Name: Isolation of Synovial Macrophages
Uploaded: 2023-02-24T13:30:00
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isolation of synovial macrophages

Desvelando la artritis inflamatoria: explorando las funciones de las células sinoviales

Rheumatoid arthritis (RA) is an autoimmune disease characterized by hyperplasia of the synovium, leading to joint destruction1,2. Tissue-resident macrophages and fibroblasts are present in healthy synovium to maintain joint homeostasis. In RA patients, synovial fibroblasts (SFs) proliferate, and immune cells, including monocytes, infiltrate into the synovium and joint fluid, processes associated with inflammation1,3,4. Synovial macrophages (SMs), which include resident macrophages and peripheral blood monocyte-derived macrophages, and SFs are aberrantly activated and have important roles in RA pathogenesis. Recent studies have suggested that cell-cell interactions between SMs and SFs contributes to both the exacerbation and remission of RA5,6. 
To understand RA pathogenesis, several rodent models of inflammatory arthritis have been used, including K/BxN serum transfer arthritis, collagen-induced arthritis, and collagen antibody-induced arthritis. Cell-based assays are generally required to clarify molecular functions in arthritis. Therefore, primary cells from animal models of arthritis have been isolated. The method to isolate SFs from murine arthritis tissue is well established, and these cells have contributed to the elucidation of molecular mechanisms in arthritis pathogenesis7,8. On the other hand, bone marrow-derived macrophages, blood monocyte-derived macrophages, and macrophage cell lines have often been used as macrophage resources for arthritis studies9,10. Since macrophages can acquire functions associated with their microenvironment, general sources of macrophages may lack responses specific to arthritis tissue. In addition, it is difficult to obtain enough synovial cells by sorting, as murine synovium is a very small tissue even in arthritis models. The lack of usage of synovial macrophages for in vitro studies has been a limitation in arthritis studies. The establishment of a protocol to isolate and expand synovial macrophages would be an advantage for the elucidation of pathological mechanisms in RA.
In the previous method to isolate SFs, SMs were discarded7. Besides that, a method to isolate and expand resident macrophages from some organs was reported11. Therefore, existing protocols were modified in combination. The modification aims to achieve the primary culture of both SMs and SFs with high purity. The overall goal of this method is to isolate and expand both SMs and SFs from murine arthritis tissue.

Autor destacado: Aislamiento y cultivo de macrófagos sinoviales primarios y fibroblastos a partir de tejido de artritis murina  

Aislamiento y cultivo de macrófagos sinoviales primarios y fibroblastos a partir de tejido murino de artritis

Cell-based assays are required to clarify molecular functions. In arthritis studies, the method to isolate primary cells is well established in synovial fibroblasts, but not in synovial macrophages. Therefore, we developed a protocol to isolate and expand both synovial macrophages and synovial fibroblasts from arthritis models.Primary synovial fibroblasts from murine arthritis tissue have contributed to the elucidation of molecular mechanisms in arthritis pathogenesis. On the other hand, bone marrow-derived macrophages, blood monocyte-derived macrophages, and macrophage cell lines have often been used as macrophage resources for arthritis studies. Since macrophages can acquire functions associated with their microenvironment, general sources of macrophages may lack responses specific to arthritis tissue.In addition, it is difficult to obtain enough synovial cells by sorting, as murine synovium is a very small tissue even in arthritis models. In the previous method to isolate synovial fibroblasts, synovial macrophages were discarded. Besides that, a method to isolate and expand resident macrophages from some organs was reported.Therefore, existing protocols were modified in combination to isolate and expand both synovial macrophages and synovial fibroblasts from murine arthritis tissue. This method can isolate both macrophages and fibroblasts from inflammatory synovium with high purity, and it is simple and reproducible. This method allows the expansion of synovial macrophages under co-culture with synovial fibroblasts.Also, the method provides an advantage, in that synovial fibroblasts can be used with fewer passages. The established protocol would be an advantage for elucidation of pathological mechanisms in rheumatoid arthritis.

Watch this Scientific Journal Video about Isolation of Synovial Macrophages at JoVE.com

Isolation of Synovial Macrophages  

Aislamiento de macrófagos sinoviales

Antes de comenzar, realice el aislamiento de fibroblastos sinoviales y utilice las células no adherentes recolectadas de la placa recubierta de colágeno en este procedimiento. Siembre las células no adherentes en placas de 40 a 60 milímetros que no hayan sido recubiertas con colágeno. Cultive las células a granel durante un día a 37 grados centígrados en una atmósfera humidificada con un 5% de dióxido de carbono.Para eliminar los linfocitos no adherentes, aspire el medio cultivado y luego agregue un medio de cultivo fresco. Cultive las células adherentes a granel durante una o dos semanas con cambios de medio cada dos días, manteniendo la confluencia. Luego lávese dos veces con PBS o HBSS.Seleccione los macrófagos sinoviales tratando con tripsina al 0,05% en HBSS e incube durante tres minutos a 37 grados centígrados en una atmósfera humidificada con dióxido de carbono al 5%. A continuación, agregue el medio de cultivo suavemente al 0,05 % de tripsina en HBSS. Después de este paso, no vierta el medio directamente sobre las células.Para eliminar las células desprendidas, aspire el medio cultivado y luego agregue suavemente un medio de cultivo fresco. Repita dos o tres veces y mantenga las células en la placa en medio de cultivo fresco hasta su uso. Se aislaron células similares a macrófagos de ratones hembra C57BL/6 de siete a ocho semanas de edad y se analizaron mediante RT-qPCR.La expresión de ARNm de los marcadores panmacrófagos CD68, EMR1, ITGAM, CSF1R mostró un aislamiento rico en macrófagos del tejido de la sinovitis. Para establecer la pureza de los macrófagos, se analizaron marcadores de proteínas de superficie para macrófagos y otros tipos celulares mediante citometría de flujo. Más del 90% de las células expresaron los marcadores de macrófagos CD45, CD11b y F4/80, mientras que la expresión del marcador de neutrófilos Ly6G y el marcador de células T CD3 fue inferior al 1%

Research

JoVE Journal

Biology

Isolation of Synovial Macrophages

Isolation and Culture of Primary Synovial Macrophages and Fibroblasts from Murine Arthritis Tissue

Rheumatoid arthritis is an autoimmune disease that leads to chronic inflammation of joints. Synovial macrophages and synovial fibroblasts have central roles in the pathogenesis of rheumatoid arthritis. It is important to understand the functions of both cell populations to reveal the mechanisms underlying pathological progression and remission in inflammatory arthritis. In general, in vitro experimental conditions should mimic the in vivo environment as much as possible. Primary tissue-derived cells have been used in experiments characterizing synovial fibroblasts in arthritis. In contrast, in experiments investigating the biological functions of macrophages in inflammatory arthritis, cell lines, bone marrow-derived macrophages, and blood monocyte-derived macrophages have been used. However, it is unclear whether such macrophages actually reflect the functions of tissue-resident macrophages. To obtain resident macrophages, previous protocols were modified to isolate and expand both primary macrophages and fibroblasts from synovial tissue in an inflammatory arthritis mouse model. These primary synovial cells may be useful for in vitro analysis of inflammatory arthritis.

The present study provides a modified protocol to isolate synovial macrophages and fibroblasts from murine inflammatory arthritis tissue.

Rheumatoid arthritis is an autoimmune disease that leads to chronic inflammation of joints. Synovial macrophages and synovial fibroblasts have central ...

Investigación

Biología

Digestion of Synovitis Tissue

Begin by placing the dissected mouse knee joints in a culture dish. Aspirate the culture medium and add fresh culture medium. Repeat the washing three or four times.Then under a stereo microscope, dislocate all the joints in the culture medium by pulling them using fine point tweezers. Remove the tibia and as many vessels, tendons, and ligaments as possible, being careful not to break the bones. Prepare two 15 milliliter tubes per sample.Using tweezers, transfer the dislocated bones with soft tissues to the first tube. For each sample obtained from both hind paws add four milliliters of digestion medium to the tube. To collect residual cells and tissue fragments transfer the culture medium from the dissection dish to the second 15 milliliter tube.Centrifuge the medium at 500 G for 5 minutes at room temperature. After removing the supernatant, resuspend the pellet with one milliliter of digestion medium. And transfer this solution to the first 15 milliliter tube so that it contains almost all the tissue, in total five milliliters of digestion medium.Then digest the sample for 60 to 120 minutes at 37 degrees Celsius with shaking in a hybridization oven. After incubation, mix the sample by pipetting and filter the cell solution through a 40 micron cell strainer into a 50 milliliter tube. Add 10 milliliters of culture medium to the tube through the cell strainer.Centrifuge at 300 G for 5 minutes at room temperature. Remove the supernatant and resuspend the cell pellet with 10 milliliters of culture medium. Repeat the centrifugation, discard the supernatant, and resuspend the pellet with two milliliters of culture medium.

Digestión del tejido de la sinovitis

Isolation of Synovial Fibroblasts

Use the cell suspensions obtained after digestion of mouse knee joints, and seed the suspension on the collagen-coated dish. Incubate the dish for one hour at 37 degrees Celsius in a humidified atmosphere with 5%carbon dioxide. After incubation, collect non-adherent cells using a pipette.Wash the collagen coated dish with culture medium, and collect the medium. Then, add fresh medium to the dish to culture the adherent cells that exhibit a fibroblastoid morphology. Treat the cells with 0.05%trypsin in Hank's balanced salt solution, and passage the sub confluent cells.If highly pure fibroblast-like cells are required, perform repeated passaging. Ensure to use cells with less than five passages. Fibroblast-like cells were isolated from inflammatory arthritis tissue, induced in seven to eight weeks old female C57BL/6 mice.The purity of the isolated cells was assessed by RTQPCR mRNA expression of synovial fibroblast markers, such as Vcam1, Cdh11, Col6a1, and Csf1 in the isolated cells suggested that the fibroblast-rich fractions were isolated from synovitis tissue.

Aislamiento de fibroblastos sinoviales

Before beginning, perform synovial fibroblast isolation and use the non-adherent cells collected from the collagen-coated dish in this procedure. Seed the non-adherent cells on 40 to 60 millimeter dishes that have not been coated with collagen. Culture the bulk cells for one day at 37 degrees Celsius in a humidified atmosphere with 5%carbon dioxide.To remove non-adherent lymphocytes, aspirate the cultured medium and then add fresh culture medium. Culture the adherent bulk cells for one to two weeks with medium changes every two days, while maintaining confluence. Then wash two times with PBS or HBSS.Select for synovial macrophages by treating with 0.05%trypsin in HBSS and incubate for three minutes at 37 degrees Celsius in a humidified atmosphere with 5%carbon dioxide. Then add culture medium gently to 0.05%trypsin in HBSS. After this step, do not pour the medium directly onto the cells.To remove detached cells, aspirate the cultured medium and then add fresh culture medium gently. Repeat two or three times and maintain the cells on the dish in fresh culture medium until use. Macrophage-like cells were isolated from seven to eight weeks old female C57BL/6 mice and analyzed by RT-qPCR.mRNA expression of pan-macrophage markers CD68, EMR1, ITGAM, CSF1R showed macrophage rich isolation from the synovitis tissue. To establish the purity of macrophages, surface protein markers for macrophages and other cell types were analyzed by flow cytometry. More than 90%of the cells expressed macrophage markers CD45, CD11b and F4/80, whereas the expression of neutrophil marker Ly6G and T-cell marker CD3 was lower than 1%