FGFR2 accommodates osteogenic cell fate determination in human mesenchymal stem cells

Construction of a Lentiviral Vector for Fgfr2 Overexpression and its Impact on the Biological Behavior of Cranial Suture Mesenchymal Stem Cells

OBJECTIVE

Suture mesenchymal stem cells (SuSCs), possessing self-renewal and multilineage differentiation abilities, play a crucial role in cranial bone growth. However, the impact of the disease-causing fibroblast growth factor receptor 2 (FGFR2) mutation on SuSCs in Crouzon syndrome has not been explored. This study aims to employ a lentivirus to overexpress Fgfr2 and investigate its role in the pathogenesis of Crouzon syndrome.

METHODS

Starting with the prevalent FGFR2 mutation site in patients with Crouzon syndrome, a lentiviral vector carrying the Fgfr2.C361Y mutation was developed and transfected into SuSCs, with a determined multiplicity of infection values. The experimental group, SuSCs+Fgfr2.C361Y, was compared with the empty vector and normal SuSC groups. Cell proliferation, cycle, apoptosis, and osteogenic functionality were assessed using CCK-8 assays, flow cytometry, ALP activity assays, and real-time quantitative polymerase chain reaction.

RESULTS

The lentiviral vector effectively infected SuSCs, leading to heightened Fgfr2 expression, with optimal multiplicity of infection values of 80. The experimental group demonstrated decreased proliferation activity and a higher apoptosis rate compared with controls (P < 0.05). After osteogenic induction, the experimental group showed significantly higher ALP activity than controls (P < 0.05). Real-time quantitative polymerase chain reaction indicated lower mRNA expression levels of Gli1, Axin2, Pcna, Cdk2, and Bcl-2 in the experimental group than controls, whereas Bax, Runx2, and Bmp-2 showed higher expression (P < 0.05).

CONCLUSION

This study constructed a lentivirus vector to upregulate Fgfr2 expression in SuSCs, suppressing stem cell stemness by inhibiting proliferation, promoting apoptosis, and accelerating premature osteogenic differentiation, resulting in premature suture closure. These findings establish the groundwork for further understanding the pathogenesis of Crouzon syndrome.

Noggin promotes osteogenesis in human adipose-derived mesenchymal stem cells via FGFR2/Src/Akt and ERK signaling pathway

The balance between Noggin and bone morphogenetic proteins (BMPs) is important during early development and skeletal regenerative therapies. Noggin binds BMPs in the extracellular space, thereby preventing BMP signaling. However, Noggin may affect cell response not necessarily through the modulation of BMP signaling, raising the possibility of direct Noggin signaling through yet unspecified receptors. Here we show that in osteogenic cultures of adipose-derived stem cells (ASCs), Noggin activates fibroblast growth factor receptors (FGFRs), Src/Akt and ERK kinases, and it stabilizes TAZ proteins in the presence of dexamethasone. Overall, this leads ASCs to increased expression of osteogenic markers and robust mineral deposition. Our results also indicate that Noggin can induce osteogenic genes expression in normal human bone marrow stem cells and alkaline phosphatase activity in normal human dental pulp stem cells. Besides, Noggin can specifically activate FGFR2 in osteosarcoma cells. We believe our findings open new research avenues to further explore the involvement of Noggin in cell fate modulation by FGFR2/Src/Akt/ERK signaling and potential applications of Noggin in bone regenerative therapies.

Unravelling microRNA regulation and miRNA-mRNA regulatory networks in osteogenesis driven by 3D nanotopographical cues

Three-dimensional (3D) culturing of cells is being adopted for developing tissues for various applications such as mechanistic studies, drug testing, tissue regeneration, and animal-free meat. These approaches often involve cost-effective differentiation of stem or progenitor cells. One approach is to exploit architectural cues on a 3D substrate to drive cellular differentiation, which has been shown to be effective in various studies. Although extensive gene expression data from such studies have shown that gene expression patterns might differ, the gene regulatory networks controlling the expression of genes are rarely studied. In this study, we profiled genes and microRNAs (miRNAs) via next-generation sequencing (NGS) in human mesenchymal stem cells (hMSCs) driven toward osteogenesis via architectural cues in 3D matrices (3D conditions) and compared with cells in two-dimensional (2D) culture driven toward osteogenesis via soluble osteoinductive factors (OF conditions). The total number of differentially expressed genes was smaller in 3D compared to OF conditions. A distinct set of genes was observed under these conditions that have been shown to control osteogenic differentiation via different pathways. Small RNA sequencing revealed a core set of miRNAs to be differentially expressed under these conditions, similar to those that have been previously implicated in osteogenesis. We also observed a distinct regulation of miRNAs in these samples that can modulate gene expression, suggesting supplementary gene regulatory networks operative under different stimuli. This study provides insights into studying gene regulatory networks for identifying critical nodes to target for enhanced cellular differentiation and reveal the differences in physical and biochemical cues to drive cell fates.

Fundamentals and Translational Applications of Stem Cells and Biomaterials in Dental, Oral and Craniofacial Regenerative Medicine

Regenerative dental medicine continuously expands to improve treatments for prevalent clinical problems in dental and oral medicine. Stem cell based translational opportunities include regenerative therapies for tooth restoration, root canal therapy, and inflammatory processes (e.g., periodontitis). The potential of regenerative approaches relies on the biological properties of dental stem cells. These and other multipotent somatic mesenchymal stem cell (MSC) types can in principle be applied as either autologous or allogeneic sources in dental procedures. Dental stem cells have distinct developmental origins and biological markers that determine their translational utility. Dental regenerative medicine is supported by mechanistic knowledge of the molecular pathways that regulate dental stem cell growth and differentiation. Cell fate determination and lineage progression of dental stem cells is regulated by multiple cell signaling pathways (e.g., WNTs, BMPs) and epigenetic mechanisms, including DNA modifications, histone modifications, and non-coding RNAs (e.g., miRNAs and lncRNAs). This review also considers a broad range of novel approaches in which stem cells are applied in combination with biopolymers, ceramics, and composite materials, as well as small molecules (agonistic or anti-agonistic ligands) and natural compounds. Materials that mimic the microenvironment of the stem cell niche are also presented. Promising concepts in bone and dental tissue engineering continue to drive innovation in dental and non-dental restorative procedures.

Molecular mechanism of a novel root-end filling material containing zirconium oxide on the osteogenic/odontogenic differentiation of human osteosarcoma MG-63 cells

Although the novel root-end filling material containing zirconium oxide (NRFM-Zr) which is hydroxyapatite-based may promote osteoblast differentiation, the molecular mechanism remains unclear. The aim of this study is to investigate it underlying the osteogenic/odontogenic differentiation of human osteosarcoma MG-63 cells induced by NRFM-Zr, compared with calcium silicate-based mineral trioxide aggregate (MTA), and glass ionomer cement (GIC). Firstly, three different types of root filling materials were co-cultured with MG-63 cells, and their cell toxicity, alkaline phosphatase (ALP) activity, and calcium ion concentration were evaluated. Next, gene expression profiling microarray was employed to analyze the impact of the materials on the gene expression profile of MG-63 cells. The results of cell viability revealed that NRFM-Zr group had no significant difference compared to the negative control group. After 5 and 7 days of cultivation, both the NRFM-Zr and MTA groups exhibited significantly higher ALP activity compared to the negative control (p < 0.05). Moreover, the NRFM-Zr group had the highest calcium ion concentration, while the GIC group was the lowest (p < 0.05). Gene expression profiling microarray analysis identified 2915 (NRFM-Zr), 2254 (MTA) and 392 (GIC) differentially expressed genes, respectively. GO functional and KEGG pathway analysis revealed that differentially expressed genes of NRFM-Zr, MTA and GIC participated in 8, 6 and 0 differentiation-related pathways, respectively. Comparing the molecular mechanisms of osteogenic/odontogenic differentiation induced by hydroxyapatite-based NRFM-Zr and calcium silicate-based MTA, it was found that they shared similarities in their molecular mechanisms of promoting osteogenic differentiation. NRFM-Zr primarily promotes differentiation and inhibits cell apoptosis, thereby enhancing osteogenic/odontogenic differentiation of MG-63 cells. Furthermore, the inducing efficacy of NRFM-Zr was found to be superior to MTA.

Research progress on the regulation of bone marrow stem cells by noncoding RNAs in adolescent idiopathic scoliosis

Adolescent idiopathic scoliosis (AIS) is a common spinal deformity in young women, but its pathogenesis remains unclear. The primary pathogenic factors contributing to its development include genetics, abnormal bone metabolism, and endocrine factors. Bone marrow stem cells (BMSCs) play a crucial role in the pathogenesis of AIS by regulating its occurrence and progression. Noncoding RNAs (ncRNAs) are also involved in the pathogenesis of AIS, and their role in regulating BMSCs in patients with AIS requires further evaluation. In this review, we discuss the relevant literature regarding the osteogenic, chondrogenic, and lipogenic differentiation of BMSCs. The corresponding mechanisms of ncRNA-mediated BMSC regulation in patients with AIS, recent advancements in AIS and ncRNA research, and the importance of ncRNA translation profiling and multiomics are highlighted.

Novel insights of EZH2-mediated epigenetic modifications in degenerative musculoskeletal diseases

Degenerative musculoskeletal diseases (Osteoporosis, Osteoarthritis, Degenerative Spinal Disease and Sarcopenia) are pathological conditions that affect the function and pain of tissues such as bone, cartilage, and muscles, and are closely associated with ageing and long-term degeneration. Enhancer of zeste homolog 2 (EZH2), an important epigenetic regulator, regulates gene expression mainly through the PRC2-dependent trimethylation of histone H3 at lysine 27 (H3K27me3). Increasing evidence suggests that EZH2 is involved in several biological processes closely related to degenerative musculoskeletal diseases, such as osteogenic-adipogenic differentiation of bone marrow mesenchymal stem cells, osteoclast activation, chondrocyte functional status, and satellite cell proliferation and differentiation, mainly through epigenetic regulation (H3K27me3). Therefore, the synthesis and elucidation of the role of EZH2 in degenerative musculoskeletal diseases have attracted increasing attention. In addition, although EZH2 inhibitors have been approved for clinical use, whether they can be repurposed for the treatment of degenerative musculoskeletal diseases needs to be considered. Here, we reviewed the role of EZH2 in the development of degenerative musculoskeletal diseases and brought forward prospects of its pharmacological inhibitors in the improvement of the treatment of the diseases.

TiO2nanotubes promote osteogenic differentiation of human bone marrow stem cells via epigenetic regulation ofRMRP/DLEU2/EZH2 pathway

TiO2nanotubes (TNTs) significantly promote osteogenic differentiation and bone regeneration of cells. Nevertheless, the biological processes by which they promote osteogenesis are currently poorly understood. Long non-coding RNAs (lncRNAs) are essential for controlling osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). Epigenetic chromatin modification is one of the pathways in which lncRNAs regulate osteogenic differentiation. Here, we reported that TNTs could upregulate lncRNARMRP, and inhibition of lncRNARMRPin human BMSCs (hBMSCs) grown on TNTs could decrease runt-related transcription factor 2 (RUNX2), alkaline phosphatase, osteopontin, and osteocalcin (OCN) expression. Furthermore, we discovered that inhibiting lncRNARMRPelevated the expression of lncRNADLEU2, and lncRNADLEU2knockdown promoted osteogenic differentiation in hBMSCs. RNA immunoprecipitation experiments showed that lncRNADLEU2could interact with EZH2 to induce H3K27 methylation in the promoter regions of RUNX2 and OCN, suppressing gene expression epigenetically. According to these results, lncRNARMRPis upregulated by TNTs to promote osteogenic differentiation throughDLEU2/EZH2-mediated epigenetic modifications.

Short heat shock has a long-term effect on mesenchymal stem cells' transcriptome

The adverse effects of heat stress (HS) on physiological systems are well documented, yet the underlying molecular mechanisms behind it remain poorly understood. To address this knowledge gap, we conducted a comprehensive investigation into the impact of HS on mesenchymal stem cells (MSCs), focusing on their morphology, phenotype, proliferative capacity, and fate determination. Our in-depth analysis of the MSCs' transcriptome revealed a significant influence of HS on the transcriptional landscape. Notably, even after a short period of stress, we observed a persistent alteration in cell identity, potentially mediated by the activation of bivalent genes. Furthermore, by comparing the differentially expressed genes following short HS with their transcriptional state after recovery, we identified the transient upregulation of MLL and other histone modifiers, providing a potential mechanistic explanation for the stable activation of bivalent genes. This could be used to predict and modify the long-term effect of HS on cell identity.

Mesenchymal stem cells and macrophages and their interactions in tendon-bone healing

Tendon-bone insertion injuries (TBI), such as anterior cruciate ligament (ACL) and rotator cuff injuries, are common degenerative or traumatic pathologies with a negative impact on the patient's daily life, and they cause huge economic losses every year. The healing process after an injury is complex and is dependent on the surrounding environment. Macrophages accumulate during the entire process of tendon and bone healing and their phenotypes progressively transform as they regenerate. As the "sensor and switch of the immune system", mesenchymal stem cells (MSCs) respond to the inflammatory environment and exert immunomodulatory effects during the tendon-bone healing process. When exposed to appropriate stimuli, they can differentiate into different tissues, including chondrocytes, osteocytes, and epithelial cells, promoting reconstruction of the complex transitional structure of the enthesis. It is well known that MSCs and macrophages communicate with each other during tissue repair. In this review, we discuss the roles of macrophages and MSCs in TBI injury and healing. Reciprocal interactions between MSCs and macrophages and some biological processes utilizing their mutual relations in tendon-bone healing are also described. Additionally, we discuss the limitations in our understanding of tendon-bone healing and propose feasible ways to exploit MSC-macrophage interplay to develop an effective therapeutic strategy for TBI injuries.

The Translational potential of this article

This paper reviewed the important functions of macrophages and mesenchymal stem cells in tendon-bone healing and described the reciprocal interactions between them during the healing process. By managing macrophage phenotypes, mesenchymal stem cells and the interactions between them, some possible novel therapies for tendon-bone injury may be proposed to promote tendon-bone healing after restoration surgery.

Facile synthesis of curcumin-containing poly(amidoamine) dendrimers as pH-responsive delivery system for osteoporosis treatment

Osteoporosis is an age-related metabolic disease of bone, resulting in bone pain and even bone fragility and brittle fracture. Inhibiting overactive osteoclasts while promoting osteoblast activity is an ideal way to treat osteoporosis. Previous studies have demonstrated that natural compounds, such as curcumin (Cur) have dual roles both in promoting bone formation and inhibiting bone resorption, making them promising candidates for osteoporosis treatment. However, their poor water solubility, high dosage of curative effect and significant toxicity to other organs have largely limited their clinical translations. In this study, a novel method was reported to conjugate Cur and poly(amidoamine) dendrimers (PAD) using hexachlorocyclotriphosphazene (HCCP) as the linkage through a one-pot reaction, forming stable and uniform Cur loaded nanospheres (HCCP-Cur-PAD, HCP NPs). Owing to the hydrophilicity of PAD and hydrophobicity of Cur, HCP NPs can self-assemble into nanoparticles with particle size of 138.8 ± 78.7 nm and display excellent water dispersity. The loading capacity of Cur can reach 27.2% and it can be released from HCP NPs with pH-responsiveness. In vitro experimental results demonstrated that the HCP NPs entered lysosomes by endocytosis and proved dual anti-osteoporosis effects of inhibiting osteoclasts and promoting osteoblasts.

MicroRNA-223 negatively regulates the osteogenic differentiation of periodontal ligament derived cells by directly targeting growth factor receptors

Background

MicroRNA (miRNA) is accepted as a critical regulator of cell differentiation. However, whether microRNA-223 (miR-223) could affect the osteogenic differentiation of periodontal ligament (PDL)-derived cells is still unknown. The aim of this study was to explore the mechanisms underlying the roles of miR-223 in the osteogenesis of PDL-derived cells in periodontitis.

Methods

Microarray analysis and real-time polymerase chain reaction (RT-PCR) were used to identify difference in miR-223 expression pattern between healthy and inflamed gingival tissue. The target genes of miR-223 were predicted based on Targetscan and selected for enrichment analyses based on Metascape database. The gain-and loss-of-function experiments were performed to discuss roles of miR-223 and growth factor receptor genes in osteogenic differentiation of PDL-derived cells. The target relationship between miR-223 and growth factor receptor genes was confirmed by a dual luciferase assay. Osteogenic differentiation of PDL-derived cells was assessed by Alizarin red staining, RT-PCR and western blot detection of osteogenic markers, including osteocalcin (OCN), osteopontin (OPN) and runt-related transcription factor 2 (Runx2).

Results

MiR-223 was significantly increased in inflamed gingival tissues and down-regulated in PDL-derived cells during osteogenesis. The expression of miR-223 in gingival tissues was positively correlated with the clinical parameters in periodontitis patients. Overexpression of miR-223 markedly inhibited PDL-derived cells osteogenesis, which was evidenced by reduced Alizarin red staining and osteogenic markers expressions. Furthermore, two growth factor receptor genes, including fibroblast growth factor receptor 2 (FGFR2) and transforming growth factor beta receptor 2 (TGFβR2), were revealed to be direct targets of miR-223 and shown to undergo up-regulation in PDL-derived cells during osteogenesis. Moreover, suppression of FGFR2 or TGFβR2 dramatically blocked PDL-derived cells osteogenic differentiation.

Conclusions

Our study provides novel evidence that miR-223 can be induced by periodontitis and acts as a negative regulator of PDL-derived cells osteogenesis by targeting two growth factor receptors (TGFβR2 and FGFR2).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03676-1.