The<unk>  (also referred to as the stromal<unk><unk>  is a collective term for the paracrine soluble factors produced by<unk> <unk> s and utilized for their inter-cell communication. In addition to inter-cell communication, the paracrine factors are also responsible for tissue development, homeostasis and (re-)generation. The<unk>  consists of extracellular vesicles, specifically exosomes, microvesicles, membrane particles, peptides and small proteins (cytokines). The paracrine activity of<unk> <unk> s, i.e. the<unk> , has been found to be the predominant mechanism by which<unk> <unk> -based therapies mediate their effects in degenerative, auto-immune and/or inflammatory diseases. Though not only<unk> <unk> s possess a<unk>  which influences their<unk> ular environment, their<unk>  currently appears to be the most relevant for therapeutic use.
Stem cell secretome
Neurotrophic factors
Protein corona
Fluid compartments
Lymphokine
Pulmonary surfactant
Pulmonary surfactant 
Reinforced lipids