Cell Storage and Preservation

Learning Objectives

  • Familiarity with cell preservation options and their pros/cons.
  • Discussion on the importance of cryoprotectants and associated challenges.
  • Identify complexities in cell therapy supply chain and logistics.

Reasons for Cell Preservation

  • Banking: For consistent starting material, cost/time efficiency, minimization of genetic changes, contamination, aging, and transformation.

Methods for Cell Storage

  1. Cryopreservation: Long-term storage using low temperatures.
  2. Desiccation: Medium to long-term; involves dehydration.
  3. Hypothermia: Short-term preservation at above 0ºC.

Cryopreservation

  • Involves preserving cells at temperatures below 0ºC, typically at $-196^{ ext{o}}C$ (liquid nitrogen).
  • Ice crystals form during freezing, leading to potential cell damage (osmotic stress).
  • Critical temperatures:
    • Above $-20^{ ext{o}}C$: ice formation; cellular dehydration.
    • Below $-130^{ ext{o}}C$: glass transition, minimal cellular activity.

Cryopreservation Protocol

  • Cooling rates: Optimal rates necessary to avoid ice formation and dehydration.
  • Cryoprotectants (CPAs) used to minimize damage:
    • Penetrating agents: e.g., DMSO, glycerol (lower freezing point).
    • Non-penetrating agents: e.g., PEG, polysaccharides (used with penetrating agents).

Cytotoxicity

  • DMSO can be cytotoxic below 0ºC and may induce cell differentiation. Alternative agents exist.

Storage Vessels

  • Critical materials resistant to extreme temperatures.
  • Types of vessels: heat-sealable glass ampules and polypropylene screw-capped vials.

Desiccation Techniques

  1. Lyophilization (freeze-drying): Removes moisture via sublimation.
  2. Vacuum desiccation: Long-term storage allowing ambient temperature transport.

Hypothermia

  • Temporary cell preservation above 0ºC, enabling transport at controlled temperatures.

Logistical Complexities in Cell Therapy

  • Issues in transport affecting product quality, requiring trained personnel at clinics.
  • Typical process chain includes tumor cell collection, manufacturing, and patient return.
  • Manufacturing strategies: Hub and Spoke (centralized) vs. Hub and Node (decentralized).