Notes on Cell Culture Conditions and Media

Culture Conditions and Media

Objective

  • Familiarize with the composition and function of cell culture media.

Cell Culture Media Overview

  • Type: Complex liquid that supports growth across generations.

  • Formats: Available as:

    • 1x liquid (ready to use)

    • 10x concentrated solution

    • Powdered form (needs dilution in pre-sterilized distilled water; subsequently filtered and sterilized).

Hybridoma Medium - RPMI 1640

  • Key Components:

    • L-Amino acids (e.g., Arginine, Aspartic acid, and Glutamine)

    • Vitamins and Co-factors (e.g., Biotin, Folic acid, Nicotinamide)

    • Inorganic ions (e.g., NaCl, KCl, Ca(NO3)2)

    • Glucose (11.0 mM)

  • Supplemented with: 10% serum; Phenol red (5 mg/L) used as a pH indicator.

Components of a Typical Culture Medium

  1. Carbohydrates

    • Commonly glucose (25 mM); can also use fructose, galactose, etc.

    • Provides energy and serves as a precursor for nucleic acid biosynthesis.

  2. Amino Acids

    • Crucial for protein synthesis; commonly requires glutamine (2-4 mM).

    • Excess ammonia from glutamine metabolism can inhibit growth; methods to reduce ammonia include using dipeptides or controlling glutamine levels in culture.

  3. Salts

    • Make solution isotonic, critical for maintaining osmolarity (~250-350 mOsm/L optimal).

    • Examples: 1 mM glucose -> 1 mOsm/L, 1 mM NaCl -> 2 mOsm/L.

  4. Buffering System

    • Bicarbonate: Used in conjunction with a CO₂ atmosphere (5-10%).

    • Alternate buffers: HEPES, MES, CHES for maintaining pH within the range of 6.9-7.4.

  5. Vitamins and Hormones

    • Present in micromolar amounts, serve as metabolic cofactors depending on cell line requirements.

  6. Antibiotics

    • Included to minimize contamination risks; common combinations:

      • Penicillin G (100 u/mL)

      • Streptomycin (50 mg/L)

      • Amphotericin B (25 mg/L) as antifungal.

  7. Phenol Red

    • Serves as a pH indicator; changes color (orange/yellow where pH lower than optimum) with acidification, indicating contamination.

Serum in Cell Culture

  • Purpose: Provides undefined materials essential for cell growth:

    • Growth factors

    • Lipids

    • Attachment factors

    • Protease inhibitors

  • Types of Serum:

    • Cow or horse serum; fetal calf serum (most effective due to embryonic growth factors).

  • Disadvantages:

    • Expensive

    • Chemically undefined

    • Potential source of contamination

  • Alternatives:

    • Serum-free media utilizing supplements like insulin, transferrin, ethanolamine, and selenite.

Media Formulation Characteristics

  • Serum-Based Media

  • Serum-Free Media

  • Protein-Free Media

  • Animal-Component Free Media

  • Chemically Defined Media: Goals include chemically defined formulations, protein-free, and devoid of animal components.