A novel three-dimensional culture system for isolation and clonal propagation of neural stem cells using a thermo-reversible gelation polymer

Recent progresses in novel in vitro models of primary neurons: A biomaterial perspective

Central nervous system (CNS) diseases have been a growing threat to the health of humanity, emphasizing the urgent need of exploring the pathogenesis and therapeutic approaches of various CNS diseases. Primary neurons are directly obtained from animals or humans, which have wide applications including disease modeling, mechanism exploration and drug development. However, traditional two-dimensional (2D) monoculture cannot resemble the native microenvironment of CNS. With the increasing understanding of the complexity of the CNS and the remarkable development of novel biomaterials, in vitro models have experienced great innovation from 2D monoculture toward three-dimensional (3D) multicellular culture. The scope of this review includes the progress of various in vitro models of primary neurons in recent years to provide a holistic view of the modalities and applications of primary neuron models and how they have been connected with the revolution of biofabrication techniques. Special attention has been paid to the interaction between primary neurons and biomaterials. First, a brief introduction on the history of CNS modeling and primary neuron culture was conducted. Next, detailed progress in novel in vitro models were discussed ranging from 2D culture, ex vivo model, spheroid, scaffold-based model, 3D bioprinting model, and microfluidic chip. Modalities, applications, advantages, and limitations of the aforementioned models were described separately. Finally, we explored future prospects, providing new insights into how basic science research methodologies have advanced our understanding of the CNS, and highlighted some future directions of primary neuron culture in the next few decades.

Organoid culture of mouse fallopian tube epithelial stem cells with a thermo-reversible gelation polymer

In this study, a three-dimensional (3D) thermo-reversible gelation polymer (TGP) culture system was established for organoid culture of mouse fallopian tube (FT) epithelial stem cells (FTESCs) without cell isolation. FT tissues from 6- to 8-week-old ICR mice were digested with collagenase, and whole FT cells (FTCs) were inoculated into the TGP. After 6 days of culture, many spheres in the TGP formed. Some cells in the spheres were positive for 5-ethynyl-2'-deoxyuridine (EdU), a marker of cell proliferation. Furthermore, all the spheres that formed in the TGP were also labelled for EpCAM and LGR5. Some cells in the spheres were stained for PAX8, a secretory cell marker, and fewer cells were labelled with TUBB4, a ciliated cell marker. These results indicate that the 3D TGP culture system is a useful tool for organoid culture of FTESCs in vitro.

Construction of a Linear Cell Cross-Linker with Multivalent Glycyrrhetinic Acid Ligands for Rapid Formation of Hepatocyte Spheroids

We report herein the development of a novel cellular cross-linker further employed in the construction of hepatocellular spheroids based on multivalent strategy. The linker structure consists of a glycyrrhetinic acid derivative (GA-N(CH₃)₂) modified alginate (ALG). GA-N(CH₃)₂ is selected as the recognition ligand due to its high affinity toward hepatocyte, whereas ALG represents the linear backbone accounting for its good biocompatibility and flexible structure. These features endow the cellular cross-linker with the ability to flexibly interact with the cell through multiple binding sites, providing superior binding force between the cell and cross-linker, and subsequently rapidly combining multiple cells into cellular spheroids.

Mebiolgel, a thermoreversible polymer as a scaffold for three dimensional culture of Huh7 cell line with improved hepatocyte differentiation marker expression and HCV replication

PURPOSE

A novel three dimensional (3D) culture system purely synthesised from co-polymer which is free from biological contamination for Huh7 cell cultivation and hepatitis C virus (HCV) replication has been attempted.

MATERIALS AND METHODS

Mebiolgel, a thermo-reversible gelation polymer was used as a 3D scaffold for culturing Huh7, a liver carcinoma cell line used in our study. The 3D culture of the cells were infected with cell culture derived HCV.

RESULT

The scaffold supported the cell growth as 3D spheroids for up to 63 days. Moreover mebiolgel was found to be improving the hepatocyte differentiation of Huh7 cells at the transcript level. Three dimensional culture was susceptible for HCV infection, and this was confirmed by detecting the HCV replication intermediate viral core antigen.

CONCLUSION

Mebiolgel based culture system was proven to be suited for 3D culture of Huh7 cells by improvising liver specific genotypic expression and was susceptible for HCV replication. Since mebiolgel based Huh 7 express better hepatocyte differentiation markers genotypically, this can be implemented as an alternate for primary hepatocytes in studies such as viral isolation from patient serum.

Growth and differentiation of neural stem cells in a three-dimensional collagen gel scaffold

Collagen protein is an ideal scaffold material for the transplantation of neural stem cells. In this study, rat neural stem cells were seeded into a three-dimensional collagen gel scaffold, with suspension cultured neural stem cells being used as a control group. Neural stem cells, which were cultured in medium containing epidermal growth factor and basic fibroblast growth factor, actively expanded and formed neurospheres in both culture groups. In serum-free medium conditions, the processes extended from neurospheres in the collagen gel group were much longer than those in the suspension culture group. Immunofluorescence staining showed that neurospheres cultured in collagen gels were stained positive for nestin and differentiated cells were stained positive for the neuronal marker βIII-tubulin, the astrocytic marker glial fibrillary acidic protein and the oligodendrocytic marker 2’,3’-cyclic nucleotide 3’-phosphodiesterase. Compared with neurospheres cultured in suspension, the differentiation potential of neural stem cells cultured in collagen gels increased, with the formation of neurons at an early stage. Our results show that the three-dimensional collagen gel culture system is superior to suspension culture in the proliferation, differentiation and process outgrowth of neural stem cells.

Scaffold-free culture of mesenchymal stem cell spheroids in suspension preserves multilineage potential

While traditional cell culture methods have relied on growing cells as monolayers, three-dimensional (3D) culture systems can provide a convenient in vitro model for the study of complex cell-cell and cell-matrix interactions in the absence of exogenous substrates and may benefit the development of regenerative medicine strategies. In this study, mesenchymal stem cell (MSC) spheroids, or "mesenspheres", of different sizes, were formed using a forced aggregation technique and maintained in suspension culture for extended periods of time thereafter. Cell proliferation and differentiation potential within mesenspheres and dissociated cells retrieved from spheroids were compared to conventional adherent monolayer cultures. Mesenspheres maintained in growth medium exhibited no evidence of cell necrosis or differentiation, while mesenspheres in differentiation media exhibited differentiation similar to conventional 2D culture methods based on histological markers of osteogenic and adipogenic commitment. Furthermore, when plated onto tissue culture plates, cells that had been cultured within mesenspheres in growth medium recovered morphology typical of cells cultured continuously in adherent monolayers and retained their capacity for multi-lineage differentiation potential. In fact, more robust matrix mineralization and lipid vacuole content were evident in recovered MSCs when compared to monolayers, suggesting enhanced differentiation by cells cultured as 3D spheroids. Thus, this study demonstrates the development of a 3D culture system for mesenchymal stem cells that may circumvent limitations associated with conventional monolayer cultures and enhance the differentiation potential of multipotent cells.

Application of a thermo-reversible gelation polymer, mebiol gel, for stem cell culture and regenerative medicine

Recent studies have revealed the possible utility of a three-dimensional culture system using a thermo-reversible gelation polymer, Mebiol Gel. It is a purely synthesized biocompatible copolymer composed of thermoresponsive polymer blocks [poly(N-isopropylacrylamide-co-n-butyl methacrylate) poly(NIPAAm-co-BMA)] and hydrophilic polymer blocks (polyethylene glycol [PEG]). Mebiol Gel is characterized by its temperature-dependent dynamic visccoelastic properties. Mebiol Gel is used as a biocompatible scaffold for three-dimensional culture without any toxicity. Representative biological scaffolds for three-dimensional culture, i.e. type I collagen and Matrigel, interact with cells and affect cellular functions, but Mebiol Gel hardly showed such effects. Because of its innertness, Mebiol Gel enables clonal expansion of single stem cells. Application of Mebiol Gel to tissue defects in animal models revealed that Mebiol Gel enhanced tissue regeneration with activation of stem cells and prevention of inflammation. Thus, Mebiol Gel is suitable for preparation of cells for transplantation and is useful for direct application to promote regeneration of damaged tissues in vivo.