Optimization and comparison of two different 3D culture methods to prepare cell aggregates as a bioink for organ printing

The ultimate goal of tissue engineering is to design and fabricate functional human tissues that are similar to natural cells and are capable of regeneration. Preparation of cell aggregates is one of the important steps in 3D tissue engineering technology, particularly in organ printing. Two simple methods, hanging drop (HD) and conical tube (CT) were utilized to prepare cell aggregates. The size and viability of the aggregates obtained at different initial cell densities and pre-culture duration were compared. The proliferative ability of the cell aggregates and their ability to spread in culture plates were also investigated. In both methods, the optimum average size of the aggregates was less than 500 µm. CT aggregates were smaller than HD aggregates. 5,000 cells per drop HD aggregates showed a marked ability to attach and spread on the culture surface. The proliferative ability reduced when the initial cell density was increased. Comparing these methods, we found that the HD method having better size controlling ability as well as enhanced ability to maintain higher rates of viability, spreading, and proliferation. In conclusion, smaller HD aggregates might be a suitable choice as building blocks for making bioink particles in bioprinting technique.

Metabolic syndrome and leptin concentrations in obese children.

OBJECTIVE: Obesity and its complications including metabolic syndrome has been increased in children and adolescents recently. Leptin is known to play an important role in the pathogenesis of obesity. METHODS: The objective of this study was to evaluate the relationship of leptin and metabolic syndrome in obese Iranian children. A cross sectional study was carried out in 65 primary schools in Tehran. The children with waist circumferences equal or above 90th percentile for their height and age were chosen for further evaluations. 505 children aged 7-12 years participated in the study. Anthropometric variables measurements, blood pressure, fasting plasma glucose, triglyceride, high-density lipoprotein cholesterol and serum leptin were obtained from the study sample. RESULTS: Serum leptin levels were significantly higher in girls in comparison to the boys (with median 11.0 Vs 8.25 ng/dl; P value = 0.007). Serum level of leptin were higher in children with metabolic syndrome (median 11.3 Vs 8.9 ng/dl; P value = 0.045). However, after adjustment for sex, this association was removed. CONCLUSION: Leptin did not appear to have a major role in metabolic syndrome, even though it was strongly associated with obesity parameters. More studies evaluating the relationship between leptin and metabolic syndrome in various ethnic groups are recommended.