Skeletal Biology Consortium, Department of Cell Biology and Anatomy, Institute of Biomedicine, University of Turku, Turku, Finland.
Gene. 2012 Apr 10;497(1):1-9. doi: 10.1016/j.gene.2012.01.045. Epub 2012 Jan 28.
The adult bone marrow, situated within the bone cavity, comprises three distinct stem cell populations: hematopoietic stem cells (HSCs), mesenchymal stromal/stem cells (MSCs) and endothelial progenitor/stem cells (EPCs). HSCs are a well-characterized population of self-renewing cells that give rise to all blood cells. The definition of MSCs is more complex due to the limited understanding of MSC properties. In general, MSCs are considered multipotent stromal cells that are able to differentiate into various cell types, including osteoblasts, chondrocytes and adipocytes. Compared to HSCs and MSCs, EPCs are a newly discovered population of stem/progenitor cells with the capacity to differentiate into endothelial cells, the cells forming the inner lining of a blood vessel. Although functionally different, HSCs, MSCs and EPCs, like stem cells in general, share the ability to self-renew and differentiate into one or more cell types. The homeostasis inside the bone marrow and within the entire body is sustained by an intricate network of growth factors and transcription factors that orchestrate the proliferation and differentiation of these multipotent stem/progenitor cells. Increasing evidence indicates that microRNAs (miRNAs), small non-coding RNAs, are among the key players of this concert. This review summarizes the current insights into miRNA-mediated regulation of bone marrow stem/progenitor cell maintenance and differentiation. Furthermore, the potential contribution of miRNAs in bone marrow stem cell niches is discussed.
成人骨髓位于骨腔中，包含三个不同的干细胞群体：造血干细胞（HSCs）、间充质基质/干细胞（MSCs）和内皮祖细胞/干细胞（EPCs）。HSCs 是一种特征明确的自我更新细胞群体，可产生所有血细胞。由于对 MSC 特性的了解有限，因此 MSC 的定义更为复杂。一般来说，MSCs 被认为是多能基质细胞，能够分化为多种细胞类型，包括成骨细胞、软骨细胞和脂肪细胞。与 HSCs 和 MSCs 相比，EPCs 是一种新发现的具有分化为内皮细胞能力的干细胞/祖细胞群体，内皮细胞是形成血管内表面的细胞。尽管功能不同，但 HSCs、MSCs 和 EPCs 与一般干细胞一样，具有自我更新和分化为一种或多种细胞类型的能力。骨髓和整个身体内部的动态平衡是由一个错综复杂的生长因子和转录因子网络维持的，这些因子协调这些多能干细胞/祖细胞的增殖和分化。越来越多的证据表明，微小 RNA（miRNAs），即小的非编码 RNA，是这种协调的关键参与者之一。这篇综述总结了 miRNA 介导的骨髓干细胞/祖细胞维持和分化的最新研究进展。此外，还讨论了 miRNAs 在骨髓干细胞龛中的潜在作用。
