Mechanisms of SCI Recovery after hCNS Stem Cell Grafts

描述（由申请人提供）：多种事件导致脊髓损伤后的最终结果，包括神经元、少突胶质细胞和轴突丢失、脱髓鞘、胶质瘢痕形成和抑制性分子沉积，以及内源性再生能力。这些事件为研究影响功能恢复的干预措施的作用机制确定了临界点。基于细胞的治疗策略的发展，包括培养的雪旺细胞和嗅鞘细胞、胎儿脊髓组织和胚胎干细胞（ES）衍生祖细胞，是目前对脊髓损伤的强烈兴趣。特别是中枢神经系统干细胞（CNS Stem Cells, CNS- sc），在移植后具有迁移和分化为神经元、少突胶质细胞和星形胶质细胞的能力，可以通过多种方式使损伤的脊髓受益。这些包括新神经元和少突胶质细胞的分化和功能植入，改变宿主细胞的再生或再髓鞘化潜力，减少宿主胶质瘢痕或抑制性基质分子（如蛋白聚糖）的沉积。我们发现，利用基于单克隆抗体的荧光活化细胞分选（FACS）技术，从前瞻性分离的人胎脑中提取的CNS-SC细胞库中的细胞能够存活并移植到免疫缺陷NOD-scid小鼠中。脊髓损伤后第9天移植人CNSSC神经球后，损伤小鼠开放野运动功能恢复明显改善。这些高度富集的人CNS-SC可以重复分离，能够作为神经球在培养中长期生长，我们的初步数据表明，它们在受损脊髓中保持分化为神经元和少突胶质细胞的能力。本研究的目的是通过实验验证观察到的功能恢复的基础，验证人类中枢神经干细胞分化和功能移植或改变宿主对上述损伤反应的假设。此外，我们还将验证运动与细胞移植协同作用以改善运动恢复的假设，这是基于运动在促进神经发生中的已知作用，以及我们的数据显示，在自愿轮式跑步范式中，运动可以增强挫伤小鼠的运动结果。

DESCRIPTION (provided by applicant): A multitude of events contribute to the ultimate outcome following SCI, including neuron, oligodendrocyte and axonal loss, demyelination, glial scar formation and inhibitory molecule deposition, and endogenous capacity for regeneration. These events define critical points for investigation of the mechanism of action of interventions that affect functional recovery. The development of cell-based therapeutic strategies, including cultured Schwann and olfactory ensheathing cells, fetal spinal cord tissues, and embryonic stem cell (ES)-derived progenitors, is of strong current interest for SCI. In particular, CNS Stem Cells (CNS-SC), which have the ability to migrate and differentiate into neurons, oligodendrocytes and astrocytes upon transplantation could benefit the injured spinal cord in a variety of ways. These include differentiation and functional engraftment of new neurons and oligodendrocytes, modifying the regenerative or remyelination potential of host cells, and decreasing host glial scaring or deposition of inhibitory matrix molecules (e.g. proteoglycans). We have found that cells from CNS-SC banks initiated from prospectively isolated human fetal brain using monoclonal antibody based fluorescence activated cell sorting (FACS) survive and engraft in contusion-injured immunodeficient NOD-scid mice. Contusion-injured mice transplanted with human CNSSC neurospheres 9 days post-SCI show improved recovery of open field locomotor function. These highly enriched human CNS-SC can be reproducibly isolated, are capable of long term growth in culture as neurospheres, and our preliminary data suggest that they maintain their capacity to differentiate into neurons and oligodendrocytes in the injured spinal cord. The objective of this proposal is to experimentally test the basis for the observed functional recovery, testing the hypothesis that human CNS-SC either differentiate and functionally engraft or modify the host response to injury as described above. Further, we will also test the hypothesis that exercise will act synergistically with cell transplantation to improve locomotor recovery, based on its known role in promoting neurogenesis and our data demonstrating enhancement of locomotor outcome in contusion-injured mice in a voluntary wheel running paradigm.