Cultivation of MC3T3-E1 cells on a newly developed material (Sponceram®) using a rotating bed system bioreactor

UiO-66 metal-organic framework as a double actor in chitosan scaffolds: Antibiotic carrier and osteogenesis promoter

Metal-organic frameworks (MOFs) have recently emerged as a useful class of nanostructures with well-suited characteristics for drug delivery applications, due to the high surface area and pore size for efficient loading. Despite their use as a nano-carrier for controlled delivery of various types of drugs, the inherent osteo-conductive properties have stolen a great attention as a growing area of investigation. Here, we evaluated the double function of UiO-66 MOF structure as a carrier for fosfomycin antibiotic and also as an osteogenic differentiation promoter when introduced in 3D chitosan scaffolds, for the first time. Our results revealed that the wet-spun chitosan scaffolds containing fosfomycin loaded UiO-66 nanocrystals (CHI/UiO-66/FOS) possessed fiber mesh structure with integrated micro-scale fibers and increased mechanical strength. In vitro antibacterial studies indicated that CHI/UiO-66/FOS scaffolds showed bactericidal activity against Staphylococcus aureus. Moreover, the scaffolds were biocompatible to MC3T3-E1 pre-osteoblasts and significantly up-regulated the expression of osteogenesis-related genes and facilitated the extracellular matrix mineralization, in vitro. Taken together, our results demonstrate UiO-66 MOFs can present double functionality and CHI/UiO-66/FOS scaffolds hold a significant potential to be further explored as an alternative approach in treating infected bone defects like osteomyelitis.

Single-Use Bioreactors for Human Pluripotent and Adult Stem Cells: Towards Regenerative Medicine Applications

Research on human stem cells, such as pluripotent stem cells and mesenchymal stromal cells, has shown much promise in their use for regenerative medicine approaches. However, their use in patients requires large-scale expansion systems while maintaining the quality of the cells. Due to their characteristics, bioreactors have been regarded as ideal platforms to harbour stem cell biomanufacturing at a large scale. Specifically, single-use bioreactors have been recommended by regulatory agencies due to reducing the risk of product contamination, and many different systems have already been developed. This review describes single-use bioreactor platforms which have been used for human stem cell expansion and differentiation, along with their comparison with reusable systems in the development of a stem cell bioprocess for clinical applications.

A differential pressure laminar flow reactor supports osteogenic differentiation and extracellular matrix formation from adipose mesenchymal stem cells in a macroporous ceramic scaffold

We present a laminar flow reactor for bone tissue engineering that was developed based on a computational fluid dynamics model. The bioreactor design permits a laminar flow field through its specific internal shape. An integrated bypass system that prevents pressure build-up through bypass openings for pressure release allows for a constant pressure environment during the changing of permeability values that are caused by cellular growth within a porous scaffold. A macroporous ceramic scaffold, composed of zirconium dioxide, was used as a test biomaterial that studies adipose stem cell behavior within a controlled three-dimensional (3D) flow and pressure environment. The topographic structure of the material provided a basis for stem cell proliferation and differentiation toward the osteogenic lineage. Dynamic culture conditions in the bioreactor supported cell viability during long-term culture and induced cell cluster formation and extra-cellular matrix deposition within the porous scaffold, though no complete closure of the pores with new-formed tissue was observed. We postulate that our system is suitable for studying fluid shear stress effects on stem cell proliferation and differentiation toward bone formation in tissue-engineered 3D constructs.

Chitosan scaffolds with BMP-6 loaded alginate microspheres for periodontal tissue engineering

The aim of this study is to develop an effective growth factor releasing scaffold-microsphere system for promoting periodontal tissue engineering. Bone morphogenetic protein-6 (BMP-6)-loaded alginate microspheres in narrow size distribution were produced by optimising electrospraying conditions. The addition of these microspheres to chitosan gels produced a novel scaffold in which not only the pore sizes and interconnectivity were preserved, but also a controlled release vehicle was generated. Loading capacity was adjusted as 50 ng or 100 ng BMP-6 for each scaffold and the controlled release behaviour of BMP-6 from chitosan scaffolds was observed during seven days. Cell culture studies were carried out with rat mesenchymal stem cells derived from bone marrow in three groups; chitosan scaffolds, chitosan scaffolds containing BMP-6-loaded alginate microspheres and chitosan scaffolds with free BMP-6 in culture medium. Results showed that controlled delivery of BMP-6 from alginate microspheres has a significant effect on osteogenic differentiation.

Biomimetic Apatite-coated PCL Scaffolds: Effect of Surface Nanotopography on Cellular Functions

In this study, polycaprolactone (PCL) scaffolds, consisting of agglomerated microspheres with nanotopographic surface structures, were fabricated by the freeze-drying method. These scaffolds were coated with bone-like apatite by using a calcium phosphate solution similar to saturated simulated body fluid (10× SBF-like) in two different immersion periods (6 and 24 h). Scanning electron microscopic views of the 6-h treatment in 10× SBF-like solution showed formation of calcium phosphate nucleation sites on the PCL scaffolds, while the apatite particles formed characteristic cauliflower-like morphology after 24 h. The X-ray diffraction (XRD) data showed that the mineral phase was made of hydroxyapatite (HA). The osteogenic activity of untreated and SBF-treated PCL scaffolds was examined by pre-osteoblastic MC3T3 cell culture studies. Cells had attached and spread on both the PCL scaffolds and the 6-h SBF immersion-treated scaffolds.

Mechanical and flow characterization of Sponceram carriers: Evaluation by homogenization theory and experimental validation

The experimental evidence of the dependence of cell proliferation and differentiation in vitro on the mechanical environment aims to the need of characterization of porous scaffolds in terms of mechanical and flow properties. In this sense, the Young's modulus and intrinsic permeability for three types of Sponceram(R) cell carriers developed for in-vitro applications are here analyzed. Young's modulus and ultimate compression stress were obtained by performing a two-plates compression test carried out in a universal microtester machine Instron(R) for several representative samples of each specimen. A permeability test was also implemented to correlate flow rate and pressure gradient in the linear range. Furthermore, porosity and specific surface were obtained through micro-CTs of the scaffold microstructure. These experimental data were compared with those obtained numerically by homogenization for several representative volume elements (RVEs) of the scaffolds microstructure. The good agreement found between numerical and experimental results let us consider that the use of numerical techniques is an attractive tool for the analysis of complex scaffold microstructures. Moreover, Sponceram(R) carriers are shown to have very appropriate properties as bone bioscaffolds which let us recommending further clinical and numerical research on these specific materials.

Development of an osteoblast-based 3D continuous-perfusion microfluidic system for drug screening

In this work, we demonstrated that biological cells could be cultured in a continuous-perfusion glass microchip system for drug screening. We used mouse Col1a1GFP MC-3T3 E1 osteoblastic cells, which have a marker gene system expressing green fluorescent protein (GFP) under the control of osteoblast-specific promoters. With our microchip-based cell culture system, we realized automated long-term monitoring of cells and sampling of the culture supernatant system for osteoblast differentiation assay using a small number of cells. The system successfully monitored cells for 10 days. Under the 3D microchannel condition, shear stress (0.07 dyne/cm(2) at a flow rate of 0.2 microL/min) was applied to the cells and it enhanced the GFP expression and differentiation of the osteoblasts. Analysis of alkaline phosphatase (ALP), which is an enzyme marker of osteoblasts, supported the results of GFP expression. In the case of differentiation medium containing bone morphogenetic protein 2, we found that ALP activity in the culture supernatant was enhanced 10 times in the microchannel compared with the static condition in 48-well dishes. A combined system of a microchip and a cell-based sensor might allow us to monitor osteogenic differentiation easily, precisely, and noninvasively. Our system can be applied in high-throughput drug screening assay for discovering osteogenic compounds.