title: Hematopoietic Stem Cells, Their Niche, and the Concept of Co-Culture Systems: A Critical Review.
abstract: Hematopoietic stem cells (HSCs) have the ability to self-renew and give rise to all lineages of blood cells. HSCs reside in niches that are local tissue microenvironments that maintain and regulate them. Although much progress has been made in elucidating the location and cellular components of the HSC niche, however it still remains incompletely defined. Transplantation using HSCs has been applied for the treatment of several diseases but with limited success. Furthermore, although human HSC transplantation has been widely used to rescue the patients after cytoablative therapies, quantitative in vivo human assays for hematopoietic cells have been considered to be neither ethical nor practical. Since HSCs persist in small quantities in the body, understanding the mechanism that govern their fate is essential for the advancement of HSC expansion and transplantation in the future. Since bone marrow is the primary site of HSC maintenance and hematopoiesis, defining the niche components that work in concert to regulate hematopoiesis is crucial to improve regeneration following injury or following HSC transplantation and to also understand how disordered niche function could contribute to disease. In recent years, there has been a growing realization of the limitations in identifying the primitive HSCs by its phenotype alone and therefore the concept of co-culture systems (functional in vitro assays) has become increasingly important to demonstrate the presence of primitive hematopoietic cells by estimating their biological functions. This system has provided a basis for the development of powerful assay procedures for expanding, quantitating and distinguishing cells at discrete stages of early hematopoietic cell differentiation.
authors.forename: Anuradha
authors.initials: A
authors.lastname: Vaidya
authors.forename: Vaijayanti
authors.initials: V
authors.lastname: Kale
mesh_terms: D015415:Biomarkers / Q000378:metabolism; D001854:Bone Marrow Cells / Q000166:cytology / Q000378:metabolism; D002454:Cell Differentiation; D019070:Cell Lineage / Q000235:genetics; D049109:Cell Proliferation; D018920:Coculture Techniques; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics; D015870:Gene Expression; D006410:Hematopoiesis / Q000502:physiology; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000378:metabolism; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000378:metabolism; D012038:Regeneration / Q000502:physiology; D055153:Stem Cell Niche / Q000502:physiology*
chemical_list: D015415:Biomarkers; D016207:Cytokines