Angiotensin (1-7) Inhibits Transforming Growth Factor-Β1-Induced Epithelial-Mesenchymal Transition of Human Keratinocyte Hacat Cells in vitro.

Introduction: Angiotensin (1-7) (Ang-(1-7)) is an emerging component of the renin-angiotensin system (RAS) with effective anti-fibrosis properties and has been shown to interfere with epithelial-mesenchymal transition (EMT) by numerous studies. In recent years, EMT has been proposed as a new therapeutic target for skin fibrotic diseases such as keloids. However, the effect of Ang-(1-7) on EMT in skin is still unclear. Hence, the purpose of this study was to explore the effect of Ang-(1-7) on Transforming growth factor-ß1(TGF-ß1)-induced EMT of human immortalized keratinocytes HaCaT in vitro. Methods: The study involved the use of the human immortalized keratinocyte cell line (HaCaT). The cells were cultured in high-glucose DMEM medium with 10% fetal bovine serum and 1% penicillin-streptomycin. Four groups were created for experimentation: control group (Group C), TGF-ß1-treated group (Group T), Ang-(1-7)-treated group (Group A), and a group treated with both TGF-ß1 and Ang-(1-7) (Group A + T). Various assays were conducted, including a cell proliferation assay using CCK-8 solution, a scratch wound healing assay to evaluate cell migration, and Western blotting to detect protein expressions related to cell characteristics. Additionally, quantitative real-time polymerase chain reaction (PCR) was performed to analyze epithelial-mesenchymal transition (EMT) related gene expression levels. The study aimed to investigate the effects of TGF-ß1 and Ang-(1-7) on HaCaT cells. Results: We found that Ang-(1-7) not only reduced the migration of HaCaT cells induced by TGF-ß1 in vitro but also reduced the expression of α-SMA and vimentin, and restored the protein expression of E-cadherin and claudin-1. Mechanistically, Ang-(1-7) inhibits the phosphorylation levels of Smad2 and Smad3 in the TGF-ß1 canonical pathway, and suppresses the expression of EMT-related transcription factors (EMT-TFs) such as SNAI2, TWIST1, and ZEB1. Discussion: Taken together, our findings suggest that Ang-(1-7) inhibits TGF-ß1-induced EMT in HaCaT cells in vitro by disrupting the TGF-ß1-Smad canonical signaling pathway. These results may be helpful in the treatment of EMT in skin fibrotic diseases such as keloids.

Silencing of topical proline hydroxylase domain 2 promotes the healing of rat diabetic wounds by phosphorylating AMPK.

BACKGROUND: For diabetic ulcers, the impaired response to hypoxia is a key feature associated with delayed healing. In the early phase of hypoxia, hypoxic signaling activates the AMPK system through direct phosphorylation of the PHD2 pathway, producing a significant endogenous hypoxic protective effect. METHODS: Twenty Sprague-Dawley (SD) rats were randomly divided into two groups: treatment (sh-PHD2) and control (sh-Control). Using lentiviral encapsulation of PHD2-shRNA and transfection, the silencing efficiency of PHD2 expression was verified in rat dermal fibroblasts (RDF) and in rat aortic endothelial cells (RAECs). Changes in the ability of RDF and RAECs to proliferate, migrate, and in the rate of ATP production were observed and then tested after inhibition of AMPK phosphorylation using dorsomorphin. The lentiviral preparation was injected directly into the wounds of rats and wound healing was recorded periodically to calculate the healing rate. Wounded tissues were excised after 14 days and the efficiency of PHD2 silencing, as well as the expression of growth factors, was examined using molecular biology methods. Histological examination was performed to assess CD31 expression and therefore determine effects on angiogenesis. RESULTS: Lentiviral-encapsulated PHD2-sh-RNA effectively suppressed PHD2 expression and improved the proliferation, migration, and ATP production rate of RDF and RAEC, which were restored to their previous levels after inhibition of AMPK. The rate of wound healing, vascular growth, and expression of growth factors were significantly improved in diabetic-model rats after local silencing of PHD2 expression. CONCLUSION: Silencing of PHD2 promoted wound healing in diabetic-model SD rats by activating AMPK phosphorylation.

Direct-current electric field stimulation promotes proliferation and maintains stemness of mesenchymal stem cells.

Mesenchymal stem cells are frequently utilized in the study of regenerative medicine. Electric fields (EFs) influence many biological processes, such as cell proliferation, migration and differentiation. In the present study, a novel device capable of delivering a direct current of EF stimulation to cells cultured in vitro is described. This bioreactor was customized to simultaneously apply a direct-current EF to six individual cell culture wells, which reduces the amount of experimental time and minimizes cost. In testing the device, adipose-derived mesenchymal stem cells stimulated with an EF in the bioreactor exhibited a greater cell proliferation rate while retaining stemness. The results provide a unique perspective on adipose-derived mesenchymal stem cell proliferation, which is needed for tissue engineering and regenerative medicine.

Hypoxia activates the PI3K/AKT/HIF-1α pathway to promote the anti-inflammatory effect of adipose mesenchymal stem cells.

This study aimed to investigate the effect of hypoxia on the anti-inflammatory effect of adipose-derived mesenchymal stem cells (AMSCs) in vitro and its possible mechanism. AMSCs were cultured in vitro in a hypoxic environment with 3% O2, and a normoxic (21% O2) environment was used as the control. The cells were identified by in vitro adipogenic and osteogenic differentiation and cell surface antigen detection, and the cell viability were detected. The effect of hypoxic AMSCs on macrophage inflammation was analyzed by co-culture. The results showed that under hypoxia, AMSCs had better viability, significantly downregulated the expression of inflammatory factors, alleviated macrophage inflammation, and activated the PI3K/AKT/HIF-1α pathway.

Mechanical signals induces reprogramming of mature adipocytes through the YAP/TAZ-binding motif.

Tissue engineering technology will be the main approach to tissue regeneration in the future and are promising for the treatment of large-area burns and refractory wounds. Dedifferentiated fat cells (DFAT) derived from mature adipocytes (MAs) as a seed cell have great potential in cell therapy and tissue engineering for the treatment of a variety of clinical diseases because of their wider availability, stronger proliferation ability, multidirectional redifferentiation potential, higher cell purity, lower heterogeneity, and greater biosafety profile. However, the triggering mechanism for MAs reprogramming in vitro is unclear. In this study, MAs were successfully induced to dedifferentiate into DFAT in a short time in vitro using an "improved ceiling culture method". Flow cytometry, adipogenic, and osteogenic differentiation experiments verified that DFAT cells present the biological characteristics of stem cells. In addition, changing the stiffness of the extracellular matrix can inhibit the dedifferentiation of MAs to DFAT, and increase the expression of Yes-associated protein/transcriptional co-activator with the PDZ-binding motif (YAP/TAZ), nuclear translocation, and the expression of reprogramming transcription factors. In conclusion, extracellular matrix stiffness can induce MAs to dedifferentiate into DFAT in vitro, and can directly transmit mechanical force signals to the nucleus via YAP/TAZ binding to trigger the expression of stem cell-related reprogramming factors.

Role of the extracellular matrix and YAP/TAZ in cell reprogramming.

Stem cells are crucial in the fields of regenerative medicine and cell therapy. Mechanical signals from the cellular microenvironment play an important role in inducing the reprogramming of somatic cells into stem cells in vitro, but the mechanisms of this process have yet to be fully explored. Mechanical signals may activate a physical pathway involving the focal adhesions-cytoskeleton-LINC complex axis, and a chemical pathway involving YAP/TAZ. ENH protein likely plays an important role in connecting and regulating these two pathways. Such mechanisms illustrate one way in which mechanical signals from the cellular microenvironment can induce reprogramming of somatic cells to stem cells, and lays the foundation for a new strategy for inducing and regulating such reprogramming in vitro by means of physical processes related to local mechanical forces.

Proline hydroxylase domain-containing enzymes regulate calcium levels in cardiomyocytes by TRPA1 ion channel.

The proline hydroxylase domain-containing enzymes (PHDs) acts as cellular oxygen sensors, inducing a series of responses to hypoxia, especially during the regulation of metabolism and energy homeostasis. The increase of Ca2+ in cardiomyocytes, induced by the opening of PHD signaling pathway, is the key initiation signal necessary for the PHD-mediated regulation of the energy metabolism pathway, but the underlying molecular mechanism remains incompletely understood. This study used PHD inhibitors (PHIs) and PHD2-specific RNA interference (PHD2shRNA) to inhibit PHD signals in cardiomyocytes to explore whether transient receptor potential ankyrin 1 (TRPA1) is involved in the regulation of calcium ion influx in the PHD activation pathway associated with to AMP-activated protein kinase (AMPK). The Fluo-3AM probe was used to measure changes in free intracellular calcium ion concentrations, and Western blot analysis was used to detect the levels of phosphorylated (P)-AMPK, TRPA1, and P-Ca2+/calmodulin-dependent protein kinase Ⅱ (CaMKⅡ) levels. The PHI-mediated inhibition of PHD resulted in an increase in free Ca2+ fluorescence in cardiomyocytes, which activated AMPK, TRPA1, and CaMKⅡ. The TRPA1 inhibitor HC030031, the CaMKII inhibitor KN93, and a ryanodine inhibitor (Ryanodine) were all able to inhibit the PHI-induced increase in intracellular Ca2+ and AMPK activation. Both PHIs and PHD2shRNA were able to effectively activate CaMKII and TRPA1. However, an inositol 1,4,5-triphosphate receptor (IP3R) inhibitor and the protein kinase A (PKA) inhibitor H89 did not significantly inhibit the PHI-induced increase in intracellular Ca2+ and AMPK activation. These results indicated that PHD might activate the CaMKⅡ pathway through the TRPA1 ion channel, inducing the release of calcium from the sarcoplasmic reticulum through ryanodine receptor 2 (RyR2), activating AMPK to initiate the protective effects of hypoxia in cardiomyocytes.