A Novel and Clinically Feasible Co-therapy of Deceased Donor Bone Marrow Combined With Donor-Matched Mesenchymal Stem Cells to Establish Immune Tolerance

一种新颖且临床可行的联合疗法，将已故供体骨髓与供体匹配的间充质干细胞相结合，以建立免疫耐受

基本信息

批准号：
10212956
负责人：
Brian H. Johnstone
金额：
$ 14.25万
依托单位：
OSSIUM HEALTH, INC.
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-07-08 至 2023-06-30
项目状态：
已结题

项目摘要

ABSTRACT Induction of immune tolerance with solid organ and vascular composite allografts is the Holy Grail for transplantation medicine. Induction of immune tolerance to mismatched grafts would obviate the need for life- long immunosuppression which is associated with serious adverse outcomes, such as renal failure, cancers and infections. Currently the most promising means of tolerance induction is through establishing a mixed chimeric state by transplantation of donor hematopoietic stem cells; however, with the exception of tolerogenic organs such as kidneys, the mixed chimerism approach has not achieved durable immune tolerance in preclinical or clinical trials with most solid organs or vascular composite allotransplants (VCA). Encouragingly, though, we have succeeded in achieving reduced immunosuppression in clinical trials of VCA using this approach. Mesenchymal stem (stromal) cells (MSC) are a potentially useful adjuvant to stem cell transplants (SCT) for promoting mixed chimerism as well as promoting complementary peripheral immunomodulatory functions. However, there are many unresolved issues to address before clinical translation of these promising therapeutic cells. A primary impediment is the source of MSC, which are rare in all tissues and require invasive procedures for procurement. Low abundance mandates extensive expansion in culture to generate sufficient numbers for human dosing. It has been observed in the clinical setting that the degree of expansion is negatively correlated with outcomes. Ossium Health has overcome this obstacle by identifying an abundant source of primary MSC associated with medullary bones of vertebral bodies obtained from deceased organ donors. These vertebral bone adherent MSC (vBA-MSC) are isolated by proteolytic digestion of bone fragments, following elution and cryopreservation of bone marrow (BM). Primary vBA-MSC are obtained at numbers that are 3 orders of magnitude higher than can be recovered from living donor iliac crest BM aspirates. A further advantage of vBA-MSC is they are matched to the donor, as opposed to third-party MSC, which enhances safety and potentially efficacy. Isolation and characterization of vBA-MSC from over 30 donors has demonstrated that the cells are no different than BM-MSC, but, because of their high numbers, unlike traditional BM-MSC, can be expanded to >5 billion cells with only 2 passages in culture. We hypothesize that donor-matched vBA-MSC will augment tolerance mechanisms of mixed chimerism with BM transplant as well as provide peripheral immunomodulatory functions to achieve durable tolerance for major histocompatibility complex mismatched solid organ and vascular composite tissue transplants. This hypothesis will be tested first in a murine orthotopic hind limb transplant VCA model and then in a murine heterotopic heart model. The hindlimb model studies will allow us to evaluate mechanisms of MSC immune tolerance due to the tolerogenic nature of BM-containing hind limbs. Durable grafts will be evaluated for T cell dynamics (especially memory T cells and regulatory T cells) and donor-specific immune tolerance with be confirmed with donor and third-party skin grafting. Information gained from this study will be used to perform similar studies in our heterotopic heart transplant model. If successful, the results of this study, combined with a plethora of MSC clinical trials as well as a long history of transplantation tolerance trials and our future Phase II studies to further define dosing parameters in small and large animal models, will provide compelling arguments to FDA for proceeding to clinical trials. Keywords: vascular composite allotransplantation; solid organ transplantation; immune tolerance; immunomodulation, regulatory T lymphocytes

抽象的用实体器官和血管复合同种异体移植物诱导免疫耐受是免疫耐受的圣杯移植医学。对不匹配的移植物诱导免疫耐受将消除对生命的需要长期免疫抑制与严重的不良后果相关，例如肾衰竭、癌症和感染。目前最有希望的耐受诱导方法是通过建立混合通过移植供体造血干细胞形成嵌合状态；然而，除了耐受性对于肾脏等器官，混合嵌合方法尚未实现持久的免疫耐受大多数实体器官或血管复合同种异体移植 (VCA) 的临床前或临床试验。令人鼓舞的是，尽管如此，我们已经在 VCA 临床试验中成功地利用这种方法实现了减少免疫抑制方法。间充质干（基质）细胞（MSC）是干细胞移植（SCT）的潜在有用佐剂促进混合嵌合以及促进互补的外周免疫调节功能。然而，在这些有希望的临床转化之前还有许多未解决的问题需要解决治疗细胞。主要障碍是 MSC 的来源，MSC 在所有组织中都很罕见，需要侵入性治疗采购程序。低丰度要求文化的广泛扩张，以产生足够的人体剂量的数字。在临床环境中观察到扩张程度为与结果呈负相关。 Ossium Health 通过识别与以下疾病相关的原代 MSC 的丰富来源克服了这一障碍：从已故器官捐献者身上获得的椎体髓质。这些椎骨粘附 MSC (vBA-MSC) 通过骨碎片的蛋白水解消化、洗脱和冷冻保存来分离骨髓（BM）。获得的原代 vBA-MSC 数量比原代 vBA-MSC 高 3 个数量级可以从活体捐献者髂嵴 BM 抽吸物中回收。 vBA-MSC 的另一个优点是它们与捐赠者匹配，而不是第三方 MSC，这增强了安全性和潜在功效。隔离来自 30 多个供体的 vBA-MSC 的特征表明，这些细胞与 BM-MSC，但与传统 BM-MSC 不同的是，由于其数量较多，可以扩展到 > 50 亿个细胞文化中只有 2 段。我们假设供体匹配的 vBA-MSC 将增强混合嵌合体的耐受机制骨髓移植并提供外周免疫调节功能，以实现持久耐受主要组织相容性复合体不匹配的实体器官和血管复合组织移植。这假设将首先在小鼠原位后肢移植 VCA 模型中进行测试，然后在小鼠中进行测试异位心脏模型。后肢模型研究将使我们能够评估间充质干细胞的免疫机制由于含有 BM 的后肢的耐受性而产生耐受性。将评估耐用移植物的 T 细胞动态（尤其是记忆 T 细胞和调节性 T 细胞）和供体特异性免疫耐受经供体和第三方植皮证实。从这项研究中获得的信息将用于执行在我们的异位心脏移植模型中进行了类似的研究。如果成功，这项研究的结果，结合大量的 MSC 临床试验以及悠久的历史移植耐受性试验和我们未来的 II 期研究，以进一步确定小剂量的剂量参数和大型动物模型，将为 FDA 进行临床试验提供令人信服的论据。关键词：同种异体复合血管移植；实体器官移植；免疫耐受；免疫调节、调节性T淋巴细胞