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BACKGROUND: As a coating material, chitosan can effectively improve biological properties of medical metal surfaces due to its excellent film-forming and metal binding abilities. However, the biological activity and osteoinductive ability of chitosan are insufficient. Graphene oxide can improve the mechanical properties and biocompatibility of various polymer materials, as well as promote osteogenic differentiation. The combination of chitosan and graphene oxide may have better biological properties and osteogenic activity. OBJECTIVE: To construct the graphene oxide-modified chitosan composite coating material, analyze the surface morphology, chemical composition, and physical properties of the coating material, as well as the effects of the coating materials on proliferation, adhesion, and osteogenic differentiation of osteoblasts. METHODS: The titanium surface was treated with 3-aminopropyltriethoxysilane to form silane groups on the surface, and then glutaraldehyde was used to cross-link chitosan with silane groups to prepare simple chitosan coating and graphene oxide/chitosan composite coating, respectively. The surface morphology, chemical structure and hydrophilic properties of the coatings were characterized by atomic force microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and contact angle measurement system. Rat osteoblasts were seeded on the surface of the two materials, and the proliferation, spreading, and osteogenic differentiation of rat osteoblasts were analyzed by CCK-8 assay, scanning electron microscopy, and reverse transcription-polymerase chain reaction analysis. RESULTS AND CONCLUSION: (1) The thickness of the graphene oxide sheets was about 2 nm as measured by atomic force microscopy; the scanning electron microscopy showed that the surfaces of both coatings were smooth and dense, in which the chitosan molecules were closely arranged and the graphene oxide was uniformly distributed in the chitosan, while wrinkles appeared on the surface of chitosan due to the addition of grapheme. The contact angle of the graphene oxide-chitosan composite coating was significantly smaller than the chitosan coating alone (P < 0.05). (2) CCK-8 assay showed that the graphene oxide-chitosan composite coating better promoted the proliferation of osteoblasts compared with the chitosan coating alone. (3) The scanning electron microscopy showed that better spreading was found in osteoblasts on the surface of the graphene oxide-chitosan composite coating compared with the chitosan coating alone. (4) Reverse transcription-polymerase chain reaction analysis showed that the mRNA expression of alkaline phosphatase and Runx2 was significantly increased in the graphene oxide/chitosan composite coating group compared with in the chitosan coating alone group (P < 0.05). (5) These findings suggest that graphene oxide/chitosan composite coating had good biocompatibility, physicochemical, and osteoinductive properties. [ABSTRACT FROM AUTHOR]

BACKGROUND: Studies have found that Telocyte interstitial cells may play a role in heart diseases, such as acute myocardial infarction, atrial fibrillation, valvular heart disease and myocardial amyloidosis, but the mechanism is unclear. The basic research of cardiac Telocyte interstitial cells is of important clinical value. OBJECTIVE: To explore the existence and characteristics of Telocyte interstitial cells in the mouse heart. METHODS: Fifty-nine Kunming mice aged from 10 days to 10 weeks (provided by Fuzhou Wu’s Experimental Animal Center in China) were chosen. The gastrointestinal tract Cajal interstitial cells and bladder Telocyte interstitial cells were used as controls. ACK2 (c-kit monoclonal antibody) was used as an indicator for the immunohistochemical staining of myocardial tissue in 13 mice. Cardiac Telocyte cells from another 41 mice were isolated, cultured in vitro and observed for cell morphology and protrusion under immunofluorescence laser confocal microscope. Ultrastructure of Cajal and Telocyte interstitial cells from the remaining five mice was observed by transmission electron microscopy. RESULTS AND CONCLUSION: (1) Positive expression of c-kit was found in the gastrointestinal and bladder tissues by immunohistochemical staining, but not in the cardiac tissues. However, in vitro cultured cells were positive for c-kit. (2) Under the immunofluorescence laser confocal microscope and transmission electron microscope, the cardiac Telocyte cells with spindle or irregular bodies were discovered in myocardial fibers or around the capillaries, and dense strips were found between cell protrusions from cardiac Telocyte cells and the capillaries. There was no difference in the shape of cell body and the number of cell protrusion compared with the control group, but a significant difference in the length of cell protrusions was found (P < 0.05). In conclusion, the presence of Telocyte cells with positive expression of c-kit in the mouse heart is confirmed by primary culture, immunofluorescence staining and transmission electron microscopy. The body size and number of cell protrusions are similar to those of gastrointestinal tract Cajal interstitial cells or bladder Telocyte interstitial cells. Ventricular Telocyte interstitial cell protrusion is the longest, atrial Telocyte interstitial cell protrusion is the shortest, and ventricular Telocyte interstitial cell protrusion is tightly connected with the capillaries. [ABSTRACT FROM AUTHOR]