The idea that peripheral blood monocytes could acquire a plasticity following an
in vitro de-differentiation has been successively supported by the report of
programmable cells of monocytic origin (PCMO). These cells are obtained from circulating monocytes isolated by plastic adherence from peripheral mononuclear cells in RPMI-1640 supplemented with 10% of human type AB serum. The subsequent treatment with low doses of M-CSF and IL-3 for six days led to proliferating PCMO capable of differentiation into neohepatocytes and pancreatic islet-like cells
\cite{Ruhnke_2005}. Moreover, PCMO express some endothelial features
\cite{Hutchinson2007} and recent data suggest that these cells are also able to differentiate
in vitro toward osteoblast-like cells
\cite{A_il_2017} and collagen type-II producing chondorcytes
\cite{Pufe2008}. Interestingly, similar to MPCs and MOMCs, PCMO express OCT-4 and NANOG but the de-differentiation process has been analyzed in more details at the molecular levels. Ungefroren
et al. demonstrated that the reactivation of OCT-4 and NANOG genes in peripheral monocytes is essential to generate PCMO, also combined with the expression of other reprogramming factors as KLF4 and MYC, but not SOX2
\cite{Ungefroren_2010}, this molecular signature is identical to what reported in MPCs
(Pacini 2010). Moreover, Authors also showed that after "reprogramming" in PCMO inducing medium the percentage of CD14-positive cells vary from 90-95% to around 45%, ranging from 30% to 60%, while other markers as CD86 and HLA-DR remained constant over the culture time. These data strongly suggest that