Promotion of Neuronal Guidance Growth by Aminated Graphene Oxide via Netrin-1/Deleted in Colorectal Cancer Signaling.

Promotion of neurite outgrowth and synapse formation is a key step for nervous tissue regeneration. It is important for finding a new biomaterial to guide neuron growth to target neurons. Aminated graphene oxide (NH2-GO) displays electrical properties and dispersibility, which may change the surface charge of neurons and further activate neuronal excitement. However, the molecular guidance mechanism of NH2-GO on neurite outgrowth is seldom reported. In this study, we compared the role of NH2-GO on the spinal cord neurons and cortical neurons. Results indicated that the proper concentrations were at 2 and 4 µg/mL as determined by the CCK-8 assay. Notably, NH2-GO (2 and 4 µg/mL) improved the dispersibility and strengthened the effect of the composite material. In addition, it enables biocompatibility and efficient guidance of growth performance, which is not neurotoxic for neuronal outgrowth under these two concentrations. More interestingly, NH2-GO at 2 µg/mL induced both marked neurite elongation and increased branches in cortical neurons, but there is no significant change of neurite length and branches in spinal cord neurons. Further, the fluorescence intensity and mRNA level of Netrin-1 and DCC (Deleted in Colorectal Cancer) were both enhanced by NH2-GO at 2 µg/mL. Moreover, the function of Netrin-1 and DCC were activated more significantly by NH2-GO at 2 µg/mL in cortical neurons than that of spinal cord neurons. When RhoA was inhibited by the C3 exoenzyme, phosphorylated Rac1 and Cdc42 expression decreased significantly. Thus, NH2-GO at 2 µg/mL could influence Netrin-1/DCC signaling and the downstream RhoGTPase pathway, which may be preferred to guide the neurite growth in cortical neurons. It will provide a promising approach for the development of novel therapeutic methods of nerve regeneration.

Topographical patterning: characteristics of current processing techniques, controllable effects on material properties and co-cultured cell fate, updated applications in tissue engineering, and improvement strategies.

Topographical patterning has recently attracted lots of attention in regulating cell fate, understanding the mechanism of cell-microenvironment interactions, and solving the great issues of regenerative medicine. The introduced patterns offer topographical cues that can affect the reconstruction of the cytoskeleton or stimulate cell membrane receptors. Numerous studies have focused on these effects on cell behavior including attachment, migration, proliferation, and differentiation. In this review, five aspects of topographical patterning are discussed: (1) the process of typical micro-/nanotechniques and their advantages and limitations; (2) the effects of patterning on the mechanical properties and surface properties of substrates; (3) the influences of micro-/nanopatterns on the behavior of mesenchymal stem cells, as well as the underlying mechanisms; (4) the application of patterns to solve the issues of targeted organs (e.g., skin, nerves, blood vessels, bones, and heart). In the end, future perspectives that would help promote the efficiency of topographical patterning are proposed.

Development of novel oxygen carriers by coupling hemoglobin to functionalized multiwall carbon nanotubes.

Preparation of stable and effective artificial oxygen carriers (AOCs) is a promising strategy to temporarily replace transfused blood and solve tissue hypoxia. Developing hemoglobin (Hb) loaded particles is one of the main ways to prepare suitable AOCs. Particles with a hierarchical micro/nanostructure can be loaded with plenty of proteins and have attracted great attention. Therefore, multiwall carbon nanotubes (MWCNTs) were chosen to fabricate AOCs. To improve the Hb-loading capacity of MWCNTs, functionalized MWCNTs, including carboxyl-functionalized MWCNTs (MWCNT-COOH), amino-functionalized MWCNTs (MWCNT-NH2), and heparin-conjugated MWCNTs (MWCNT-Hep), were prepared. Then, in this study, Hb was coupled to the functionalized MWCNTs to fabricate the AOCs. The functionalized MWCNTs and the AOCs were characterized by FTIR, SEM, TEM, and zeta potential analysis. The oxygen/Hb-loading capacity of the AOCs was also measured. The adverse effects of the AOCs on human umbilical vein endothelial cells (HUVECs) and human red blood cells (RBCs) were evaluated. The results showed that (1) the functional groups were grafted on the surface of the MWCNTs, and Hb was bound to the functionalized MWCNTs, thus the AOCs were successfully prepared; (2) MWCNT-Hep-Hb had the most stable dispersibility (i.e., the most negative zeta potential) in 0.9 wt% NaCl solution (MWCNT-Hep-Hb < MWCNT-COOH-Hb < MWCNT-Hb < MWCNT-NH2-Hb < 0); (3) MWCNT-Hep had the best Hb-loading capability, which was three times that of purified MWCNTs; (4) with concentrations increased up to 400 µg mL-1, MWCNT-Hep-Hb still had the highest cell viability (97.63% > 80%, ISO 10993-5:2009) and excellent blood biocompatibility. Therefore, MWCNT-Hep-Hb might be a satisfactory candidate as a blood substitute.

Effect of Long-Term Systolic Blood Pressure Trajectory on Kidney Damage in the Diabetic Population: A Prospective Study in a Community-Based Chinese Cohort.

BACKGROUND: Previous studies have shown that hypertension is an important factor contributing to the occurrence and progression of diabetic kidney damage. However, the relationship between the patterns of blood pressure (BP) trajectory and kidney damage in the diabetic population remains unclear. This prospective study investigated the effect of long-term systolic BP (SBP) trajectory on kidney damage in the diabetic population based on an 8-year follow-up community-based cohort. METHODS: This study included 4556 diabetic participants among 101,510 participants. BP, estimated glomerular filtration rate (eGFR), and urinary protein were measured every 2 years from 2006 to 2014. SBP trajectory was identified by the censored normal modeling. Five discrete SBP trajectories were identified according to SBP range and the changing pattern over time. Kidney damage was evaluated through eGFR and urinary protein value. A multivariate logistic regression model was used to analyze the influence of different SBP trajectory groups on kidney damage. RESULTS: We identified five discrete SBP trajectories: low-stable group (n = 864), moderate-stable group (n = 1980), moderate increasing group (n = 609), elevated decreasing group, (n = 679), and elevated stable group (n = 424). The detection rate of kidney damage in the low-stable group (SBP: 118-124 mmHg) was the lowest among the five groups. The detection rate of each kidney damage index was higher in the elevated stable group (SBP: 159-172 mmHg) compared with the low-stable group. For details, the gap was 4.14 (11.6% vs. 2.8%) in eGFR <60 ml·min-1·1.73 m-2 and 3.66 (17.2% vs. 4.7%), 3.38 (25.0% vs. 7.4%), and 1.8 (10.6% vs. 5.9%) times in positive urinary protein, eGFR <60 ml·min-1·1.73 m-2 and/or positive urinary protein, and eGFR decline ≥30%, respectively (P < 0.01). CONCLUSION: An elevated stable SBP trajectory is an independent risk factor for kidney damage in the diabetic population.

Carboxylated graphene oxide promoted axonal guidance growth by activating Netrin-1/deleted in colorectal cancer signaling in rat primary cultured cortical neurons.

Nanomaterials of graphene and its derivatives have been widely applied in recent years, but whose impacts on the neuronal guidance growth are still not reported. In the present study, graphene oxide (GO) and carboxylated graphene oxide (GO-COOH) were used to investigate the potential effects on axonal guidance growth in the primary cultured cortical neurons. In addition, we characterized the structure and chemical composition of synthesized GO and GO-COOH using Fourier transform infrared spectrophotometer and scanning electron microscope assays and Raman analysis. GO is not neurotoxic and not conductive in a soluble form. However, GO-COOH has higher solubility and conductivity. Cell viability was assessed using CCK-8 assays and fluorescein diacetate after GO and GO-COOH treatment (0, 1, 2, 4, 5, 6, 8, 10, 12, 14, 16, 18, 20, 50, and 100 µg/mL). There are significant increases of cell viability and axonal growth after GO (2 and 4 µg/mL) and GO-COOH treatment (2 and 4 µg/mL). We further investigated the molecular mechanism of axonal guidance growth after GO and GO-COOH (2 and 4 µg/mL) application. Additionally, GO and GO-COOH up-regulated expression of Netrin-1 and its receptor, deleted in colorectal cancer by immunofluorescence assays and western blots assay. Our study demonstrated that GO-COOH activated Cdc42 and Rac1 and dramatically decreased RhoA. Thus, GO-COOH (2 µg/mL) is much better to be nanocarriers than GO for axonal guidance and growth in this study. GO-COOH may be used to facilitate guidance for regenerating neurons in the future. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1500-1510, 2018.