Adult Stem Cells (ASC) – Unspecialized, multipotent cells with a high differentiation potential found in virtually all tissues of the body. Their capacity for asymmetrical division allows them to both maintain the pool of stem cells in the tissue, whilst providing the supply of new proliferative cells essential for tissue homeostasis and stem cell self-renewal.

Animal Product Free (APF) or Animal Component Free Media (ACF) – Media made without animal derived components, thus typically, recombinant growth factors are used.

Bovine Pituitary Extract (BPE) – Extract from bovine pituitary gland used as a non-defined source of growth factors in cell culture.

Confluency – The amount of surface area of the tissue culture plate that is covered with cells expressed as a percent (e.g. 100% means that the whole culture vessel surface is covered with cells).

Defined Media – Media with a defined known set of purified compounds. Defined media therefore contain no serum, BPE, or conditioned media.

Dermis - Layer of the skin, located below the epidermis. Comprised primarily of fibroblasts in an extracellular matrix which consists mainly of collagen. Also contains nerve endings, sweat and sebaceous glands and blood and lymph vessels.

Embryonic Stem Cells (ESC) – Pluripotent cells, able to differentiate into all tissue types of the body. Mainly isolated from the inner cell mass of the blastocyst that forms during early embryonic development.

Epidermis - Multilayered epithelium forming the uppermost layer of the skin. Comprised primarily of keratinocytes. Key role is to provide the barrier function essential for protecting the body. The barrier is formed by fully differentiated, highly cohesive keratinocytes (corneocytes) embedded in lipid layers.

Epithelium - Tissue composed of one or more cell layers which form the covering of internal and external surfaces of the body and its organs. Epithelial layers are separated from the underlying connective tissue by a membrane, and are typically polarized.

Fetal Bovine Serum (FBS) or Fetal Calf Serum (FCS) – Serum obtained from fetal bovine / calf by blood clotting and subsequent sterile filtrations. Used as a non-defined source of growth factors and proliferation supporting factors in cell culture media.

Keratinocyte - An epithelial cell that produces keratins. Most commonly located in the epidermis, although also present in other epithelia (e.g. cornea, oral mucosa).

Passage Number – The number of times confluent cells have been detached from their culture vessel and then seeded into new vessels at a lower density to allow continued proliferation. Passage zero cultures are formed by seeding cells directly taken from a tissue. Following one detachment and seeding (or subcultivation), such cultures reach Passage 1 (P1). Also a freezing and thawing step of cells is a passage.

Primary Cell Culture – Term used by researchers denoting a recently isolated cell culture. Strictly speaking, only cells immediately following isolation (e.g. up to passage 1) are primary cells, but the term is commonly used to describe cell cultures in their first passages. Primary cells typically provide the most accurate modeling of cell behavior in vivo, and are also able to differentiate, dependent on the cells type. Primary cell cultures generally have a finite lifespan, i.e. they stop proliferating and enter senescence after a certain period in vitro.

Progenitor Cells – Unspecialized, unipotent sometimes oligopotent cells with a high differentiation and proliferation capacity found in tissues. This term is used in different ways but the exact definition and the term are still being discussed.

Progenitor Cell Targeted (PCT) – PCT media are developed using CELLnTEC’s specialized approach to create very precise progenitor cell environments, which accurately mimic the situation found in vivo. As a result, PCT media deliver improved cell isolation and growth of cells with high differentiation potential.

Serum Free Media (SFM) – Media which do not require the addition of serum.

Stem Cell Niche – The location within a tissue where adult stem cells reside. It is characterized by a very specific environment, which controls both the maintenance of the stem cell pool, as well as the release of cells from the niche to supply the needs of tissue maintenance and regeneration (homeostasis).