Why does macrophage differentiation in the PromoCell protocol take 10 days instead of 7 days?

In the PromoCell macrophage differentiation system, the polarization into M1 or M2 macrophages is completed within 7 days, which is consistent with reports in the literature and protocols used by other researchers.
 
Why the protocol spans 10 days
The PromoCell protocol includes an additional 2–3 days for optional macrophage activation. These extra days are intentionally included to improve overall culture performance.
Even if you aim to obtain non‑activated M1 or M2 macrophages, PromoCell does not recommend shortening the full 10‑day protocol, because:

• A medium change on days 8–10 promotes re‑attachment of previously floating cells
• This results in higher cell viability
• Overall cell yield is increased