obtaining induced microglia-like cells from whole-blood derived monocytes for probing microglial dynamics in human diseases

Desarrollo de células similares a la microglía inducidas por la sangre para estudiar los trastornos del cerebro humano

In recent years, brain inflammation has been suggested to assume pivotal roles in the pathophysiology of various brain and neuropsychiatric disorders; the microglia have been highlighted as key immunomodulatory cells by human postmortem brain analysis and positron emission tomography (PET)-based bio-imaging techniques1,2,3,4. Postmortem brain and PET imaging analyses reveal significant findings; nevertheless, however, these approaches are inefficient in terms of capturing the dynamic molecular activities of human microglia in the brain in their entirety. Therefore, novel strategies are required to enable the comprehensive evaluation of human microglial functions and dysfunctions at the molecular and cellular levels.
In 2014, we originally engineered a novel technique to produce directly induced microglia-like(iMG) cells5,6, prior to the first publication of human-induced pluripotent stem cell (iPSC)-derived microglia-like cells in 20167. In just 2 weeks, we successfully converted human peripheral blood monocytes into iMG cells by optimizing the cytokines, granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin 34 (IL-34). When we developed this technique, the innovative reprogramming method of inducing neuronal cells from iPS cells or fibroblasts was just beginning to prevail in the world8,9,10,11. However, at that time, a method for inducing iPS-derived microglial cells had not yet been reported, and the generation of a human somatic cell-derived microglial model was desired. Since cytokines such as GM-CSF and IL-34, macrophage colony-stimulating factor, were reported to be necessary for the development and maintenance of microglia12,13,14,15, we hypothesized that a combination of these cytokines could be applied directly to generate a microglial cellular model from blood monocytes. Finally, we succeeded in developing a model of microglia derived from monocytes by combining GM-CSF and IL-345. In addition, some of these combinations of cytokines are also employed to induce microglia from iPS cells7,16 and are assumed to be an important factor in acquiring microglial characteristics.
In contrast to iPSC methods, iMG cells do not require any genetic modification and can be generated in a very short time by simple chemical induction, resulting in lower time and financial costs. Furthermore, iMG cells do not require genetic reprogramming, so we believe that iMG cells are potent surrogate cells to evaluate not only the traits but also the states of human microglia. In the initial paper on the iMG technique in 2014, we confirmed that iMG cells exhibit a phenotype of human microglia, which can be distinct from monocytes and macrophages. For example, iMG cells exhibited an overexpression ratio of CX3C chemokine receptor 1 (CX3CR1) and C-C chemokine receptor type 2 (CCR2) than monocytes and typical microglia markers, including transmembrane protein 119(TMEM 119) and purinergic receptor P2RY125,17. Recently, we validated that peripheral blood-derived iMG cells resemble brain microglia in their gene expression profile of well-known microglial markers in the same patient who underwent brain surgeries18. The iMG cells can be analyzed for dynamic functions at the molecular level, such as phagocytosis and cytokine production, and are expected to compensate for the disadvantages of postmortem brain research and PET studies.
We have discovered previously unknown dynamic pathophysiological mechanisms involving microglia in patients diagnosed with Nasu-Hakola disease5, fibromyalgia19, bipolar disorder20,21, or Moyamoya disease22. Furthermore, based on our original methodology, various laboratories have employed the iMG cells (certain laboratories have designated alternative names to these cells) as a crucial reverse-translational research tool23,24,25,26,27. Sellgren et al. successfully generated iMG cells in compliance with our recommendations and conducted a microarray analysis, which revealed that these cells closely resemble human brain microglia23. Recently, we confirmed the resemblance between human iMG cells and brain primary microglia using RNA sequencing18.
This study aimed to document the methodology to generate iMG cells from human peripheral blood to facilitate reverse-translational research focused on neuropsychiatric diseases. This technique presents potential as a reasonable analytical tool that can effortlessly produce microglial cellular models in a brief duration, even in ill-equipped laboratories that lack gene transfer apparatus or proficient personnel.

Autor destacado: Tecnología de células similares a la microglía inducida para arrojar luz sobre el papel de la disfunción microglial en los trastornos neuropsiquiátricos

Ingeniería de células similares a la microglía inducidas por sangre humana para la investigación traslacional inversa del cerebro

Our lab at Kyushu University aimed to clarify the roles of microglial dysfunction in various neuropsychiatric disorders. We believe that our iMG cell technology will shed new light on microglial dynamic function and dysfunction at the cellular level in human beyond the limitation of human brain analysis, such as postmortem study and also pet brain studies. Even now, animal experiments are essential to clarify the brain pathophysiology of mental disorders, but it is unclear how well rodent data can be applied to human pathophysiology.Our human blood-induced iMG cell technology will this gap between rodent data, clinical data, and microglial function and/or dysfunction. Other human-derived cellular disease model, human iPS cell-derived microglia cells are also developed, which need much time and much money to develop and can assess trait markers but not state markers. The advantage of our iMG method is that it is much simpler, less time-consuming, and cost-effective.We have already revealed several candidate molecular factors by our reverse translational iMG research focusing on neuropsychiatric disorders such as dementia disease, bipolar disorder, fibromyalgia, glioma, and disease. We believe that our iMG cell technology will shed new light on microglial dynamic function and dysfunction at the cellular levels in various neuropsychiatric disorders.

Obtención de células similares a la microglía inducidas a partir de monocitos derivados de la sangre total para sondear la dinámica microglial en enfermedades humanas 

Para empezar, obtenga células mononucleares humanas de sangre completa. Reactivo de bloqueo FcR humano Vortex y agregue la cantidad requerida de reactivo a las células. Incubar el tubo con células a cuatro grados centígrados durante cinco minutos.Agregue 20 microlitros de CD11b MicroBeads por cada 10 a la potencia de siete células totales e incube a cuatro grados centígrados durante 20 minutos. Desinfecte a fondo el soporte magnético con etanol al 70%. Después de la incubación, agregue 10 mililitros de tampón de aislamiento.Mezcle y centrifugue el tubo a 300 g durante 10 minutos a cuatro grados centígrados. Una vez que el soporte se seque, coloque la columna magnética en el soporte magnético. Después de retirar el sobrenadante, agregue un mililitro de tampón aislante y mezcle suavemente con la pipeta.A continuación, cargue la suspensión de la celda en la columna y lávela tres veces con tres mililitros de tampón de aislamiento cada vez que el depósito de la columna esté vacío. Coloque la columna en un tubo cónico de 15 mililitros sin tocar la parte magnética. Después de agregar cinco mililitros de tampón de aislamiento, empuje el émbolo hacia adentro del tubo para forzar la salida del líquido a través de la columna.Centrifugar la suspensión celular recogida en el tubo. Aspirar el sobrenadante y volver a suspender las células en un medio de aislamiento. Después del recuento de células, alícuota 500 microlitros de suspensión celular en cada pocillo de una placa de 24 pocillos e incubar durante la noche.Para inducir células similares a la microglía, reemplace el medio de aislamiento de la siembra del día anterior por un medio de inducción e incube las células durante 14 días. Las células inducidas similares a la microglía exhibían diminutos cuerpos de soma y numerosos colaterales ramificados.

Research

JoVE Journal

Immunology and Infection

Obtaining Induced Microglia-Like Cells from Whole-Blood Derived Monocytes for Probing Microglial Dynamics in Human Diseases

Developing Blood-Induced Microglia-Like Cells for Studying Human Brain Disorders

Engineering of Human Blood-Induced Microglia-like Cells for Reverse-Translational Brain Research

Author Spotlight: Induced Microglia-Like Cell Technology to Shed Light on the Role of Microglial Dysfunction in Neuropsychiatric Disorders

Recent investigations employing animal models have highlighted the significance of microglia as crucial immunological modulators in various ...

Investigación

Inmunología e Infección

Isolation of Mononuclear Cells from Whole Blood to Obtain Induced Microglia-Like Cells for Brain Research

Aislamiento de células mononucleares de sangre total para obtener células similares a la microglía inducidas para la investigación del cerebro