The GIBCO Roswell Park Memorial Institute (RPMI) 1640 Medium is a foundational nutrient broth used in biological research to facilitate the growth of cells outside of a living organism. This specialized liquid medium provides the necessary amino acids, vitamins, and inorganic salts that mammalian cells require to survive and proliferate in a controlled laboratory setting. Its formulation is one of the most widely used in the life sciences, supporting a broad spectrum of cellular studies.
The Foundation of RPMI 1640
The medium’s name reflects its origin: RPMI stands for the Roswell Park Memorial Institute, now the Roswell Park Comprehensive Cancer Center. Developed in the mid-1960s by George E. Moore and colleagues, the 1640 formulation was a modification of earlier RPMI media, specifically tailored to address the nutritional needs of particular cell types. The original design purpose for this formulation was the successful culture of human leukocytes, or white blood cells.
This initial focus meant the medium was optimized to support non-adherent, or suspension, cells, such as lymphocytes, which naturally float rather than sticking to a surface. This design choice created an environment conducive to the demanding growth requirements of blood-derived cells, making the product indispensable for studies involving the immune system.
Key Components and Unique Formulation
RPMI 1640 distinguishes itself from other common basal media, such as Dulbecco’s Modified Eagle Medium (DMEM), through its particular chemical makeup. The formulation includes a higher concentration of certain vitamins often absent in other media, specifically Biotin, Vitamin B12, and PABA (para-aminobenzoic acid). This rich vitamin profile, alongside a higher overall phosphate concentration, helps meet the metabolic demands of lymphocytes and other fast-growing cell lines.
The medium also contains a comprehensive mixture of amino acids, including L-Glutamine, a major energy source for many cells. Because L-Glutamine degrades in liquid, commercial formulations often include a stable substitute, such as GlutaMAX, to prevent the buildup of toxic ammonia byproducts. A significant characteristic of RPMI 1640 is its reliance on a sodium bicarbonate buffer system to maintain the physiological pH necessary for cell survival. Like most basal media, the 1640 formulation lacks the complex proteins and growth factors required for proliferation, meaning it must be supplemented before use.
Essential Applications in Research
RPMI 1640 is used for culturing cells that naturally grow in suspension. This includes its original purpose of growing human T and B lymphocytes, making it a standard medium in immunological studies. The medium’s robust composition supports the manipulation and expansion of immune cells for experiments related to vaccine development and fundamental research into immune function.
The medium is also a foundational tool in cancer research, especially for cultivating human malignant cell lines derived from blood cancers. Leukemic and lymphoblastoid cell lines, such as Jurkat and HL-60, thrive in this formulation, allowing researchers to study cancer cell biology, test new therapeutic drugs, and perform toxicity testing. Its versatility extends to the culture of hybridoma cells for monoclonal antibody production and even some adherent cell lines.
Preparation and Handling Requirements
Before RPMI 1640 medium can support cell growth, it requires specific preparation and controlled handling. The basal medium is incomplete and must be supplemented with a source of proteins and growth factors, most commonly Fetal Bovine Serum (FBS), typically added at 5-10% by volume to create “complete media.”
To guard against microbial contamination, it is standard practice to add antibiotics, such as Penicillin and Streptomycin, to the complete medium. The sodium bicarbonate buffer system necessitates that cell cultures be incubated in an atmosphere containing 5-10% Carbon Dioxide (CO2). This CO2 level ensures the buffer maintains the correct pH range of 7.2–7.4, preventing the medium from becoming too alkaline. For storage, both the unprepared liquid medium and the complete, supplemented medium must be kept refrigerated at 2-8°C and protected from strong light to preserve the integrity of the components.