一人皮肤成纤维细胞培养

PRIMARY FIBROBLAST CULTURE FROM HUMAN SKIN BIOPSY This protocol describes the steps for obtaining a primary fibroblast cell line from human skin biopsies. Fibroblasts are derived directly from excised skin as explants; enzyme digestion by collagenase may help obtain cells in a shorter time. This protocol describes the different steps for obtaining a primary cell line from a skin biopsy. Equipment and materials Laminar flow hood CO2 incubator Inverted microscope Sterile surgical Instruments for microdissection BME fibroblast medium PBS 10x without Ca+2 or Mg+2 Collagenase type II (4mg/ml) Petri dishes 100 mm Pasteur pipettes Culture flask, 25 cm2 15 ml sterile plastic tube BME Fibroblast medium BME 80 ml Foetal bovine serum 20 ml Penicillin-streptomycin solution 100x 1 ml Filter and store at +4°C, up to 1 month. The skin biopsy sample should be shaped as a diamond and about 5-10 mm in diameter. Collect the tissue sample in sterile BME fibroblast medium. Procedure 1 Rapidly wash the skin biopsy in PBS in a Petri dish, cut into small fragments and transfer these to a flask. Using a sterile Pasteur pipette with flame-rounded tip, distribute the small tissue fragments over the bottom surface of the culture flask. Pass the flask rapidly and carefully through the Bunsen flame in order to evaporate the medium so that the minced tissue pieces adhere to the plastic surface, but so as not to heat-damage the minced tissue. Take care not to cook the tissue! Carefully add BME medium for fibroblast growth, firmly close the lid of the flask and place in CO2 incubator. The next day, slightly unscrew the lid of the flask so that the tissue can “breathe.” Replace the culture medium after two days and, from this point on, replace it three times a week. The fibroblasts will start to grow from the minced fragments in 2-3 days. When there are sufficient cells, they are detached enzymatically and plated in Petri dishes, or 75 cm2 culture flasks, for proliferation (see next steps: “Maintenance of cell cultures in dishes and flasks” and “Routine subculture of adherent cell lines”).The minced fragments in the flask will continue to produce cells for a while. Procedure 2 Add collagenase to BME medium containing 20% FBS; so that the ratio medium : collagenase is 6:1, and filter. Place the skin biopsy in a Petri dish, mince it into a coarse slurry using sterile scalpel and transfer to a 15 ml sterile plastic tube containing the BME-collagenase solution. Place the tube in incubator at 37°C for 24 hours. The next day centrifuge at 1 600 g for 10 min. Using a sterile pipette, remove supernatant and wash pellet twice with PBS. Prepare 1.5 ml of BME fibroblast medium in 2 flasks. Suspend the pellet in 1 ml of BME fibroblast medium, transfer 500 microliter of suspension to each of the two flasks and distribute it over their bottom surface. Place flasks overnight in CO2 incubator at 37°C tightly closed. The next day, slightly unscrew the lid of the flasks. After a few days, fibroblasts should start to grow; if cells have developed, replace the culture medium with fresh medium after one week. From this point on, replace the culture medium three times a week. MAINTENANCE OF CELL CULTURES IN DISHES AND FLASKS In culture, cells grow either as a single cell layer attached to specially treated plastic surfaces or in suspension. In order to keep adherent cells healthy and actively growing it is usually necessary to subculture them at regular intervals. Equipment and Materials Laminar flow hood CO2 incubator Proliferating medium (BME fibroblast medium) pre-warmed to 37°C Petri dishes 100 mm Inverted microscope Procedure The general morphology and growth of a cell population, and the presence of any microbial contaminants, should be checked regularly under an inverted microscope in phase contrast. Dishes or flasks with cells at about 70% confluence are treated with trypsin; the cells are then harvested and either frozen or divided for further prolifera tion (see below “Routine Subculture of adherent cell lines”). For dishes with non-confluent cells the medium is discarded and replaced with fresh medium: 7 ml for 100 mm Petri dishes 5 ml for 60 mm Petri dishes 5 ml for 25 cm2 flasks. Medium has to be changed three times a week, usually Mondays, Wednesdays and Fridays. NB: When introducing medium to flasks, a new sterile pipette must be used for each flask; when changing medium in Petri dishes, one pipette may be used for 2 or 3 dishes if the cell line is the same, but the tip must be flamed at each passage. Lids of flasks containing cells must be slightly unscrewed after being placed in the CO2 incubator. ROUTINE SUBCULTURE OF ADHERENT CELL LINES Subculturing requires prior rupture of intercellular and cell-to-substrate connections using proteolytic enzymes such as trypsin. After the cells have been dissociated into a suspension of mainly single cells, they are diluted and transferred to new culture dishes containing fresh medium or to cryotubes containing freezing medium. How often a cell line is subcultured depends on its growth properties which are determined by observation of cell growth under the microscope, and by counting. Equipment and Materials Laminar flow hood CO2 incubator Proliferating medium (BME fibroblast medium) PBS Trypsin-EDTA solution 1X Petri dishes 100 mm Inverted microscope Procedure Thaw trypsin at 37°C and allow PBS and proliferating medium to reach room temperature. Flask cultures containing tissue fragments: Using a sterile pipette remove medium from flask and replace with 5 ml PBS in order to eliminate serum residue that could inactivate the trypsin. After a few minutes remove PBS (pipette) and add 1 ml trypsin Place flask in incubator at 37°C for 3-5 minutes Observe the cells under the microscope: if they are seen to be rounded, they are detached, if most are not rounded, leave the suspension in the incubator for a further minute or two (until rounded). Add 5 ml or more of proliferating medium (add volume equal to or more than that of volume of trypsin) to inhibit enzyme activity. Use the tip of the pipette (or gently pipette up and down) to detach cells from the bottom of the flask, but be careful not to touch, or detach, the tissue fragments. Transfer the cells (pipette) to a 100 mm Petri dish containing 7 ml of proliferating medium. Write the date, number of passages, and cell line code on the Petri dish lid and place in incubator. The initial flask (treated with trypsin) is refilled with proliferating medium and placed in incubator with cap slightly unscrewed. Petri dish cultures: Remove medium from Petri dish and add PBS (7 ml to 100 mm Petri dish, 4 ml to 60 mm Petri dish) After a few minutes, remove PBS and add trypsin (1 ml to 100 mm dishes, 0.5 ml to 60 mm dishes) Place in incubator at 37°C for 3-5 minutes. Check under the microscope that cells have detached and proceed as trypsinization of flask cultures (above) Add proliferating medium (volume equal to or greater than volume of trypsin added) in order to inhibit trypsin activity. Mechanically detach cells from dish surface with the help of a pipette tip, then gently pipette the cell suspension up and down so as to obtain a suspension of individual cells. Dispense appropriate aliquots of the cell suspension to new 100 mm Petri dishes and add 6 ml of growth medium: Label each new dish with cell line code, date and passage number. Place the dishes in the CO2 incubator at 37°C. The following day, check under the microscope that the cells have reattached and are growing.