Osteogenic Differentiation Medium for Human Bone Marrow Mesenchymal Stem Cells

Preparation of Osteogenic Differentiation Complete Medium:

1. The 20 ml nutrient bottle should be thawed at 4°C the day before Preparation of Osteogenic Differentiation Complete Medium.
2. Bring all components to room temperature (18-25°C), mix reagents before use and add all components to the basal medium.
3. Store prepared complete medium at 4°C in the dark for up to 1 month.

For Osteogenic Differentiation: 

1. Reagents required: Complete medium for mesenchymal stem cell culture, 0.25% trypsin (with EDTA), PBS, deionized or ultrapure water, Human Bone Marrow Mesenchymal Stem Cell Osteogenic Differentiation Medium.
2. Gelatin coating: Gelatin coating can help reduce cell retraction, floating, curling, and non-adhesion during cell induction. Coating is optional and should be based on the condition of the cells.
3. Coating procedure: Under aseptic conditions, add enough gelatin coating solution to cover the bottom of the culture plate. Incubate for 30 mins in cell culture incubator. Remove the coating solution after 30 mins and use the gelatin-coated plate for experimental inoculation.
4. Temperature: During osteogenic induction, cells form a monolayer on the culture surface and may shrink when exposed to cold temperatures. Keep the medium and culture vessels as close to 37°C as possible to help prevent cell detachment and curling.
5. Replacing medium: Before changing the medium, pre-warm the required amount of Osteogenic Differentiation Complete Medium to 37°C in a water bath or incubator.
6. Place an empty culture plate underneath the culture plate during medium changes to reduce exposure to the cold work surface.
7. The culture plate should be placed flat and gently remove approx. 80% of the old medium. Do not remove all of the medium, leaving approx. 20% helps keep the cells moist and may retain early calcium deposits.
8. Slowly add fresh, pre-warmed Osteogenic Differentiation Medium along the side of the well. Avoid directing the medium onto the cell layer, as this may cause cells to detach. Place the plate gently in a 37°C incubator.
9. When changing medium in multi-well plates (e.g., 12 or 24 well plates), do not change all wells simultaneously. Process wells individually or in small groups (e.g., up to 6 wells at a time).

Osteogenic Induction Operation (Six-Well Plate):

1. When human bone marrow mesenchymal stem cells reach 80–95% confluence, add 0.25% trypsin (with EDTA) to detach the cells.
2. Count the cells and seed them into a six-well plate at 2–3 × 10⁴ cells/cm². Adjust the seeding density according to the cell growth rate so that cells reach 80–95% confluence within 24–72 hours. Add 2 ml of mesenchymal stem cell complete medium to each well.
3. Incubate the cells at 37°C with 5% CO₂.
4. When the cells reach 80–95% confluence, carefully remove the culture medium and add 2 ml of Osteogenic Differentiation Complete Medium to each well.
5. Replace the medium with fresh, pre-warmed Osteogenic Differentiation Complete Medium every 48–72 hours.
6. Continue induction for 2–4 weeks. Monitor cell morphology and growth, and perform the analysis according to the experimental requirements.

Alizarin Red Staining to Detect Osteogenic Differentiation (Six-Well Plate):

1. Reagents required: 4% paraformaldehyde, PBS, and deionized or ultrapure water.
2. Remove the osteogenic differentiation medium and wash the cells with PBS 1–2 times.
3. Add 4% paraformaldehyde to cover and fix the cells for 10 mins.
4. Remove the paraformaldehyde and wash with deionized or ultrapure water 1–2 times.
5. For a six-well plate, add 1 ml of Alizarin Red staining solution per well. Incubate for 5–10 mins at room temperature.
6. Remove the staining solution and wash with deionized or ultrapure water 1–2 times to remove background staining. Observe the cells under a microscope. The wells should be left with a small amount of water for imaging.
7. Calcium nodules appear red, red-yellow, or red-purple following Alizarin Red staining.

Notes:

1. It is recommended to make up only enough Complete Media as required. Media components should be aliquoted to avoid repeated freeze/thaw cycles.
2. Osteogenic differentiation requires an extended culture period. Maintain aseptic technique throughout preparation and use.
3. Microscopic observation alone may not reliably determine whether differentiation is complete. Once a plate has been stained, it cannot continue to be induced. Therefore, at the beginning of the experiment, it is recommended to prepare 1–3 additional parallel wells/plates as induction controls. These can be stained with Alizarin Red at later time points to monitor differentiation progress without interrupting the main experiment.
4. The Supplement For Stem Cells Osteogenic Differentiation may appear white to yellow. This does not affect its performance.
5. A slight white precipitate may appear after thawing the Supplement For Stem Cells Osteogenic Differentiation. This is L-glutamine and does not affect use. The supplement can be added directly to the Basal Medium.