Safety Profile of Good Manufacturing Practice Manufactured Interferon γ-Primed Mesenchymal Stem/Stromal Cells for Clinical Trials

Abstract

Mesenchymal stem/stromal cells (MSCs) are widely studied by both academia and industry for a broad array of clinical indications. The collective body of data provides compelling evidence of the clinical safety of MSC therapy. However, generally accepted proof of therapeutic efficacy has not yet been reported. In an effort to generate a more effective therapeutic cell product, investigators are focused on modifying MSC processing protocols to enhance the intrinsic biologic activity. Here, we report a Good Manufacturing Practice-compliant two-step MSC manufacturing protocol to generate MSCs or interferon c (IFNc) primed MSCs which allows freshly expanded cells to be infused in patients on a predetermined schedule. This protocol eliminates the need to infuse cryopreserved, just thawed cells which may reduce the immune modulatory activity. Moreover, using (IFNc) as a prototypic cytokine, we demonstrate the feasibility of priming the cells with any biologic agent. We then characterized MSCs and IFNc primed MSCs prepared with our protocol, by karyotype, in vitro potential for malignant transformation, biodistribution, effect on engraftment of transplanted hematopoietic cells, and in vivo toxicity in immune deficient mice including a complete post-mortem examination. We found no evidence of toxicity attributable to the MSC or IFNc primed MSCs. Our data suggest that the clinical risk of infusing MSCs or IFNc primed MSCs produced by our two-step protocol is not greater than MSCs currently in practice. While actual proof of safety requires phase I clinical trials, our data support the use of either cell product in new clinical studies. STEM CELLS TRANSLATIONAL MEDICINE 2017;6:1868-1879 SIGNIFICANCE STATEMENTMesenchymal stem/stromal cells (MSCs) are one of the most widely studied cells for the development of cellular therapies. While these cells are unequivocally safe to use in humans, the efficacy of MSCs to treat diseases has not been established. Hence, current efforts are focused on developing the technology to enhance the efficacy of MSCs. Here, we report a novel strategy to prepare MSCs that would mitigate the potential reduction of cell potency observed when infusing freshly thawed, cryopreserved cells. Additionally, we show extensive preclinical data to support the safety of interferon g-primed MSCs, which are designed to enhance the immune modulatory potency of MSCs.

Interferon-Gamma Impairs Maintenance and Alters Hematopoietic Support of Bone Marrow Mesenchymal Stromal Cells

“…Prelicensing with a short exposure of IFN-γ enhances immunomodulatory capacities of cultured human MSC, and may therefore be an attractive strategy for clinical application in inflammatory conditions (reviewed in Ref. [ 11 ]), especially because it has recently been suggested that the clinical risk of infusing MSCγ is not greater than the risk of infusing nontreated MSCs [ 45 ]. It has also been reported that IFN-γ exposure of MSCs can mediate a shift from adipogenesis toward osteoblastogenesis both in vitro and in vivo [ 30 ], which may be beneficial for clinical application of cultured human MSC in bone degenerative disorder.…”

Intratumoral Delivery of Interferonγ-Secreting Mesenchymal Stromal Cells Repolarizes Tumor-Associated Macrophages and Suppresses Neuroblastoma Proliferation In Vivo

“…Athymic nu/nu (nude) mice were obtained from Envigo (Huntingdon, UK). Clinical and anatomic pathology was performed as described in . All animal protocols were approved by the Institutional Animal Care and Use Committees of the Research Institute at Nationwide Children's Hospital.…”

Progress in research on functional mechanisms of mesenchymal stem cells

“…增强MSCs的旁分泌作用, 如低氧或γ-IFN预处理MSCs 可提高MSCs产生生物活性物质的能力 [189,190] . 通常基 因修饰MSCs可显著增强操作基因的功能, 如过量表 达CXCR4基因, 可增强修饰MSCs的迁移能力 [69] ; 过量 表达Bcl-2基因, 可增强修饰MSCs的抗凋亡能力, 修饰 细胞能够产生更多的血管内皮细胞生长因子, 显著提 高损伤心肌细胞的存活能力 [191] ; 过量表达Miro1基因, 可增强修饰MSCs的线粒体转移能力 [158] .…”