Blood vessel assembly from multipotent hemangioma-derived stem cells

 描述（由申请人提供）：婴儿血管瘤（IH）是一种血管肿瘤，在婴儿期的前6-9个月内具有快速生长的独特生命周期，随后是几年的缓慢自发消退期。对于大多数儿童来说，IH不会构成严重威胁，治疗是不必要的;然而，在大约10%的情况下，IH可以急剧扩大，威胁器官并导致永久性毁容。尽管有相对安全的治疗方法，但一些IH生长如此迅速，以至于在治疗开始或生效之前发生显著的组织损伤，而一些IH没有反应。因此，迫切需要更深入地了解IH发生的细胞和分子驱动因素，以便开发更有效，快速起效的疗法。在上一个资助周期中，我们发现血管瘤干细胞（HemSC）分化为内皮细胞（EC）和周细胞，并在体内（7天内）形成功能和灌注的血管网络。重要的是，由HemSC在体内形成的血管表达葡萄糖转运蛋白1（GLUT 1），这是IH血管的独特标志物。我们还首次分离出血管瘤周细胞（HemPericytes），并表明来自增殖IH的HemPericytes是促血管生成的，表达低促血管生成素-1，并且与正常周细胞相比收缩性较低。我们还重新检查了IH内皮细胞，以将葡萄糖转运蛋白1阳性（GLUT 1+）EC与GLUT 1阴性EC区分开来。我们有一个惊人的发现，IH中的GLUT 1 + EC是兼性干细胞-它们表现出内皮细胞的表型和功能特征， 当从IH中取出时，表达克隆形成和多谱系分化的干细胞样特性。有了这四个不同的细胞群体，我们将解决有关IH未解决的问题。第一个是是否有一个遗传成分爆炸性血管生长发生在IH。在目的1中，将对四个纯化的细胞群体进行全外显子组测序和生物信息学分析。将对患者外周血单核细胞进行测序以进行比较。这种基于纯化细胞的方法将大大降低检测异源IH标本中体细胞突变的难度，并将精确定位携带突变的细胞类型。在目标2中，我们将讨论HemPericytes在退化期开始时的作用以及它们如何影响GLUT 1 + EC。在目标3中，我们将研究雷帕霉素如何将GLUT 1 +EC从IH转化为非增殖状态，并破译雷帕霉素改变以实现这一目标的分子靶点。从我们的研究中获得的信息可能会带来新的见解，并对IH的临床管理产生影响。此外，从解开IH血管生长获得的知识将产生对正常人类出生后新生血管形成机制的基本见解。

 DESCRIPTION (provided by applicant): Infantile hemangioma (IH) is a vascular tumor with a unique lifecycle of rapid growth over the first 6-9 months of infancy, followed by a slow spontaneous involuting phase of several years. For most children, IH does not pose a serious threat and therapy is unnecessary; however, in about 10% of cases, IH can enlarge dramatically, threaten organs and cause permanent disfigurement. Despite the availability of relatively safe therapies, some IH grow so rapidly that significant tissue damage occurs before therapy can be started or take effect, and some IH do not respond. Thus, there is a pressing need to reach a deeper understanding of the cellular and molecular drivers of IH-genesis so that more effective, fast-acting therapies can be developed. In the previous funding cycle, we showed that hemangioma stem cells (HemSC) differentiate into endothelial cells (EC) and pericytes and form functional and perfused vascular networks in vivo (within 7 days). Importantly, the vessels formed in vivo from the HemSC express glucose transporter-1 (GLUT1), a unique marker of IH blood vessels. We also isolated hemangioma pericytes (HemPericytes) for the first time and showed that HemPericytes from proliferating IH are pro-angiogenic, express low angiopoietin-1 and are less contractile compared to normal pericytes. We also re-examined the IH endothelial cells to sort out glucose transporter-1-positive (GLUT1+) EC from GLUT1-negative EC. We made a striking finding that GLUT1+ EC in IH are facultative stem cells - they exhibit phenotypic and functional characteristics of endothelium, but when removed from the IH express stem cell-like properties of clonogenicity and multi-lineage differentiation. With these four distinct cell populations from IH, we will address unsolved questions regarding IH. The first is whether there is a genetic component to explosive vascular growth that occurs in IH. In Aim 1, the four purified cell populations will be subjected to whole exome sequencing and bioinformatics analysis. Patient peripheral blood mononuclear cells will be sequenced for comparison. This purified cell-based approach will greatly reduce the difficulty of detecting a somatic mutation in heterogenous IH specimens and it will pinpoint the cell types that carry the mutation. In Aim 2, we will address the role HemPericytes play in the onset of the involuting phase and how they affect the GLUT1+ EC. In Aim 3, we will study how rapamycin converts GLUT1+EC from IH to a non-proliferative status and decipher the molecular targets rapamycin alters to achieve this. The information gained from our studies may lead to new insights and have impact on clinical management of IH. In addition, the knowledge gained from unraveling vascular growth in IH will yield fundamental insights into the mechanisms of normal, human post-natal neovascularization.