Bone Marrow Mesenchymal Cells Research Articles

Effects of Different Surface Functionalizations of Silica Nanoparticles on Mesenchymal Stem Cells.

Physicochemical properties of nanoparticles, such as particle size, surface charge, and particle shape, have a significant impact on cell activities. However, the effects of surface functionalization of nanoparticles with small chemical groups on stem cell behavior and function remain understudied. Herein, we incorporated different chemical functional groups (amino, DETA, hydroxyl, phosphate, and sulfonate with charges of +9.5, + 21.7, -14.1, -25.6, and -37.7, respectively) to the surface of inorganic silica nanoparticles. To trace their effects on mesenchymal stem cells (MSCs) of rat bone marrow, these functionalized silica nanoparticles were used to encapsulate Rhodamine B fluorophore dye. We found that surface functionalization with positively charged and short-chain chemical groups facilitates cell internalization and retention of nanoparticles in MSCs. The endocytic pathway differed among functionalized nanoparticles when tested with ion-channel inhibitors. Negatively charged nanoparticles mainly use lysosomal exocytosis to exit cells, while positively charged nanoparticles can undergo endosomal escape to avoid scavenging. The cytotoxic profiles of these functionalized silica nanoparticles are still within acceptable limits and tolerable. They exerted subtle effects on the actin cytoskeleton and migration ability. Last, phosphate-functionalized nanoparticles upregulate osteogenesis-related genes and induce osteoblast-like morphology, implying that it can direct MSCs lineage specification for bone tissue engineering. Our study provides insights into the rational design of biomaterials for effective drug delivery and regenerative medicine.

Complex hydrogel for cartilage regeneration and anti-inflammation

With the increasing incidence of osteoarthritis (OA) in elderly patients and the challenges posed by its multifaceted pathogenesis in developing effective treatments, this study explores the effective protein loading mode of Progranulin (PGRN) and its therapeutic potential for treating OA. GelMA hydrogels prepared with different concentrations of PGRN, employing AC-PEG-NHS as a crosslinking agent for drug encapsulation, were used to test the sustained release effect of the composite hydrogel drug delivery system. Additionally, we conducted in vitro assays to investigate the regulatory effects on rat bone marrow mesenchymal atromal cells (BMSCs), chondrocytes, and mouse macrophages - focusing on cell proliferation, and differentiation. For in vivo studies, histological staining techniques were utilized to assess inflammatory cell polarization and cartilage repair in a rat knee injury model. The results demonstrated that PGRN-loaded hydrogels significantly accelerated cell proliferation, enhance differentiation of BMSCs into chondrocytes, maintained a healthy chondrocyte phenotype, and induce M2-type polarization while inhibiting M1-type polarization in macrophages. Histological analyses also showed markedly improved tissue repair in the group treated with GelMA–NHS–PGRN hydrogels. As a result, these GelMA–NHS–PGRN hydrogels present a promising therapeutic approach for OA, potentially mitigating chronic inflammation and facilitating cartilage repair through controlled release of PGRN. Key worldPGRN, Osteoarthritis, Anti-inflammatory hydrogels, Cartilage regeneration.

Safety and potential efficacy of expanded mesenchymal stromal cells of bone marrow and umbilical cord origins in patients with chronic spinal cord injuries: a phase I/II study

Background aimsSpinal cord injury (SCI) affects patients' physical, psychological, and social well-being. Presently, treatment modalities for chronic SCI have restricted clinical effectiveness. Mesenchymal stromal cells (MSCs) demonstrate promise in addressing nervous tissue damage. This single-center, open-label, parallel-group randomized clinical trial aimed to assess the safety and efficacy of intraoperative perilesional administration of expanded autologous bone marrow-derived MSCs (BMMSCs), followed by monthly intrathecal injections, in comparison to monthly intrathecal administration of expanded allogeneic umbilical cord-derived MSCs (UCMSCs) for individuals with chronic SCI. MethodsTwenty participants, who had a minimum of 1 year of SCI duration, were enrolled. Each participant in Group A received perilesional BMMSCs, followed by monthly intrathecal BMMSCs for three injections, while Group B received monthly intrathecal UCMSCs for three injections. Safety and efficacy were evaluated using the American Spinal Cord Injury Association (ASIA) score for at least 1 year post the final injection. Statistical analysis was conducted using the Wilcoxon signed-rank test. ResultsGroup A comprised 11 participants, while Group B included 9. The mean follow-up duration was 22.65 months. Mild short-term adverse events encompassed headaches and back pain, with no instances of long-term adverse events. Both groups demonstrated significant improvements in total ASIA scores, with Group A displaying more pronounced motor improvements. ConclusionsOur findings indicate that perilesional administration of expanded autologous BMMSCs, followed by monthly intrathecal BMMSCs for three injections, or monthly intrathecal UCMSCs for three injections appear to be safe and hold promise for individuals with chronic SCI. Nonetheless, larger-scale clinical trials are imperative to validate these observations.

SIRT3: A Potential Target of Different Types of Osteoporosis.

Osteoporosis (OP) is a common age-related disease. OP is mainly a decrease in bone density and mass caused by the destruction of bone microstructure, which leads to an increase in bone fragility. SIRT3 is a mitochondrial deacetylase that plays critical roles in mitochondrial homeostasis, metabolic regulation, gene transcription, stress response, and gene stability. Studies have shown that the higher expression levels of SIRT3 are associated with decreased levels of oxidative stress in the body and may play important roles in the prevention of age-related diseases. SIRTs can enhance the osteogenic potential and osteoblastic activity of bone marrow mesenchymal stromal cells not only by enhancing PGC-1α, FOXO3, SOD2, and oxidative phosphorylation, but also by anti-aging and reducing mitochondrial autophagy. SIRT3 is able to upregulate antioxidant enzymes to exert an inhibitory effect on osteoclasts, however, it has been shown that the inflammatory cascade response can in turn increase SIRT3 and inhibit osteoclast differentiation through the AMPK-PGC-1β pathway. SIRT3 plays an important role in different types of osteoporosis by affecting osteoblasts, osteoclasts, and bone marrow mesenchymal cells. In this review, we discuss the classification and physiological functions of SIRTs, the effects of SIRT3 on OCs osteoblasts, and BMSCs, and the roles and mechanisms of SIRT3 in different types of OP, such as diabetic OP, glucocorticoid-induced OP, postmenopausal OP, and senile OP.

β-catenin inhibition disrupts the homeostasis of osteogenic/adipogenic differentiation leading to the development of glucocorticoid-induced osteonecrosis of the femoral head

Glucocorticoid-induced osteonecrosis of the femoral head (GONFH) is a common refractory joint disease characterized by bone damage and the collapse of femoral head structure. However, the exact pathological mechanisms of GONFH remain unknown. Here, we observed abnormal osteogenesis and adipogenesis associated with decreased β-catenin in the necrotic femoral head of GONFH patients. In vivo and in vitro studies further revealed that glucocorticoid exposure disrupted osteogenic/adipogenic differentiation of bone marrow mesenchymal cells (BMSCs) by inhibiting β-catenin signaling in glucocorticoid-induced GONFH rats. Col2+ lineage largely contributes to BMSCs and was found an osteogenic commitment in the femoral head through 9 mo of lineage trace. Specific deletion of β-catenin gene (Ctnnb1) in Col2+ cells shifted their commitment from osteoblasts to adipocytes, leading to a full spectrum of disease phenotype of GONFH in adult mice. Overall, we uncover that β-catenin inhibition disrupting the homeostasis of osteogenic/adipogenic differentiation contributes to the development of GONFH and identify an ideal genetic-modified mouse model of GONFH.

CHRONIC HIGH-FAT DIET CONSUMPTION ACCELERATES OSTEOBLAST DYSFUNCTION AND OSTEOPOROSIS BY GUT MICROBIAL METABOLITE TRIMETHYLAMINE-N-OXIDE

Obesity is correlated with the development of osteoporotic diseases. Gut microbiota-derived metabolite trimethylamine-n-oxide (TMAO) accelerates obesity-mediated tissue deterioration. This study was aimed to investigate what role TMAO may play in osteoporosis development during obesity.Mice were fed with high-fat diet (HFD; 60 kcal% fat) or chow diet (CD; 10 kcal% fat) or 0.2% TMAO in drinking water for 6 months. Body adiposis and bone microstructure were investigated using μCT imaging. Gut microbiome and serum metabolome were characterized using 16S rRNA sequencing and liquid chromatography-tandem mass spectrometry. Osteogenic differentiation of bone-marrow mesenchymal cells was quantified using RT-PCR and von Kossa staining. Cellular senescence was evaluated by key senescence markers p16, p21, p53, and senescence association β-galactosidase staining.HFD-fed mice developed hyperglycemia, body adiposis and osteoporosis signs, including low bone mineral density, sparse trabecular microarchitecture, and decreased biomechanical strength. HFD consumption induced gut microbiota dysbiosis, which revealed a high Firmicutes/Bacteroidetes ratio and decreased α-diversity and abundances of beneficial microorganisms Akkermansiaceae, Lactobacillaceae, and Bifidobacteriaceae. Serum metabolome uncovered increased serum L-carnitine and TMAO levels in HFD-fed mice. Of note, transplantation of fecal microbiota from CD-fed mice compromised HFD consumption-induced TMAO overproduction and attenuated loss in bone mass, trabecular microstructure, and bone formation rate. TMAO treatment inhibited trabecular and cortical bone mass and biomechanical characteristics; and repressed osteogenic differentiation capacity of bone-marrow mesenchymal cells. Mechanistically, TMAO accelerated mitochondrial dysfunction and senescence program, interrupted mineralized matrix production in osteoblasts.Gut microbial metabolite TMAO induced osteoblast dysfunction, accelerating the development of obesity-induced skeletal deterioration. This study, for the first time, conveys a productive insight into the catabolic role of gut microflora metabolite TMAO in regulating osteoblast activity and bone tissue integrity during obesity.

Synergistic Effect of Lovastatin and Selegiline on the Differentiation of Bone Marrow Stromal Cells Into Neuron-Like Cells

Background: The effect of selegiline as an oxidase inhibitor on cell differentiation into neuron-like cells has been demonstrated by altering gene expression. Based on the results of studies on the role of statins in neurotrophin regulation, in this study, we examined the effect of lovastatin (HMG-CoA reductase inhibitor) on the differentiation of bone marrow mesenchymal cells (BMSCs) into neuron-like cells. Selegiline is an irreversible inhibitor of monoamine oxidase (MAO) type B. Since dopamine in the human brain is metabolized primarily by MAO-B, selegiline increases dopamine levels in the central nervous system. In addition to inhibiting MAO-B, selegiline also inhibits the uptake of dopamine and norepinephrine into presynaptic nerves and increases dopamine turnover. Methods: Bone marrow mesenchymal cells were collected from 28-day-old rats and cultured under standard conditions on the medium. The experimental groups in this study were as follows: BMSCs (control); BMSCs induced with 20 µM selegiline for 24 hours (experiment 1); BMSCs induced with 6 µM lovastatin for 24 hours (experiment 2); BMSCs were induced with 20 µM selegiline for 24 hours and 6 µM lovastatin for the next 24 hours (experiment 3). Real-time RT-PCR was performed to determine the mRNA levels of the nestin and NF-68 genes. Results: Real-time RT-PCR results showed that nestin and NF-68 mRNA levels were significantly increased in the co-treatment group (experiment 3) compared to the other experimental groups (P < 0.05). Conclusions: Based on the increased expression of nestin and NF-68 genes, the presence of lovastatin has a synergistic effect on neuronal differentiation and optimization of stem cell therapeutic approaches.

Retracted: Impacts of Angelica Polysaccharide on Proliferation and Differentiation of Mesenchymal Stem Cells of Rat Bone Marrow

Retracted: Impacts of Angelica Polysaccharide on Proliferation and Differentiation of Mesenchymal Stem Cells of Rat Bone Marrow

Acute myeloid leukemia-derived bone marrow mesenchymal cells exhibit improved support for leukemic cell proliferation

IntroductionThe bone marrow (BM) microenvironment plays a significant role in acute myeloid leukemia (AML) genesis and there is evidence that BM mesenchymal stromal cells (BMMSCs) can support leukemia progenitor cell proliferation and survival and provide resistance to cytotoxic therapies. Hypothesis and methodNevertheless, currently unknown are the relevance of the spatial localization of AML cells relative to the BMMSCs and whether BMMSCs from patients with AML and healthy subjects have similar properties. To address these issues, we performed a differential gene expression analysis using RNA-sequencing data generated from healthy donors (HDs) and leukemic BMMSCs. ResultsThe Gene Set Enrichment Analysis (GSEA) revealed that leukemic BMMSCs were associated with the terms “positive regulation of cell cycle”, “angiogenesis” and “signaling by the estimated glomerular filtration rate (eGFR)”, whereas healthy donor (HD)-derived BMMSCs were associated with “programmed cell death in response to the reactive oxygen species (ROS)”, “negative regulation of the cytochrome C from the mitochondria” and “interferon signaling”. Next, we evaluated the mitochondrial superoxide production in AML cells in a co-culture layered model. The superoxide production was reduced in leukemic cells in close contact (adhered to the surface or beneath the cell layer) with BMMSCs, indicating lower oxidative stress. ConclusionTaken together, our results suggest that AML-derived BMMSCs are transcriptionally rewired and can reduce the metabolic stress of leukemic cells.

Genome-Wide Methylome and Transcriptome Profiling of Acute Myeloid Leukemia Derived Bone Marrow Mesenchymal Cells Identify Age Group Specific Biological Pathway Dysregulation in the Bone Marrow Microenvironment of AML

Adult patients with acute myeloid leukemia (AML) have a proportionate increase in mortality from their disease and therapy as age increases. In great part, this mortality is due to disease relapse that occurs at a higher rate irrespective of genetic assigned risk. While intensification of therapy in patients with favorable genomics such as core-binding-factor AML (CBF-AML) has yielded a high proportion of long-term remission and potential cure, this benefit has been less frequently observed in patients with AML age 60 and older despite receipt of similar therapy. Moreover, even less benefit has been observed in patients with unfavorable genomics such when bearing a complex karyotype (karyotype with ≥ 3 chromosome abnormalities). Reasons for this unfavorable outcome among older patients is unknown. We hypothesized that tumor-induced aging in cells of bone marrow microenvironment, specifically, in bone marrow mesenchymal stromal cells (BMSCs) plays a significant role in AML survival and progression in older compared to younger patients and that the difference in prognosis may depend on specific aging induced changes in the BMSCs. We expanded BMSCs under physiologic hypoxic conditions (91% nitrogen, 4% oxygen and 5% CO 2) to mimic the bone marrow microenvironment, isolated DNA and RNA from early passaged cells and performed methylation analysis using 850k Illumina DNAmehtylation arrays and gene expression analysis using mRNAseq. We used the Horvath Skin and Blood clock to calculate epigenetic age (DNA methylation age). We determined differentially expressed genes with increasing epigenetic or chronological age in the different AML genetic risk groups (n=9 CBF-AML, n=11 CK-AML and n=7 Normal donor BMSC) as well as in older (>60) and younger (<60) AML-BMSCs, and performed Gene Set Enrichment Analysis (GSEA) for the Hallmarks as well as aging and senescence related genesets (n=33 genesets). We found that BMSCs derived from AML bone marrow cells are more age accelerated than normal donor BMSCs. Our GSEA analysis revealed enrichment for age-associated gene networks that reflected hallmarks of aging, including mitochondrial dysfunction, inflammation, and cellular senescence. Specifically, we observed a positive enrichment for the SenMayo gene signature ( Saul et al. 2022, Nature Communications) and a negative enrichment of proliferation and mitotic gene sets with increasing epigenetic and chronological age (padj<0.05). Gene sets that are related to inhibition of adipogenesis were positively enriched in the CBF-AML BMSCs compared to the CK-AML BMSCs. Our integrated analysis revealed novel observations regarding the cellular changes that occur in the AML stromal microenvironment with increasing age. Most interestingly, our findings suggest that AML derived BMSCs have increased epigenetic age compared to normal donor BMSCs. Additional experiments are ongoing to functionally validate the findings predicted by the enrichment analysis. Our study is the first to suggest an increased epigenetic age in the stromal bone marrow microenvironment of older AML patients.

EDNRA-Expressing Mesenchymal Cells Are Expanded in Myeloma Interstitial Bone Marrow and Associated with Disease Progression.

Multiple myeloma (MM) induces dysfunctional bone marrow (BM) mesenchymal cells and neoangiogenesis. Pericytes and smooth muscle cells (SMCs) could detach from vessels and become cancer-associated fibroblasts. We found that the pericyte and SMC marker endothelin receptor type A (EDNRA) is overexpressed in whole MM bone biopsies; we sought to characterize its expression. EDNRA expression gradually increased with disease progression. High-risk MM patients had higher EDNRA expression than low-risk MM patients and EDNRA expression was highest in focal lesions. High EDNRA expression was associated with high expression of pericyte markers (e.g., RGS5, POSTN, and CD146) and the angiogenic marker FLT1. A single-cell analysis of unexpanded BM mesenchymal cells detected EDNRA expression in a subset of cells that coexpressed mesenchymal cell markers and had higher expression of proliferation genes. Immunohistochemistry revealed that the number of EDNRA+ cells in the interstitial BM increased as MM progressed; EDNRA+ cells were prevalent in areas near the MM focal growth. EDNRA+ cells were detached from CD34+ angiogenic cells and coexpressed RGS5 and periostin. Therefore, they likely originated from pericytes or SMCs. These findings identify a novel microenvironmental biomarker in MM and suggest that the presence of detached EDNRA+ cells indicates disrupted vasculature and increased angiogenesis.

The bone marrow stroma in human myelodysplastic syndrome reveals alterations that regulate disease progression

AbstractMyelodysplastic syndromes (MDSs) are a heterogenous group of diseases affecting the hematopoietic stem cell that are curable only by stem cell transplantation. Both hematopoietic cell intrinsic changes and extrinsic signals from the bone marrow (BM) niche seem to ultimately lead to MDS. Animal models of MDS indicate that alterations in specific mesenchymal progenitor subsets in the BM microenvironment can induce or select for abnormal hematopoietic cells. Here, we identify a subset of human BM mesenchymal cells marked by the expression of CD271, CD146, and CD106. This subset of human mesenchymal cells is comparable with mouse mesenchymal cells that, when perturbed, result in an MDS-like syndrome. Its transcriptional analysis identified Osteopontin (SPP1) as the most overexpressed gene. Selective depletion of Spp1 in the microenvironment of the mouse MDS model, Vav-driven Nup98-HoxD13, resulted in an accelerated progression as demonstrated by increased chimerism, higher mutant myeloid cell burden, and a more pronounced anemia when compared with that in wild-type microenvironment controls. These data indicate that molecular perturbations can occur in specific BM mesenchymal subsets of patients with MDS. However, the niche adaptations to dysplastic clones include Spp1 overexpression that can constrain disease fitness and potentially progression. Therefore, niche changes with malignant disease can also serve to protect the host.

Regenerative potential of multinucleated cells: bone marrow adiponectin-positive multinucleated cells take the lead

BackgroundPolyploid cells can be found in a wide evolutionary spectrum of organisms. These cells are assumed to be involved in tissue regeneration and resistance to stressors. Although the appearance of large multinucleated cells (LMCs) in long-term culture of bone marrow (BM) mesenchymal cells has been reported, the presence and characteristics of such cells in native BM and their putative role in BM reconstitution following injury have not been fully investigated.MethodsBM-derived LMCs were explored by time-lapse microscopy from the first hours post-isolation to assess their colony formation and plasticity. In addition, sub-lethally irradiated mice were killed every other day for four weeks to investigate the histopathological processes during BM regeneration. Moreover, LMCs from GFP transgenic mice were transplanted to BM-ablated recipients to evaluate their contribution to tissue reconstruction.ResultsBM-isolated LMCs produced mononucleated cells with characteristics of mesenchymal stromal cells. Time-series inspections of BM sections following irradiation revealed that LMCs are highly resistant to injury and originate mononucleated cells which reconstitute the tissue. The regeneration process was synchronized with a transient augmentation of adipocytes suggesting their contribution to tissue repair. Additionally, LMCs were found to be adiponectin positive linking the observations on multinucleation and adipogenesis to BM regeneration. Notably, transplantation of LMCs to myeloablated recipients could reconstitute both the hematopoietic system and BM stroma.ConclusionsA population of resistant multinucleated cells reside in the BM that serves as the common origin of stromal and hematopoietic lineages with a key role in tissue regeneration. Furthermore, this study underscores the contribution of adipocytes in BM reconstruction.Graphical

Injectable EC-BMSC hydrogel with prolonged VEGF action for enhanced angiogenesis

Tissue regeneration necessitates rapid and mature angiogenesis, while insufficient vascularization along with tissue implantation hinders the great potential applications. Endothelial cells (ECs) and bone marrow mesenchymal cells (BMSCs) are responsible for the angiogenesis in preparing bone tissue. Herein, we proposed the realization of the angiogenesis by co-culturing ECs and BMSCs within an injectable multi-crosslinked double-network (DN) hydrogel, composed of glycol chitosan (GC)/benzaldehyde-capped poly (ethylene oxide) (OHC-PEO-CHO) and calcium alginate (Alg). The hydrogel is crosslinked by dynamic interplay allowing the encapsulation, migration and proliferation of the cells. The hydrogel is capable to carry vascular endothelial growth factor (VEGF) with prolonging action within the matrix to effectively regulate the cell behavior. Co-existence of ECs and BMSCs with the VEGF within the hydrogel-based extracellular matrix (ECM) plays a key role in mediating the formation of a mature vascular structure with endothelium and pericyte. The neovascularization is closely related with the VEGF/VEGFR2/ERK signaling pathway. The finding indicates the direction toward future vascularized tissue regeneration by using a hydrogel-based scaffold with adjustable microenvironment by incorporation of functional growth factors.

Salvianolic acid C promotes osteogenic differentiation of bone marrow mesenchymal stem cells in osteoporotic rats through activation of AMPK/SIRT1 pathway.

This study aimed to explore the molecular mechanism underlying the therapeutic effect of salvianolic acid C (SAC) on osteoporosis. Osteoporotic (OVX) rats were used as the model, and the impacts of SAC treatment on their serum and urine biochemical indicators were assessed. The biomechanical parameters of these rats were also evaluated. The effects of SAC treatment on the bone of OVX rats was quantified using hematoxylin & eosin staining and alizarin red staining, which reflect calcium deposition. The potential signaling pathway involved in SAC treatment was identified and confirmed through Western blotting, AMP-activated protein kinase (AMPK) inhibitors, and sirtuin-1 (small interfering RNA-SIRT1). The results showed that SAC could ameliorate the serum and urine biochemical metabolism, and the pathological alterations of bone tissue in OVX rats. SAC promoted the osteogenic differentiation of bone marrow mesenchymal cells in OVX rats, one of the key mechanisms for modulation of Runx2, Osx, and OCN, involved in the AMPK/SIRT1 signaling pathway. The findings from this study suggest that SAC promotes the osteogenic differentiation of bone marrow mesenchymal stem cells in osteoporotic rats by activating the AMPK/SIRT1 pathway.

Possibilities for nasal septum perforation healing: from the past to the future

The article discusses application of various methods for nasal septum perforation healing (NSP). The types and options of surgical treatment in the historical aspect are described. These operations have a number of disadvantages, such as: the complexity of the material taking, the risk of inflammatory reaction and scar formation, as well as other postoperative complications leading to a relapse of the disease. Effectiveness of various allo- and autografts that used to restore the defect of the nasal septum is observed. Publications of regenerative medicine methods to eliminate perforation of the nasal septum are analyzed. Implantation of stromal cells, scaffolds; growth factors or their combinations is used. Such approaches make possible the restoration of the damaged tissue due to targeted and controlled cell differentiation, accompanied by the synthesis of the intercellular matrix and a decrease in inflammatory processes. In preclinical and clinical studies, special attention is paid to stromal cells. Mesenchymal stromal cells (MSCs) of bone marrow, adipose and other tissues are most often used. The regenerative effects of mesenchymal stromal cells are realized through the secretion of a wide range of anti-inflammatory mediators, cytokines and trophic factors, the positive effects of cell therapy of this type of cells should not be associated with the differentiation of implanted cells into cells of damaged tissues. The use of various materials for the treatment of NSP is also described with an assessment of their effectiveness and future prospects.

Osteoblast-intrinsic defect in glucose metabolism impairs bone formation in type II diabetic male mice.

Skeletal fragility is associated with type 2 diabetes mellitus (T2D), but the underlying mechanism is not well understood. Here, in a mouse model for youth-onset T2D, we show that both trabecular and cortical bone mass is reduced due to diminished osteoblast activity. Stable isotope tracing in vivo with 13C-glucose demonstrates that both glycolysis and glucose fueling of the TCA cycle are impaired in diabetic bones. Similarly, Seahorse assays show suppression of both glycolysis and oxidative phosphorylation by diabetes in bone marrow mesenchymal cells as a whole, whereas single-cell RNA sequencing reveals distinct modes of metabolic dysregulation among the subpopulations. Metformin not only promotes glycolysis and osteoblast differentiation in vitro, but also improves bone mass in diabetic mice. Finally, osteoblast-specific overexpression of either Hif1a, a general inducer of glycolysis, or Pfkfb3 which stimulates a specific step in glycolysis, averts bone loss in T2D mice. The study identifies osteoblast-intrinsic defects in glucose metabolism as an underlying cause of diabetic osteopenia, which may be targeted therapeutically.

Micro-nano porous structured tantalum-coated dental implants promote osteogenic activity in vitro and enhance osseointegration in vivo.

Due to its excellent biocompatibility and corrosion resistance, tantalum demonstrates versatility as an implant material. However, limited studies investigated the role of tantalum coated titanium-based dental implants. This study aimed to investigate the potential application of micro-nano porous structured tantalum coating on the surface of titanium dental implant. In the present study, micro-nano porous structured tantalum coating was prepared by vacuum plasma spraying (VPS) under selected optimum parameters, various characteristics of tantalum coating (Ta/Ti), including the morphology, potential, constituent, and hydrophilia, were investigated in comparison with its respective control groups, sandblasted titanium (Ti) and titanium coating (Ti/Ti). The adhesion, proliferation, and osteogenic differentiation ability of rat bone marrow mesenchymal cells (BMSCs) on different materials were assessed in vitro. Then the osseointegration capacity of Ti, Ti/Ti, Ta/Ti, and Straumann implants in canine mandible was evaluated with micro-CT, histological sections, and energy dispersive X-ray spectroscopy. These results demonstrated that micro-nanostructured, uneven, and granular tantalum coating was successfully prepared on titanium substrate by VPS with pore size ranging from 50 nm to 5μm and thickness ranging from 80 to 100 μm. Tantalum coating revealed the highest surface potential, best hydrophilia, and most protein adsorption among Ta/Ti, Ti/Ti, and Ti. Furthermore, Ta/Ti surfaces significantly promoted the adhesion, proliferation, and osteogenic differentiation of BMSCs. In vivo, Ta/Ti implants displayed positive osseointegration capability associated with increased bone mineral density and formation of new bone around implants without tantalum particles released. Together, these findings indicate that tantalum-coated titanium dental implants may serve as a new type of dental implant.

Characterization of mesenchymal stem cells in human fetal bone marrow by single-cell transcriptomic and functional analysis

Bone marrow mesenchymal stromal/stem cells (MSCs) are a heterogeneous population that can self-renew and generate stroma, cartilage, fat, and bone. Although a significant progress has been made toward recognizing about the phenotypic characteristics of MSCs, the true identity and properties of MSCs in bone marrow remain unclear. Here, we report the expression landscape of human fetal BM nucleated cells (BMNCs) based on the single-cell transcriptomic analysis. Unexpectedly, while the common cell surface markers such as CD146, CD271, and PDGFRa used for isolating MSCs were not detected, LIFR+PDGFRB+ were identified to be specific markers of MSCs as the early progenitors. In vivo transplantation demonstrated that LIFR+PDGFRB+CD45-CD31-CD235a- MSCs could form bone tissues and reconstitute the hematopoietic microenvironment (HME) effectively in vivo. Interestingly, we also identified a subpopulation of bone unipotent progenitor expressing TM4SF1+CD44+CD73+CD45-CD31-CD235a-, which had osteogenic potentials, but could not reconstitute HME. MSCs expressed a set of different transcription factors at the different stages of human fetal bone marrow, indicating that the stemness properties of MSCs might change during development. Moreover, transcriptional characteristics of cultured MSCs were significantly changed compared with freshly isolated primary MSCs. Our cellular profiling provides a general landscape of heterogeneity, development, hierarchy, microenvironment of the human fetal BM-derived stem cells at single-cell resolution.

CircRBM23 regulates the switch between osteogenesis and adipogenesis of mesenchymal stem cells via sponging miR-338-3p.

The disruption of the differentiation between osteogenic and adipogenic differentiation of mesenchymal stem cells (MSCs) in bone marrow contributes to the adipocytes accumulation and bone loss, which leads to the development of osteoporosis (OP). The circular RNA (circRNA), circRBM23, was generated from the RNA binding motif protein 23 (RBM23) gene. It was reported that circRBM23 was downregulated in OP patients, but it remains unknown whether its downregulation is involved in the lineage switch of MSCs. We aimed to explore the role and mechanism of circRBM23 in regulating the switch between osteogenic and adipogenic differentiation of MSCs. The expression and function of circRBM23 in vitro was detected by qRT-PCR, alizarin red staining, and oil Red O staining. The interactions between circRBM23 and microRNA-338-3p (miR-338-3p) were analyzed by RNA pull-down assay, FISH, and dual-luciferase reporter assay. MSCs treated with lentivirus overexpression of circRBM23 was applied for both in vitro and in vivo experiments. CircRBM23 was expressed at lower levels in OP patients. Besides, circRBM23 was upregulated during osteogenesis and downregulated during adipogenesis of MSCs. CircRBM23 could promote the osteogenic differentiation, but inhibit the adipogenic differentiation of MSCs. Mechanistically, circRBM23 acted as a sponge for microRNA-338-3p (miR-338-3p) to enhance the expression of RUNX family transcription factor 2 (RUNX2). Our research indicates that circRBM23 could promote the switch from adipogenic to osteogenic differentiation of MSCs via sponging miR-338-3p. It might improve the understanding of the lineage switch of MSCs and provide a potential target for diagnosing and treating OP.