The augmented demand for medical devices devoted to tissue regeneration and possessing a controlled micro-architecture means there is a need for industrial scale-up in the production of hydrogels. A new 3D printing technique was applied to the automation of a freeze-gelation method for the preparation of chitosan scaffolds with controlled porosity. For this aim, a dedicated 3D printer was built in-house: a preliminary effort has been necessary to explore the printing parameter space to optimize the printing results in terms of geometry, tolerances and mechanical properties of the product. Analysed parameters included viscosity of the starting chitosan solution, which was measured with a Brookfield viscometer, and temperature of deposition, which was determined by filming the process with a cryocooled sensor thermal camera. Optimized parameters were applied to the production of scaffolds from solutions of chitosan alone or with the addition of raffinose as a viscosity modifier. Resulting hydrogels were characterized in terms of morphology and porosity. In vitro cell culture studies comparing 3D printed scaffolds with their homologous produced by solution casting evidenced an improvement in biocompatibility deriving from the production technique as well as from the solid state modification of chitosan stemming from the addition of the viscosity modifier.

3D biomaterial manufacturing strategies show an extraordinary driving force for the development of innovative therapies in the tissue engineering field. Here, the behaviour of 3D printed chitosan (CH)-based scaffolds was explored as a function of the post-printing gelation process. To this purpose, gel forming properties of different media were tested on their capability to retain 3D structure, water content, mechanical resistance and surface/internal porosity. Three different gelation media (i.e. KOH 1.5 M, Na2CO3 1.5 M, ammonia vapours) were selected and the 3D CH scaffolds were tested in terms of biocompatibility toward fibroblast as skin associated human cell line.

Dysregulation of cholesterol homeostasis in the CNS has been associated with various neurodegenerative disorders, including Parkinson's, Huntington's, and Alzheimer's disease (AD) (1). Evidence supporting this relationship derives, for example, from recent genomic-wide association studies that have identified several loci involved in lipid metabolism among the AD-susceptible genes (2, 3). For example, the 4 allele of the APOE gene encoding apoE is undoubtedly the most strong genetic risk factor, but recently other genes have been identified such as BIN1, CLU, PICALM, ABCA7, ABCA1, ABCG1, and SORL1 (4). However, the exact mechanisms linking cholesterol homeostasis derangement and AD pathogenesis are far from being understood and conflicting data have been released, describing both increased, decreased, or no change of cholesterol levels in different brain sections and the cerebrospinal fluid (CSF) of AD patients compared with control subjects (5). Approximately 30% of the total body cholesterol is present in the brain, where it plays a crucial role in the synaptogenesis and maintenance of neuronal plasticity and function (6). The brain relies on endogenous local cholesterol synthesis because it is isolated from other body compartments by the blood-brain barrier (7, 8). While cholesterol synthesis in neurons and glial cells is very high during embryogenesis, adult neurons progressively lose this capacity and most exclusively rely on cholesterol produced from other Abstract HDL-like particles in human cerebrospinal fluid (CSF) promote the efflux of cholesterol from astrocytes toward the neurons that rely on this supply for their functions. We evaluated whether cell cholesterol efflux capacity of CSF (CSF-CEC) is impaired in Alzheimer's disease (AD) by analyzing AD (n = 37) patients, non-AD dementia (non-AD DEM; n = 16) patients, and control subjects (n = 39). As expected, AD patients showed reduced CSF A 1-42, increased total and phosphorylated tau, and a higher frequency of the apo4 genotype. ABCA1-and ABCG1-mediated CSF-CEC was markedly reduced in AD (73% and 33%, respectively) but not in non-AD DEM patients, in which a reduced passive diffusion CEC (40%) was observed. Non-AD DEM patients displayed lower CSF apoE concentrations (24%) compared with controls, while apoA-I levels were similar among groups. No differences in CSF-CEC were found by stratifying subjects for apo4 status. ABCG1 CSF-CEC positively correlated with A 1-42 (r = 0.305, P = 0.025), while ABCA1 CSF-CEC inversely correlated with total and phosphorylated tau (r = 0.348, P = 0.018 and r = 0.294, P = 0.048, respectively). The CSF-CEC impairment and the correlation with the neurobiochemical markers suggest a pathophysiological link between CSF HDL-like particle dysfunction and neurodegeneration in AD.

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Background: Parathyroid hormone (PTH) is important in the assessment of calcium metabolism disorders. However, there are few data regarding PTH levels in childhood and adolescence. Aim: The aim of this study was to determine PTH levels in a large group of healthy children and adolescents. Patients and Methods: We retrospectively evaluated PTH levels in 1,580 healthy Caucasian children and adolescents (849 females, 731 males, aged 2.0-17.2 years) with 25-hydroxyvitamin D [25(OH)D] levels ≥30 ng/ml. All subjects with genetic, endocrine, hepatic, renal, or other known diseases were excluded. Results: The serum intact PTH concentration (median and inter-quartile range) was 23.00 (15.00-31.60) pg/ml. In our population, the mean 25(OH)D value was 34.27 ± 4.12 ng/ml. The median PTH concentration in boys was 23.00 (15.00-32.00) pg/ml, whereas in girls it was 23.10 (15.00-31.10) pg/ml. However, in girls, PTH levels significantly increased in the age group of 8.1-10.0 years compared to the age group of 2.1-4.0 years (p < 0.0001), whereas in boys it significantly increased in the age groups of 10.1-12.0 years (p < 0.0001) and 12.1-14.0 years (p < 0.0001), leading to the hypothesis of a relationship between PTH level and pubertal and bone growth spurts. Conclusions: PTH levels in healthy children and adolescents covered a narrower range than the adult values. Obtaining reference values of PTH in childhood and adolescence could aid in the estimation of appropriate values of bone metabolites.