TICEBA GmbH, Im Neuenheimer Feld 517, 69120, Heidelberg, Germany.
RHEACELL GmbH & Co. KG, Im Neuenheimer Feld 517, Heidelberg, 69120, Germany.
Stem Cell Res Ther. 2021 Mar 19;12(1):194. doi: 10.1186/s13287-021-02272-2.
While therapeutic success of the limbal tissue or cell transplantation to treat severe cases of limbal stem cell (LSC) deficiency (LSCD) strongly depends on the percentage of LSCs within the transplanted cells, prospective LSC enrichment has been hampered by the intranuclear localization of the previously reported LSC marker p63. The recent identification of the ATP-binding cassette transporter ABCB5 as a plasma membrane-spanning marker of LSCs that are capable of restoring the cornea and the development of an antibody directed against an extracellular loop of the ABCB5 molecule stimulated us to develop a novel treatment strategy based on the utilization of in vitro expanded allogeneic ABCB5 LSCs derived from human cadaveric limbal tissue.
We developed and validated a Good Manufacturing Practice- and European Pharmacopeia-conform production and quality-control process, by which ABCB5 LSCs are derived from human corneal rims, expanded ex vivo, isolated as homogenous cell population, and manufactured as an advanced-therapy medicinal product (ATMP). This product was tested in a preclinical study program investigating the cells' engraftment potential, biodistribution behavior, and safety.
ABCB5 LSCs were reliably expanded and manufactured as an ATMP that contains comparably high percentages of cells expressing transcription factors critical for LSC stemness maintenance (p63) and corneal epithelial differentiation (PAX6). Preclinical studies confirmed local engraftment potential of the cells and gave no signals of toxicity and tumorgenicity. These findings were sufficient for the product to be approved by the German Paul Ehrlich Institute and the U.S. Food & Drug Administration to be tested in an international multicenter phase I/IIa clinical trial (NCT03549299) to evaluate the safety and therapeutic efficacy in patients with LSCD.
Building upon these data in conjunction with the previously shown cornea-restoring capacity of human ABCB5 LSCs in animal models of LSCD, we provide an advanced allogeneic LSC-based treatment strategy that shows promise for replenishment of the patient's LSC pool, recreation of a functional barrier against invading conjunctival cells and restoration of a transparent, avascular cornea.
虽然边缘组织或细胞移植治疗严重边缘干细胞（LSC）缺乏症（LSCD）的治疗成功率强烈依赖于移植细胞中 LSC 的百分比，但由于先前报道的 LSC 标志物 p63 的核内定位，前瞻性 LSC 富集受到了阻碍。最近发现 ABCB5 作为一种 ABCB5 作为 LSC 的质膜跨膜标志物，能够重建角膜，并开发出一种针对 ABCB5 分子的细胞外环的抗体，这激发我们开发了一种基于利用从人尸体眼角膜组织中获得的体外扩增的同种异体 ABCB5 LSC 的新治疗策略。
我们开发并验证了符合良好生产规范和欧洲药典的生产和质量控制流程，通过该流程从人角膜边缘衍生、体外扩增、分离为同质细胞群的 ABCB5 LSC，并作为先进治疗药物产品（ATMP）制造。该产品在一项临床前研究计划中进行了测试，该计划调查了细胞的植入潜力、生物分布行为和安全性。
ABCB5 LSC 可可靠地扩增并制造为 ATMP，其中包含相对较高百分比的表达对 LSC 干细胞维持（p63）和角膜上皮分化（PAX6）至关重要的转录因子的细胞。临床前研究证实了细胞的局部植入潜力，并且没有毒性和致瘤性的信号。这些发现足以使该产品获得德国保罗埃利希研究所和美国食品和药物管理局的批准，并在一项国际多中心 I/IIa 期临床试验（NCT03549299）中进行测试，以评估 LSCD 患者的安全性和治疗效果。
基于这些数据以及先前在 LSCD 动物模型中显示的人 ABCB5 LSC 具有角膜修复能力的研究结果，我们提供了一种基于先进的同种异体 LSC 的治疗策略，有望补充患者的 LSC 池，重建对抗侵入性结膜细胞的功能屏障，并恢复透明、无血管的角膜。
