Search Results (120)

7-ketocholesterol (7-KC) is a bioactive oxysterol generated under oxidative stress and may contribute to bone marrow niche reprogramming in acute myeloid leukemia (AML), thereby promoting stress tolerance and therapeutic resistance Bone marrow mesenchymal stromal cells (MSCs) from healthy donors and AML patients were exposed to subtoxic 7-KC concentrations for 24 h. We evaluated the ABC transporters involved in lipid transport, multidrug resistance and membrane microdomain remodeling; Hedgehog pathway proteins; stress–survival signaling; redox balance by glutathione measurements, and mitochondrial function and dynamics, including membrane potential and gene expression of mitochondrial fission and fusion regulators. Results were integrated using principal component analysis (PCA), heatmaps, and correlation-based networks. Multivariate analyses revealed an integrated, lineage-dependent response. Healthy donor MSCs showed greater plasticity of the efflux and microdomain axis and higher oxidative and mitochondrial vulnerability at high 7-KC doses. AML-MSCs exhibited a basal preconditioned state phenotype and preferentially routed the response toward Hedgehog and stress–survival modules, accompanied by glutathione expansion and adaptive mitochondrial remodeling. 7-KC acts as a broad modulator of several MSC functions, linking sterol homeostasis to Hedgehog signaling, stress–survival pathways, redox balance, and mitochondrial remodeling, potentially supporting a pro-survival, more therapy-tolerant leukemic niche. Full article

Retinoblastoma (Rb) is an intraocular tumor caused by genetic alterations in the RB1 and MYCN genes within developing retinal cells. Chemoresistance and metastasis are major challenges for treatment, with the bone marrow (BM) representing the most common metastatic site. We investigated the effect of tumor-derived sEVs (TDsEVs) on the crosstalk between metastatic site cells (BM-derived mesenchymal stem cells (BM-MSC)) and tumor cells, and characterized them according to MISEV guidelines. The uptake of sEVs and the associated phenotypic changes in the BM-MSCs were analyzed with confocal microcopy. The functional effects were assessed through MTT assays for viability, scratch and Transwell assays for migration, and colony- and sphere-formation assays to evaluate clonogenicity and self-renewal, while stemness marker expression was examined by immunoblotting. Secretome changes following sEV exposure were analyzed using dot blot assays. sEVs were taken up by both cells. TD-sEVs significantly enhanced BM-MSC migration and induced differentiation into a myofibroblast-like phenotype without affecting cell viability. Conversely, BM-MSC-derived sEVs promoted tumor cell viability, migration, and stemness marker expression. Both the BM-MSCs and tumor cells exhibited altered secretory profiles after sEV treatment. The in vitro findings provide cumulative evidence that sEV-mediated interactions contribute to a tumor-supportive milieu or premetastatic niche at the BM in Rb. Full article

Background/Objectives: B-cell precursor acute lymphoblastic leukemia (B-ALL), the most common pediatric acute leukemia (AL), is frequently characterized by aberrant antigen expression, which aids diagnosis and prognosis. The myeloid antigen CD66c is notably frequent in B-ALL and has been proposed as a marker of disease aggressiveness and treatment response. Evaluating CD66c in Mexican pediatric patients may provide insights into disease biology. Methods: A cohort of 128 pediatric patients was referred to the Laboratory of Oncoimmunology and Cytomics of Childhood Cancer (OCL) at Instituto Mexicano del Seguro Social (IMSS) for immunophenotyping tests between March 2022 and November 2023. Additionally, control bone marrow (BM) samples were assessed. Aberrant antigen expression in hematopoietic populations and BM microenvironment stroma phenotyping were performed. Results: In total, 84.38% of B-ALL patients exhibited aberrant expression of ≥1 myeloid antigen. Among CD66c-positive patients, 13.79% had detectable measurable residual disease (MRD) during follow-up and 20.69% died. Mesenchymal stromal cells (MSCs) from patients with positive or low CD66c expression displayed inflammatory profiles. ProB leukemias with low CD66c expression were more likely to exhibit detectable MRD, increased mortality, and reduced survival. Conclusions: Low CD66c expression induces molecular stealth that could favor immune evasion and niche persistence, thereby increasing the risk of relapse and therapeutic failure. Full article

Bone marrow mesenchymal stem/stromal cells (BM-MSCs) are important components of bone marrow, possessing multipotent differentiation potential and the ability to support hematopoiesis. Exposure to ionizing radiation (IR) induces cellular damage in BM-MSCs, such as DNA lesions and mitochondrial dysfunction. Despite their relative radioresistance, most surviving BM-MSCs enter senescence post-irradiation. This senescent state disrupts the bone marrow niche, impairs stem cell proliferation and differentiation, and contributes to acute radiation syndrome (ARS) and myelosuppression. To clarify the impact of IR on BM-MSCs, this review systematically summarizes the general mechanisms of radiation-induced cellular senescence, examines the effects of different radiation types (e.g., gamma rays, X-rays, and heavy-ion radiation) and doses on BM-MSCs senescence, and outlines senotherapeutic strategies targeting BM-MSCs senescence. The analysis indicates that the senescence of BM-MSCs caused by IR is type- and dose-dependent. The review identifies key factors in IR-induced BM-MSCs senescence to guide targeted interventions, highlighting the need for future studies to elucidate the underlying mechanisms of IR-induced BM-MSCs senescence. Full article

Age-related osteoporosis is driven in part by senescence-associated rewiring of bone marrow mesenchymal stem cells (MSCs) from osteogenic toward adipogenic fates. Accumulating evidence indicates that epigenetic drift and reduced autophagy are not isolated lesions but are mechanistically coupled through a bidirectional DNA methylation and autophagy axis. Here, we summarize how promoter hypermethylation of genes involved in autophagy and osteogenesis suppresses autophagic flux and osteoblast lineage transcriptional programs. Conversely, autophagy insufficiency reshapes the methylome by limiting methyl donor availability, most notably S-adenosylmethionine (SAM), and by reducing the turnover of key epigenetic regulators, including DNA methyltransferases (DNMTs), ten-eleven translocation (TET) dioxygenases, and histone deacetylases (HDACs). This self-reinforcing circuitry exacerbates mitochondrial dysfunction, oxidative stress, and inflammation driven by the senescence-associated secretory phenotype (SASP), thereby stabilizing adipogenic bias and progressively impairing marrow niche homeostasis and bone remodeling. We further discuss therapeutic strategies to restore balance within this axis, including selective modulation of epigenetic enzymes; activation of AMP-activated protein kinase (AMPK) and mechanistic target of rapamycin (mTOR) signaling with downstream engagement of Unc-51-like autophagy-activating kinase 1 (ULK1) and transcription factor EB (TFEB); targeting sirtuin pathways; mitochondria- and autophagy-supportive natural compounds; and bone-targeted delivery approaches or rational combination regimens. Full article

Mesenchymal stem/stromal cells (MSCs) exhibit broad differentiation capability and strong immunoregulatory potential mediated through intercellular communication and the release of diverse paracrine mediators. They represent a promising but still investigational therapeutic approach for managing complications associated with allogeneic hematopoietic stem cell transplantation (allo-HSCT). This review provides an updated synthesis of MSC biology, their bidirectional interaction with immune cells, and their functional contribution to the hematopoietic niche. It also evaluates current clinical evidence regarding the therapeutic roles of MSCs and MSC-derived extracellular vesicles (EVs) in acute and chronic graft-versus-host disease (aGVHD/cGVHD), as well as in poor graft function. Mechanistic insights encompass macrophage polarization toward an anti-inflammatory phenotype, inhibition of dendritic cell maturation, enhancement of regulatory T-cell expansion, and modulation of cytokine signaling pathways. Within the bone marrow milieu, MSCs contribute to stromal restoration and angiogenic repair. Recent phase II/III trials in steroid-refractory (SR)-aGVHD have demonstrated overall response rates ranging from 48 to 71%. Efficacy appears particularly enhanced in pediatric patients and with early MSC administration. Across studies, MSC therapy shows a favorable safety profile; however, heterogeneity in response and inconsistent survival outcomes remain notable limitations. For poor graft function, limited prospective studies indicate hematopoietic recovery following third-party MSC infusions, and combination approaches such as co-administration with thrombopoietin receptor agonists are under investigation. MSC-derived EVs emulate many immunomodulatory effects of their parental cells with a potentially safer profile, though clinical validation remains in its infancy. MSC-oriented interventions hold substantial biological and therapeutic promise, offering a favorable safety margin; however, clinical translation is hindered by product variability, suboptimal engraftment and persistence, and inconsistent efficacy across studies. Future directions should emphasize standardized manufacturing and potency assays, biomarker-driven patient and timing selection, optimized conditioning and dosing strategies, and the systematic appraisal of EV-based or genetically modified MSC products through controlled trials. Full article

Cell therapies hold great promise for advancing wound healing; however, translating this promise into consistent clinical benefit has proven elusive. Numerous trials have failed to reproduce the robust outcomes suggested by preclinical studies, reflecting a landscape marked by hidden traps. These include the hostile wound microenvironment, the cytotoxicity of antimicrobial dressings, poor retention and engraftment, immune clearance, and the paradoxical risk of fibrosis and scarring. Across these challenges emerge paradoxes that redefine how traps are understood. The Scarring Paradox reveals that MSCs and EVs may either suppress or reinforce fibrosis, depending on the niche context. The Immune Double-Edged Sword captures the duality of clearance and regenerative modulation. These paradoxes illustrate that traps are not static obstacles but dynamic inflection points. Recognition of these paradoxes has inspired tricks: protective biomaterial carriers, preconditioning strategies, engineered exosomes, and combinatorial therapies with anti-fibrotic, neuromodulatory, or microbiome-targeted adjuncts. Case studies illustrate how classical traps manifest in clinical practice and how paradoxes guide innovation. Emerging adjuncts, ranging from herbal bioactives and bioelectric modulation to circadian synchronization and digital twins, point toward more unconventional but increasingly plausible frameworks for niche control. This perspective review demonstrates that the future of regenerative wound therapy depends not on avoiding traps but on reframing them through paradoxes and converting them into tricks. Stem cell and exosome therapy is thus moving beyond a linear “promise versus failure” narrative toward a systemic, context-aware, programmable approach in which paradoxes drive conceptual renewal and transformative paradigms in wound care. Full article

Multipotent hematopoietic stem cells (HSC) reside in specialized niches of the bone marrow (BM). The maintenance of their stemness requires a precisely regulated bone marrow microenvironment (BMM), supported by mesenchymal stem cells (MSCs), stromal reticular cells, and endothelial and nerve cells located within the vascular and endosteal niches. The heterogeneity of the niche environment is caused by the diversity of cell populations from HSCs to more mature hematopoietic cell types and MSCs, which collectively influence the complex intercellular interactions involved in hematopoiesis. MSC subclusters in BM are characterized by the phenotypes of CXC-chemokine ligand 12, leptin receptor, neuron-glial antigen 2, and Nestin+ cells. The article presents a detailed characterization of individual stem cell types in the BM, their reciprocal interaction, and the possibility of in vitro simulation of the bone marrow niche as a dynamic structure. Development of a suitable simulation of the BMM is essential for advancing research into both physiological and pathological processes of hematopoiesis. The main goal is to simulate 3D cell culture using biomaterials that mimic the BM niche in the form of hydrogels and scaffolds, in combination with extracellular matrix components. Full article

Mesenchymal stromal/stem cells (MSCs) are known to secrete a wide range of pleiotropic molecules promoting tissue repair and regeneration. Recent advances in cell sheet technology have demonstrated significant improvements in the regenerative capacity of MSCs within the sheet, retaining appropriate microenvironmental cues, and have suggested an instructing role of extracellular matrix (ECM). We previously found that the secretome of MSCs cultured on a decellularized MSC-derived ECM (dECM) was significantly enriched in dozens of cytokines, chemokines and growth factors compared to the secretome of MSCs grown on standard plastic dishes. The enriched secretome has been shown to have enhanced chemotactic and angiogenic properties, stimulate C2C12 myoblast proliferation and promote skeletal muscle regeneration in a murine in vivo model. Here, we report novel findings about dECM-induced changes in the miRNA profile of MSCs. We performed miRNA-seq and found 17 differentially expressed miRNAs in endometrial MSCs (MESCs) with miR-146a-5p being the most upregulated. Additionally, we investigated miR-146a-5p expression in MSCs of various origins after exposure to dECM, and found a correlation between miR-146a-5p upregulation and the general dECM-induced paracrine response. Furthermore, we demonstrated that miR-146a-5p mimics, transfected into C2C12 myoblasts, promoted their proliferation, suggesting a role for miR-146a-5p in myotropic effects mediated by the enriched secretome. These findings provide new insights into how ECM as a component of the MSC niche influences the secretory phenotype and modulates therapeutic properties of MSCs. Full article

Osteochondral regeneration remains a major clinical challenge due to the complex architecture and biomechanical demands of the osteochondral unit. Bioactive hydrogels have emerged as promising materials capable of supporting repair through their capacity to mimic the extracellular matrix (ECM), enable cell encapsulation, and deliver bioactive cues. However, recent insights reveal that simply engineering hydrogels for structural and cellular support is insufficient. A new paradigm is emerging—one that embraces the complexity of the osteochondral niche by integrating immunomodulatory and mechanobiological cues into biomaterial design. In particular, the hydrogel’s capacity to modulate macrophage polarization and support the immunoregulatory function of mesenchymal stem cells (MSCs) is critical to orchestrate regenerative outcomes. Simultaneously, the mechanical properties of hydrogels—such as stiffness, porosity, and viscoelasticity—can profoundly influence stem cell fate and local tissue morphogenesis. This review discusses recent advances in hydrogel-based strategies for osteochondral repair, highlighting the interplay between immunological signals and the mechanical microenvironment, and calls for a shift from reductionist tissue-engineering approaches to systems-level design of tunable, immuno-mechanobiological microenvironments. Full article

Xylosyltransferase-I (XT-I) plays a crucial role in skeletal development and cartilage integrity. An XT-I deficiency is linked to severe bone disorders, such as Desbuquois dysplasia type 2. While animal models have provided insights into XT-I’s role during skeletal development, its specific effects on adult bone homeostasis, particularly in human mesenchymal stem cell (hMSC) differentiation, remain unclear. This study investigates how XT-I deficiency impacts the differentiation of hMSCs into chondrocytes, osteoblasts, and adipocytes—key processes in bone formation and repair. The aim of this study was to elucidate for the first time the molecular mechanisms by which XT-I deficiency leads to impaired bone homeostasis. Using CRISPR-Cas9-mediated gene editing, we generated XYLT1 knockdown (KD) hMSCs to assess their differentiation potential. Our findings revealed significant disruption in the chondrogenic differentiation in KD hMSCs, characterized by the altered expression of regulatory factors and extracellular matrix components, suggesting premature chondrocyte hypertrophy. Despite the presence of perilipin-coated lipid droplets in the adipogenic pathway, the overall leptin mRNA and protein expression was reduced in KD hMSCs, indicating a compromised lipid metabolism. Conversely, osteogenic differentiation was largely unaffected, with KD and wild-type hMSCs exhibiting comparable mineralization processes, indicating that critical aspects of osteogenesis were preserved despite the XYLT1 deficiency. In summary, these results underscore XT-I’s pivotal role in regulating differentiation pathways within the bone marrow niche, influencing cellular functions critical for skeletal health. A deeper insight into bone biology may pave the way for the development of innovative therapeutic approaches to improve bone health and treat skeletal disorders. Full article

Mesenchymal stromal cells of the tumor microenvironment (TME) play a significant role in the progression of multiple myeloma (MM). The cells of the TME demonstrate resistance to treatment, thereby creating a favorable environment for disease relapse. The status of the TME during remission is poorly understood. An association between treatment response and TME status (including signaling pathways) has been suggested. One of the key players in the establishment of the MM TME is WNT signaling. In this study, we evaluated the expression of WNT family proteins in the TME and MM cells to assess their potential as TME markers and predictors of treatment response. A bioinformatic analysis of normal and malignant plasma cells, combined with an analysis of published data, revealed the following differentially expressed WNT genes: WNT5A, WNT10B, CTNNB1, and WNT3A. Immunohistochemical staining with the antibodies against the proteins encoded by the genes was conducted on trephine biopsy samples of bone marrow from healthy donors and patients with different responses to therapy. A quantitative analysis of the immunohistochemical data revealed differences in the amounts of WNT3A, WNT5A, WNT10B, and β-catenin proteins in the bone marrow before treatment depending on the subsequent responses of the patients to therapy. Multiplex fluorescent immunohistochemical staining with tyramide signal amplification revealed that WNT3A was predominantly present in mesenchymal stromal cells, whereas WNT5A and WNT10B were primarily observed in plasma cells. β-catenin was detected in both cell types. We analyzed the mRNA levels of the WNT gene family and CTNNB1 in MSC cultures from healthy donors and patients using qPCR. These genes were differentially expressed in MSC cultures derived from patients and healthy donors, as well as between patients grouped according to their response to therapy. Therefore, WNT proteins and β-catenin can be considered potential markers to assess the state of the tumor niche. Full article

Sutures such as fibrous joints in craniofacial bones provide a niche for Gli1+ mesenchymal stem cells (MSCs) in promoting calvarial bone development and growth. However, the underlying molecular mechanism behind the fate of the Wnt/β-catenin regulation of Gli1+ MSCs during calvarial bone formation remains unclear. Here, we showed that β-catenin was colocalized with Gli1+ lineage cells near the osteogenic front within a suture, and postnatal skull development was delayed via a conditional knockout of Ctnnb1 in Gli1+ MSCs. Calcein–Alizarin Red dual staining revealed that Wnt/β-catenin signal inhibition impaired the rate of bone formation. Furthermore, immunofluorescent staining indicated that Wnt/β-catenin signaling was crucial in facilitating the proliferative capacity of Gli1+ MSCs and their commitment to the osteogenic lineage. Notably, activating hedgehog (Hh) signaling partially restored the suture morphology in Ctnnb1 knockout mice. Collectively, our findings revealed the crosstalk between Wnt and Hh signaling modulates the fate of Gli1+ MSCs during calvarial bone formation. Full article

Stem cell-based therapies hold significant potential for cancer treatment due to their unique properties, including migration toward tumor niche, secretion of bioactive molecules, and immunosuppression. Mesenchymal stem cells (MSCs) from adult tissues can inhibit tumor progression, angiogenesis, and apoptosis of cancer cells. We have previously reported the isolation and characterization of placenta-derived decidua basalis mesenchymal stem cells (DBMSCs), which demonstrated higher levels of pro-migratory and anti-apoptotic genes, indicating potential anti-cancer effects. In this study, we analyzed the anti-cancer effects of DBMSCs on human breast cancer cell lines MDA231 and MCF7, with MCF 10A used as control. We also investigated how these cancer cells lines affect the functional competence of DBMSCs. By co-culturing DBMSCs with cancer cells, we analyzed changes in functions of both cell types, as well as alterations in their genomic and proteomic profile. Our results showed that treatment with DBMSCs significantly reduced the functionality of MDA231 and MCF7 cells, while MCF 10A cells remained unaffected. DBMSC treatment decreased epithelial-to-mesenchymal transition (EMT)-related protein levels in MDA231 cells and modulated expression of other cancer-related genes in MDA231 and MCF7 cells. Although cancer cells reduced DBMSC proliferation, they increased their expression of anti-apoptotic genes. These findings suggest that DBMSCs can inhibit EMT-related proteins and reduce the invasive characteristics of MDA231 and MCF7 breast cancer cells, highlighting their potential as candidates for cell-based cancer therapies. Full article

Constructing artificial tertiary lymphoid structures (TLSs) opens new avenues for advancing cancer immunotherapy and personalized medicine by creating controllable immune niches. Mesenchymal stromal cells (MSCs) offer an ideal stromal source for such constructs, given their potent immunomodulatory abilities and accessibility. In this study, we explored the potential of adipose-derived MSCs to adopt TLS-supportive phenotypes and facilitate lymphocyte organization. Single-cell RNA sequencing revealed a distinct subpopulation of MSCs expressing key fibroblastic reticular cell (FRC)-associated markers, including IL-7, PDPN, and IL-15, though lacking follicular dendritic cell (FDC) markers. TNF-α stimulation, but not LTα2β1, further enhanced FRC marker expression (IL-7, PDPN, and ICAM1). Notably, in 3D spheroid co-culture with lymphocytes, MSCs upregulated additional FRC markers, specifically CCL21. Upon implantation into adipose tissue, MSC-lymphocyte organoids maintained structural integrity and showed extensive T-cell infiltration and partial vascularization after 15 days in vivo, although organized B-cell follicles and FDC markers were still lacking. These findings highlight MSCs’ intrinsic ability to adopt an FRC-like phenotype that supports T-cell and HEV organization, suggesting that further optimization, including genetic modification, may be needed to achieve an FDC phenotype and replicate the full architectural and functional complexity of TLSs. Full article