Cell encapsulation is a widely used technique in the field of Tissue Engineering and Regenerative Medicine (TERM). However, for the particular case of liquefied compartmentalised systems, only a limited number of studies have been reported in the literature. We have been exploring a unique cell encapsulation system composed by liquefied and multilayered capsules. This system transfigured the concept of 3D scaffolds for TERM, and was already successfully applied for bone and cartilage regeneration. Due to a number of appealing features, we envisage that it can be applied in many other fields, including in advanced therapies or as disease models for drug discovery. In this review, we intend to highlight the advantages of this new system, while discussing the methodology, and sharing the protocol optimization and results. The different liquefied systems for cell encapsulation reported in the literature will be also discussed, considering the different encapsulation matrixes as core templates, the types of membranes, and the core liquefaction treatments.

Recent studies have shown that mesenchymal stem cells (MSCs), under appropriate conditions, can differentiate into cell types including germ cells (GCs). These studies also show that MSCs without any induction express some GC-specific genes innately. Moreover, one report suggests that female MSCs have a greater tendency to differentiate into female instead of male GCs. Therefore, for the first time, this study attempts to assay and determine the differences between the expression levels of some important GC-specific genes (Stra8, Vasa, Dazl, Stella, Piwil2, Oct4, Fragilis, Rnf17 and c-Kit) in male and female bone marrow (BM)-MSCs of rats. BM sampling of the rate was performed by a newly established method. We cultured rat BM samples, then characterized male and female MSCs according to their adhesion onto the culture dish, their differentiation potential into bone, cartilage and fat cells, and phenotype analysis by flow cytometry. The expression of GC-specific genes and their expression levels were evaluated with reverse transcription polymerase chain reaction (RT-PCR) and real-time RT-PCR. Our results showed that Dazl and Rnf17 did not express in the cells. The majority of examined genes, except Piwil2, expressed at almost the same levels in male and female MSCs. Piwil2 had higher expression in male MSCs which was probably related to the more prominent role of Piwil2 in the male GC development process. Male BM-MSCs appeared more prone to differentiate into male rather than female GCs. Additional research should be performed to determine the exact role of different genes in the male and female GC development process.

It is essential to design a multifunctional well‐controlled platform to transfer mechanical cues to the cells in different magnitudes. This study introduces a platform, a miniaturized bioreactor, which enables to study the effect of shear stress in microsized compartmentalized structures. In this system, the well‐established cell encapsulation system of liquefied capsules (LCs) is used as microbioreactors in which the encapsulated cells are exposed to variable core viscosities to experience different mechanical forces under a 3D dynamic culture. The LC technology is joined with electrospraying to produce such microbioreactors at high rates, thus allowing the application of microcapsules for high‐throughput screening. Using this platform for osteogenic differentiation as an example, shows that microbioreactors with higher core viscosity which produce higher shear stress lead to significantly higher osteogenic characteristics. Moreover, in this system the forces experienced by cells in each LC are simulated by computational modeling. The maximum wall shear stress applied to the cells inside the bioreactor with low, and high core viscosity environment is estimated to be 297 and 1367 mPa, respectively, for the experimental setup employed. This work outlines the potential of LC microbioreactors as a reliable in vitro customizable platform with a wide range of applications.

Chemical approaches and small molecules are considered as an inseparable part of regenerative medicine and stem-cell-based therapies. Zinc (Zn) is a well-known trace element essential for normal spermatogenesis and has a regulatory role on the expression of several genes in different tissues of the body. This study determines and compares the effects of organic (acetate, ZnA) and inorganic Zinc (sulfate, ZnS) on the expression of a number of germ cell (GC)-specific genes in retinoic acid (RA)treated ram bone marrow mesenchymal stem cells (BM-MSCs). First, BM-MSCs were treated with 10 μM RA for 21 days, realtime RT-PCR and immunocytochemistry (ICC) confirmed the expression of the markers in treated cells. Then, in vitro-derived GCs were treated with 1 μM of either ZnS or ZnA for one week. Treatment of in vitro-derived GCs with ZnA significantly downregulated all tested genes. ZnS treatment also induced a significant downregulation in Piwil2 and Vasa, and a moderate decrease in ITG b1 and Oct4 expression levels. Cells treated with ZnS or ZnA showed almost similar gene expression patterns. Zn treatments appeared to make in vitro-derived GCs return to a state similar to the untreated MSCs. We also studied the effects of simultaneous use of RA and one of zinc ions on BM-MSCs. The results showed that presence of organic or inorganic zinc in culture medium containing RA inhibited BM-MSCs to differentiate into GCs. This study showed a new dimension of zinc effect on stem cells which will be really helpful for establishment of novel strategies for Zn applications.