Long-Term Stability and Differentiation Potential of Cryopreserved cGMP-Compliant Human Induced Pluripotent Stem Cells

Characterization of human induced pluripotent stems cells: Current approaches, challenges, and future solutions

Human induced pluripotent stem cells (iPSC) have demonstrated massive potentials for use in regenerative and personalized medicine due to their ability to expand in culture and differentiate into specialized cells with therapeutic benefits. However, in order to industrialize iPSC-derived therapies, it is necessary to address the existing challenges surrounding the analytics implemented in the manufacturing process to evaluate and monitor cell expansion, differentiation, and quality of the final products. Here, we review some of the key analytical methods used as part of identity, potency, or safety for in-process or final product release testing and highlighted the challenges and potential solutions for consideration in the Chemistry, Manufacturing and Controls (CMC) strategy for iPSC-based therapies. Some of the challenges associated with characterization and testing of iPSC-based products are related to the choice of analytical technology (to ensure fit-for-purpose), assay reliability and robustness. Automation of analytical methods may be required to reduce hands on time, and improve reliability of the methods through reducing assay variability. Indeed, we have shown that automation of analytical methods is feasible (evaluated using an ELISA based assay) and would result in more precise measurements (demonstrated by lower co-efficient of Variation and standard deviation), less hands-on time, and swift compared to a manually run assay. Therefore, in order to support commercialization of iPSC-based therapies we suggest a well-designed testing strategy to be established in the development phase while incorporating robust, reproducible, reliable, and potentially automated analytics in the manufacturing process.

Cryopreservation does not change the performance and characteristics of allogenic mesenchymal stem cells highly over-expressing a cytoplasmic therapeutic transgene for cancer treatment

Background

Mesenchymal stem cells (MSCs) driven gene directed enzyme prodrug therapy is a promising approach to deliver therapeutic agents to target heterogenous solid tumours. To democratize such a therapy, cryopreservation along with cold chain transportation is an essential part of the logistical process and supply chain. Previously, we have successfully engineered MSCs by a non-viral DNA transfection approach for prolonged and exceptionally high expression of the fused transgene cytosine deaminase, uracil phosphoribosyl transferase and green fluorescent protein (CD::UPRT::GFP). The aim of this study was to determine the effects of cryopreservation of MSCs engineered to highly overexpress this cytoplasmic therapeutic transgene.

Methods

Modified MSCs were preserved in a commercially available, GMP-grade cryopreservative—CryoStor10 (CS10) for up to 11 months. Performance of frozen-modified MSCs was compared to freshly modified equivalents in vitro. Cancer killing potency was evaluated using four different cancer cell lines. Migratory potential was assessed using matrigel invasion assay and flow cytometric analysis for CXCR4 expression. Frozen-modified MSC was used to treat canine patients via intra-tumoral injections, or by intravenous infusion followed by a daily dose of 5-flucytosine (5FC).

Results

We found that cryopreservation did not affect the transgene expression, cell viability, adhesion, phenotypic profile, and migration of gene modified canine adipose tissue derived MSCs. In the presence of 5FC, the thawed and freshly modified MSCs showed comparable cytotoxicity towards one canine and three human cancer cell lines in vitro. These cryopreserved cells were stored for about a year and then used to treat no-option-left canine patients with two different types of cancers and notably, the patients showed progression-free interval of more than 20 months, evidence of the effectiveness in treating spontaneously occurring cancers.

Conclusion

This study supports the use of cryopreserved, off-the-shelf transiently transfected MSCs for cancer treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03198-z.

A comprehensive report of long-term stability data for a range ATMPs: A need to develop guidelines for safe and harmonized stability studies

BACKGROUND AIMS

Advanced therapy medicinal products (ATMPs) are novel drugs based on genes, cells or tissues developed to treat many different diseases. Stability studies of each new ATMP need to be performed to define its shelf life and guarantee efficacy and safety upon infusion, and these are presently based on guidelines originally drafted for standard pharmaceutical drugs, which have properties and are stored in conditions quite different from cell products. The aim of this report is to provide evidence-based information for stability studies on ATMPs that will facilitate the interlaboratory harmonization of practices in this area.

METHODS

We have collected and analyzed the results of stability studies on 19 different cell-based experimental ATMPs, produced by five authorized cell factories forming the Lombardy "Plagencell network" for use in 36 approved phase I/II clinical trials; most were cryopreserved and stored in liquid nitrogen vapors for 1 to 13 years.

RESULTS

The cell attributes collected in stability studies included cell viability, immunophenotype and potency assays, in particular immunosuppression, cytotoxicity, cytokine release and proliferation/differentiation capacity. Microbiological attributes including sterility, endotoxin levels and mycoplasma contamination were also analyzed. All drug products (DPs), cryopreserved in various excipients containing 10% DMSO and in different primary containers, were very stable long term at <-150°C and did not show any tendency for diminished viability or efficacy for up to 13.5 years.

CONCLUSIONS

Our data indicate that new guidelines for stability studies, specific for ATMPs and based on risk analyses, should be drafted to harmonize practices, significantly reduce the costs of stability studies without diminishing safety. Some specific suggestions are presented in the discussion.

The Rise of Induced Pluripotent Stem Cell Approach to Hair Restoration

SUMMARY

The advent of pluripotent stem cells following the discovery of Shinya Yamanaka (2012 Nobel prize in Medicine) brought about a regenerative medicine approach to virtually every human condition including hair loss. It is now possible to reprogram somatic cells (eg, blood or skin cells) from a person experiencing hair loss to generate autologous induced pluripotent stem cells (iPSCs), which could be amplified and cryopreserved. Subsequently, these iPSCs could be differentiated into various cell types such as dermal papilla cells, epithelial cells, melanocytes, and other cell types constituting functional hair follicle. Transplantation of human iPSC-derived folliculogenic cells into the nude mice has successfully generated xenografts with hair outgrowth. Because iPSCs provide a virtually unlimited source of folliculogenic cells for de novo formation of hair follicles, this approach has major advantages over current surgical hair restoration procedures, which merely redistribute existing hair follicles from one part of the sculp to another. Combined with robotics and automation of the transplantation process, this novel regenerative medicine approach is well poised to make hair restoration a routine procedure affordable for everybody who can benefit from it.

Testing the Stability of Drug Resistance on Cryopreserved, Gene-Engineered Human Induced Pluripotent Stem Cells

Human induced pluripotent stem cells (hiPSCs) have emerged as a powerful tool for in vitro modelling of diseases with broad application in drug development or toxicology testing. These assays usually require large quantities of hiPSC, which can entail long-term storage via cryopreservation of the same cell charges. However, it is essential that cryopreservation does not oppose durable changes on the cells. In this project, we characterize one parameter of functionality of one that is well established in the field, in a different research context, an applied hiPSC line (iPS11), namely their resistance to a medium size library of chemo interventions (>160 drugs). We demonstrate that cells, before and after cryopreservation, do not change their relative overall drug response phenotypes, as defined by identification of the top 20 interventions causing dose-dependent reduction of cell growth. Importantly, also frozen cells that are exogenously enforced for stable overexpression of oncogenes myelocytomatosis (cMYC) or tumor protein 53 mutation (TP53R175H), respectively, are not changed in their relative top 20 drugs response compared to their non-frozen counterparts. Taken together, our results support iPSCs as a reliable in vitro platform for in vitro pharmacology, further raising hopes that this technology supports biomarker-associated drug development. Given the general debate on ethical and economic problems associated with the reproducibly crisis in biomedicine, our results may be of interest to a wider audience beyond stem cell research.

Cell Banking of hiPSCs: A Practical Guide to Cryopreservation and Quality Control in Basic Research

The reproducibility of stem cell research relies on the constant availability of quality-controlled cells. As the quality of human induced pluripotent stem cells (hiPSCs) can deteriorate in the course of a few passages, cell banking is key to achieve consistent results and low batch-to-batch variation. Here, we provide a cost-efficient route to generate master and working cell banks for basic research projects. In addition, we describe minimal protocols for quality assurance including tests for sterility, viability, pluripotency, and genetic integrity. © 2020 The Authors. Basic Protocol 1: Expansion of hiPSCs Basic Protocol 2: Cell banking of hiPSCs Support Protocol 1: Pluripotency assessment by flow cytometry Support Protocol 2: Thawing control: Viability and sterility Support Protocol 3: Potency, viral clearance, and pluripotency: Spontaneous differentiation and qRT-PCR Support Protocol 4: Identity: Short tandem repeat analysis.

Addressing Manufacturing Challenges for Commercialization of iPSC-Based Therapies

The development of reprogramming technology to generate human induced pluripotent stem cells (iPSCs) has tremendously influenced the field of regenerative medicine and clinical therapeutics where curative cell replacement therapies can be used in the treatment of devastating diseases such as Parkinson's disease (PD) and diabetes. In order to commercialize these therapies to treat a large number of individuals, it is important to demonstrate the safety and efficacy of these therapies and ensure that the manufacturing process for iPSC-derived functional cells can be industrialized at an affordable cost. However, there are a number of manufacturing obstacles that need to be addressed in order to meet this vision. It is important to note that the manufacturing process for generation of iPSC-derived specialized cells is relatively long and fairly complex and requires differentiation of high-quality iPSCs into specialized cells in a controlled manner. In this chapter, we have summarized our efforts to address the main challenges present in the industrialization of iPSC-derived cell therapy products with focus on the development of a current Good Manufacturing Practice (cGMP)-compliant iPSC manufacturing process, a comprehensive iPSC characterization platform, long-term stability of cGMP compliant iPSCs, and innovative technologies to address some of the scale-up challenges in establishment of iPSC processing in 3D computer-controlled bioreactors.