**3. Conclusions**

The membrane markers CD73, CD90, and CD105 allow stem cells and other stromal cells such as fibroblasts to react to stimuli and quickly leave their quiescent state, thereby going into a proliferation state and generating growth factors. Those capacities allow the recovery of parenchymal tissue in which they are found. CD73 is an ectoenzyme that dephosphorylates nucleoside AMP given free ADO. This purine binding to its membrane receptor leads to the activation of the G protein and results in the activation of a pathway that reaches the nucleus. As a consequence, extracellular matrix and growth factors such as VEGF are synthesized. CD90 influences the cell cycle and cell proliferation. CD90 also induce several cytoskeletal changes allowing cell differentiation. CD105 is a co-factor to the TGF-β receptor and following TGF-β union with its receptor a signaling cascade is activated, resulting in the transcription of different effectors including the synthesis of pro-inflammatory cytokines, which have an important role in angiogenesis and proliferation. In conclusion, those membrane markers are related to pathways that regulate the immune response, cell proliferation, and differentiation, thereby allowing lost tissue recovery and the formation of new angiogenic pathways.
