Is Urine the Next Source of Stem Cells?

Abstract

committee’s knowledge of the availability and the feasibility of using other tissue sources such as hair. This is especially an issue in the case of pediatric disorders where the parent or guardian provides informed consent. The recent reports that iPSCs can be successfully derived from cells collected from human urine [2–5] could potentially address the aforementioned problems and greatly expand the number of patient-specific stem cells available to the research community. The few thousand epithelial-like cells harvested by centrifugation from a 50–250-ml sample of urine have been used as a source of iPSCs (UiPSCs) and neural progenitors (UiNPCs) [2–5]. UiPSCs, which have been generated using standard reprogramming factors, show the markers of pluripotency that are typical of iPSCs produced from other somatic cell types. UiPSCs can also be differentiated into at least three different lineages: hepatocytes, neurons and cardiomyocytes [5], and disease-specific UiPSCs have been generated for systemic lupus erythematosus [2]. It is also reported that UiNPCs can be reprogrammed directly from the urine epithelial-like cells using episomal vectors that, in contrast to retroand lenti-viruses, do not integrate into the genome [3]. It is further observed that the UiNPCs have the capacity to self-renew and can be differentiated into different types of functional neurons in vitro, and in vivo upon transplant into newborn rat brain. There is no question that urine offers benefits over dermal fibroblasts and most other tissues in terms of ease of collection and institutional study approval. The investigations of other groups will confirm whether UiPSCs are similar to standard iPSCs with respect to efficiency of reprogramming as well as degree of pluripotency and capacity for multilineage differentiation. Should this prove to be the case, UiPSCs The discovery that pluripotent stem cells can be induced by exposure of somatic cells to reprogramming factors has proven to be one of the most surprising and potentially useful discoveries in regenerative biology [1]. Patient-specific induced pluripotent stem cells (iPSCs) are being widely used to study disease mechanisms and to screen for novel drug therapies for a variety of human disorders. Fibroblasts were the first somatic cell type to be used in the successful generation of iPSCs and remain in widespread use despite the demonstration that iPSCs can be derived from other readily accessible sources, such as peripheral and cord blood, melanocytes, amniotic and periodontal tissue and hair follicle keratinocytes. The continued popularity of fibroblasts as a source of iPSCs may be historical in the sense that many laboratories began deriving fibroblasts from skin biopsies in anticipation of generating iPSCs and are now in the process of characterizing the disease-specific iPSC lines.