Chondrocytes (from Greek χόνδρος, chondros = cartilage + κύτος, kytos = cell) are the only cells found in healthy cartilage. They produce and maintain the cartilaginous matrix, which consists mainly of collagen and proteoglycans. Although the word chondroblast is commonly used to describe an immature chondrocyte, the term is imprecise, since the progenitor of chondrocytes (which are mesenchymal stem cells) can differentiate into various cell types, including osteoblasts.
Mesenchymal (mesoderm origin) stem cells (MSC) are undifferentiated, meaning they can differentiate into a variety of generative cells commonly known as osteochondrogenic (or osteogenic, chondrogenic, osteoprogenitor, etc.) cells. When referring to bone, or in this case cartilage, the originally undifferentiated mesenchymal stem cells lose their pluripotency, proliferate and crowd together in a dense aggregate of chondrogenic cells (cartilage) at the location of chondrification. These chondrogenic cells differentiate into so-called chondroblasts, which then synthesize the cartilage extra cellular matrix (ECM), consisting of a ground substance (proteoglycans, glycosaminoglycans for low osmotic potential) and fibers. The chondroblast is now a mature chondrocyte that is usually inactive but can still secrete and degrade the matrix, depending on conditions.
The Origin of Stem Cells The origin of stem cells includes human mesenchymal stem cells which are cells with the capacity to differentiate into, among other tissues, osteocytes, adipocytes, and chondrocytes (cartilage producing cells). The isolation and characterization of mesenchymal stem cells occurred decades ago (1966). It wasn’t much longer before scientist began to study […]