Circulating progenitor stem cells are important biomarkers of chondrogenesis and osteogenesis: employment in diagnosis and treatment follow up

Adult multipotent mesenchymal stem cells (MSCs) arouse great scientific interest because of their many possible clinical applications. Besides the therapeutic potential for tissue regeneration and repair, they also offer new opportunities as diagnostic tools. For diagnostic purposes peripheral blood represents an easily accessible source of circulating MSCs which show similar characteristics compared to bone marrow MSCs. Dysfunctions in chondrogenic and osteogenic differentiation of MSCs are involved in the genesis of age-related degenerative disorders as osteoarthritis and osteoporosis. Altered expression profiles of specific transcription factors may be monitored in the ex vivo analysis of patients’ peripheral blood MSCs; they represent important biomarkers for diagnosis. Furthermore, changes in MSCs expression profiles induced by pharmacological treatments are useful biomarkers for therapy followup. MicroRNAs also play a crucial role in chondrogenic and osteogenic differentiation of progenitor cells; differentially expressed microRNAs have been associated with osteoarthritis and osteoporosis, respectively. MicroRNAs can be recovered from blood, urine, and synovial fluid and represent useful supplemental tools for the diagnosis of these degenerative disorders. In conclusion, circulating MSCs can be obtained by a non-invasive approach and provide an “ex vivo” source for monitoring various differentiation pathways in normal and pathological conditions; thus they represent a remarkable resource for various clinical applications.