Growth Suppression Basal Medium for Human Pluripotent Stem Cells (iPS/ES Cells) Xyltech™ BOF-01

■ Product Composition & Preparation

Q-1.: Is the formulation of this medium disclosed?
A-1.: The exact formulation remains proprietary. While its components are highly similar to standard basal media (like DMEM/F12) used for human pluripotent stem cells, it contains no glucose.

Q-2.: What is the shelf life of the medium?
A-2.: The product can be stored for up to one year from the date of manufacture when kept refrigerated at 4°C or below.

Q-3.: How should the complete medium be formulated?
A-3.: We recommend preparing the complete medium based on standard human ES cell culture protocols, using mouse embryonic fibroblasts (MEFs) as the feeder cell layer. (Ref: Curr Protoc Stem Cell Biol. 2009 Jun; Chapter 4: Unit 4A.2.).

Recommended Formulation Example:

■ Protocol & Cell Handling

Q-4.: Can cells be cultured in BOF-01 complete medium for longer than 3 days?
A-4.: In tests with human iPS cells, extended growth-controlling cultures occasionally led to the emergence of colonies showing differentiation tendencies. Therefore, we recommend limiting the culture period to a maximum of 3 days.

Q-5.: Is passaging required immediately after the 3-day growth-suppressed　culture?
A-5.: For routine maintenance, we recommend switching back to regular human ES medium after the growth-suppressed culture period. Incubate the cells overnight, and then passage them according to their current condition. Typically, cells should be passaged within 1 to 3 days after returning to the regular growth medium.

Q-6.: Is a washing step necessary when switching between media?
A-6.: No washing or rinsing step is required. You can perform a standard medium exchange when switching between BOF-01 complete medium and normal growth medium.

Q-7.: For how many passages can this growth-control cycle be repeated?
A-7.: While results depend heavily on your specific cell line, it can generally be used for up to approximately 10 passages. However, repeating growth-controlled cultures in quick succession may slow down the overall cell doubling time. If this occurs, we recommend increasing your cell seeding density.

Q-8.: Can this be used in feeder-free culture systems?
A-8.: No. This product was developed strictly for on-feeder culture systems and is not compatible with feeder-free conditions.

Q-9.: Can differentiated cells be cultured with this medium?
A-8.: No. This medium is explicitly designed for the undifferentiated maintenance culture of pluripotent stem cells and cannot be used for differentiated cells.

■ Technical & Biological Dynamics

Q-10.: Do cells die during the growth-controlling culture?
A-10.: Generally, significant cell death is not observed during the recommended culture period. However, if the cell density is already very high and no medium changes are performed, floating cells may increase. Under high-density conditions (e.g., large colonies), replacing the medium with fresh BOF-01 complete medium during the control period is highly recommended.

Q-11.: Is cell proliferation completely stopped?
A-11.: During the 3-day growth-controlled culture, cells may still proliferate slightly, but within a range of less than a 2-fold increase. While standard growth medium yields a more than 2-fold expansion, BOF-01 successfully reduces this proliferation to less than half of that rate.

Q-12.: Does it prevent the expansion of spontaneously differentiated colonies?
A-12.: If the culture period is under 3 days, new differentiated colonies rarely emerge. However, because results depend on the initial cell condition, any baseline differentiation tendencies may become more pronounced during growth-controlled culture.

Q-13.: Can it control the growth of non-pluripotent cells?
A-13.: No. This is a basal medium and cannot support cells on its own without correct supplementation. While certain established cell lines might exhibit growth regulation when cultured with specialized supplement blends, this is outside our product warranty.

Q-14.: What happens to the cell cycle during this culture?
A-14.: Cell cycle assays demonstrate an increased proportion of pluripotent stem cells remaining in the G0/G1 phase when cultured under growth-controlled conditions.

Q-15.: What is the exact mechanism or active component driving this effect?
A-15.: Detailed formulation and mechanistic data are proprietary and cannot be disclosed.

Q-16.: Does this culture cycle affect the lifespan of the cells?
A-16.: Based on our laboratory findings, cells subjected to this growth-controlling culture do not suddenly exhibit a finite lifespan like primary cells.