This is an exciting time for the field of stem cell biology. It would have been difficult to predict four years ago the tremendous progress that the field has seen both in basic research discoveries, as well as in therapeutic potential. From the first descriptions of the human embryonic and germ stem cells to the multipotentiality of adult stem cells, dramatic developments have occurred on all fronts. These developments have taken place under heightened awareness from scientists, the medical community, elected officials and interested citizens. All of us know much more about stem cells today than at any previous time, yet the foreseeable future promises even more exciting breakthroughs, including the discovery of new adult stem cells, and greater plasticity of these cells. Osiris is delighted to support this Nature Insight on the biology and potential of stem cells.

Almost 20 years ago the field of stem cell therapeutics was launched with the isolation of the hematopoietic stem cell. It took another 10 years before the mesenchymal stem cell was identified and utilized in the repair of connective tissues in pre-clinical models. Subsequently, fetal neural stem cells were used to treat patients with Parkinson's disease and adult liver stem cells have been identified. The search for other adult stem cells, such as those giving rise to pancreatic islets, continues. Preclinical and clinical studies have shown that the in vivo environment provides the necessary cues for tissue-appropriate differentiation and regulation of adult mesenchymal stem cells (MSCs). Additionally, recent studies have shown that MSCs are an “immune privileged” cell type and therefore do not stimulate an immune response in vitro or in vivo and can be used clinically without immunosuppression. Whether other adult or even embryonic stem cells will demonstrate the same immune privilege remains to be shown. Osiris' scientists and collaborators have demonstrated in several large animal models that the use of fully mismatched, donor-derived MSCs repaired bone, cardiac muscle and meniscus without evidence of immune rejection. The use of stem cells in such an “off-the-shelf” manner could make stem cell based cellular therapies feasible and cost-effective in the acute injury setting as well as in chronic disease states. The era of cellular and tissue regeneration for the treatment of disease and the effects of aging has indeed begun.

Though the articles in this publication can only touch on the possibilities that stem cell biology may provide, we can be certain that continued research will enhance significantly our understanding of human development. Through the dedication of many individuals, research teams and institutions, physicians and healthcare professionals, and in cooperation with industry and regulatory agencies, we are confident that stem cell biology will beneficially impact healthcare for all mankind.