Growth on poly(l-lactic acid) porous scaffold preserves CD73 and CD90 immunophenotype markers of rat bone marrow mesenchymal stromal cells

Few data are available on the effect of biomaterials on surface antigens of mammalian bone marrow-derived, adult mesenchymal stromal cells (MSCs). Since poly(l-lactic acid) or PLLA is largely used in tissue engineering of human bones, and we are developing a reverse engineering program to prototype with biomaterials the vascular architecture of bones for their bioartificial reconstruction, both in humans and animal models, we have studied the effect of porous, flat and smooth PLLA scaffolds on the immunophenotype of in vitro grown, rat MSCs in the absence of any coating, co-polymeric enrichment, and differentiation stimuli. Similar to controls on plastic, we show that our PLLA scaffold does not modify the distribution of some surface markers in rat MSCs. In particular, the maintained expression of CD73 and CD90 on two different subpopulations (small and large cells) is consistent with their adhesion to the PLLA scaffold through specialized appendages, and to their prominent content in actin. In addition, our PLLA scaffold favours retention of the intermediate filament desmin, believed a putative marker of undifferentiated state. Finally, it preserves all rat MSCs morphotypes, and allows for their survival, adhesion to the substrate, and replication. Remarkably, a subpopulation of rat MSCs grown on our PLLA scaffold exhibited formation of membrane protrusions of uncertain significance, although in a size range and morphology compatible with either motility blebs or shedding vesicles. In summary, our PLLA scaffold has no detrimental effect on a number of features of rat MSCs, primarily the expression of CD73 and CD90.     

Modeling Lac du Bonnet granite using a discrete element model

A discrete element method code developed by the authors is used to model Lac du Bonnet granite in triaxial compression. The paper first presents the features of the model and the algorithms used to identify the micro deformability and strength parameters. With these identification algorithms, the model was calibrated to match experimental triaxial test data on Lac du Bonnet granite. With the calibrated model, investigation on failure evolution was then performed. The monitored evolution of the number and type of contact failures (micro cracks) reveals that at micro level tensile failures occur first, followed by mobilization of residual friction. Three distinct stages of stress–strain curve can be well identified by the accumulated number of contact failures and the mode of contact failures.     

New method to calibrate and validate a high-resolution 3D scanner,based on photogrammetry

In the last years close-range photogrammetric scanning systems, are acquiring a larger market share. This is due to low-cost hardware, components and to new user-friendly software. The ultimate, photogrammetric 3D scanning systems are very accurate and precise because, of the high-resolution cameras (over 10 Mpixels) they are equipped of and, the more precise algorithms of their software. The calibration phase is the primary step for the development of a, precise photogrammetric scanner. Through a good calibration it is indeed, possible to eliminate optical aberration issues and to obtain precise and, accurate three-dimensional measurements. In this study a powerful, calibration method, named full-field calibration, was implemented to, obtain high-precision values, using an original three-dimensional, calibrator, developed so as to increase the performance of this type of, calibration. Prior to using any measurement or 3D scanning system, precision and, accuracy have to be assessed. In this study a robust validation method, for photogrammetric scanning systems has been proposed. The validation, procedure consisted in: (1) operator error analysis, (2) reproducibility, error-analysis, (3) control-system error analysis, (4) scanning system, error analysis., The measurements taken using the “control system” (certified equipment in, terms of precision and accuracy) were considered as “gold standard”. The, photogrammetric measurements, subsequently obtained by the scanning, system, were aligned to the “gold standard” using Procrustes, registration. The system error was expressed as the displacement between, these two sets of measurements.     

The 3D Pattern of the Rainbow Trout (Oncorhynchus mykiss) Enterocytes and Intestinal Stem Cells

We previously showed that, according to the frequency and distribution of specific cell types, the rainbow trout (RT) intestinal mucosa can be divided in two regions that form a complex nonlinear three-dimensional (3D) pattern and have a different renewal rate. This work had two aims. First, we investigated whether the unusual distribution of cell populations reflects a similar distribution of functional activities. To this end, we determined the protein expression pattern of three well-defined enterocytes functional markers: peptide transporter 1 (PepT1), sodium–glucose/galactose transporter 1 (SGLT-1), and fatty-acid-binding protein 2 (Fabp2). Second, we characterized the structure of RT intestinal stem-cell (ISC) niche and determined whether the different proliferative is accompanied by a different organization and/or extension of the stem-cell population. We studied the expression and localization of well-characterized mammal ISC markers: LGR5, HOPX, SOX9, NOTCH1, DLL1, and WNT3A. Our results indicate that morphological similarity is associated with similar function only between the first portion of the mid-intestine and the apical part of the complex folds in the second portion. Mammal ISC markers are all expressed in RT, but their localization is completely different, suggesting also substantial functional differences. Lastly, higher renewal rates are supported by a more abundant ISC population.     

Current Advances in 3D Tissue and Organ Reconstruction

Bi-dimensional culture systems have represented the most used method to study cell biology outside the body for over a century. Although they convey useful information, such systems may lose tissue-specific architecture, biomechanical effectors, and biochemical cues deriving from the native extracellular matrix, with significant alterations in several cellular functions and processes. Notably, the introduction of three-dimensional (3D) platforms that are able to re-create in vitro the structures of the native tissue, have overcome some of these issues, since they better mimic the in vivo milieu and reduce the gap between the cell culture ambient and the tissue environment. 3D culture systems are currently used in a broad range of studies, from cancer and stem cell biology, to drug testing and discovery. Here, we describe the mechanisms used by cells to perceive and respond to biomechanical cues and the main signaling pathways involved. We provide an overall perspective of the most recent 3D technologies. Given the breadth of the subject, we concentrate on the use of hydrogels, bioreactors, 3D printing and bioprinting, nanofiber-based scaffolds, and preparation of a decellularized bio-matrix. In addition, we report the possibility to combine the use of 3D cultures with functionalized nanoparticles to obtain highly predictive in vitro models for use in the nanomedicine field.     

Mesenchymal Stem Cell Treatment Perspectives in Peripheral Nerve Regeneration: Systematic Review

Traumatic peripheral nerve lesions affect hundreds of thousands of patients every year; their consequences are life-altering and often devastating and cause alterations in movement and sensitivity. Spontaneous peripheral nerve recovery is often inadequate. In this context, nowadays, cell therapy represents one of the most innovative approaches in the field of nerve repair therapies. The purpose of this systematic review is to discuss the features of different types of mesenchymal stem cells (MSCs) relevant for peripheral nerve regeneration after nerve injury. The published literature was reviewed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A combination of the keywords “nerve regeneration”, “stem cells”, “peripheral nerve injury”, “rat”, and “human” were used. Additionally, a “MeSH” research was performed in PubMed using the terms “stem cells” and “nerve regeneration”. The characteristics of the most widely used MSCs, their paracrine potential, targeted stimulation, and differentiation potentials into Schwann-like and neuronal-like cells are described in this paper. Considering their ability to support and stimulate axonal growth, their remarkable paracrine activity, their presumed differentiation potential, their extremely low immunogenicity, and their high survival rate after transplantation, ADSCs appear to be the most suitable and promising MSCs for the recovery of peripheral nerve lesion. Clinical considerations are finally reported.     

Creating portable and efficient packet processing applications

Network processors are special-purpose programmable units deployed in many modern high-speed network devices, which combine flexibility and high performance. However, software development for these platforms is traditionally cumbersome due both to the lack of adequate programming abstractions and to the impossibility of reusing the same software on different hardware platforms.