HOX decoy peptide enhances the ex vivo expansion of human umbilical cord blood CD34+ hematopoietic stem cells/hematopoietic progenitor cells.
HOX decoy peptide enhances the ex vivo expansion of human umbilical cord blood CD34+ hematopoietic stem cells/hematopoietic progenitor cells.
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DOI：
10.1634/stemcells.2006-0434
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发表时间：
2006-06
期刊：
影响因子：
5.2
通讯作者：
A. Terunuma;V. Kapoor;C. Yee;W. Telford;M. Udey;J. Vogel
中科院分区：
文献类型：
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作者：
A. Terunuma;V. Kapoor;C. Yee;W. Telford;M. Udey;J. Vogel
活的人上皮干细胞的分离和鉴定是困难的，因为区分细胞表面标记还没有确定的鉴定。侧群角质形成细胞(SP-KCs)类似于骨髓源性侧群(SP)造血干细胞，可外排Hoechst 33342荧光染料，已在人体皮肤中被发现，但其在体内作为角质形成干细胞(KSCs)的潜力尚不清楚。另一方面，根据已报道的体外细胞培养试验结果，表达高水平β1和α6整合素的人角质形成细胞群与表达低整合素水平的SP-KCs不同，可能对KSCs具有浓集作用。当使用体外实验测量人SP-KCs和整合素亮的角质形成细胞的总细胞产量时，我们不能证明它们比未分离的角质形成细胞具有更好的长期增殖活性。为了进一步评估SP-KCs和整合素亮的角质形成细胞的KSC特性，我们采用了体内竞争再繁殖实验，将含有不同人类主要组织相容性(MHC)I类抗原的竞争角质形成细胞群的生物工程化人表皮移植到免疫低下的小鼠身上，并使用固有的MHC I类抗原来量化竞争群体的扩张。在这些体内研究中，人的SP-KCs在体内几乎没有显示出竞争性扩张，也没有对KSCS进行浓缩。相比之下，在33周的体内研究中，表达高水平的α6整合素和低水平的CD71(α6-Bright/CD71-Dim)的角质形成细胞扩大了200多倍。这些结果明确地表明，人α6-Bright/CD71-Dim角质形成细胞富含KSCs，而SP-KCs不富含KSCs。
The isolation and characterization of living human epithelial stem cells is difficult because distinguishing cell surface markers have not been identified with certainty. Side population keratinocytes (SP-KCs) that efflux Hoechst 33342 fluorescent dye, analogous to bone marrow-derived side population (SP) hematopoietic stem cells, have been identified in human skin, but their potential to function as keratinocyte stem cells (KSCs) in vivo is not known. On the other hand, human keratinocyte populations that express elevated levels of beta1 and alpha6 integrins and are distinct from SP-KCs, which express low levels of integrins, may be enriched for KSCs based on reported results of in vitro cell culture assays. When in vitro assays were used to measure total cell output of human SP-KCs and integrin-bright keratinocytes, we could not document their superior long-term proliferative activity versus unfractionated keratinocytes. To further assess the KSC characteristics in SP-KCs and integrin-bright keratinocytes, we used an in vivo competitive repopulation assay in which bioengineered human epidermis containing competing keratinocyte populations with different human major histocompatibility (MHC) class I antigens were grafted onto immunocompromised mice, and the intrinsic MHC class I antigens are used to quantify expansion of competing populations. In these in vivo studies, human SP-KCs showed little competitive expansion in vivo and were not enriched for KSCs. In contrast, keratinocytes expressing elevated levels of alpha6 integrin and low levels of CD71 (alpha6-bright/CD71-dim) expanded over 200-fold during the 33-week in vivo study. These results definitively demonstrate that human alpha6-bright/CD71-dim keratinocytes are enriched with KSCs, whereas SP-KCs are not.