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.

A new photodynamic therapy photosensitizer (p1) promotes apoptosis of keloid fibroblasts by targeting caspase-8.

Photodynamic therapy (PDT) is a new therapy for treating cancer with less toxicity, high selectivity, good cooperativity, and repetitive usability. However, keloid treatment by PDT is mainly focused on clinical appearance, and few studies have been conducted on the mechanisms of PDT. In this study, key factors of the classical mitochondrial apoptosis signaling pathway were measured to assess the effect of a new PDT photosensitizer (p1). A specific inhibitor of caspase-8 (Z-IETD-FMK) was also used to verify the possible mechanisms. Twelve samples were obtained from 12 patients (six with keloids and six without) selected randomly from the Department of Plastic Surgery at Peking Union Medical College Hospital from January to December 2020. After cell culture, fibroblasts were divided into 13 groups. The morphology of fibroblasts in each group was observed by microscopy. Cell activity was measured by cell counting kit-8, and cell apoptotic morphology was observed by TUNEL staining. The reactive oxygen species (ROS) relative value was measured by a ROS test kit. The expression levels of key mitochondrial factors (caspase-3, caspase-8, cytochrome-c, Bax, and Bcl-2) were assessed by western blot, and mRNA expression of caspase-3 and caspase-8 was measured by RT-qPCR. We showed that p1 had a satisfactory proapoptotic effect on keloid fibroblasts by increasing the expression of ROS, caspase-3, caspase-8, and cytochrome-c, and decreasing the Bcl-2/Bax ratio; however, this effect was partially inhibited by Z-IETD-FMK, indicating that caspase-8 may be one of the p1's targets to achieve the proapoptotic effect.

A comparison of proliferation levels in normal skin, physiological scar and keloid tissue.

Proliferation is an important characteristic of life, and many signaling pathways participate in this complicated process. The MAPK/Erk pathway is a classic pathway in cell proliferation. In this study, expression levels of key factors in the MAPK/Erk pathway were measured to assess the proliferation level among normal skin, physiological scar, and keloid tissue. Thirty patients were selected randomly from the Department of Plastic Surgery at Peking Union Medical College Hospital from January 2019 to December 2020. Histological appearance and fiber tissue content were observed by Hematoxylin and eosin staining and Masson staining. Expression levels of key factors in the MAPK/Erk pathway (ATF2, c-Jun, c-Myc, p38 and STAT1) and relative proteins (HIF-1α and PCNA) in tissues were detected by immunohistochemistry and analyzed as the percentage of positively stained cells in both the tissue epidermis and dermis. Western blot was used for quantitative analysis of the above factors. In results, keloid tissue showed a significantly higher fiber and less cell content. In the immunohistochemical result, higher expression of key factors was observed in the epidermis than in the dermal layer, and the expression of all factors was increased remarkably in keloid tissue. In western blot analysis, all factors (except STAT1) showed higher expression in keloid tissue. In our former research, keloid showed similar apoptosis level as physiological scar and normal skin. On combining our former conclusion and results in this study, an imbalance condition between the high proliferation level and normal apoptosis level may lead to the growth characteristics of keloid.

The Effect of Yes-Associated Protein on the Interaction Between the MEK/Extracellular Signal-Regulated Kinase and Hippo Pathways in Osteoblasts Co-Cultured With Fibroblast Growth Factor Receptor 2-Mutated Dura Cells.

BACKGROUND: C342Y (Cys342Tyr) point mutation of FGFR2 (fibroblast growth factor receptor 2) is closely associated with the pathogenesis of Crouzon syndrome. The dura mater plays an important role in mediating the closure of cranial sutures. However, the underlying mechanisms of these pathological processes have been rarely investigated. in this study, the authors analyzed the effects of dura cells with FGFR2 mutations on the biological function of osteoblasts. METHODS: Dura cells and cranial osteoblasts from C57BL/6 mice were extracted and cultured. C342Y-FGFR2 mutant constructs were established via lentivirus and applied to infect dura cells. A co-cultured trans-well system with dura cells and osteoblasts was established. Three experimental groups were set up: oste group, Oste + Dura-vector group, and Oste + Dura-C342Y group. The expression levels of key factors in MEK (Mitogen-activated protein kinase kinase, MAPKK)/extracellular signal-regulated kinase (ERK) and Hippo pathway were detected by western blot and RT-qPCR (Real Time Quantitative PCR). Finally, a rescue experiment was carried out with small interference RUA. RESULTS: The proliferation level of osteoblasts in Oste + Dura- C342Y group was significantly up-regulated. Our studies indicated that the activation of MEK/ERK pathway in Oste + Dura-C342Y group could inhibit the Hippo pathway, lead to down-regulation of large tumor suppressor 1 and promote the activation and nuclear localization of yes-associated protein, and the results of rescue experiments showed a reverse expression trend, further confirming the effects of C342Y-FGFR2 mutation in dura cells on osteoblasts and its potential mechanism. CONCLUSIONS: This study suggested that the C342Y-FGFR2 mutation in dura cells could promote osteoblastic proliferation, and shown the crosstalk between MEK/ERK and Hippo pathways. As the regulatory machinery center, yes-associated protein might play a bridging role in these pathways, and might influence the pathogenesis of craniosynostosis by activating downstream transcriptional factors.

A comparison expression analysis of CXCR4, CXCL9 and Caspase-9 in dermal vascular endothelial cells between keloids and normal skin on chemotaxis and apoptosis.

This present study was designed to explore key biological characteristics and biomarkers associated with dermal vascular endothelial cells of keloids. GSE121618 dataset was downloaded in the Gene Expression Omnibus (GEO) Database, including the KECs group and NVECs group. Through GEO2R, we have screened the differentially expressed genes (DEGs) and performed gene ontology (GO), Gene Set Enrichment Analysis (GSEA), and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Then, we constructed a protein-protein interaction (PPI) network and analyzed hub genes via the Search Tool for the Retrieval of Interacting Genes (STRING) Online Database and Cytoscape software. Furthermore, experiments were performed to validate the expression of selected genes, including H&E staining, immunohistochemical staining, Western blot, and RT-qPCR. A total of 1040 DEGs were selected with GEO2R online tools. Most of the enriched pathways and processes focus on cell migration, tube development, chemotaxis, cell motility, and regulation of apoptosis. With the assistance of STRING and Cytoscape, hub genes were selected. In our validation experiments of RT-qPCR, the mRNA expression of selected genes has significant differences between different groups in tissue and cell experiments. As was shown in immunohistochemical staining, the proteins of CXCR4, CXCL9, and Caspase-9 had higher expression levels in tissue samples of the Keloid group than the Normal skin group. Western blot and RT-qPCR in dermal vascular endothelial cell experiments were consistent with the aforementioned results. This study has provided a deeper analysis of the pathogenesis of dermal vascular endothelial cells in keloids. Genes of CXCR4, CXCL9, and Caspase-9 may influence the processes of inflammatory responses and vascular endothelial cell apoptosis to exert crucial effects in the development of keloids. Abbreviations: GEO: gene expression omnibus; DEGs: differentially expressed genes; KVECs: keloid vascular endothelial cells; NVECs: normal skin vascular endothelial cells; GO: gene ontology; KEGG: Kyoto encyclopedia of genes and genomes; PPI: protein protein interaction; BP: biological process; CC: cellular component; MF: molecular function; GSEA: gene set enrichment analysis; STRING: search tool for the retrieval of interacting genes; MCODE: molecular complex detection.