Mesenchymal Stromal Cell Conditioning by Carbon Monoxide

项目摘要（参见说明）： 脓毒症是一种代表对严重感染的全身反应的疾病过程。感染性损伤会激活宿主的免疫细胞，包括中性粒细胞、单核细胞/巨噬细胞和淋巴细胞。免疫细胞的早期激活会引发促炎反应，有助于消灭入侵的微生物。如果不根除病原体，败血症可能会进展为严重败血症（败血症加上器官功能障碍，如肺损伤和呼吸衰竭）和败血性休克（严重败血症） 加上难治性低血压和循环衰竭），这常常导致死亡。一旦入侵的微生物被根除，那么免疫反应的解决就至关重要，因为持续的全身炎症将导致器官损伤。不幸的是，这种早期的促炎症反应也可能伴随着后期的免疫麻痹状态，部分原因是免疫效应细胞的凋亡。脓毒症期间发生的一系列生物学事件是复杂的，需要根据诊断时脓毒症的阶段来调整治疗策略。多能间充质基质细胞（MSC）被认为是基于细胞的治疗的一个有前途的平台。众所周知，间充质干细胞具有免疫调节作用 最近有人提出，间充质干细胞在小鼠盲肠结扎和穿刺的早期促炎阶段是有益的。我们假设，当在多种微生物或单一生物体脓毒症发作后给小鼠施用 MSC 时，MSC 将适应脓毒症的特定阶段并导致改善的结果。我们实验室之前的研究表明，血红素加氧酶 (H0)-1 衍生的一氧化碳 (CO)（一种已知的抗炎分子）在脓毒症期间也具有抗微生物特性。因此，我们还假设用 CO 离体调节 MSC 将改善其体内功能，并在小鼠脓毒症发作后增加 MSC 的有益作用。深入了解 CO 条件下 MSC 的这种增强反应的机制将使我们能够进一步了解 MSC 作为一种基于细胞的疗法，并为这种破坏性疾病过程开发新的治疗策略。间充质干细胞 ¿ CO 调节也将在具有“人性化”免疫系统的小鼠中进行研究。 最后，我们将通过评估从脓毒症或脓毒症合并急性肺损伤患者中采集的中性粒细胞和单核细胞与对照患者的细胞相比的吞噬功能，增进对脓毒症的人体免疫反应的理解。我们将确定体外给予 MSCs ¿ CO 是否可以改善吞噬细胞功能。这些功能测定将与患者的结果相关。

PROJECT SUMMARY (See instmctions): Sepsis is a disease process representing the systemic response to severe infection. The infectious insult activates immune cells of the host, including neutrophils, monocytes/macrophages, and lymphocytes. Early activation of immune cells triggers a pro-inflammatory response that contributes to eradication of the invading microorganism(s). If the pathogens are not eradicated, sepsis may progress to severe sepsis (sepsis plus organ dysfunction, such as lung injury and respiratory failure) and septic shock (severe sepsis plus refractory hypotension and circulatory failure), which frequently leads to death. Once the invading microorganism(s) are eradicated, then resolution of the immune response is critical, as continued systemic inflammation will lead to organ injury. Unfortunately, this early pro-inflammatory response may also be followed by a later state of immunoparalysis, due in part to apoptosis of immune effector cells. The cascade of biologic events that occur during sepsis is complex, and therapeutic strategies need to be tailored depending upon the stage of sepsis at the time of diagnosis. Multipotent mesenchymal stromal cells (MSCs) are considered to be a promising platform for cell-based therapy. MSCs are known to have immunomodulatory properties, and recently it has been suggested that MSCs are beneficial during the early proinflammatory stage of cecal ligation and puncture in mice. We hypothesize that MSCs, when administered to mice after the onset of polymicrobial or single organism sepsis, will adapt to the specific stage of sepsis and lead to an improved outcome. Prior studies in our laboratory demonstrated that heme oxygenase (H0)-1-derived carbon monoxide (CO), a known anti-inflammatory molecule, also has anti-microbial properties during sepsis. Thus, we also hypothesize that conditioning MSCs with CO ex vivo will improve their function In vivo, and increase the beneficial effects of MSCs after the onset of sepsis in mice. Gaining insight into the mechanisms responsible for this enhanced response of MSCs conditioned with CO will allow us to further understand MSCs as a cell-based therapy, and to develop novel therapeutic strategies for this devastating disease process. MSCs ¿ CO conditioning will also be studied in mice with a "humanized" immune system. Finally we will advance the understanding of the human immune response to sepsis by assessing phagocytic function of neutrophils and monocytes harvested from patients with sepsis or sepsis plus acute lung injury, compared with cells from control patients. We will determine whether the administration of MSCs ¿ CO ex vivo can improve phagocyte function. These functional assays will be correlated with patient outcome.