Bioprocess design: what is an acceptable osmolality (mOsm/kg H2O) operating range commonly tolerated by mammalian cells in culture media?

Introduction / Context:
Osmolality is a key media parameter affecting mammalian cell viability, productivity, and product quality (e.g., glycosylation). Cultures are typically maintained near physiologic osmolality, with some tolerance window depending on cell line and process strategy.

Given Data / Assumptions:

• Physiological osmolality is roughly 280–300 mOsm/kg for many cells.
• Some fed-batch processes tolerate moderately higher osmolality (up to ~350–360 mOsm/kg).
• Extremes away from physiologic can impair growth and quality.

Concept / Approach:
Choose the range that captures the typical span seen in practical mammalian cell culture operations, allowing some headroom for feed additions and metabolite accumulation without causing severe stress.

Step-by-Step Solution:

Verification / Alternative check:
Media recipes (e.g., DMEM variants) and process guidelines align with this range; product-quality studies often manage osmolality within this window.

Why Other Options Are Wrong:

• A/E: Too low for typical mammalian systems; risks swelling and lysis.
• C: Narrow band that may be overly restrictive for fed-batch dynamics.
• D: Skews too high; many cell lines suffer above ~360 mOsm/kg.

Common Pitfalls:
Confusing osmolarity with osmolality; ignoring cumulative feed effects that raise osmolality.

Final Answer:
280–360 mOsm/kg