Expression of Id2 in the developing limb is associated with zones of active BMP signaling and marks the regions of growth and differentiation of the developing digits.

Here we report the pattern of expression of inhibitor of DNA binding/differentiation factor 2 (Id2) in the developing chicken limb. We show that prior to stage 25, Id2 is expressed in the anterior and posterior mesoderm, the AER, and in the early skeletal chondrogenic aggregates. At more advanced stages of limb development Id2 is expressed in the undifferentiated subectodermal and interdigital mesenchyme and exhibits specific domains of expression in the growing digits.

Migration and differentiation of human umbilical cord stem cells after heart injury in chicken embryos.

Here we have analyzed the behavior and fate of stem cells from human umbilical cord blood (scHUCBs) when grafted into the myocardial wall of normal and damaged hearts of chicken embryos. We started by characterizing the scHUCBs before grafting and we found that they express precardiogenic genes including Nkx2.5, GATA4, MEF-2, and SERCA2a together with undifferentiation markers as CD34 or c-kit.

Experimental models for cardiac regeneration.

Simple ex vivo or in vitro models are most useful for testing putative cell therapy protocols, as they allow quick and controlled screening of variants and possible improvements. We discuss here three different models: coculture of precursors of human bone marrow cells (BMCs) with mouse heart slices bearing a cryogenic lesion; coculture of human BMCs and rat cardiomyocytes separated by a porous membrane that allows passage of soluble substances but prevents migration of nuclear material; and injection of human BMCs in developing chick heart bearing burn lesions. Our results indicate that the damaged areas express specific genes such as MPC1 and SDF1, and that some human BMCs migrate and graft near the lesion, where they can originate cells with a cardiac phenotype that produce human cardiac proteins.