ZÉLL-V Optimised Special Purpose Application (O.S.P.A.) is a combination of Mesenchymal Stem Cells and organ cell factors of the endocrine system, immune system and detox system to optimise overall rejuvenation and regeneration of the human body. What are Mesenchymal Stem Cells? Mesenchymal Stem Cells are multipotent stromal cells derived from the mesoderm, one of the three primary germ cell layers formed at the very beginning of life. Mesenchymal Stem Cells are the most elementary building blocks of all the connective tissue in our body, including skin, muscle, tendon, ligaments, blood vessels, nerves, bone and cartilage.