Degradable hydrogel fibers encapsulate and deliver metformin and periodontal ligament stem cells for dental and periodontal regeneration

Abstract Human periodontal ligament stem cells (hPDLSCs) are promising cells for dental and periodontal regeneration. Objective This study aimed to develop novel alginate-fibrin fibers that encapsulates hPDLSCs and metformin, to investigate the effect of metformin on the osteogenic differentiation of hPDLSCs, and to determine the regulatory role of the Shh/Gli1 signaling pathway in the metformin-induced osteogenic differentiation of hPDLSCs for the first time. Methodology CCK8 assay was used to evaluate hPDLSCs. Alkaline phosphatase (ALP) staining, alizarin red S staining, and the expression of osteogenic genes were evaluated. Metformin and hPDLSCs were encapsulated in alginate-fibrinogen solutions, which were injected to form alginate-fibrin fibers. The activation of Shh/Gli1 signaling pathway was examined using qRT-PCR and western blot. A mechanistic study was conducted by inhibiting the Shh/Gli1 pathway using GANT61. Results The administration of 50 μM metformin resulted in a significant upregulation of osteogenic gene expression in hPDLSCs by 1.4-fold compared to the osteogenic induction group (P < 0.01), including ALP and runt-related transcription factor-2 (RUNX2). Furthermore, metformin increased ALP activity by 1.7-fold and bone mineral nodule formation by 2.6-fold (P<0.001). We observed that hPDLSCs proliferated with the degradation of alginate-fibrin fibers, and metformin induced their differentiation into the osteogenic lineage. Metformin also promoted the osteogenic differentiation of hPDLSCs by upregulating the Shh/Gli1 signaling pathway by 3- to 6- fold compared to the osteogenic induction group (P<0.001). The osteogenic differentiation ability of hPDLSCs were decreased 1.3- to 1.6-fold when the Shh/Gli1 pathway was inhibited, according to ALP staining and alizarin red S staining (P<0.01). Conclusions Metformin enhanced the osteogenic differentiation of hPDLSCs via the Shh/Gli1 signaling pathway. Degradable alginate-fibrin hydrogel fibers encapsulating hPDLSCs and metformin have significant potential for use in dental and periodontal tissue engineering applications. Clinical Significance Alginate-fibrin fibers encapsulating hPDLSCs and metformin have a great potential for use in the treatment of maxillofacial bone defects caused by trauma, tumors, and tooth extraction. Additionally, they may facilitate the regeneration of periodontal tissue in patients with periodontitis.

Diagnosis, prevention and treatment of post-operative rare complications after radical gastrectomy for gastric cancer / 中华胃肠外科杂志

Radical gastrectomy for gastric cancer results in various post-operative complications, and the influencing factors are complicated. The diagnosis, treatment and prevention of common complications have been reported in many literatures. However, there are few reports on the prevention and treatment of rare complications. Rare complications after radical gastrectomy are often overlooked due to their low incidence. In addition, there are few guidelines and expert consensus regarding to the rare complications. Therefore, clinicians may lack experience in the diagnosis, treatment and prevention of rare complications after radical gastrectomy. Based on the literature review and the author's experience, this article systematically reviews seven rare complications after radical gastrectomy (duodenal stump fistula, pancreatic fistula, chyle leakage, esophagomediastinal fistula, internal hernia, gastroparesis, and intussusception). This article aims to provide a comprehensive reference for the diagnosis, treatment and prevention of rare complications after radical gastrectomy for gastric cancer patients.

Mechanism of action of chemotherapy drugs in promoting liver injury / 临床肝胆病杂志

Drugs are an important cause of liver injury, and according to statistics, about 1100 drugs may induce liver injury. Due to the difficulty in differential diagnosis, drug-related liver injury is still misjudged. As different drugs have different mechanisms of action in inducing liver injury and may cause different degrees of liver injury, targeted countermeasures should be adopted. There are fewer systematic reviews of liver injury caused by chemotherapy drugs. This article mainly introduces the hepatotoxic mechanisms of various chemotherapy drugs, elaborates on the degree of hepatotoxicity caused by chemotherapy drugs, summarizes the clinical manifestations of liver injury caused by chemotherapy drugs, and gives recommendations to clinical treatment.

Dental remineralization via poly(amido amine) and restorative materials containing calcium phosphate nanoparticles / 国际口腔科学杂志·英文版

Tooth decay is prevalent, and secondary caries causes restoration failures, both of which are related to demineralization. There is an urgent need to develop new therapeutic materials with remineralization functions. This article represents the first review on the cutting edge research of poly(amido amine) (PAMAM) in combination with nanoparticles of amorphous calcium phosphate (NACP). PAMAM was excellent nucleation template, and could absorb calcium (Ca) and phosphate (P) ions via its functional groups to activate remineralization. NACP composite and adhesive showed acid-neutralization and Ca and P ion release capabilities. PAMAM+NACP together showed synergistic effects and produced triple benefits: excellent nucleation templates, superior acid-neutralization, and ions release. Therefore, the PAMAM+NACP strategy possessed much greater remineralization capacity than using PAMAM or NACP alone. PAMAM+NACP achieved dentin remineralization even in an acidic solution without any initial Ca and P ions. Besides, the long-term remineralization capability of PAMAM+NACP was established. After prolonged fluid challenge, the immersed PAMAM with the recharged NACP still induced effective dentin mineral regeneration. Furthermore, the hardness of pre-demineralized dentin was increased back to that of healthy dentin, indicating a complete remineralization. Therefore, the novel PAMAM+NACP approach is promising to provide long-term therapeutic effects including tooth remineralization, hardness increase, and caries-inhibition capabilities.

Effects of water-aging for 6 months on the durability of a novel antimicrobial and protein-repellent dental bonding agent / 国际口腔科学杂志·英文版

Biofilms at the tooth-restoration bonded interface can produce acids and cause recurrent caries. Recurrent caries is a primary reason for restoration failures. The objectives of this study were to synthesize a novel bioactive dental bonding agent containing dimethylaminohexadecyl methacrylate (DMAHDM) and 2-methacryloyloxyethyl phosphorylcholine (MPC) to inhibit biofilm formation at the tooth-restoration margin and to investigate the effects of water-aging for 6 months on the dentin bond strength and protein-repellent and antibacterial durability. A protein-repellent agent (MPC) and antibacterial agent (DMAHDM) were added to a Scotchbond multi-purpose (SBMP) primer and adhesive. Specimens were stored in water at 37 °C for 1, 30, 90, or 180 days (d). At the end of each time period, the dentin bond strength and protein-repellent and antibacterial properties were evaluated. Protein attachment onto resin specimens was measured by the micro-bicinchoninic acid approach. A dental plaque microcosm biofilm model was used to test the biofilm response. The SBMP + MPC + DMAHDM group showed no decline in dentin bond strength after water-aging for 6 months, which was significantly higher than that of the control (P  0.1). In conclusion, a bonding agent with MPC and DMAHDM achieved a durable dentin bond strength and long-term resistance to proteins and oral bacteria. The novel dental bonding agent is promising for applications in preventive and restorative dentistry to reduce biofilm formation at the tooth-restoration margin.

Retrospects and prospects of transjugular intrahepatic portosystemic shunt in China / 临床肝胆病杂志

In recent years, transjugular intrahepatic portosystemic shunt (TIPS) has been gradually applied and widely accepted in China, and the technical standards, indications, and contraindications of this technique have also been established gradually. The invention of covered stents successfully solved the issue of a high rate of shunt occlusion seen in bare stents, and thus TIPS is greatly developed. Unfortunately, since most clinical studies were published before the invention of covered stents, the clinical effect of TIPS cannot represent the current status in this field. With the development of this technique, the indications for TIPS are gradually expanded, and as a country with many patients in need of TIPS, high-quality multicenter randomized controlled clinical trials are urgently needed in China. TIPS has been accepted in the treatment of various complications of portal hypertension and hepatic vascular diseases and will enjoy a promising future.

Evaluation of three-dimensional biofilms on antibacterial bonding agents containing novel quaternary ammonium methacrylates / 国际口腔科学杂志·英文版

Antibacterial adhesives are promising to inhibit biofilms and secondary caries. The objectives of this study were to synthesize and incorporate quaternary ammonium methacrylates into adhesives, and investigate the alkyl chain length effects on three-dimensional biofilms adherent on adhesives for the first time. Six quaternary ammonium methacrylates with chain lengths of 3, 6, 9, 12, 16 and 18 were synthesized and incorporated into Scotchbond Multi-Purpose. Streptococcus mutans bacteria were cultured on resin to form biofilms. Confocal laser scanning microscopy was used to measure biofilm thickness, live/dead volumes and live-bacteria percentage vs. distance from resin surface. Biofilm thickness was the greatest for Scotchbond control; it decreased with increasing chain length, reaching a minimum at chain length 16. Live-biofilm volume had a similar trend. Dead-biofilm volume increased with increasing chain length. The adhesive with chain length 9 had 37% live bacteria near resin surface, but close to 100% live bacteria in the biofilm top section. For chain length 16, there were nearly 0% live bacteria throughout the three-dimensional biofilm. In conclusion, strong antibacterial activity was achieved by adding quaternary ammonium into adhesive, with biofilm thickness and live-biofilm volume decreasing as chain length was increased from 3 to 16. Antibacterial adhesives typically only inhibited bacteria close to its surface; however, adhesive with chain length 16 had mostly dead bacteria in the entire three-dimensional biofilm. Antibacterial adhesive with chain length 16 is promising to inhibit biofilms at the margins and combat secondary caries.

Mechanism of action of chemotherapy drugs in promoting liver injury / 临床肝胆病杂志

Drugs are an important cause of liver injury, and according to statistics, about 1100 drugs may induce liver injury. Due to the difficulty in differential diagnosis, drug-related liver injury is still misjudged. As different drugs have different mechanisms of action in inducing liver injury and may cause different degrees of liver injury, targeted countermeasures should be adopted. There are fewer systematic reviews of liver injury caused by chemotherapy drugs. This article mainly introduces the hepatotoxic mechanisms of various chemotherapy drugs, elaborates on the degree of hepatotoxicity caused by chemotherapy drugs, summarizes the clinical manifestations of liver injury caused by chemotherapy drugs, and gives recommendations to clinical treatment.