Human placenta-derived adherent cells prevent bone loss, stimulate bone formation, and suppress growth of multiple myeloma in bone.

Human placenta has emerged as a valuable source of transplantable cells of mesenchymal and hematopoietic origin for multiple cytotherapeutic purposes, including enhanced engraftment of hematopoietic stem cells, modulation of inflammation, bone repair, and cancer. Placenta-derived adherent cells (PDACs) are mesenchymal-like stem cells isolated from postpartum human placenta. Multiple myeloma is closely associated with induction of bone disease and large lytic lesions, which are often not repaired and are usually the sites of relapses.

Stem cells in adult tissues.

In recent years the concept of a stem cell has evolved to encompass the hypotheses that stem cells exist within many adult tissues, and that a common 'interchangeable' progenitor cell may exist within the bone marrow capable of regenerating and repairing tissues throughout the body. As more knowledge is gained about stem cells, their potential roles in disease processes, including the development and progression of cancer, have moved to the forefront. The underlying hypothesis of this review is that cell fate is determined by a combination of intrinsic and extrinsic factors; growth and differentiation are regulated through intracellular integration of a multitude of signals initiated by internal and external stimuli.

Molecular signaling in bioengineered tissue microenvironments.

Biological tissues and organs consist of specialized living cells arrayed within a complex structural and functional framework known generally as the extracellular matrix (ECM). The great diversity observed in the morphology and composition of the ECM contributes enormously to the properties and function of each organ and tissue. For example, the ECM contributes to the rigidity and tensile strength of bone, the resilience of cartilage, the flexibility and hydrostatic strength of blood vessels, and the elasticity of skin.