Selective Formation of Osteogenic and Vasculogenic Tissues for Cartilage Regeneration

Tissue-engineered periosteum substitutes (TEPSs) incorporating hierarchical architecture with osteoprogenitor and vascular niches are drawing much attention as a promising tool to support functional cells in defined zones and nourish the cortical bone. Current TEPSs usually lack technologies to closely observe cell performance, especially at the cell contact interface between distinct compartments containing defined biological configurations and functions. Here, an electrodeposition strategy is reported, which enables the selective formation of TEPSs with osteoprogenitor and vascular niches in a multiphasic scaffold in combination with different human cell types for cartilage regeneration in an in vivo osteochondral defect model. Human umbilical vein endothelial cells (HUVECs), dermal fibroblasts (HDFs), and bone marrow mesenchymal stem cells (hMSCs) are used to mirror both the vascular and osteogenic niches, respectively. It is observed that the intrinsic viscoelastic nature of the porous solid matrix is essential to successfully induce angiogenesis. Coculture of hMSCs with functional cells (HUVECs/HDFs) in TEPSs also effectively promoted periosteal regeneration, including osteogenic and angiogenic processes. The osteoarthritis cartilage histopathology assessment and histologic/histochemical grading system data indicate that the TEPSs containing hMSCs/HUVECs/HDFs exhibit superior potential for cartilage regeneration.

Magnetic phase transition of monolayer chromium trihalides investigated with machine learning: toward a universal magnetic Hamiltonian

The prediction of magnetic phase transitions often requires model Hamiltonians to describe the necessary magnetic interactions. The advance of machine learning provides an opportunity to build a unified approach that can treat various magnetic systems without proposing new model Hamiltonians. Here, we develop such an approach by proposing a novel set of descriptors that describes the magnetic interactions and training the artificial neural network (ANN) that plays the role of a universal magnetic Hamiltonian. We then employ this approach and Monte Carlo simulation to investigate the magnetic phase transition of two-dimensional monolayer chromium trihalides using the trained ANNs as energy calculator. We show that the machine-learning-based approach shows advantages over traditional methods in the investigation of ferromagnetic and antiferromagnetic phase transitions, demonstrating its potential for other magnetic systems.

Heterogeneous spheroids with tunable interior morphologies by droplet-based microfluidics

Heterogeneous spheroids that mimic the complex three-dimensional environment of natural tissues are needed in various biomedical applications. Geometric cues from cellular matrix play invaluable roles in governing cell behavior and phenotype. However, the structural complexity of interior morphologies of spheroids is currently limited due to poor spatial resolution of positioning/orientation of cellular constructs. Here, a coaxial capillary microfluidic device is developed to generate gelatin methacrylate (GelMA) microspheres with tunable dimensions and interior morphologies, such as core-shell, or microspheres with interior undulated wavy, or spiral canals, by manipulating the two-phase flow of hydrogel precursor solution and methylcellulose solution. The formation of diverse and exquisite interior morphologies is caused by the interacting viscous instabilities of the two-phase flow in the microfluidic system, followed by water-in-oil emulsion and photo-initiated polymerization. Polyethylene glycol diacrylate (PEGDA) is incorporated into the GelMA solution to tune the mechanical properties of the fabricated microspheres, and an optimized concentration of PEGDA is confirmed by evaluating the in vitro proliferation and vascularization of human umbilical endothelial cells. Further, a heterogeneous spheroid with spiral blood vessel lumen is constructed to demonstrate the versatility and potential of the proposed droplet-based microfluidic approach for building functional tissue constructs.

Programmable Electrodeposition of Janus Alginate/Poly-L-Lysine/Alginate (APA) Microcapsules for High-Resolution Cell Patterning and Compartmentalization

Encapsulation of live cells in protective, semipermeable microcapsules is one of the kernel techniques for in vitro tissue regeneration, cell therapies, and pharmaceutical screening. Advanced fabrication techniques for cell encapsulation have been developed to meet different requirements. Existing cell encapsulation techniques place substantial constraints on the spatial patterning of live cells as well as on the compartmentalization of heterotypic cells. Alginate-Poly-L-lysine-alginate (APA) microcapsules that use sodium alginate as the polyanion and poly-L-lysine (PLL) as the polycation have been extensively employed for cell microencapsulation due to their excellent biocompatibility and biodegradability. This study proposes a novel method for developing programmable Janus APA microcapsules with variable shapes and sizes by using electrodeposition. By the versatile design of the microelectrode device, sequential electrodeposition is triggered to electro-address the cells at specific locations immobilized within a Janus APA microcapsule. The osteogenesis is evaluated by resembling cell compartmentalized and vascularized osteoblast-laden constructs. This technique allows precise spatial patterning of heterotypic cells inside the APA microcapsule, enabling the observation of cellular growth, interactions, and differentiation in a well-controlled chemical and mechanical microenvironment.

Rootstock mediates transcriptional regulation of citrulline metabolism in grafted watermelon

Citrulline is a non-essential amino acid, involved in key biological functions in plants and humans. Rootstocks have a major impact on citrulline accumulation in grafted watermelon. Information regarding rootstock induced changes in citrulline metabolism is elusive. To understand the regulatory mechanism, parallel changes in the expression profiles of citrulline metabolic genes and citrulline content of watermelon were monitored during the development of self-rooted watermelon and watermelon grafted onto pumpkin, wild and bottle gourd rootstocks. Results demonstrated that rootstocks regulated the expression profiles in different ways to influence the citrulline content. GAT, NAGPR, ASS3 ASS2 and Asl2 showed the negative correlation with citrulline content in pumpkin grafted watermelon. Pumpkin rootstock promoted the citrulline content by high down-regulation and synergistic effect of ASS2, ASS3, ASL1 and ASl2 genes. In wild grafted watermelon, citrulline was accumulated as a result of down regulation of GAT, NAGS and ASL2 genes, which showed an inverse correlation with citrulline. In gourd grafted watermelon, changes in citrulline content were observed to be linked with lower expressions of GAT, NAGK, ASS2, ASS3, ASL1 and ARG which were negatively correlated with citrulline content. Our study will provide the basis to understand the molecular mechanism of citrulline accumulation in various rootstocks.

Mild formation of core-shell hydrogel microcapsules for cell encapsulation

Internal gelation has been an important sol-gel route for the preparation of spherical microgel for drug delivery, cell therapy, or tissue regeneration. Despite high homogeneity and permeability, the internal gelated microgels often result in weak mechanical stability, unregular interface morphology and low cell survival rate. In this work, we have extensively improved the existing internal gelation approach and core-shell hydrogel microcapsules (200-600 μm) with a smooth surface, high mechanical stability and cell survival rate, are successfully prepared by using internal gelation. A coaxial flow-focusing capillary-assembled microfluidic (CFCM) device was developed for the gelation. Rapid gelling behavior of alginate in the internal gelation makes it suitable for producing well-defined and homogenous alginate hydrogel microstructures that serve as the shell of the microcapsules. 2-[4-(2-hydroxyethyl)piperazin-1-yl]ethanesulfonic acid (HEPES) was used in the shell stream during the internal gelation. Thus, a high concentration of acid in the oil solution can be used for better crosslinking the alginate while maintaining high cell viability. We further demonstrated that the gelation conditions in our approach were mild enough for encapsulating HepG2 cells and 3T3 fibroblasts without losing their viability and functionality in a co-culture environment.

Genetic variants in the folate metabolic pathway genes predict cutaneous melanoma-specific survival

BACKGROUND

Folate metabolism plays an important role in DNA methylation and nucleic acid synthesis and thus may function as a regulatory factor in cancer development. Genome-wide association studies (GWASs) have identified some single-nucleotide polymorphisms (SNPs) associated with cutaneous melanoma-specific survival (CMSS), but no SNPs were found in genes involved in the folate metabolic pathway.

OBJECTIVES

To examine associations between SNPs in folate metabolic pathway genes and CMSS.

METHODS

We comprehensively evaluated 2645 (422 genotyped and 2223 imputed) common SNPs in folate metabolic pathway genes from a published GWAS of 858 patients from The University of Texas MD Anderson Cancer Center and performed the validation in another GWAS of 409 patients from the Nurses' Health Study and Health Professionals Follow-up Study, in which 95/858 (11·1%) and 48/409 (11·7%) patients died of cutaneous melanoma, respectively.

RESULTS

We identified two independent SNPs (MTHFD1 rs1950902 G>A and ALPL rs10917006 C>T) to be associated with CMSS in both datasets, and their meta-analysis yielded an allelic hazards ratio of 1·75 (95% confidence interval 1·32-2·32, P = 9·96 × 10^-5 ) and 2·05 (1·39-3·01, P = 2·84 × 10^-4 ), respectively. The genotype-phenotype correlation analyses provided additional support for the biological plausibility of these two variants' roles in tumour progression, suggesting that variation in SNP-related mRNA expression levels is likely to be the mechanism underlying the observed associations with CMSS.

CONCLUSIONS

Two possibly functional genetic variants, MTHFD1 rs1950902 and ALPL rs10917006, were likely to be independently or jointly associated with CMSS, which may add to personalized treatment in the future, once further validated. What is already known about this topic? Existing data show that survival rates vary among patients with melanoma with similar clinical characteristics; therefore, it is necessary to identify additional complementary biomarkers for melanoma-specific prognosis. A hypothesis-driven approach, by pooling the effects of single-nucleotide polymorphisms (SNPs) in a specific biological pathway as genetic risk scores, may provide a prognostic utility, and genetic variants of genes in folate metabolism have been reported to be associated with cancer risk. What does this study add? Two genetic variants in the folate metabolic pathway genes, MTHFD1 rs1950902 and ALPL rs10917006, are significantly associated with cutaneous melanoma-specific survival (CMSS). What is the translational message? The identification of genetic variants will make a risk-prediction model possible for CMSS. The SNPs in the folate metabolic pathway genes, once validated in larger studies, may be useful in the personalized management and treatment of patients with cutaneous melanoma.

Simultaneous topographic and chemical patterning via imprinting defined nano-reactors

A novel, universal strategy to realize simultaneous topographic and chemical patterning via imprinting defined nano-reactors.

Interaction between p53 codon 72 polymorphism and melanocortin 1 receptor variants on suntan response and cutaneous melanoma risk

BACKGROUND

Ultraviolet (UV) radiation-induced p53 activation promotes cutaneous pigmentation by increasing transcriptional activity of pro-opiomelanocortin (POMC) in the skin. Induction of POMC/alpha-melanocyte-stimulating hormone (alpha-MSH) activates the melanocortin 1 receptor (MC1R), resulting in skin pigmentation. The common p53 codon 72 polymorphism alters the protein's transcriptional activity, which may influence the UV radiation-induced tanning response.

OBJECTIVES

We assessed the association of the p53 codon 72 polymorphism with tanning response, and its interaction with MC1R variants on tanning response and skin cancer risk.

METHODS

The assessment was done in a nested case-control study within the Nurses' Health Study [219 melanoma cases, 286 squamous cell carcinoma (SCC) cases, 300 basal cell carcinoma (BCC) cases and 874 controls], and among controls from four nested case-control studies within the Nurses' Health Study.

RESULTS

We found that the p53 Proline (Pro) allele was positively associated with childhood tanning response only among black/dark brown-haired women. Compared with the Arginine/Arginine (Arg/Arg) genotype, odds ratios (ORs) of childhood tanning tendency for Arg/Pro and Pro/Pro genotypes were 1.59 (95% CI, 0.96-2.65) and 1.56 (95% CI, 0.55-4.40), respectively. The association between MC1R variants and childhood tanning tendency was similar in both p53 Arg/Arg genotype and Pro allele carriers (Arg/Pro or Pro/Pro). The association of the p53 Pro/Pro genotype with melanoma risk was strongest among women with light pigmentation, and with MC1R variants, with the joint risk categories having the highest overall risk. We did not observe such interaction for SCC and BCC.

CONCLUSIONS

Our study suggests the involvement of the p53 codon 72 polymorphism in the skin tanning response and potential interaction with skin pigmentation on melanoma risk. Further work is needed to evaluate the association between p53 and its associated proteins and skin cancer risk.

Prevalence of Type 2 diabetes in urban and rural Chinese populations in Qingdao, China

AIMS

To determine the prevalence of diabetes in the Chinese adult population in rural and urban areas of Qingdao city.

METHODS

A population-based cross-sectional study of diabetes was performed in 12 436 (5346 men) Chinese adults (20-74 years old) from 2001 to 2002. Fasting capillary whole blood glucose test (FCG) was performed in all participants and a 2-h 75-g oral glucose tolerance test in those with FCG > or = 6.1 mmol/l following initial screening. The 1999 World Health Organization diagnostic criteria for diabetes were used.

RESULTS

The age-standardized prevalence of diabetes was 6.1% (4.1% for undiagnosed and 2.1% for previously known diabetes) in adults aged 20-74 years. Diabetes prevalence increased with age up to the oldest age group (70-74); in subjects over 50 years of age, the prevalence reached 10%. Men tended to have a higher prevalence of known diabetes than women, whereas the prevalence of undiagnosed diabetes was lower in men than in women (4.6% vs. 3.3%, d.f. = 1, P = 0.001). Diabetes was more prevalent in the urban than in the rural population (6.9% vs. 5.6%, d.f. = 1, P < 0.001). However, the proportion of undiagnosed diabetes was higher in the rural than in the urban areas (70.5% vs. 58.0%, d.f. = 1, P < 0.001).

CONCLUSIONS

The prevalence of Type 2 diabetes in Qingdao city is moderately high, but much higher than reported in 1996. The large proportion of undiagnosed cases of diabetes indicates the lack of public awareness of diabetes and shortage of medical facilities. In view of the huge population in China, the results of this study emphasize the need to improve the early detection and prevention of diabetes in China to prevent the emerging diabetes epidemic.

Blood compatibility of amorphous titanium oxide films synthesized by ion beam enhanced deposition

Titanium oxide films were synthesized on titanium, cobalt alloy and low-temperature isotropic pryolytic carbon by ion beam enhanced deposition. The non-stoichiometrical titanium oxide films were obtained. Blood compatibility of the films were evaluated by clotting time measurement, platelet adhesion investigation and hemolysis analyses. The results revealed that blood compatibility of the materials was improved by the coating of titanium oxide films. Semiconductor nature of non-stoichiometric titanium oxide films might be responsible for the improvement of blood compatibility.

Surface modification of titanium based biomaterials by ion beam

Ion beam enhanced deposition (IBED) was adopted to synthesize biocompatible titanium oxide film. Structure characteristics of titanium oxide film were investigated by RBS, AES, and XRD. The blood compatibility of the titanium oxide film was studied by measurements of blood clotting time and platelet adhesion. The results show that the anticoagulation property of titanium oxide film is improved significantly. The mechanism of anticoagulation of the titanium oxide film was discussed.