Magnetic Separation of Cells in Coculture Systems Using Magnetite Cationic Liposomes

Expansion of human mesenchymal stem cells on poly(vinyl alcohol) microcarriers

Microcarriers provide a high surface-area-to-volume ratio that can realize high yields of cell products, including human mesenchymal stem cells (hMSCs). Here, we report a novel poly(vinyl alcohol) (PVA)-based microcarrier for hMSC expansion in suspension culture. PVA microcarriers were prepared as collagen-coated PVA hydrogels 181 μm in size and a high surface-area-to-weight ratio of 2945 cm2/g. The PVA microcarriers supported a 2.6-fold expansion of hMSCs in a 30-mL single-use stirred bioreactor after a 7 d culture period, comparable to that of commercially available microcarriers. Interestingly, we observed that hMSCs on PVA microcarriers adhered to adjacent microcarriers, resulting in the aggregation of hMSC-PVA microcarriers. Therefore, we conducted a long-term expansion culture using a bead-to-bead cell transfer method with PVA microcarriers. Fresh microcarriers were added to the cell-populated microcarriers in the bioreactor on days 7 and 14. hMSCs on PVA microcarriers continued to grow for 21 d using the bead-to-bead cell transfer method. Furthermore, magnetic PVA (PVA-mag) microcarriers were developed by loading magnetic nanoparticles into PVA microcarriers, and we demonstrated that these PVA-mag microcarriers enabled cell recovery by magnetic separation. These results suggest that these PVA microcarriers can contribute to the large-scale culture of hMSCs for regenerative medicine and cell therapy.

Advances in Magnetic Nanoparticles for Biomedical Applications

Magnetic nanoparticles (NPs) are emerging as an important class of biomedical functional nanomaterials in areas such as hyperthermia, drug release, tissue engineering, theranostic, and lab-on-a-chip, due to their exclusive chemical and physical properties. Although some works can be found reviewing the main application of magnetic NPs in the area of biomedical engineering, recent and intense progress on magnetic nanoparticle research, from synthesis to surface functionalization strategies, demands for a work that includes, summarizes, and debates current directions and ongoing advancements in this research field. Thus, the present work addresses the structure, synthesis, properties, and the incorporation of magnetic NPs in nanocomposites, highlighting the most relevant effects of the synthesis on the magnetic and structural properties of the magnetic NPs and how these effects limit their utilization in the biomedical area. Furthermore, this review next focuses on the application of magnetic NPs on the biomedical field. Finally, a discussion of the main challenges and an outlook of the future developments in the use of magnetic NPs for advanced biomedical applications are critically provided.

Study of iron oxide nanoparticle phases in graphene aerogels for oxygen reduction reaction

Four iron oxide phases incorporated in a graphene support were examined; differences in their catalytic properties depended on their phases.

Magnetically labeled feeder system for mouse pluripotent stem cell culture

We report here a magnetically labeled feeder system for mouse embryonic stem/induced pluripotent stem (ES/iPS) cells. Magnetic attraction of feeder cells labeled with magnetite nanoparticles significantly increased ES/iPS colony-forming efficiency. Magnetic labeling of feeder cells also facilitated separation of ES/iPS cells from feeder cells.

Systematic screening of the cellular uptake of designed alpha-helix peptides

The cellular penetration (CP) activity of functional molecules has attracted significant attention as one of the most promising new approaches for drug delivery. In particular, cell-penetrating peptides (CPPs) have been studied extensively in cellular engineering. Because there have been few large-scale systematic studies to identify peptide sequences with optimal CP activity or that are suitable for further applications in cell engineering, such as cell-specific penetration and cell-selective culture, we screened and compared the cellular uptake (CU) activity of 54 systematically designed α-helical peptides in HeLa cells. Furthermore, the CU activity of 24 designed peptides was examined in four cell lines using a cell fingerprinting technique and statistical approaches. The CU activities in various cells depended on amino acid residues of peptide sequences as well as charge, α-helical content and hydrophobicity of the peptides. Notably, the mutation of a single residue significantly altered the CU ability of a peptide, highlighting the variability of cell uptake mechanisms. Moreover, these results demonstrated the feasibility of cell-selective culture by conducting cell-selective permeation and death in cultures containing two cell types. These studies may lead to further peptide library design and screening for new classes of CPPs with useful functions.