Gibco Essential 8 Flex Medium is formulated to extend the activity of key heat-sensitive components found in PSC medium, including FGF2, to enable a truly weekend-free culture feeding schedule.

  • Flexible feeding schedule—maintain pluripotency over a full 2-day period without feeding cells
  • Robust cultures—optimized stability of heat sensitive components, like FGF2, increases maintenance of pluripotency
  • Easy to transition—same setup, applications and protocol as the original Essential 8 Medium formulation, but without the daily feeding
  • Proven—based on the original Gibco Essential 8 Medium formulation, maintains pluripotency and normal karyotypes in long-term culture

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Essential 8 Flex: Eliminating daily feeding in a feeder-free, xeno-free PSC culture system

Routine PSC expansion and maintenance without the need for daily feeding

Essential 8 Flex Medium is a serum-free, xeno-free medium that supports the culture and expansion of pluripotent stem cells (PSCs) while eliminating the need for daily feeding schedules (Figure 1).  Just like the original Essential 8 Medium formulation, the Essential 8 Flex Medium does not include BSA (bovine serum albumin) or HSA (human serum albumin) components, helping to minimize batch variability and maintain long-term health and pluripotency of PSCs (Figures 2–3).

Illustration demonstrating a typical 7-days-per-week feeding schedule for human PSCs when using traditional media and the weekend-free feeding schedule when using Essential 8 Flex Medium.

Figure 1. Culture schedule comparison. Unlike other feeder-free media, Gibco Essential 8 Flex Medium eliminates the need to manage cultures daily, enabling a truly weekend-free schedule for expansion and maintenance of PSCs. The Essential 8 Flex medium workflow can be adjusted to a once-per-week passage if required to fit existing workflows. Simply change day 1 to a feed day in the workflow above.

Line graph of growth factor activity as a function of time showing FGF2 activity is well preserved in Essential 8 Flex Medium.
Karyotype shown as 22 pairs of somatic chromosomes and one pair of sex chromosomes stained by G-banding.

Figure 2. FGF2 activity over time in PSC culture medium. Unlike other feeder-free PSC culture media, Essential 8 Flex Medium has been optimized to extend the activity of unstable components such as FGF2. Extended activity allows for routine culture without the daily feeding.

Figure 3. Long-term stability of cells cultured in Essential 8 Flex medium.  Healthy karyotypes of pluripotent stem cells cultured in Essential 8 Flex medium have been observed after long term culture of cells.

Robust pluripotent stem cell cultures

FGF2 levels widely fluctuate in standard PSC culture medium, even with daily feeding (Figure 4). The use of Essential 8 Flex medium significantly limits these fluctuations, producing more robust, stable culture conditions with the added value of a weekend-free feeding schedule.

Figure 4. Essential 8 Flex medium limits fluctuations in levels of active FGF2. Measurements of heat-mediated loss of active FGF2 were used to simulate active FGF2 levels in PSC cultures over the course of a week. Standard PSC culture medium (red curve) cultures would be fed on a daily basis while Essential 8 Flex medium (blue curves) cultures would be follow the suggested protocol outlined in Figure 1.

Complete media system

The following components are recommended to create a complete media system for weekend-free routine expansion and maintenance of PSCs with Essential 8 Flex Medium.

Essential 8 Flex Protocol

Culture medium


Passaging reagent

Webinar: Essential 8 Flex: Eliminating daily feeding in a feeder-free, xeno-free PSC culture system