute to the regeneration of affected bone tissue, representing a significant advance in regenerative medicine. This review article comprehensively analyzes the transition from existing methods and technologies for implants and bone tissue regeneration to innovative biomaterials. These biomaterials have been of great interest in the last decade due to their physicochemical characteristics, which allow them to overcome the most common limitations of traditional grafting methods, such as the availability of biomaterials and the risk of rejection after their application in regenerative medicine. This could be achieved through an exhaustive study of the applications and properties of various materials with potential applications in regenerative medicine, such as using magnetic nanoparticles and hydrogels sensitive to external stimuli, including pH and temperature. In this regard, this review article describes the most relevant compounds used in bone tissue regeneration, promoting the integration of these biomaterials with the affected area's bone structure, thereby allowing for regeneration and preventing amputation. Additionally, the types of interactions between biomaterials and mesenchymal stem cells and their effects on bone tissue are discussed, which is critical for developing biomaterials with optimal regenerative properties. Furthermore, the mechanisms of action of the various biomaterials that enhance osteoconduction and osteoinduction, ensuring the success of orthopedic therapies, are analyzed. This enables the treatment of bone defects tailored to each patient's condition, thereby avoiding limb amputation. Consequently, a promising future for regenerative medicine is emerging, with various therapies that could revolutionize the management of bone defects, offering more efficient and safer solutions.

A Mathematical Model for Determining Probabilistic Design Space in Mesenchymal Stem Cell Passage Culture

With their many therapeutic functions, mesenchymal stem cells (MSCs) are promising sources for regenerative medicine. However, in the manufacture of MSCs, without a method for exploring the effects of long-term passage on cell proliferation potentials, the design of passage culture processes is challenging. Here, for the process design of the MSC passage culture, we propose a model for predicting the growth rate as a function of the cumulative population doubling level (cPDL) for each passage. Three steps were implemented: (1) passage culture experiments to correlate apparent growth rate with cPDL were conducted, (2) a model for predicting the growth rate as a function of cPDL was developed, and (3) a model to design the passage culture of MSCs from bone marrow (BM-MSCs) and umbilical cord (UC-MSCs) with stochastic simulation was applied. Two design variables (passage number and harvesting time) were investigated to define feasible operation regions as probabilistic design spaces to meet three quality indicators (senescence level, confluency level, and total number of cells) with given probabilities. Consequently, 10 and 62 conditions out of 165 were identified as feasible for BM- and UC-MSCs, respectively, which would contribute to the industrial MSC passage culture process design.

Mesenchymal stem cells and their extracellular vesicles: new therapies for cartilage repair

Cartilage is crucial for joints, and its damage can lead to pain and functional impairment, causing financial burden to patients. Due to its weak self-repair, cartilage injury control is a research focus. Cartilage injury naturally with age, but mechanical trauma, lifestyle factors and certain genetic abnormalities can increase the likelihood of symptomatic disease progression. Current treatments for cartilage injury include pharmacological and surgical interventions, but these lack the ability to stop the progression of disease and restore the regeneration of the cartilage. Biological therapies have been evaluated but show varying degrees of efficacy in cartilage regeneration long-term. The mesenchymal stem cell (MSC) therapy attracts attention as it is easily harvested and expanded. Once thought to repair via differentiation, MSCs are now known to secrete extracellular vesicles (EVs) paracrinely. These EVs, rich in bioactive molecules, enable cell communication, boost growth factor secretion, regulate the synthesis and degradation of extracellular matrix (ECM), and modulate inflammation, vital for cartilage repair. However, further research and clinical validation are still required for the application of MSC and MSC-EVs. This review highlights the current state of research on the use of MSC and MSC-EVs in the treatment of cartilage injury. It is hoped that the review in this paper will provide valuable references and inspiration for future researchers in therapeutic studies of cartilage repair.

Therapeutic Potential of Local and Systemic Adipose-Derived Mesenchymal Stem Cell Injections in a Rat Model of Experimental Periodontitis: Implications for Cardiac Function

Periodontitis is a common inflammatory disease that not only damages periodontal tissues but also induces systemic effects, including cardiac dysfunction. Mesenchymal stem cells (MSCs) offer regenerative potential due to their ability to differentiate, modulate immune responses, and secrete anti-inflammatory factors. However, the relative efficacy of local versus systemic MSC administration remains unclear. This study evaluated the therapeutic effects of adipose-derived MSCs (AD-MSCs) in a rat model of experimental periodontitis, comparing local and systemic administration. AD-MSCs were characterized based on morphology, surface marker expression, and differentiation potential. Ligature-induced periodontitis was established over 60 days, after which AD-MSCs (1 × 106 cells) were administered either supraperiosteally (local group) or intravenously (systemic group). Periodontal regeneration was assessed through clinical, radiographic, and histopathological analyses, while cardiac function was evaluated using echocardiography and histopathological examinations. Results demonstrated that local AD-MSC administration provided superior therapeutic benefits compared to systemic delivery. Locally administered cells significantly enhanced bone regeneration, reduced inflammation, and improved periodontal tissue architecture. In contrast, systemic administration offered moderate benefits but was less effective in restoring periodontal integrity. Similarly, in the heart, local treatment resulted in greater improvements in systolic function, as indicated by enhanced ejection fraction and fractional shortening, along with reduced myocardial fibrosis. Although systemic administration also provided cardioprotective effects, diastolic dysfunction persisted in both treatment groups. In conclusion, local AD-MSC administration proved more effective in regenerating periodontal tissues and mitigating cardiac dysfunction, highlighting its potential as an optimized therapeutic strategy for periodontitis and its systemic complications.

Effects of chorionic mesenchymal stromal cells, their conditioned medium, and membrane particles on neutrophil functionality

Mesenchymal stromal cells (MSC) are multipotent cells that can modulate immune cells, affecting macrophages, monocytes, and lymphocytes. Neutrophils are circulating leucocytes responsible for the first line of defense and can assume different phenotypes depending on their environment: N0, the naïve form, N1 (inflammatory), N2 (anti-inflammatory). This study explores the potentially protective roles of chorionic membrane MSCs and their products-conditioned medium and pre-conditioned cMSC-derived membrane microparticles (MP-cMSC)-on neutrophils. Conditioned medium treatment reduced the rate of apoptosis and enhanced the immunosuppressive potential consistent with an anti-inflammatory profile. MP-cMSC are a noteworthy cell-free therapy, consisting of artificially generated circular lipid bilayer structures with no cargo and approximately 200 nm in size. When added to neutrophil culture, MPs increased neutral red uptake, suggesting an enhanced phagocytic activity. In the MSC co-culture group, a reduced rate of apoptosis, increased neutral red uptake, and elevated programed death-ligand 1 (PD-L1) expression were observed. These findings suggest that the distinct effects elicited by conditioned media, microparticles, and co-culture are likely influenced by the specific nature of the interactions involved-whether purely paracrine, mediated through direct cell-to-cell contact, or a combination of both.

The photobiomodulation effects of continuous and pulsed blue diode laser on proliferation and osteogenic differentiation of periodontal ligament stem cells

This study investigated the photobiomodulation effect of pulsed and continuous blue diode laser on osteogenic differentiation and proliferation of periodontal ligament mesenchymal stem cells. Periodontal Ligament Stem cells were seeded in 96-well plates, and 450 nm blue laser irradiation procedure was performed a day after cell seeding. Each experimental group was divided into two subgroups according to their energy density and irradiation duration: Continuous wave (100 mW, 10s, 2 J/cm2 and 100 mW, 20 s, 4 J/cm2) and pulse wave (200 mW, 10 s, 2 J/cm2 and 200 mW, 20 s, 4 J/cm2 and duty cycle 50% for both). Then, all groups were evaluated with a cell viability test (MTT), cell apoptosis (Annexin V) on the second and fourth days after irradiation, Alizarin Red staining on the 14th day after irradiation based on genes. Real-time PCR was conducted 7 and 14 days after irradiation. GAPD gene primers were used as internal control, and OPN, OCN, ALP, and RUNX2 gene primers were used as tests. The one-way ANOVA statistical analysis revealed that cell proliferation in the continuous-irradiated groups was significantly higher than in pulsed groups. However, there is no significant difference in comparison with the control group. Also, pulsed-irradiated groups demonstrated a higher rate of necrosis. The osteogenic differentiation in the continuous groups was more substantial than in the pulsed and the control groups. In comparison to all other study groups, the group that received continuous mode irradiation at an energy density of 2 J/cm2, power of 100 mW, and a radiation time of 10 s exhibited significantly higher numbers of calcified nodules and increased expression of OPN, OCN, and ALP genes (p < 0.05). Overall, treating periodontal ligament stem cells with a continuous blue diode laser and appropriate parameters can enhance their osteogenic differentiation and proliferation, accelerating the regeneration of periodontal tissues.

Peptidomic profiling of mesenchymal stem cell-derived extracellular vesicles and anti-inflammatory activity of degraded peptides

Mesenchymal stem cell derived extracellular vesicles (MSC-EVs) are key paracrine mediators involved in various autoimmune diseases. While current research on EVs predominantly focuses on their protein and nucleic acid components, small peptides received less attention. In this study, we found IFN-γ-treated MSC-EVs, as engineered EVs, exhibit better anti-inflammatory effects both in vitro and in vivo. Through LC-MS/MS and bioinformatics analysis, we identified four peptides-C3-1, C3-2, B2M-1, and IFIT3-1-that are highly expressed in IFN-γ-treated MSCs-EVs. These peptides significantly mitigate the proliferation inhibition of HUVEC cells induced by H₂O₂ and enhance their migratory capacity. Furthermore, they downregulate the expression of inflammatory cytokines TNF-α and IL-6 in H₂O₂-induced oxidative stress models of HUVEC and LPS-induced inflammatory models of RAW264.7 macrophages. The peptides also upregulate p-AKT and HIF-1α, with C3-1 demonstrating superior anti-inflammatory efficacy in both cell models. Consistent with the in vitro findings, in vivo experiments revealed that C3-1 reduces LPS-induced inflammatory cell infiltration in liver tissue and restores hepatocyte structural integrity, as evidenced by HE-stained liver sections. Western blot analysis further confirmed that C3-1 upregulates p-AKT expression and suppresses inflammatory cytokines. Collectively, these findings suggest that C3-1 exerts its anti-inflammatory effects via activation of the AKT signaling pathway and regulation of TNF-α and IL-6. This study not only highlights the anti-inflammatory potential of IFN-γ-treated MSC-derived EVs but also identifies C3-1 as a promising candidate for anti-inflammatory drug development. Notably, this is the first study to identify degraded peptides within EVs, providing a foundation for future research in this area.

Bioadhesive levan-based coaxial nanofibrous membranes with enhanced cell adhesion and mesenchymal stem cell differentiation

Conventional electrospun nanofibrous membranes have been widely used for tissue engineering scaffolds because they can mimic extracellular matrix (ECM), which plays a significant role in cell proliferation, adhesion, and differentiation. However, the inadequate mechanical strength and biological functions of electrospun nanofibrous scaffolds limit the range of their practical applications. In this study, we prepared a uniform levan-based core-shell composite (csCAL) nanofibrous membrane using the coaxial electrospinning technique. The coaxial csCAL membrane with levan and cellulose acetate (CA) as shell and core, respectively, exhibited highly enhanced mechanical properties and adhesive strength. Moreover, the unique bioadhesive nature of these membranes significantly enhanced cell attachment and proliferation, while their high biocompatibility and biodegradability hold substantial promise for application as functional cell carriers. Upon incorporating mesenchymal stem cells (MSCs) into the csCAL nanofibrous membrane, we observed enhanced osteogenesis and chondrogenesis, as evidenced by alizarin red and alcian blue staining, respectively. These results indicate that the levan-based nanofiber architecture has the potential to deliver scaffolds for supporting the differentiation of MSCs.

The mutual effects of stearoyl-CoA desaturase and cancer-associated fibroblasts: A focus on cancer biology

The tumor microenvironment (TME) 's primary constituents that promote cancer development are cancer-associated fibroblasts (CAFs). Metabolic remodeling has been shown to control CAF activity, particularly aberrant lipid metabolism. SCD1 can be thought of as the primary enzyme controlling the fluidity of lipid bilayers by gradually converting saturated fatty acids into monounsaturated fatty acids. Furthermore, its crucial function in the onset and spread of cancer is well acknowledged. Even with the increasing amount of research on changes in lipid metabolism, this problem remains a relatively understudied aspect of cancer research. Blocking several fatty acid synthesis-related enzymes highly expressed in cancerous cells inhibits cell division and encourages apoptosis. This is the situation with SCD1, whose overexpression has been linked to several changed tumors and cells. Both genetic and pharmacological silencing of SCD1 in cancer cells prevents glucose-mediated lipogenesis and tumor cell growth. However, its role in CAFs, hence, cancer biology, has been less studied. This study aimed to review the role of SCD1 in CAF biology, shedding light on their function in cancer cell biology.

Decellularized Porcine Aorta as a Scaffold for Human Induced Pluripotent Stem Cell-Derived Mesenchymal Stem Cells in Tissue Engineering

Tissue engineering has been an integral part of regenerative medicine. Functional biomimetic structures were assembled by combining appropriate scaffolds with specific cells. The decellularization of animal tissue preserved the natural biochemical components and structural properties of the extracellular matrix (ECM) of specific organs, thereby providing a suitable niche for tissue-specific cell differentiation and growth. In this study, the extracellular matrix (ECM) of the porcine aorta was obtained through trypsin-based decellularization. The resulting porcine aortic ECM retained a favorable collagen composition, exhibited no cytotoxicity, and demonstrated chemophilic properties for mesenchymal stem cells. Human adipose-derived mesenchymal stem cells (hADSCs) and human induced pluripotent stem cell-derived mesenchymal stem cells (hiMSCs) were transplanted onto the decellularized porcine aortic ECM, where successful differentiation into a mature cartilage layer was observed. These findings suggested that the porcine aortic ECM could serve as a potential scaffold with tubular and linear structures for tissue engineering applications. Functional human iMSCs (induced-mesenchymal stem cells) were generated from human iPSCs (induced-pluripotent stem cells) and analyzed for differences compared to primary MSCs via RNA-seq. The hiMSCs were applied to decellularized porcine aortic ECM (extracellular matrix), demonstrating chondrogenic differentiation and confirming the usability of xenogeneic ECM.

Transplantation of Exercise-Enhanced Mesenchymal Stem Cells Improves Obesity and Glucose Tolerance via Immune Modulation in Adipose Tissue

Exercise-conditioned mesenchymal stem cells (MSCs) may modulate immune responses and improve white adipose tissue (WAT) function. While MSCs are known to reduce inflammation, it remains unclear if exercise-stimulated MSCs can improve obesity-related dysfunctions. This study is the first to explore how exercise-conditioned MSCs may influence adipose tissue inflammation and remodeling in the context of obesity. MSCs were isolated from exercised- and sedentary donor mice, then cultured in vitro. After culture, MSCs were assessed for differentiation capacity and cytokine gene expression, including Il10, as indicators of immune modulation. Exercise-conditioned MSCs were then transplanted into obese recipient mice. Following transplantation, immune cell profiles, inflammatory markers, and adipocyte morphology in recipient WAT were analyzed. Flow cytometry was used to quantify macrophage subtypes (pro-inflammatory and anti-inflammatory), and histological analysis was performed to measure changes in adipocyte size. Exercise-activated MSCs showed a ± 35% increase in Il10 expression and a ± 20% enhancement in differentiation capacity compared to controls, indicating improved immunomodulatory potential. In recipient mice, transplantation led to a ± 25% reduction in pro-inflammatory macrophages (CD86+ CD206-) and a 15% decrease in adipocyte size within WAT. Additionally, WAT in treated mice showed balanced inflammatory profiles and reduced adipose hypertrophy, suggesting restored immune balance and metabolic health. These findings suggest that exercise-modified MSCs exhibit enhanced immunomodulatory and metabolic regulatory properties. This study provides evidence that exercise enhances MSC characteristics, potentially improving their capacity to modulate adipose tissue immune balance and metabolic function in obesity. Exercise-conditioned MSCs may serve as a foundation for future strategies that integrate exercise-induced stem cell modifications to modulate obesity-related metabolic dysfunction.

The inconclusive superiority debate of allogeneic versus autologous MSCs in treating patients with HFrEF: a systematic review and meta-analysis of RCTs

BACKGROUND

Recent randomized controlled trials have consistently demonstrated the safety and potential efficacy of MSC therapy for heart failure patients. This study delves into mesenchymal stem cells' promising potential, offering a beacon of hope for the future of heart failure treatment with reduced ejection fraction (HFrEF).

METHODS

We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for this systematic review and meta-analysis. We searched four databases and registers for RCTs, including PubMed, EBSCO, clinicaltrials.gov, ICTRP, and other relevant websites. We then selected thirteen RCTs with 1184 participants based on our pre-defined inclusion/exclusion criteria. Two independent assessors extracted the data and performed a quality assessment. The data were then plotted for various outcomes, including death, hospitalization, major adverse cardiac events, pump function parameters, and 6-min walk distance.

RESULTS

The safety of MSC-based treatment has been consistently demonstrated with MSCs from autologous (AutoMSCs) and allogeneic (AlloMSCs) sources. This reassuring finding underscores the reliability of MSC-based therapy irrespective of their source. However, AutoMSCs showed a trend toward greater protective benefits. Subgroup analysis revealed no significant differences between AutoMSCs and AlloMSCs in improving LVEF; 0.86% (95% CI - 1.21-2.94%) for AlloMSCs versus 2.17% (- 0.48%; 95% CI - 1.33-5.67%) for AutoMSCs. AlloMSCs significantly reduced end-diastolic volume (LVEDV) by - 2.08 mL (95% CI - 3.52-0.64 mL). Only AlloMSCs significantly improved 6-min walking distance (6-MWD); 31.88 m (95% CI 5.03-58.74 m) for AlloMSCs versus 31.71 m (95% CI - 8.91-71.25 m) for AutoMSCs. The exclusion of studies using adipose-derived cells resulted in even better safety and a significant improvement in LVEF for AlloMSCs treatment.

CONCLUSION

Our findings suggest that AlloMSCs are at par with AutoMSCs in improving functional outcomes in heart failure patients. This underscores the need for future investigations in a larger patient cohort, emphasizing the urgency and importance of further research to fully understand the potential of MSCs in treating heart failure.

Engineered mesenchymal stromal cells with interleukin-1beta sticky-trap attenuate osteoarthritis in knee joints

Osteoarthritis (OA) is a common chronic inflammatory joint disease, in which innate immunity plays a pivotal role in pathogenesis. Anti-interleukin-1(IL-1) therapies have shown inconsistent results in clinical trials, potentially due to a mismatch in the spatial and temporal dynamics of interleukin-1beta (IL-1β) production and therapeutic interventions. To address this issue, we developed a novel IL-1β "sticky-trap" utilizing cell and gene-based technologies from our lab and evaluated its efficacy in reducing osteoarthritis progression using a murine destabilization of the medial meniscus (DMM) OA model and a compact bone-derived mesenchymal stromal cell (MSC)-based gene expression system. The extracellular domain of interleukin-1 receptor 2 (IL1R2) was employed to design the sticky IL1R2 trap (stkIL1R2). A murine compact bone-derived MSC line was engineered for gene delivery. Although stkIL1R2 was undetectable in the engineered MSC supernatants by enzyme-linked immunosorbent assay (ELISA) and Western blot, it was localized on the cell surface and extracellular matrix (ECM) and demonstrated specific binding to IL-1β using a fluorescent protein-fused binding assay. Doxycycline (Dox)-induced expression of stkIL1R2 significantly inhibited lipocalin-2 (LCN2) expression which is a biomarker of IL-1β activity. For in vivo experiments, 5 × 104 Dox-inducible stkIL1R2f expressing MSCs were injected into the knee joints of DMM mice. Bioluminescence imaging revealed MSC survival in the knee joints for up to 7 weeks post-injection. Histological analyses at 10 weeks post-injection, including Safranin-O and Masson trichrome staining, showed that stkIL1R2 treated joints exhibited significantly less cartilage degradation and synovitis compared to controls, as assessed by Osteoarthritis Research Society International (OARSI) scoring of the femur, tibia, and synovium. Moreover, stkIL1R2 treatment reduced matrix metalloproteinases-13 (MMP-13) positive cells and collagen type II degradation in the affected joints. In conclusion, we developed a MSC line expressing an inducible IL1 sticky-trap, which localized to the cell surface and ECM and specifically bound IL-1β. These engineered MSCs survived in normal and DMM knee joints for up to 7 weeks and significantly delayed OA progression and inflammation in the murine model. This study introduces a promising therapeutic approach to combat OA progression.

Deciphering the role of lncRNA-mediated ceRNA network in disuse osteoporosis: insights from bone marrow mesenchymal stem cells under simulated microgravity

Background

Disuse osteoporosis (DOP) poses a significant health risk during extended space missions. Although the importance of long non-coding RNA (lncRNA) in bone marrow mesenchymal stem cells (BMSCs) and orthopedic diseases is recognized, the precise mechanism by which lncRNAs contribute to DOP remains elusive. This research aims to elucidate the potential regulatory role of lncRNAs in DOP.

Methods

Sequencing data were obtained from Gene Expression Omnibus (GEO) datasets, including coding and non-coding RNAs. Positive co-expression pairs of lncRNA-mRNA were identified using weighted gene co-expression network analysis, while miRNA-mRNA expression pairs were derived from the prediction database. A mRNA-miRNA-lncRNA network was established according to the shared mRNA. Functional enrichment analysis was conducted for the shared mRNAs using genome ontology and KEGG pathways. Hub genes were identified through protein-protein interaction analysis, and connectivity map analysis was employed to identify potential therapeutic agents for DOP.

Results

Integration of 74 lncRNAs, 19 miRNAs, and 200 mRNAs yielded a comprehensive mRNA-miRNA-lncRNA network. Enrichment analysis highlighted endoplasmic reticulum stress and extracellular matrix (ECM) pathways as significant in the ceRNA network. PPI analysis revealed three hub genes (COL4A1, LAMC1, and LAMA4) and identified five lncRNA-miRNA-hub gene regulatory axes. Furthermore, three potential therapeutic compounds (SB-216763, oxymetholone, and flubendazole) for DOP were identified.

Conclusion

This study sheds light on the involvement of lncRNAs in the pathogenesis and treatment of DOP through the construction of a ceRNA network, linking protein-coding mRNA functions with non-coding RNAs.

The therapeutic potential of different mesenchymal stem cells and their derived exosomes in metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease is a metabolic disease with an increasing incidence. Its pathogenesis involves the interaction of multiple factors. There is currently no specific treatment, so early prevention and treatment are crucial. Mesenchymal stem cells are a type of cell with the ability to self-renew and differentiate in multiple directions. They have a wide range of sources, including umbilical cords, bone marrow, and fat, and have various biological functions such as anti-inflammation, immune regulation, anti-oxidation, and inhibition of fibrosis. They have shown significant potential in the treatment of non-alcoholic fatty liver disease. In recent years, mesenchymal stem cells derived exosomes have been shown to be rich in bioactive substances, and to be involved in intercellular communication, regulating metabolism, reducing inflammatory responses, improving lipid metabolism, inhibiting fibrosis, and other processes that contribute to the treatment of metabolic dysfunction-associated steatotic liver disease. Mesenchymal stem cells and mesenchymal stem cell-derived exosomes play an important role in the pathogenesis and treatment of metabolic dysfunction-associated steatotic liver disease and provide new potential and direction for the treatment of Metabolic dysfunction-associated steatotic liver disease. This article reviews the role and effects of mesenchymal stem cells and mesenchymal stem cell-derived exosomes from different sources in Metabolic dysfunction-associated steatotic liver disease and discusses their prospects as potential therapeutic strategies.

Stem cell injections for osteoarthritis of the knee

BACKGROUND

Stem cells are specialised precursor cells that can replace aged or damaged cells and thereby maintain healthy tissue function. Stem cell therapy is increasingly used as a treatment for knee osteoarthritis, despite the lack of clarity around the mechanism by which stem cell therapy may slow down disease progression in osteoarthritis, and uncertainty regarding its benefits and harms.

OBJECTIVES

To assess the benefits and harms of stem cell injections for people with osteoarthritis of the knee. A secondary objective is to maintain the currency of the evidence, using a living systematic review approach.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and Embase on 15 September 2023, unrestricted by date or language of publication. We also searched ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP) for relevant trial protocols and ongoing trials.

SELECTION CRITERIA

We included randomised controlled trials (RCTs), or trials using quasi-randomised methods of participant allocation, comparing stem cell injection with placebo injection, no treatment or usual care, glucocorticoid injection, other injections, exercise, drug therapy, surgical interventions, and supplements and complementary therapies in people with knee osteoarthritis.

DATA COLLECTION AND ANALYSIS

Two review authors selected studies for inclusion, extracted trial characteristics and outcome data, assessed risk of bias and assessed the certainty of evidence using the GRADE approach. The primary comparison was stem cell injection compared with placebo injection. The primary time point for pain, function and quality of life was three to six months, and the end of the trial period for participant-reported success, joint structure changes and adverse event outcomes. Major outcomes were pain, function, quality of life, global assessment of success, radiographic joint progression, withdrawals due to adverse events and serious adverse events.

MAIN RESULTS

We found 25 randomised trials (1341 participants) comparing stem cell injections with placebo injection (eight trials), no treatment or usual care (analgesia, weight loss and exercise) (two trials), glucocorticoid injection (one trial), hyaluronic acid injection (seven trials), platelet-rich plasma injections (two trials), oral acetaminophen (paracetamol) (one trial), non-steroidal anti-inflammatory drugs plus physical therapy plus hyaluronic acid injection (one trial) and stem cell injection plus intra-articular co-intervention versus co-intervention alone (three trials) in people with osteoarthritis of the knee. Trials were predominantly small, with sample sizes ranging from 6 to 252 participants, with only two trials having more than 100 participants. The average age of participants across trials ranged from 51 to 66 years, and symptom duration varied from one to 10 years. Placebo-controlled trials were largely free from bias, while most trials without a placebo control were susceptible to performance and detection biases. Here, we limit reporting to the main comparison, stem cell injection versus placebo injection. Compared with placebo injection, stem cell injection may slightly improve pain and function up to six months after treatment. Mean pain (0 to 10 scale, 0 no pain) was 4.5 out of 10 points with placebo injection and 1.2 points better (2.5 points better to 0 points better) with stem cell injection (I2 = 80%; 7 studies, 445 participants). Mean function (0 to 100 scale, 0 best function) was 46.3 points with placebo injection and 14.2 points better (25.3 points better to 3.1 points better) with stem cell injection (I2 = 82%; 7 studies, 432 participants). We are uncertain whether stem cell injections improve quality of life or increase the number of people who report treatment success compared to placebo injection, because the certainty of the evidence was very low. Mean quality of life was 45.3 points with placebo injection and 22.8 points better (18.0 points worse to 63.7 points better) with stem cell injection (I2 = 96%; 2 studies, 288 participants) at up to six months follow-up. At the end of follow-up, 89/168 participants (530 per 1000) in the placebo injection group reported treatment success compared with 126/180 participants (683 per 1000) in the stem cell injection group (risk ratio (RR) 1.29, 95% CI 1.10 to 1.53; I2 = 0%; 4 trials, 348 participants). We downgraded the evidence to low certainty for pain and function due to indirectness (as the source, method of preparation and dose of stem cells varied across studies), and suspected publication bias (up to three larger RCTs have been conducted but withdrawn prior to reporting of results). For quality of life and treatment success, we further downgraded the evidence to very low certainty due to imprecision in addition to indirectness and suspected publication bias. We are uncertain of the potential harms associated with stem cell injection, as there were very low event rates for serious adverse events. At the end of follow-up, 5/219 participants (23 per 1000) in the placebo injection group experienced serious adverse events compared with 4/242 participants (16 per 1000) in the stem cell injection group (RR 0.72, 95% CI 0.20 to 2.64; I2 = 0%; 7 trials, 461 participants) and there were no reported withdrawals due to adverse events. We downgraded the evidence to very low certainty due to indirectness, suspected publication bias and imprecision. Radiographic progression was not assessed in any of the included studies.

AUTHORS' CONCLUSIONS

Compared with placebo injections and based upon low-certainty evidence, stem cell injections for people with knee osteoarthritis may slightly improve pain and function. We are uncertain of the effects of stem cell injections on quality of life or the number who report treatment success. Although the putative benefits of stem cell therapies for osteoarthritis include potential regenerative effects on damaged tissues, particularly articular cartilage, we remain uncertain of the effect of stem cell injections on structural progression in the knee (measured by radiographic appearance). There is also uncertainty regarding the safety of stem cell injections. Serious adverse events were infrequently reported, although all invasive joint procedures (including injections) carry a small risk of septic arthritis. The risk of other important harms, including potential concerns related to the use of a therapy with the theoretical capacity to promote cell growth, or to the use of allogeneic cells, remains unknown.

Mesenchymal Stem Cells Expressing Baculovirus-Engineered Brain-Derived Neurotrophic Factor Improve Peripheral Nerve Regeneration in a Rat Model

BACKGROUND

Peripheral nerve injuries are a major clinical challenge because of their complex nature and limited regenerative capacity. This study aimed to improve peripheral nerve regeneration using Wharton's jelly mesenchymal stem cells (WJ-MSCs) engineered to express brain-derived neurotrophic factor (BDNF) via a baculovirus (BV) vector. The cells were evaluated for efficacy when seeded into acellular nerve grafts (ANGs) in a rat sciatic nerve defect model.

METHODS

WJ-MSCs were transfected with recombinant BV to upregulate BDNF expression. Conditioned medium (CM) from these cells was utilized to treat Schwann cells (SCs), and the impact on myelination-related markers, including KROX20, myelin basic protein (MBP), glial fibrillary acidic protein (GFAP), and S100 calcium-binding protein β (S100β), and the activation of the mammalian target of rapamycin (mTOR)/ protein kinase B (AKT)/p38 signaling pathways were evaluated. In vivo, BDNF-expressing WJ-MSCs were seeded into ANGs and implanted into a rat sciatic nerve defect model. Functional recovery was evaluated via video gait analysis, isometric tetanic force measurement, muscle weight evaluation, ankle contracture angle measurement, and histological analysis using toluidine blue staining.

RESULTS

BDNF expression was significantly upregulated in WJ-MSCs post-transfection. BDNF-MSC CM substantially promoted the expression of myelination markers in SCs and activated the mTOR/AKT/p38 signaling pathway. In the rat model, seeding of ANGs with BDNF-expressing WJ-MSCs resulted in improved functional outcomes, including enhanced toe-off angles, increased isometric tetanic force, greater muscle weight recovery, and a higher total number of myelinated axons compared with controls.

CONCLUSION

WJ-MSCs engineered to express BDNF significantly enhanced peripheral nerve regeneration when utilized in conjunction with ANGs. These findings indicate BDNF-expressing WJ-MSCs are a promising therapeutic approach for treating peripheral nerve injuries.

Role of the Aryl Hydrocarbon Receptor in the Self-Renewal, Differentiation, and Immunomodulation of Adult Stem Cells

Adult stem cells are a rare population of undifferentiated cells present in almost all body tissues. Depending on their location, stem cells can differentiate into various tissue types, primarily contributing to maintenance, repair, and immune system regulation. Stem cell therapies have significant potential in regenerative medicine and treatment of inflammatory diseases. However, many factors must be considered for successful clinical commercialization, including enhancing therapeutic potential, ensuring product differentiation, and optimizing the manufacturing process for large-scale production. The development of sophisticated regulatory mechanisms may enhance therapeutic applications. The aryl hydrocarbon receptor (AhR) is expressed in all adult stem cells, and its activation and function are tightly regulated. Understanding the role and regulation of AhR is crucial for developing effective stem cell therapies. This review examines the role of the AhR in regulating the fundamental characteristics of adult stem cells, which may contribute to advancing adult stem cell therapies.