The programmable cell of monocytic origin (PCMO): a potential adult stem/progenitor cell source for the generation of islet cells.

Adult stem or programmable cells hold great promise in diseases in which damaged or non-functional cells need to be replaced, such as in type 1 diabetes. We have recently demonstrated that peripheral blood monocytes can be differentiated in vitro into pancreatic beta-cell-like cells capable of synthesizing insulin. The two-step phenotypic conversion commences with growth factor-induced partial reprogramming during which the cells acquire a state of plasticity along with expression of various markers of pluripotency. These cells, termed "programmable cells of monocytic origin" (PCMOs), can then be induced with appropriate differentiation media to become insulin-producing cells (NeoIslet cells). Expression profiling of transcription factors known to determine endocrine and beta-cell development in vivo indicated that NeoIslet cells resemble cells with an immature beta-cell phenotype. Current efforts focus on establishing culture conditions that (i) increase the plasticity and proliferation potential of PCMOs by enhancing the reprogramming process and (ii) improve insulin production by mimicking in vivo lineage specification and normal pancreatic endocrine development. Combining these two strategies has great potential in generating large amounts of blood-derived cells suitable for both autologous and allogeneic therapy of type 1 diabetes.