干细胞

Macrophages are key cells in the innate immune system and play a role in a variety of diseases. However, macrophages are terminally differentiated and difficult to manipulate genetically via transfection or through CRISPR-Cas9 gene editing. To overcome this limitation, we provide a simplified protocol for the generation of mouse embryonic stem cells-derived macrophages (ESDM). Thus, genetic manipulation can be performed using embryonic stem cells, selecting for the desired changes, and finally producing macrophages to study the effects of the previous genetic manipulation. These studies can contribute to many areas of research, including atherosclerosis and inflammation. Production of ESDM has been previously achieved using embryoid body (EB) intermediates. Here, we optimized the EB method using a simplified medium, reducing the number of recombinant proteins and medium recipes required. Our EB-based differentiation protocol consists of three stages: 1) floating EB formation; 2) adherence of EBs and release of floating macrophage progenitors; and, 3) terminal differentiation of harvested macrophage progenitors. The advantages of this protocol include achieving independent floating EBs in stage 1 by using a rocker within the tissue culture incubator, as well as the exclusion of small EBs and cell clusters when harvesting macrophage progenitors via cell filtration.

Extracellular vesicles (EVs) are thought to mediate intercellular communication through the delivery of cargo proteins and RNA to target cells. The uptake of EVs is often followed visually using lipophilic-dyes or fluorescently-tagged proteins to label membrane constituents that are then internalized into recipient cells (Christianson et al., 2013; De Jong et al., 2019). However, these methods do not probe the exposure of EV cargo to intracellular compartments, such as the cytoplasm and nucleus, where protein or RNA molecules could elicit functional changes in recipient cells. In this protocol, we employ an EV cargo protein-APEX fusion to detect proximity interactions with recipient cell cytoplasmic/nuclear targets. This approach results in the biotinylation of proteins in close contact with the reporter fusion and thus permits profiling of biotinylated proteins affinity purified on immobilized streptavidin beads.

Graphic abstract:

Schematic showing three steps of APEX-mediated proximity labeling of proteins in cells targeted by EVs.

Post-implantation mammalian embryogenesis involves profound molecular, cellular, and morphogenetic changes. The study of these highly dynamic processes is complicated by the limited accessibility of in utero development. In recent years, several complementary in vitro systems comprising self-organized assemblies of mouse embryonic stem cells, such as gastruloids, have been reported. We recently demonstrated that the morphogenetic potential of gastruloids can be further unlocked by the addition of a low percentage of Matrigel as an extracellular matrix surrogate. This resulted in the formation of highly organized trunk-like structures (TLSs) with a neural tube that is frequently flanked by bilateral somites. Notably, development at the molecular and morphogenetic levels is highly reminiscent of the natural embryo. To facilitate access to this powerful model, here we provide a detailed step-by-step protocol that should allow any lab with access to standard cell culture techniques to implement the culture system. This will provide the user with a means to investigate early mid-gestational mouse embryogenesis at an unprecedented spatiotemporal resolution.

Controlled differentiation of embryonic stem cells is an essential tool in stem cell research. In this protocol, we describe a simple differentiation protocol involving the induction of embryoid body formation in mouse embryonic stem cells (mESC) using hanging droplets, followed by differentiation into a neuronal lineage.

Retinal degeneration leads to loss of light-sensing photoreceptors eventually resulting in vision impairment and impose a heavy burden on both patients and the society. Currently available treatment options are very limited and mainly palliative. Ever since the discovery of human pluripotent stem cell technologies, cell replacement therapy has become a promising therapeutic strategy for these patients and may help restore visual function. Reproducibly generating enriched retinal cells including retinal progenitors and differentiated retinal neurons such as photoreceptors using human embryonic stem (ES) cells and induced pluripotent stem (iPS) cells in a dish is an essential first step for developing stem cell-based therapies. In addition, this will provide a reliable and sufficient supply of human retinal cells for studying the mechanisms of diseases. Here we describe a small molecule-based retinal induction protocol that has been used to generate retinal progenitors and differentiated retinal neurons including photoreceptors from several human ES and iPS cell lines. The retinal cells generated by this protocol can survive and functionally integrate into normal and diseased mouse retinas for several months following subretinal transplantation.