Effects of interleukin-10 treated macrophages on bone marrow mesenchymal stem cells via signal transducer and activator of transcription 3 pathway

BACKGROUND

Alveolar bone defects caused by inflammation are an urgent issue in oral implant surgery that must be solved. Regulating the various phenotypes of macrophages to enhance the inflammatory environment can significantly affect the progression of diseases and tissue engineering repair process.

AIM

To assess the influence of interleukin-10 (IL-10) on the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) following their interaction with macrophages in an inflammatory environment.

METHODS

IL-10 modulates the differentiation of peritoneal macrophages in Wistar rats in an inflammatory environment. In this study, we investigated its impact on the proliferation, migration, and osteogenesis of BMSCs. The expression levels of signal transducer and activator of transcription 3 (STAT3) and its activated form, phosphorylated-STAT3, were examined in IL-10-stimulated macrophages. Subsequently, a specific STAT3 signaling inhibitor was used to impede STAT3 signal activation to further investigate the role of STAT3 signaling.

RESULTS

IL-10-stimulated macrophages underwent polarization to the M2 type through substitution, and these M2 macrophages actively facilitated the osteogenic differentiation of BMSCs. Mechanistically, STAT3 signaling plays a crucial role in the process by which IL-10 influences macrophages. Specifically, IL-10 stimulated the activation of the STAT3 signaling pathway and reduced the macrophage inflammatory response, as evidenced by its diminished impact on the osteogenic differentiation of BMSCs.

CONCLUSION

Stimulating macrophages with IL-10 proved effective in improving the inflammatory environment and promoting the osteogenic differentiation of BMSCs. The IL-10/STAT3 signaling pathway has emerged as a key regulator in the macrophage-mediated control of BMSCs' osteogenic differentiation.

GATA binding protein 2 mediated ankyrin repeat domain containing 26 high expression in myeloid-derived cell lines

BACKGROUND

Thrombocytopenia 2, an autosomal dominant inherited disease characterized by moderate thrombocytopenia, predisposition to myeloid malignancies and normal platelet size and function, can be caused by 5'-untranslated region (UTR) point mutations in ankyrin repeat domain containing 26 (ANKRD26). Runt related transcription factor 1 (RUNX1) and friend leukemia integration 1 (FLI1) have been identified as negative regulators of ANKRD26. However, the positive regulators of ANKRD26 are still unknown.

AIM

To prove the positive regulatory effect of GATA binding protein 2 (GATA2) on ANKRD26 transcription.

METHODS

Human induced pluripotent stem cells derived from bone marrow (hiPSC-BM) and urothelium (hiPSC-U) were used to examine the ANKRD26 expression pattern in the early stage of differentiation. Then, transcriptome sequencing of these iPSCs and three public transcription factor (TF) databases (Cistrome DB, animal TFDB and ENCODE) were used to identify potential TF candidates for ANKRD26. Furthermore, overexpression and dual-luciferase reporter experiments were used to verify the regulatory effect of the candidate TFs on ANKRD26. Moreover, using the GENT2 platform, we analyzed the relationship between ANKRD26 expression and overall survival in cancer patients.

RESULTS

In hiPSC-BMs and hiPSC-Us, we found that the transcription levels of ANKRD26 varied in the absence of RUNX1 and FLI1. We sequenced hiPSC-BM and hiPSC-U and identified 68 candidate TFs for ANKRD26. Together with three public TF databases, we found that GATA2 was the only candidate gene that could positively regulate ANKRD26. Using dual-luciferase reporter experiments, we showed that GATA2 directly binds to the 5'-UTR of ANKRD26 and promotes its transcription. There are two identified binding sites of GATA2 that are located 2 kb upstream of the TSS of ANKRD26. In addition, we discovered that high ANKRD26 expression is always related to a more favorable prognosis in breast and lung cancer patients.

CONCLUSION

We first discovered that the transcription factor GATA2 plays a positive role in ANKRD26 transcription and identified its precise binding sites at the promoter region, and we revealed the importance of ANKRD26 in many tissue-derived cancers.

Therapeutic potential of urine-derived stem cells in renal regeneration following acute kidney injury: A comparative analysis with mesenchymal stem cells

BACKGROUND

Acute kidney injury (AKI) is a common clinical syndrome with high morbidity and mortality rates. The use of pluripotent stem cells holds great promise for the treatment of AKI. Urine-derived stem cells (USCs) are a novel and versatile cell source in cell-based therapy and regenerative medicine that provide advantages of a noninvasive, simple, and low-cost approach and are induced with high multidifferentiation potential. Whether these cells could serve as a potential stem cell source for the treatment of AKI has not been determined.

AIM

To investigate whether USCs can serve as a potential stem cell source to improve renal function and histological structure after experimental AKI.

METHODS

Stem cell markers with multidifferentiation potential were isolated from human amniotic fluid. AKI severe combined immune deficiency (SCID) mice models were induced by means of an intramuscular injection with glycerol. USCs isolated from human-voided urine were administered via tail veins. The functional changes in the kidney were assessed by the levels of blood urea nitrogen and serum creatinine. The histologic changes were evaluated by hematoxylin and eosin staining and transferase dUTP nick-end labeling staining. Meanwhile, we compared the regenerative potential of USCs with bone marrow-derived mesenchymal stem cells (MSCs).

RESULTS

Treatment with USCs significantly alleviated histological destruction and functional decline. The renal function was rapidly restored after intravenous injection of 5 × 105 human USCs into SCID mice with glycerol-induced AKI compared with injection of saline. Results from secretion assays conducted in vitro demonstrated that both stem cell varieties released a wide array of cytokines and growth factors. This suggests that a mixture of various mediators closely interacts with their biochemical functions. Two types of stem cells showed enhanced tubular cell proliferation and decreased tubular cell apoptosis, although USC treatment was not more effective than MSC treatment. We found that USC therapy significantly improved renal function and histological damage, inhibited inflammation and apoptosis processes in the kidney, and promoted tubular epithelial proliferation.

CONCLUSION

Our study demonstrated the potential of USCs for the treatment of AKI, representing a new clinical therapeutic strategy.

Effect of ginsenoside Rg1 on hematopoietic stem cells in treating aplastic anemia in mice via MAPK pathway

BACKGROUND

Aplastic anemia (AA) presents a significant clinical challenge as a life-threatening condition due to failure to produce essential blood cells, with the current therapeutic options being notably limited.

AIM

To assess the therapeutic potential of ginsenoside Rg1 on AA, specifically its protective effects, while elucidating the mechanism at play.

METHODS

We employed a model of myelosuppression induced by cyclophosphamide (CTX) in C57 mice, followed by administration of ginsenoside Rg1 over 13 d. The investigation included examining the bone marrow, thymus and spleen for pathological changes via hematoxylin-eosin staining. Moreover, orbital blood of mice was collected for blood routine examinations. Flow cytometry was employed to identify the impact of ginsenoside Rg1 on cell apoptosis and cycle in the bone marrow of AA mice. Additionally, the study further evaluated cytokine levels with enzyme-linked immunosorbent assay and analyzed the expression of key proteins in the MAPK signaling pathway via western blot.

RESULTS

Administration of CTX led to significant damage to the bone marrow's structural integrity and a reduction in hematopoietic cells, establishing a model of AA. Ginsenoside Rg1 successfully reversed hematopoietic dysfunction in AA mice. In comparison to the AA group, ginsenoside Rg1 provided relief by reducing the induction of cell apoptosis and inflammation factors caused by CTX. Furthermore, it helped alleviate the blockade in the cell cycle. Treatment with ginsenoside Rg1 significantly alleviated myelosuppression in mice by inhibiting the MAPK signaling pathway.

CONCLUSION

This study suggested that ginsenoside Rg1 addresses AA by alleviating myelosuppression, primarily through modulating the MAPK signaling pathway, which paves the way for a novel therapeutic strategy in treating AA, highlighting the potential of ginsenoside Rg1 as a beneficial intervention.

Mesenchymal stem cells' "garbage bags" at work: Treating radial nerve injury with mesenchymal stem cell-derived exosomes

Unlike central nervous system injuries, peripheral nerve injuries (PNIs) are often characterized by more or less successful axonal regeneration. However, structural and functional recovery is a senile process involving multifaceted cellular and molecular processes. The contemporary treatment options are limited, with surgical intervention as the gold-standard method; however, each treatment option has its associated limitations, especially when the injury is severe with a large gap. Recent advancements in cell-based therapy and cell-free therapy approaches using stem cell-derived soluble and insoluble components of the cell secretome are fast-emerging therapeutic approaches to treating acute and chronic PNI. The recent pilot study is a leap forward in the field, which is expected to pave the way for more enormous, systematic, and well-designed clinical trials to assess the therapeutic efficacy of mesenchymal stem cell-derived exosomes as a bio-drug either alone or as part of a combinatorial approach, in an attempt synergize the best of novel treatment approaches to address the complexity of the neural repair and regeneration.

Role of glioma stem cells in promoting tumor chemo- and radioresistance: A systematic review of potential targeted treatments

BACKGROUND

Gliomas pose a significant challenge to effective treatment despite advancements in chemotherapy and radiotherapy. Glioma stem cells (GSCs), a subset within tumors, contribute to resistance, tumor heterogeneity, and plasticity. Recent studies reveal GSCs' role in therapeutic resistance, driven by DNA repair mechanisms and dynamic transitions between cellular states. Resistance mechanisms can involve different cellular pathways, most of which have been recently reported in the literature. Despite progress, targeted therapeutic approaches lack consensus due to GSCs' high plasticity.

AIM

To analyze targeted therapies against GSC-mediated resistance to radio- and chemotherapy in gliomas, focusing on underlying mechanisms.

METHODS

A systematic search was conducted across major medical databases (PubMed, Embase, and Cochrane Library) up to September 30, 2023. The search strategy utilized relevant Medical Subject Heading terms and keywords related to including "glioma stem cells", "radiotherapy", "chemotherapy", "resistance", and "targeted therapies". Studies included in this review were publications focusing on targeted therapies against the molecular mechanism of GSC-mediated resistance to radiotherapy resistance (RTR).

RESULTS

In a comprehensive review of 66 studies on stem cell therapies for SCI, 452 papers were initially identified, with 203 chosen for full-text analysis. Among them, 201 were deemed eligible after excluding 168 for various reasons. The temporal breakdown of studies illustrates this trend: 2005-2010 (33.3%), 2011-2015 (36.4%), and 2016-2022 (30.3%). Key GSC models, particularly U87 (33.3%), U251 (15.2%), and T98G (15.2%), emerge as significant in research, reflecting their representativeness of glioma characteristics. Pathway analysis indicates a focus on phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin (mTOR) (27.3%) and Notch (12.1%) pathways, suggesting their crucial roles in resistance development. Targeted molecules with mTOR (18.2%), CHK1/2 (15.2%), and ATP binding cassette G2 (12.1%) as frequent targets underscore their importance in overcoming GSC-mediated resistance. Various therapeutic agents, notably RNA inhibitor/short hairpin RNA (27.3%), inhibitors (e.g., LY294002, NVP-BEZ235) (24.2%), and monoclonal antibodies (e.g., cetuximab) (9.1%), demonstrate versatility in targeted therapies. among 20 studies (60.6%), the most common effect on the chemotherapy resistance response is a reduction in temozolomide resistance (51.5%), followed by reductions in carmustine resistance (9.1%) and doxorubicin resistance (3.0%), while resistance to RTR is reduced in 42.4% of studies.

CONCLUSION

GSCs play a complex role in mediating radioresistance and chemoresistance, emphasizing the necessity for precision therapies that consider the heterogeneity within the GSC population and the dynamic tumor microenvironment to enhance outcomes for glioblastoma patients.

Deer antler stem cell niche: An interesting perspective

In recent years, there has been considerable exploration into methods aimed at enhancing the regenerative capacity of transplanted and/or tissue-resident cells. Biomaterials, in particular, have garnered significant interest for their potential to serve as natural scaffolds for cells. In this editorial, we provide commentary on the study by Wang et al, in a recently published issue of World J Stem Cells, which investigates the use of a decellularized xenogeneic extracellular matrix (ECM) derived from antler stem cells for repairing osteochondral defects in rat knee joints. Our focus lies specifically on the crucial role of biological scaffolds as a strategy for augmenting stem cell potential and regenerative capabilities, thanks to the establishment of a favorable microenvironment (niche). Stem cell differentiation heavily depends on exposure to intrinsic properties of the ECM, including its chemical and protein composition, as well as the mechanical forces it can generate. Collectively, these physicochemical cues contribute to a bio-instructive signaling environment that offers tissue-specific guidance for achieving effective repair and regeneration. The interest in mechanobiology, often conceptualized as a form of "structural memory", is steadily gaining more validation and momentum, especially in light of findings such as these.

Cardiac differentiation is modulated by anti-apoptotic signals in murine embryonic stem cells

BACKGROUND

Embryonic stem cells (ESCs) serve as a crucial ex vivo model, representing epiblast cells derived from the inner cell mass of blastocyst-stage embryos. ESCs exhibit a unique combination of self-renewal potency, unlimited proliferation, and pluripotency. The latter is evident by the ability of the isolated cells to differentiate spontaneously into multiple cell lineages, representing the three primary embryonic germ layers. Multiple regulatory networks guide ESCs, directing their self-renewal and lineage-specific differentiation. Apoptosis, or programmed cell death, emerges as a key event involved in sculpting and forming various organs and structures ensuring proper embryonic development. However, the molecular mechanisms underlying the dynamic interplay between differentiation and apoptosis remain poorly understood.

AIM

To investigate the regulatory impact of apoptosis on the early differentiation of ESCs into cardiac cells, using mouse ESC (mESC) models - mESC-B-cell lymphoma 2 (BCL-2), mESC-PIM-2, and mESC-metallothionein-1 (MET-1) - which overexpress the anti-apoptotic genes Bcl-2, Pim-2, and Met-1, respectively.

METHODS

mESC-T2 (wild-type), mESC-BCL-2, mESC-PIM-2, and mESC-MET-1 have been used to assess the effect of potentiated apoptotic signals on cardiac differentiation. The hanging drop method was adopted to generate embryoid bodies (EBs) and induce terminal differentiation of mESCs. The size of the generated EBs was measured in each condition compared to the wild type. At the functional level, the percentage of cardiac differentiation was measured by calculating the number of beating cardiomyocytes in the manipulated mESCs compared to the control. At the molecular level, quantitative reverse transcription-polymerase chain reaction was used to assess the mRNA expression of three cardiac markers: Troponin T, GATA4, and NKX2.5. Additionally, troponin T protein expression was evaluated through immunofluorescence and western blot assays.

RESULTS

Our findings showed that the upregulation of Bcl-2, Pim-2, and Met-1 genes led to a reduction in the size of the EBs derived from the manipulated mESCs, in comparison with their wild-type counterpart. Additionally, a decrease in the count of beating cardiomyocytes among differentiated cells was observed. Furthermore, the mRNA expression of three cardiac markers - troponin T, GATA4, and NKX2.5 - was diminished in mESCs overexpressing the three anti-apoptotic genes compared to the control cell line. Moreover, the overexpression of the anti-apoptotic genes resulted in a reduction in troponin T protein expression.

CONCLUSION

Our findings revealed that the upregulation of Bcl-2, Pim-2, and Met-1 genes altered cardiac differentiation, providing insight into the intricate interplay between apoptosis and ESC fate determination.

Single-cell sequencing technology in diabetic wound healing: New insights into the progenitors-based repair strategies

Diabetes mellitus (DM), an increasingly prevalent chronic metabolic disease, is characterised by prolonged hyperglycaemia, which leads to long-term health consequences. Although much effort has been put into understanding the pathogenesis of diabetic wounds, the underlying mechanisms remain unclear. The advent of single-cell RNA sequencing (scRNAseq) has revolutionised biological research by enabling the identification of novel cell types, the discovery of cellular markers, the analysis of gene expression patterns and the prediction of developmental trajectories. This powerful tool allows for an in-depth exploration of pathogenesis at the cellular and molecular levels. In this editorial, we focus on progenitor-based repair strategies for diabetic wound healing as revealed by scRNAseq and highlight the biological behaviour of various healing-related cells and the alteration of signalling pathways in the process of diabetic wound healing. ScRNAseq could not only deepen our understanding of the complex biology of diabetic wounds but also identify and validate new targets for intervention, offering hope for improved patient outcomes in the management of this challenging complication of DM.

Hepatocyte growth factor enhances the ability of dental pulp stem cells to ameliorate atherosclerosis in apolipoprotein E-knockout mice

BACKGROUND

Atherosclerosis (AS), a chronic inflammatory disease of blood vessels, is a major contributor to cardiovascular disease. Dental pulp stem cells (DPSCs) are capable of exerting immunomodulatory and anti-inflammatory effects by secreting cytokines and exosomes and are widely used to treat autoimmune and inflammation-related diseases. Hepatocyte growth factor (HGF) is a pleiotropic cytokine that plays a key role in many inflammatory and autoimmune diseases.

AIM

To modify DPSCs with HGF (DPSC-HGF) and evaluate the therapeutic effect of DPSC-HGF on AS using an apolipoprotein E-knockout (ApoE-/-) mouse model and an in vitro cellular model.

METHODS

ApoE-/- mice were fed with a high-fat diet (HFD) for 12 wk and injected with DPSC-HGF or Ad-Null modified DPSCs (DPSC-Null) through tail vein at weeks 4, 7, and 11, respectively, and the therapeutic efficacy and mechanisms were analyzed by histopathology, flow cytometry, lipid and glucose measurements, real-time reverse transcription polymerase chain reaction (RT-PCR), and enzyme-linked immunosorbent assay at the different time points of the experiment. An in vitro inflammatory cell model was established by using RAW264.7 cells and human aortic endothelial cells (HAOECs), and indirect co-cultured with supernatant of DPSC-Null (DPSC-Null-CM) or DPSC-HGF-CM, and the effect and mechanisms were analyzed by flow cytometry, RT-PCR and western blot. Nuclear factor-κB (NF-κB) activators and inhibitors were also used to validate the related signaling pathways.

RESULTS

DPSC-Null and DPSC-HGF treatments decreased the area of atherosclerotic plaques and reduced the expression of inflammatory factors, and the percentage of macrophages in the aorta, and DPSC-HGF treatment had more pronounced effects. DPSCs treatment had no effect on serum lipoprotein levels. The FACS results showed that DPSCs treatment reduced the percentages of monocytes, neutrophils, and M1 macrophages in the peripheral blood and spleen. DPSC-Null-CM and DPSC-HGF-CM reduced adhesion molecule expression in tumor necrosis factor-α stimulated HAOECs and regulated M1 polarization and inflammatory factor expression in lipopolysaccharide-induced RAW264.7 cells by inhibiting the NF-κB signaling pathway.

CONCLUSION

This study suggested that DPSC-HGF could more effectively ameliorate AS in ApoE-/- mice on a HFD, and could be of greater value in stem cell-based treatments for AS.

Sinomenine increases osteogenesis in mice with ovariectomy-induced bone loss by modulating autophagy

BACKGROUND

A decreased autophagic capacity of bone marrow mesenchymal stromal cells (BMSCs) has been suggested to be an important cause of decreased osteogenic differentiation. A pharmacological increase in autophagy of BMSCs is a potential therapeutic option to increase osteoblast viability and ameliorate osteoporosis.

AIM

To explore the effects of sinomenine (SIN) on the osteogenic differentiation of BMSCs and the underlying mechanisms.

METHODS

For in vitro experiments, BMSCs were extracted from sham-treated mice and ovariectomized mice, and the levels of autophagy markers and osteogenic differentiation were examined after treatment with the appropriate concentrations of SIN and the autophagy inhibitor 3-methyladenine. In vivo, the therapeutic effect of SIN was verified by establishing an ovariectomy-induced mouse model and by morphological and histological assays of the mouse femur.

RESULTS

SIN reduced the levels of AKT and mammalian target of the rapamycin (mTOR) phosphorylation in the phosphatidylinositol 3-kinase (PI3K)/AKT/mTOR signaling pathway, inhibited mTOR activity, and increased autophagy ability of BMSCs, thereby promoting the osteogenic differentiation of BMSCs and effectively alleviating bone loss in ovariectomized mice in vivo.

CONCLUSION

The Chinese medicine SIN has potential for the treatment of various types of osteoporosis, bone homeostasis disorders, and autophagy-related diseases.

Hydrogel loaded with bone marrow stromal cell-derived exosomes promotes bone regeneration by inhibiting inflammatory responses and angiogenesis

BACKGROUND

Bone healing is a complex process involving early inflammatory immune regulation, angiogenesis, osteogenic differentiation, and biomineralization. Fracture repair poses challenges for orthopedic surgeons, necessitating the search for efficient healing methods.

AIM

To investigate the underlying mechanism by which hydrogel-loaded exosomes derived from bone marrow mesenchymal stem cells (BMSCs) facilitate the process of fracture healing.

METHODS

Hydrogels and loaded BMSC-derived exosome (BMSC-exo) gels were characterized to validate their properties. In vitro evaluations were conducted to assess the impact of hydrogels on various stages of the healing process. Hydrogels could recruit macrophages and inhibit inflammatory responses, enhance of human umbilical vein endothelial cell angiogenesis, and promote the osteogenic differentiation of primary cranial osteoblasts. Furthermore, the effect of hydrogel on fracture healing was confirmed using a mouse fracture model.

RESULTS

The hydrogel effectively attenuated the inflammatory response during the initial repair stage and subsequently facilitated vascular migration, promoted the formation of large vessels, and enabled functional vascularization during bone repair. These effects were further validated in fracture models.

CONCLUSION

We successfully fabricated a hydrogel loaded with BMSC-exo that modulates macrophage polarization and angiogenesis to influence bone regeneration.

Biological scaffold as potential platforms for stem cells: Current development and applications in wound healing

Wound repair is a complex challenge for both clinical practitioners and researchers. Conventional approaches for wound repair have several limitations. Stem cell-based therapy has emerged as a novel strategy to address this issue, exhibiting significant potential for enhancing wound healing rates, improving wound quality, and promoting skin regeneration. However, the use of stem cells in skin regeneration presents several challenges. Recently, stem cells and biomaterials have been identified as crucial components of the wound-healing process. Combination therapy involving the development of biocompatible scaffolds, accompanying cells, multiple biological factors, and structures resembling the natural extracellular matrix (ECM) has gained considerable attention. Biological scaffolds encompass a range of biomaterials that serve as platforms for seeding stem cells, providing them with an environment conducive to growth, similar to that of the ECM. These scaffolds facilitate the delivery and application of stem cells for tissue regeneration and wound healing. This article provides a comprehensive review of the current developments and applications of biological scaffolds for stem cells in wound healing, emphasizing their capacity to facilitate stem cell adhesion, proliferation, differentiation, and paracrine functions. Additionally, we identify the pivotal characteristics of the scaffolds that contribute to enhanced cellular activity.

Unveiling the role of hypoxia-inducible factor 2alpha in osteoporosis: Implications for bone health

BACKGROUND

Osteoporosis (OP) has become a major public health problem worldwide. Most OP treatments are based on the inhibition of bone resorption, and it is necessary to identify additional treatments aimed at enhancing osteogenesis. In the bone marrow (BM) niche, bone mesenchymal stem cells (BMSCs) are exposed to a hypoxic environment. Recently, a few studies have demonstrated that hypoxia-inducible factor 2alpha (HIF-2α) is involved in BMSC osteogenic differentiation, but the molecular mechanism involved has not been determined.

AIM

To investigate the effect of HIF-2α on the osteogenic and adipogenic differentiation of BMSCs and the hematopoietic function of hematopoietic stem cells (HSCs) in the BM niche on the progression of OP.

METHODS

Mice with BMSC-specific HIF-2α knockout (Prx1-Cre;Hif-2αfl/fl mice) were used for in vivo experiments. Bone quantification was performed on mice of two genotypes with three interventions: Bilateral ovariectomy, semilethal irradiation, and dexamethasone treatment. Moreover, the hematopoietic function of HSCs in the BM niche was compared between the two mouse genotypes. In vitro, the HIF-2α agonist roxadustat and the HIF-2α inhibitor PT2399 were used to investigate the function of HIF-2α in BMSC osteogenic and adipogenic differentiation. Finally, we investigated the effect of HIF-2α on BMSCs via treatment with the mechanistic target of rapamycin (mTOR) agonist MHY1485 and the mTOR inhibitor rapamycin.

RESULTS

The quantitative index determined by microcomputed tomography indicated that the femoral bone density of Prx1-Cre;Hif-2αfl/fl mice was lower than that of Hif-2αfl/fl mice under the three intervention conditions. In vitro, Hif-2αfl/fl mouse BMSCs were cultured and treated with the HIF-2α agonist roxadustat, and after 7 d of BMSC adipogenic differentiation, the oil red O staining intensity and mRNA expression levels of adipogenesis-related genes in BMSCs treated with roxadustat were decreased; in addition, after 14 d of osteogenic differentiation, BMSCs treated with roxadustat exhibited increased expression of osteogenesis-related genes. The opposite effects were shown for mouse BMSCs treated with the HIF-2α inhibitor PT2399. The mTOR inhibitor rapamycin was used to confirm that HIF-2α regulated BMSC osteogenic and adipogenic differentiation by inhibiting the mTOR pathway. Consequently, there was no significant difference in the hematopoietic function of HSCs between Prx1-Cre;Hif-2αfl/fl and Hif-2αfl/fl mice.

CONCLUSION

Our study showed that inhibition of HIF-2α decreases bone mass by inhibiting the osteogenic differentiation and increasing the adipogenic differentiation of BMSCs through inhibition of mTOR signaling in the BM niche.

Expansion of human umbilical cord derived mesenchymal stem cells in regenerative medicine

BACKGROUND

Stem cells are undifferentiated cells that possess the potential for self-renewal with the capacity to differentiate into multiple lineages. In humans, their limited numbers pose a challenge in fulfilling the necessary demands for the regeneration and repair of damaged tissues or organs. Studies suggested that mesenchymal stem cells (MSCs), necessary for repair and regeneration via transplantation, require doses ranging from 10 to 400 million cells. Furthermore, the limited expansion of MSCs restricts their therapeutic application.

AIM

To optimize a novel protocol to achieve qualitative and quantitative expansion of MSCs to reach the targeted number of cells for cellular transplantation and minimize the limitations in stem cell therapy protocols.

METHODS

Human umbilical cord (hUC) tissue derived MSCs were obtained and re-cultured. These cultured cells were subjected to the following evaluation procedures: Immunophenotyping, immunocytochemical staining, trilineage differentiation, population doubling time and number, gene expression markers for proliferation, cell cycle progression, senescence-associated β-galactosidase assay, human telomerase reverse transcriptase (hTERT) expression, mycoplasma, cytomegalovirus and endotoxin detection.

RESULTS

Analysis of pluripotent gene markers Oct4, Sox2, and Nanog in recultured hUC-MSC revealed no significant differences. The immunophenotypic markers CD90, CD73, CD105, CD44, vimentin, CD29, Stro-1, and Lin28 were positively expressed by these recultured expanded MSCs, and were found negative for CD34, CD11b, CD19, CD45, and HLA-DR. The recultured hUC-MSC population continued to expand through passage 15. Proliferative gene expression of Pax6, BMP2, and TGFb1 showed no significant variation between recultured hUC-MSC groups. Nevertheless, a significant increase (P < 0.001) in the mitotic phase of the cell cycle was observed in recultured hUC-MSCs. Cellular senescence markers (hTERT expression and β-galactosidase activity) did not show any negative effect on recultured hUC-MSCs. Additionally, quality control assessments consistently confirmed the absence of mycoplasma, cytomegalovirus, and endotoxin contamination.

CONCLUSION

This study proposes the development of a novel protocol for efficiently expanding stem cell population. This would address the growing demand for larger stem cell doses needed for cellular transplantation and will significantly improve the feasibility of stem cell based therapies.

Effects of high glucose and severe hypoxia on the biological behavior of mesenchymal stem cells at various passages

BACKGROUND

Mesenchymal stem cells (MSCs) have been extensively studied for therapeutic potential, due to their regenerative and immunomodulatory properties. Serial passage and stress factors may affect the biological characteristics of MSCs, but the details of these effects have not been recognized yet.

AIM

To investigate the effects of stress factors (high glucose and severe hypoxia) on the biological characteristics of MSCs at different passages, in order to optimize the therapeutic applications of MSCs.

METHODS

In this study, we investigated the impact of two stress conditions; severe hypoxia and high glucose on human adipose-tissue derived MSCs (hAD-MSCs) at passages 6 (P6), P8, and P10. Proliferation, senescence and apoptosis were evaluated measuring WST-1, senescence-associated beta-galactosidase, and annexin V, respectively.

RESULTS

Cells at P6 showed decreased proliferation and increased apoptosis under conditions of high glucose and hypoxia compared to control, while the extent of senescence did not change significantly under stress conditions. At P8 hAD-MSCs cultured in stress conditions had a significant decrease in proliferation and apoptosis and a significant increase in senescence compared to counterpart cells at P6. Cells cultured in high glucose at P10 had lower proliferation and higher senescence than their counterparts in the previous passage, while no change in apoptosis was observed. On the other hand, MSCs cultured under hypoxia showed decreased senescence, increased apoptosis and no significant change in proliferation when compared to the same conditions at P8.

CONCLUSION

These results indicate that stress factors had distinct effects on the biological processes of MSCs at different passages, and suggest that senescence may be a protective mechanism for MSCs to survive under stress conditions at higher passage numbers.

Gossypol acetic acid regulates leukemia stem cells by degrading LRPPRC via inhibiting IL-6/JAK1/STAT3 signaling or resulting mitochondrial dysfunction

BACKGROUND

Leukemia stem cells (LSCs) are found to be one of the main factors contributing to poor therapeutic effects in acute myeloid leukemia (AML), as they are protected by the bone marrow microenvironment (BMM) against conventional therapies. Gossypol acetic acid (GAA), which is extracted from the seeds of cotton plants, exerts anti-tumor roles in several types of cancer and has been reported to induce apoptosis of LSCs by inhibiting Bcl2.

AIM

To investigate the exact roles of GAA in regulating LSCs under different microenvironments and the exact mechanism.

METHODS

In this study, LSCs were magnetically sorted from AML cell lines and the CD34+CD38- population was obtained. The expression of leucine-rich pentatricopeptide repeat-containing protein (LRPPRC) and forkhead box M1 (FOXM1) was evaluated in LSCs, and the effects of GAA on malignancies and mitochondrial function were measured.

RESULTS

LRPPRC was found to be upregulated, and GAA inhibited cell proliferation by degrading LRPPRC. GAA induced LRPPRC degradation and inhibited the activation of interleukin 6 (IL-6)/janus kinase (JAK) 1/signal transducer and activator of transcription (STAT) 3 signaling, enhancing chemosensitivity in LSCs against conventional chemotherapies, including L-Asparaginase, Dexamethasone, and cytarabine. GAA was also found to downregulate FOXM1 indirectly by regulating LRPPRC. Furthermore, GAA induced reactive oxygen species accumulation, disturbed mitochondrial homeostasis, and caused mitochondrial dysfunction. By inhibiting IL-6/JAK1/STAT3 signaling via degrading LRPPRC, GAA resulted in the elimination of LSCs. Meanwhile, GAA induced oxidative stress and subsequent cell damage by causing mitochondrial damage.

CONCLUSION

Taken together, the results indicate that GAA might overcome the BMM protective effect and be considered as a novel and effective combination therapy for AML.

Adipose-derived regenerative therapies for the treatment of knee osteoarthritis

Knee osteoarthritis is a degenerative condition with a significant disease burden and no disease-modifying therapy. Definitive treatment ultimately requires joint replacement. Therapies capable of regenerating cartilage could significantly reduce financial and clinical costs. The regenerative potential of mesenchymal stromal cells (MSCs) has been extensively studied in the context of knee osteoarthritis. This has yielded promising results in human studies, and is likely a product of immunomodulatory and chondroprotective biomolecules produced by MSCs in response to inflammation. Adipose-derived MSCs (ASCs) are becoming increasingly popular owing to their relative ease of isolation and high proliferative capacity. Stromal vascular fraction (SVF) and micro-fragmented adipose tissue (MFAT) are produced by the enzymatic and mechanical disruption of adipose tissue, respectively. This avoids expansion of isolated ASCs ex vivo and their composition of heterogeneous cell populations, including immune cells, may potentiate the reparative function of ASCs. In this editorial, we comment on a multicenter randomized trial regarding the efficacy of MFAT in treating knee osteoarthritis. We discuss the study's findings in the context of emerging evidence regarding adipose-derived regenerative therapies. An underlying mechanism of action of ASCs is proposed while drawing important distinctions between the properties of isolated ASCs, SVF, and MFAT.

Reveal more mechanisms of precondition mesenchymal stem cells inhibiting inflammation

Hypoxia can get more ability to inhibit inflammation. But how it impact on survival time of mesenchymal stem cells (MSCs) is confusing and how preconditioned MSCs inhibiting inflammation are partially known. Those issues decided the value of preconditioned MSCs by hypoxia.

Interplay between mesenchymal stem cells and macrophages: Promoting bone tissue repair

The repair of bone tissue damage is a complex process that is well-orchestrated in time and space, a focus and difficulty in orthopedic treatment. In recent years, the success of mesenchymal stem cells (MSCs)-mediated bone repair in clinical trials of large-area bone defects and bone necrosis has made it a candidate in bone tissue repair engineering and regenerative medicine. MSCs are closely related to macrophages. On one hand, MSCs regulate the immune regulatory function by influencing macrophages proliferation, infiltration, and phenotype polarization, while also affecting the osteoclasts differentiation of macrophages. On the other hand, macrophages activate MSCs and mediate the multilineage differentiation of MSCs by regulating the immune microenvironment. The cross-talk between MSCs and macrophages plays a crucial role in regulating the immune system and in promoting tissue regeneration. Making full use of the relationship between MSCs and macrophages will enhance the efficacy of MSCs therapy in bone tissue repair, and will also provide a reference for further application of MSCs in other diseases.

Mesenchymal stem cells and their derived exosomes for the treatment of COVID-19

Coronavirus disease 2019 (COVID-19) is an acute respiratory infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). SARS-CoV-2 infection typically presents with fever and respiratory symptoms, which can progress to severe respiratory distress syndrome and multiple organ failure. In severe cases, these complications may even lead to death. One of the causes of COVID-19 deaths is the cytokine storm caused by an overactive immune response. Therefore, suppressing the overactive immune response may be an effective strategy for treating COVID-19. Mesenchymal stem cells (MSCs) and their derived exosomes (MSCs-Exo) have potent homing abilities, immunomodulatory functions, regenerative repair, and antifibrotic effects, promising an effective tool in treating COVID-19. In this paper, we review the main mechanisms and potential roles of MSCs and MSCs-Exo in treating COVID-19. We also summarize relevant recent clinical trials, including the source of cells, the dosage and the efficacy, and the clinical value and problems in this field, providing more theoretical references for the clinical use of MSCs and MSCs-Exo in the treatment of COVID-19.

Long-term outcome of stem cell transplantation with and without anti-tumor necrotic factor therapy in perianal fistula with Crohn's disease

BACKGROUND

Stem cell transplantation is a promising therapeutic option for curing perianal fistula in Crohn's disease (CD). Anti-tumor necrotic factor (TNF) therapy combined with drainage procedure is effective as well. However, previous studies are limited to proving whether the combination treatment of biologics and stem cell transplantation improves the effect of fistula closure.

AIM

This study aimed to evaluate the long-term outcomes of stem cell transplantation and compare Crohn's perianal fistula (CPF) closure rates after stem cell transplantation with and without anti-TNF therapy, and to identify the factors affecting CPF closure and recurrence.

METHODS

The patients with CD who underwent stem cell transplantation for treating perianal fistula in our institution between Jun 2014 and December 2022 were enrolled. Clinical data were compared according to anti-TNF therapy and CPF closure.

RESULTS

A total of 65 patients were included. The median age of females was 26 years (range: 21-31) and that of males was 29 (44.6%). The mean follow-up duration was 65.88 ± 32.65 months, and complete closure was observed in 50 (76.9%) patients. The closure rates were similar after stem cell transplantation with and without anti-TNF therapy (66.7% vs 81.6% at 3 year, P = 0.098). The patients with fistula closure had short fistulous tract and infrequent proctitis and anorectal stricture (P = 0.027, 0.002, and 0.008, respectively). Clinical factors such as complexity, number of fistulas, presence of concurrent abscess, and medication were not significant for closure. The cumulative 1-, 2-, and 3-year closure rates were 66.2%, 73.8%, and 75.4%, respectively.

CONCLUSION

Anti-TNF therapy does not increase CPF closure rates in patients with stem cell transplantation. However, both refractory and non-refractory CPF have similar closure rates after additional anti-TNF therapy. Fistulous tract length, proctitis, and anal stricture are risk factors for non-closure in patients with CPF after stem cell transplantation.

High glucose microenvironment and human mesenchymal stem cell behavior

High glucose (HG) culture conditions in vitro and persistent exposure to hyperglycemia in diabetes patients are detrimental to stem cells, analogous to any other cell type in our body. It interferes with diverse signaling pathways, i.e. mammalian target of rapamycin (mTOR)-phosphoinositide 3-kinase (PI3K)-Akt signaling, to impact physiological cellular functions, leading to low cell survival and higher cell apoptosis rates. While elucidating the underlying mechanism responsible for the apoptosis of adipose tissue-derived mesenchymal stem cells (MSCs), a recent study has shown that HG culture conditions dysregulate mTOR-PI3K-Akt signaling in addition to mitochondrial malfunctioning due to defective mitochondrial membrane potential (MtMP) that lowers ATP production. This organelle-level dysfunction energy-starves the cells and increases oxidative stress and ultrastructural abnormalities. Disruption of the mitochondrial electron transport chain produces an altered mitochondrial NAD+/NADH redox state as evidenced by a low NAD+/NADH ratio that primarily contributes to the reduced cell survival in HG. Some previous studies have also reported altered mitochondrial membrane polarity (causing hyperpolarization) and reduced mitochondrial cell mass, leading to perturbed mitochondrial homeostasis. The hostile microenvironment created by HG exposure creates structural and functional changes in the mitochondria, altering their bioenergetics and reducing their capacity to produce ATP. These are significant data, as MSCs are extensively studied for tissue regeneration and restoring their normal functioning in cell-based therapy. Therefore, MSCs from hyperglycemic donors should be cautiously used in clinical settings for cell-based therapy due to concerns of their poor survival rates and increased rates of post engraftment proliferation. As hyperglycemia alters the bioenergetics of donor MSCs, rectifying the loss of MtMP may be an excellent target for future research to restore the normal functioning of MSCs in hyperglycemic patients.

Self-assembly of differentiated dental pulp stem cells facilitates spheroid human dental organoid formation and prevascularization

BACKGROUND

The self-assembly of solid organs from stem cells has the potential to greatly expand the applicability of regenerative medicine. Stem cells can self-organise into microsized organ units, partially modelling tissue function and regeneration. Dental pulp organoids have been used to recapitulate the processes of tooth development and related diseases. However, the lack of vasculature limits the utility of dental pulp organoids.

AIM

To improve survival and aid in recovery after stem cell transplantation, we demonstrated the three-dimensional (3D) self-assembly of adult stem cell-human dental pulp stem cells (hDPSCs) and endothelial cells (ECs) into a novel type of spheroid-shaped dental pulp organoid in vitro under hypoxia and conditioned medium (CM).

METHODS

During culture, primary hDPSCs were induced to differentiate into ECs by exposing them to a hypoxic environment and CM. The hypoxic pretreated hDPSCs were then mixed with ECs at specific ratios and conditioned in a 3D environment to produce prevascularized dental pulp organoids. The biological characteristics of the organoids were analysed, and the regulatory pathways associated with angiogenesis were studied.

RESULTS

The combination of these two agents resulted in prevascularized human dental pulp organoids (Vorganoids) that more closely resembled dental pulp tissue in terms of morphology and function. Single-cell RNA sequencing of dental pulp tissue and RNA sequencing of Vorganoids were integrated to analyse key regulatory pathways associated with angiogenesis. The biomarkers forkhead box protein O1 and fibroblast growth factor 2 were identified to be involved in the regulation of Vorganoids.

CONCLUSION

In this innovative study, we effectively established an in vitro model of Vorganoids and used it to elucidate new mechanisms of angiogenesis during regeneration, facilitating the development of clinical treatment strategies.

Understanding host-graft crosstalk for predicting the outcome of stem cell transplantation

Mesenchymal stromal cells (MSCs) hold great promise for tissue regeneration in debilitating disorders. Despite reported improvements, the short-term outcomes of MSC transplantation, which is possibly linked to poor cell survival, demand extensive investigation. Disease-associated stress microenvironments further complicate outcomes. This debate underscores the need for a deeper understanding of the phenotypes of transplanted MSCs and their environment-induced fluctuations. Additionally, questions arise about how to predict, track, and comprehend cell fate post-transplantation. In vivo cellular imaging has emerged as a critical requirement for both short- and long-term safety and efficacy studies. However, translating preclinical imaging methods to clinical settings remains challenging. The fate and function of transplanted cells within the host environment present intricate challenges, including MSC engraftment, variability, and inconsistencies between preclinical and clinical data. The study explored the impact of high glucose concentrations on MSC survival in diabetic environments, emphasizing mitochondrial factors. Preserving these factors may enhance MSC survival, suggesting potential strategies involving genetic modification, biomaterials, and nanoparticles. Understanding stressors in diabetic patients is crucial for predicting the effects of MSC-based therapies. These multifaceted challenges call for a holistic approach involving the incorporation of large-scale data, computational disease modeling, and possibly artificial intelligence to enable deterministic insights.