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

Summary

This study delineates a novel approach for the establishment of human monocyte-derived microglia-like (iMG) cells that enable the indirect assessment of brain inflammation. This presents a cellular model that may be beneficial to research focusing on potential inflammation of the brain and associated neuropsychiatric disorders.

Abstract

Recent investigations employing animal models have highlighted the significance of microglia as crucial immunological modulators in various neuropsychiatric and physical diseases. Postmortem brain analysis and positron emission tomography imaging are representative research methods that evaluate microglial activation in human patients; the findings have revealed the activation of microglia in the brains of patients presenting with various neuropsychiatric disorders and chronic pain. Nonetheless, the aforementioned technique merely facilitates the assessment of limited aspects of microglial activation.

In lieu of brain biopsy and the induced pluripotent stem cell technique, we initially devised a technique to generate directly induced microglia-like (iMG) cells from freshly derived human peripheral blood monocytes by supplementing them with granulocyte-macrophage colony-stimulating factor and interleukin 34 for 2 weeks. These iMG cells can be employed to perform dynamic morphological and molecular-level analyses concerning phagocytic capacity and cytokine releases following cellular-level stress stimulation. Recently, comprehensive transcriptome analysis has been used to verify the similarity between human iMG cells and brain primary microglia.

The patient-derived iMG cells may serve as key surrogate markers for predicting microglial activation in human brains and have aided in the unveiling of previously unknown dynamic pathophysiology of microglia in patients with Nasu-Hakola disease, fibromyalgia, bipolar disorder, and Moyamoya disease. Therefore, the iMG-based technique serves as a valuable reverse-translational tool and provides novel insights into elucidating dynamic the molecular pathophysiology of microglia in a variety of mental and physical diseases.

Introduction

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 techniques^1,2,3,4. 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 th....

Protocol

The study protocol was approved by the Ethics Committee of Kyushu University and complied with all the provisions of the Declaration of Helsinki. Written informed consent was obtained from all participants, including healthy volunteers and patients, to analyze their blood and publish their data. Materials and equipment are listed in the Table of Materials, and the compositions of the solutions are detailed in Table 1.

1. Preparation of media and buffers .......

Discussion

Analytical techniques employing iMG cells may serve as potent reverse-translational research tools^5,6. To generate sufficient quantities of human iMG cells, experimenters should design their studies taking certain issues into consideration. Blood samples derived from human beings are extremely sensitive; consequently, the obtained samples warrant prompt processing, and meticulous handling to avoid contamination. Specifically, blood samples should be separated imm.......

Materials

Name	Company	Catalog Number	Comments
0.1% Triton X-100	Sigma-Aldrich	30-5140-5
4% paraformaldehyde	Nacalai Tesque	09154-14
Antibiotic-Antimycotic (100x)	gibco	15240-062	described as "antibiotic-antimycotic solution"
autoMACS Rinsing Solution	Miltenyi Biotec	130-091-222	described as "basic buffer solution" and used for "isolation buffer"
CD11b MicroBeads	Miltenyi Biotec	130–049-601
DAPI solution	DOJINDO	28718-90-3
Dulbecco's Phosphate Buffered Saline	Nacalai Tesque	14249-24	described as "PBS (−)"
Fetal Bovine Serum	biowest	S1760-500
Histopaque-1077	Sigma-Aldrich	10771	described as "density gradient medium"
Human FcR Blocking Reagent	Miltenyi Biotec	130–059-901
Leucosep	Greiner Bio-One	227290	described as "density gradient centrifugation tube"
MACS LS columns	Miltenyi Biotec	130-042-401	described as "magnetic column"
MACS BSA Stock Solution	Miltenyi Biotec	130-091-376	described as "bovine serum albumin (BSA) stock solution"
MACS MultiStand	Miltenyi Biotec	130-042-303	described as "magnetic stand"
Penicillin-Streptomycin	Nacalai Tesque	26253–84
ProLong Gold Antifade Mountant	Invitrogen	P10144	described as "mounting media"
recombinant human GM-CSF	R&D Systems	215-GM
recombinant human IL-34	R&D Systems	5265-IL
RPMI 1640 Medium + GlutaMAX Supplement (pre-supplemented medium)	Thermo Fisher Scientific	61870036	described as "basal induction medium"
RPMI-1640	Nacalai Tesque	30264-56
Antibodies
anti-P2RY12 antibody	Sigma-Aldrich	HPA014518	primary antibody, rabbit, 1:100
anti-TMEM119 antibody	Sigma-Aldrich	HPA051870	primary antibody, rabbit, 1:100
Goat anti-Rabbit IgG (H+L) Cross-Adsorbed Secondary Antibody, Alexa Fluor 568	invitrogen	A-11011	secondary antibody, rabbit, 1:1000