Hematopoietic stem cells (HSCs) are characterized by two key features: Self-renewal ability and multilineage differentiation potential (multipotentiality). With aging, these key features gradually change. This is thought to be related to hematological diseases. However, clonal in vivo analysis assessing the potential of HSCs to differentiate along erythroid and platelet lineages (“five-lineage tracing”) has not been performed in the aged bone marrow. By contrast, in young HSCs clonal in vivo analysis combined with five-lineage tracing has provided us with novel insights into HSC biology. Understanding HSC aging at the clonal level will help us to elucidate aging mechanisms and disease progression. We review recent progress towards understanding HSC aging at the clonal cell level in the transplantation setting.

造血干细胞 (HSC) 具有两个关键特征：自我更新能力和多向分化潜能（multipotentiality）。随着年龄的增长，这些关键特征会逐渐发生变化。这被认为与血液系统疾病有关。然而，尚未在老化的骨髓中进行评估 HSC 沿红细胞和血小板谱系分化的潜力的克隆体内分析（“五谱系追踪”）。相比之下，在体内克隆的年轻 HSC中分析结合五谱系追踪为我们提供了对 HSC 生物学的新见解。在克隆水平上了解 HSC 衰老将有助于我们阐明衰老机制和疾病进展。我们回顾了在移植环境中在克隆细胞水平上了解 HSC 老化的最新进展。