Radiation Damage Repair in the Brain via Human ES cells

描述（申请人提供）：脑辐照是治疗癌症的有力工具，包括原发性和转移性肿瘤，甚至白血病和淋巴瘤。然而，它的使用受到神经组织耐受性差和长期幸存者严重副作用发展的限制。其中包括智商和认知功能的下降。这种现象是非常频繁和不可逆的。其发病机制尚未完全阐明，但它涉及广泛脱髓鞘发生在延迟的方式（数月至数年）。根据在大鼠身上获得的初步数据，我们假设辐射耗尽了分裂的少突胶质细胞祖细胞（OPC），因此大脑取代髓鞘细胞的能力。我们已经在人类胚胎干细胞（hES）的神经分化方面积累了丰富的经验，我们建议移植胚胎干细胞衍生的神经前体作为修复辐射引起的脑损伤的有效策略。

DESCRIPTION (provided by applicant): Brain irradiation is a powerful tool in the treatment of cancers including primary and metastatic many tumors, and even leukemias and lymphomas. However its use is restricted by the poor tolerance of the nervous tissue and the development of serious side effects among long-term survivors. These include a decline in IQ and cognitive function. This phenomenon is very frequent and irreversible. Its pathogenesis is not fully elucidated but it involves extensive demyelination occurring in a delayed fashion (months to years). Based on preliminary data obtained in the rat, we hypothesize that radiation exhausts the pool of dividing oligodendrocyte progenitors (OPC) and therefore the brain's ability to replace the myelinating cells. We have developed significant experience in the neural differentiation of human ES (hES) cells and we propose the transplantation of hES-derived neural precursors as an effective strategy for repair of radiation-induced brain damage. We will study the temporal and topographic pattern of cell loss following whole brain irradiation in the rat at five timepoints over the course of one year. The rats will receive BrdU prior to sacrifice and the brains will be processed for BrdU, NG2 (an OPC marker) and other neural markers. We will then graft irradiated rats with two different populations of neural precursors obtained from hES cells: a multipotential neural stem cell-like population, and an oligodendroglial progenitor population. In our preliminary data we have successfully derived such cells from hES cells and established stable eGFP-expressing hES cells via lentiviral gene transfer for reliable in vitro and in vivo identification. Grafted animals will be examined at 6 weeks after transplantation to assess cell survival, migration, and ability to replace the OPC niche, and at 6-8 months after transplantation to evaluate the ability of hES cells to contribute to remyelination of the injured brain. This work addresses a therapeutically important problem in brain cancer treatment and will provide a wealth of information on the behavior of grafted human ES cells within the context of an injured brain. If successful, we plan to initiate future studies addressing the functional impact of hES-derived neural precursor grafts on radiation-induced cognitive decline. This grant will only use the INIH-approved cell line: HI. NIH code WA01.