Porous aligned ZnSr-doped ß-TCP/silk fibroin scaffolds using ice-templating method for bone tissue engineering applications.

The bone is a complex and dynamic structure subjected to constant stress and remodeling. Due to the worldwide incidence of bone disorders, tissue scaffolds and engineered bone tissues have emerged as solutions for bone grafting, which require sophisticated scaffolding architectures while keeping high mechanical performance. However, the conjugation of a bone-like scaffold architecture with efficient mechanical properties is still a critical challenge for biomedical applications. In this sense, the present study focused on the modulating the architecture of silk fibroin (SF) scaffolds crosslinked with horseradish peroxidase and mixed with zinc (Zn) and strontium (Sr)-doped ß-tricalcium phosphate (ZnSr.TCP) to mimic bone structures. The ZnSr.TCP-SF hydrogels were tuned by programmable ice-templating parameters, and further freeze-dried, in order to obtain 3D scaffolds with controlled pore orientation. The results showed interconnected channels in the ZnSr.TCP-SF scaffolds that mimic the porous network of the native subchondral bone matrix. The architecture of the scaffolds was characterized by microCT, showing tunable pore size according to freezing temperatures (-196 °C: ∼80.2 ± 20.5 µm; -80 °C: ∼73.1 ± 20.5 µm; -20 °C: ∼104.7 ± 33.7 µm). The swelling ratio, weight loss, and rheological properties were also assessed, revealing efficient scaffold integrity and morphology after aqueous immersion. Thus, the ZnSr.TCP-SF scaffolds made of aligned porous structure were developed as affordable candidates for future applications in clinical osteoregeneration and in vitro bone tissue modelling.

Occurrence of common plastic additives and contaminants in mussel samples: Validation of analytical method based on matrix solid-phase dispersion.

A new matrix solid-phase dispersion (MSPD) extraction methodology, combined with high-performance liquid chromatography equipped with a diode-array detector, was developed and validated for the simultaneous determination of 10 compounds in mussels from Galician Rias (Spain). These pollutants are compounds commonly used for plastic production as additives, as well as common plastic contaminants. The compounds selected were bisphenol-A, bisphenol-F, bisphenol-S, nonylphenol-9, nonylphenol, diethyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dichlorodiphenyltrichloroethane, dichlorodiphenyldichloroethane, and dichlorodiphenyldichloroethylene. The parameters affecting the MSPD extraction efficiency such as the type of sorbent, mass sample-sorbent ratio, and extraction solvent were optimised. The proposed method provided satisfactory quantitative recoveries (80-100%), with relative standard deviations lower than 7%. In all cases, the matrix-matched calibration curves were linear in the concentration range of 0.32-120.00 µg/kg, with quantification limits of 0.25-16.20 µg/kg. The novel developed MSPD-high-performance liquid chromatography methodology provided good sensitivity, accuracy, and repeatability for quality control analysis in mussels.

Biofunctional Ionic-Doped Calcium Phosphates: Silk Fibroin Composites for Bone Tissue Engineering Scaffolding.

The treatment and regeneration of bone defects caused by traumatism or diseases have not been completely addressed by current therapies. Lately, advanced tools and technologies have been successfully developed for bone tissue regeneration. Functional scaffolding materials such as biopolymers and bioresorbable fillers have gained particular attention, owing to their ability to promote cell adhesion, proliferation, and extracellular matrix production, which promote new bone growth. Here, we present novel biofunctional scaffolds for bone regeneration composed of silk fibroin (SF) and ß-tricalcium phosphate (ß-TCP) and incorporating Sr, Zn, and Mn, which were successfully developed using salt-leaching followed by a freeze-drying technique. The scaffolds presented a suitable pore size, porosity, and high interconnectivity, adequate for promoting cell attachment and proliferation. The degradation behavior and compressive mechanical strengths showed that SF/ionic-doped TCP scaffolds exhibit improved characteristics for bone tissue engineering when compared with SF scaffolds alone. The in vitro bioactivity assays using a simulated body fluid showed the growth of an apatite layer. Furthermore, in vitro assays using human adipose-derived stem cells presented different effects on cell proliferation/differentiation when varying the doping agents in the biofunctional scaffolds. The incorporation of Zn into the scaffolds led to improved proliferation, while the Sr- and Mn-doped scaffolds presented higher osteogenic potential as demonstrated by DNA quantification and alkaline phosphatase activity. The combination of Sr with Zn led to an influence on cell proliferation and osteogenesis when compared with single ions. Our results indicate that biofunctional ionic-doped composite scaffolds are good candidates for further in vivo studies on bone tissue regeneration.

Posterior talar process as a suitable cell source for treatment of cartilage and osteochondral defects of the talus.

Osteochondral defects of the ankle are common lesions affecting the talar cartilage and subchondral bone. Current treatments include cell-based therapies but are frequently associated with donor-site morbidity. Our objective is to characterize the posterior process of the talus (SP) and the os trigonum (OT) tissues and investigate their potential as a new source of viable cells for application in tissue engineering and regenerative medicine. SP and OT tissues obtained from six patients were characterized by micro-computed tomography and histological, histomorphometric and immunohistochemical analyses. Proliferation and viability of isolated cells were evaluated by MTS assay, DNA quantification and live/dead staining. The TUNEL assay was performed to evaluate cell death by apoptosis. Moreover, the production of extracellular matrix was evaluated by toluidine blue staining, whereas cells phenotype was investigated by flow cytometry. Characterization of ankle explants showed the presence of a cartilage tissue layer in both SP and OT tissues, which represented at least 20%, on average, of the explant. The presence of type II collagen was detected in the extracellular matrix. Isolated cells presented a round morphology typical of chondrocytes. In in vitro studies, cells were viable and proliferating for up to 21 days of culture. No signs of apoptosis were detected. Flow-cytometry analysis revealed that isolated cells maintained the expression of several chondrocytic markers during culture. The results indicated that the SP and OT tissues were a reliable source of viable chondrocytes, which could find promising applications in ACI/MACI strategies with minimal concerns regarding donor zone complications. Copyright © 2015 John Wiley & Sons, Ltd.

Characterization of Gcf2/Lrrfip1 in experimental cerebral ischemia and its role as a modulator of Akt, mTOR and ß-catenin signaling pathways.

Leucine-rich repeat in Flightless-1 interaction protein 1 (Lrrfip1) is an up-regulated protein after cerebral ischemia whose precise role in the brain both in healthy and ischemic conditions is unclear. Different Lrrfip1 isoforms with distinct roles have been reported in human and mouse species. The present study aimed to analyze the Lrrfip1 transcriptional variants expressed in rat cortex, to characterize their expression patterns and subcellular location after ischemia, and to define their putative role in the brain. Five transcripts were identified and three of them (Lrrfip1, CRA_g and CRA_a' (Fli-I leucine-rich repeat associated protein 1 - Flap-1)) were analyzed by quantitative real-time polymerase chain reaction (qPCR). All the transcripts were up-regulated and showed differential expression patterns after in vivo and in vitro ischemia models. The main isoform, Lrrfip1, was found to be up-regulated from the acute to the late phases of ischemia in the cytoplasm of neurons and astrocytes of the peri-infarct area. This study demonstrates that Lrrfip1 activates ß-catenin, Akt, and mammalian target of rapamycin (mTOR) proteins in astrocytes and positively regulates the expression of the excitatory amino acid transporter subtype 2 (GLT-1). Our findings point to Lrrfip1 as a key brain protein that regulates pro-survival pathways and proteins and encourages further studies to elucidate its role in cerebral ischemia as a potential target to prevent brain damage and promote functional recovery after stroke.

Protocolo de manejo de pancreatitis aguda. Hospital Universitario San Ignacio (HUSI) Bogotá / Acute Pancreatitis Protocol, Hospital Universitario San Ignacio (HUSI), Bogotá

La pancreatitis aguda es la inflamación aguda del páncreas con grado variable de compromiso de los tejidos regionales y diferente grado de compromiso sistémico. Se utilizan como definiciones las establecidas en el consenso de Atlanta (anexo 1). B. Diagnóstico 1. Historia clínica. Se presenta dolor en hemiabdomen superior, usualmente serio y acompañado de grados variables de vómito, náuseas y fiebre. Son importantes los antecedentes personales y familiares. 2. En el examen físico siempre se deben incluir el peso, la talla, el índice de masa corporal (IMC), la temperatura, la saturación de oxígeno (SAO2), la frecuencia cardiaca, la frecuencia respiratoria y la tensión arterial.