Platelets Facilitate the Wound-Healing Capability of Mesenchymal Stem Cells by Mitochondrial Transfer and Metabolic Reprogramming.

Platelets are known to enhance the wound-healing activity of mesenchymal stem cells (MSCs). However, the mechanism by which platelets improve the therapeutic potential of MSCs has not been elucidated. Here, we provide evidence that, upon their activation, platelets transfer respiratory-competent mitochondria to MSCs primarily via dynamin-dependent clathrin-mediated endocytosis.

Neuraminidase enhances in vitro expansion of human erythroid progenitors.

In spite of recent key improvements, in vitro mass production of erythrocytes from human stem cells is still limited by difficulties in obtaining sufficient numbers of erythroid progenitors. In fact, such progenitors are as scarce in the bone marrow as in peripheral blood. We used a two-step culture model of human cord blood-derived erythroid progenitors in the presence or absence of high-purity neuraminidase, in a serum-free, defined culture medium.

HOXC4 homeoprotein efficiently expands human hematopoietic stem cells and triggers similar molecular alterations as HOXB4.

Background: Expansion of hematopoietic stem cells represents an important objective for improving cell and gene therapy protocols. Retroviral transduction of the HoxB4 homeogene in mouse and human hematopoietic stem cells and hematopoietic progenitors is known to promote the cells' expansion. A safer approach consists in transferring homeobox proteins into hematopoietic stem cells taking advantage of the natural ability of homeoproteins to cross cell membranes.

Efficient in vitro myogenic reprogramming of human primary mesenchymal stem cells and endothelial cells by Myf5.

Background Information: The identification of a source of stem cells able to regenerate skeletal muscle was the goal of numerous studies with the aim to develop new therapeutic approaches for genetic muscle diseases or muscle injuries. A series of studies have demonstrated that stem cells derived from various tissues may have a role in the regeneration of damaged muscles, but this contribution is always very weak. Thus we established a project aiming to reprogramme non-muscle cells into the skeletal striated differentiation pathway.

Chromatin modifications in hematopoietic multipotent and committed progenitors are independent of gene subnuclear positioning relative to repressive compartments.

To further clarify the contribution of nuclear architecture in the regulation of gene expression patterns during differentiation of human multipotent cells, we analyzed expression status, histone modifications, and subnuclear positioning relative to repressive compartments, of hematopoietic loci in multipotent and lineage-committed primary human hematopoietic progenitors. We report here that positioning of lineage-affiliated loci relative to pericentromeric heterochromatin compartments (PCH) is identical in multipotent cells from various origins and is unchanged between multipotent and lineage-committed hematopoietic progenitors. However, during differentiation of multipotent hematopoietic progenitors, changes in gene expression and histone modifications at these loci occur in committed progenitors, prior to changes in gene positioning relative to pericentromeric heterochromatin compartments, detected at later stages in precursor and mature cells.