Human Tenocytes are responsible for the synthesis and maintenance of a mechanically unique connective tissue; endowing them with the ability to resist the high tensile forces subjected to the tendon in vivo. Tenocytes are part of an extensive three-dimensional network of extracellular matrix components consisting predominantly of collagen type I fibrils (>95% of tendon collagen), but also other types of collagen (type III and type V), proteoglycans, elastin and fibronectin. These tendon-specific matrix components give tendon its resilience and biomechanical stability. Immortalized Human Tenocytes are useful in vitro models for studying tendon regeneration and repair, cytokine and growth factor effects on tendon; but also specific gene regulation and pathophysiology of tendon disorders. Immortalized Human Tenocytes Line is a useful tool to understand the highly integrated balance between proliferation, differentiation, and cell death. This cell line also allow to stablish in vitro models for HIgh Throughput and High Content Screening.