The blood samples and polarization of the mononuclear cells
Peripheral blood samples were collected from donors and stored in a collecting tube with EDTA or heparin, approved by the Research Ethics Committee of Chinese Medical University and Hospital in Taichung, Taiwan (CMUH109-Rec1-012) and carried out in Asia University Hospital, Taichung, Taiwan. Twenty mL of the peripheral blood sample was carefully loaded on the 20 mL Ficoll-Paque premium interface. After centrifuging at 700 ´g for 15 min, the cells in the upper layer of the tube (i.e., peripheral blood mononuclear cells, PBMNCs) were transferred to 50 mL tubes. The cell pellet was obtained after centrifuging at 500 ´g for 5 min and the percentage of monocyte in the cell pellet was measured by flow cytometry (Accuri, Becton-Dickinson, USA) using anti-CD14 FITC conjugated antibody (BioLegend, USA). In general, 1-3 ´107 PBMNCs can be harvested from 20 mL blood.
The isolated PBMNCs (including lymphocytes, monocytes and NK cells) were further incubated with M-CSF (R&D Systems, USA), GM-CSF (Peprotech, USA) or G-CSF (Peprotech, USA) in a basal medium containing RPMI-1640 medium (Thermo-Fisher, USA) with 2% human platelet lysate (Compass, USA) for indicated days on low-binding culture dishes (Alpha Plus Scientific, Taiwan) or 2.5 mg/cm2 fibronectin (STEMCELL Technologies)-coated slides. The other cytokines used for the Col II induction, such as IL-4, IL-10, IL-13 and TGF-b, were all obtained from R&D Systems.
The immunocytostaining
Adherent monocyte-derived macrophages were fixed on a fibronectin-coated glass slides with a paraformaldehyde buffer. After the treatment with an intracellular staining permeabilization wash buffer (BioLegend), the cells were stained with the anti-human Col II antibodies (Abs), including rabbit polyclonal (AB761, Millipore) and mouse monoclonal Abs (MA5-12789, Invitrogen, USA) for 1 hour. Col II expressing cells were visualized with green Alexa Fluor 488-conjugated goat anti-rabbit IgG antibody (A11008, Invitrogen) or anti-mouse IgG antibody (31569, Invitrogen). The total cell number was estimated by the 4',6-diamidino-2-phenylindole (DAPI) staining in the nuclei (blue).
The RT and real-time PCR
The 1´108 PBMNCs were cultured with a combination of 100 ng/mL M-CSF100 ng/mL IL-4 or PBS at 0.5, 1, 2, 4, 6 hrs in low-binding dishes (Alpha Sciences, Taiwan). The monocytes amongst the cultured PBMNCs were sorted with Easysep selection kit containing anti-CD14 antibody on magnetic beads (Stemcell Technology, Vancouver, Canada), according to the manufacturer’s instrument. The purity of the monocytes was analyzed by flow cytometry with FITC conjugated anti-CD14 monoclonal antibody (BioLegend).
The total RNA of CD14+ cells was extracted by RNeasy mini kit (Qiagen) according to manufacturer’s recommendation. Reverse transcribed into first-strand cDNA using the Moloney murine leukemia virus reverse transcription kit (M-MuLV RT kit, Protech Technology Enterprise, Taiwan). Total RNA was initially denatured at 65 °C for 5 min and quickly placed on ice for at least 1 min. The annealing with oligo (dT)18 and random hexamers was conducted at 25 °C for 10 min and the cDNA was synthesized at 42 °C for 60 min. The quantitative Col II mRNA expression levels were analyzed by the real-time reverse transcriptase-polymerase chain reaction (RT-PCR) (QuantStudio™ Pro 6 System, Thermo Fisher Scientific). The RNA expression level of Col II was normalized to that of glyceraldehyde 3-phosphate (GAPDH) and the fold differences were compared to PBS control. The forward primer and reverse primer of Col II were 5’- CCC TGA GTG GAA GAG TGG AG -3’, and 5’- GAG GCG TGA GGT CTT CTG TG -3’, respectively. The primers for GAPDH were forward 5’- TCG ACA GTC AGC CGC ATC TTC TTT -3’, reverse 5’- ACC AAA TCC GTT GAC TCC GAC CTT -3’. The real-time PCR applied SYBR green dye with low rox concentration (PowerUP SYBR green master mix, Thermo Fisher Scientific). Each sample was initially denatured at 95 °C for 10 min and then underwent 40-cycles reactions, including denaturation at 95 °C for 15 sec, annealing and extension at 60 °C for 1 min.
Animal experiments
The in vivo evaluation of the effect of modified macrophages in rodents was approved by the Institutional Animal Care and Use Committee (IACUC) of National Chung Hsing University (NCHU) (NCHU 109-093) in Taichung, Taiwan and carried out in the Department of Life Sciences NCHU, Taichung, Taiwan. Experiments were performed in accordance with Taiwan Animal Protection Act and in compliance with the ARRIVE guidelines. Animals were housed and maintained at room temperature under a typical light cycle environment. The food and water were provided ad libitum.
Adult male Sprague-Dawley (SD) rats, weighing 200-250 g, were housed in a room with constant temperature (24-26 ℃) and humidity (40-60 %) and had free access to food and water. A 0.25 mL of complete Freund’s adjuvant (CFA, Sigma-Aldrich, USA) was injected into the hind knee joint of each rat to induce inflammatory arthritis. On day 6, the inflammation was boosted by injecting an additional 0.05 mL of CFA into the same sites. On Day 7, when the arthritis was established, the arthritic knee joints were treated with 0.2 mL of PBS (control) or 2´105 M-CSF/IL-4-induced modified macrophages in 0.2 mL PBS. Non-binding cytokines to the cells were cleared by PBS wash twice. Knee joints were measured using a vernier every 2-3 days for two weeks.
Collagen-induced arthritis (CIA) in rodents is a classical model of human rheumatoid arthritis (RA). CIA was successfully established in both C57BL/6 mice and SD rats via the subcutaneous injection of type II collagen (200 μg) into the tail vein. Significant paw swelling was observed on day 40 and persisted to day 105. The 2´105 modified macrophages were intra-articularly (IA) injected into the left knee of each mouse or rat on day 50 (1st dose) and day 80 (2nd dose). The PBS (phosphate buffer saline) was IA-injected into the right knee of each mouse or rat as a mock-treatment control. Knee joints were measured using a vernier every 2-3 days for two weeks.
Statistic analysis
We used Student t-test or one way ANOVA to determine the significance of differences between the experimental groups. This study's graphics creation and statistical analysis were conducted using Microsoft Excel (version 2019) or GraphPad Prism 9 (GraphPad, La Jolla, CA, USA).