Developing standards to support the clinical translation of stem cells

Quality and Regulatory Requirements for the Manufacture of Master Cell Banks of Clinical Grade iPSCs: The EU and USA Perspectives

The discovery of induced pluripotent stem cells (iPSCs) and protocols for their differentiation into various cell types have revolutionized the field of tissue engineering and regenerative medicine. Developing manufacturing guidelines for safe and GMP-compliant final products has become essential. Allogeneic iPSCs-derived cell therapies are now the preferred manufacturing alternative. This option requires the establishment of clinical-grade master cell banks of iPSCs. This study aimed at reviewing the Quality and Regulatory requirements from the two main authorities in the world-Europe (EMA) and the United States (FDA)-regarding the manufacture of clinical grade master cell banks (iPSCs). The minimum requirements for iPSCs to be used in first-in-human clinical trials were also reviewed, as well as current best practices currently followed by iPSC bank manufacturers for final product characterisation. The methodology used for this work was a review of various sources of information ranging from scientific literature, published guidance documents available on the EMA and FDA websites, GMP and ICH guidelines, and applicable compendial monographs. Manufacturers of iPSCs cell banks looking to qualify them for clinical use are turning to the ICH guidelines and trying to adapt their requirements. Specifically with the impact of the field of iPSC cell banks, the following areas should be subject to guidance and harmonisation: i) expression vectors authorized for iPSC generation; ii) minimum identity testing; iii) minimum purity testing (including adventitious agent testing); and iv) stability testing. Current ICH guidelines for biotechnological/biological products should be extended to cover cell banks used for cell therapies.

Deciphering the Transcriptional Metabolic Profile of Adipose-Derived Stem Cells During Osteogenic Differentiation and Epigenetic Drug Treatment

Adipose-derived mesenchymal stem cells (ASCs) are commonly employed in clinical treatment for various diseases due to their ability to differentiate into multi-lineage and anti-inflammatory/immunomodulatory properties. Preclinical studies support their use for bone regeneration, healing, and the improvement of functional outcomes. However, a deeper understanding of the molecular mechanisms underlying ASC biology is crucial to identifying key regulatory pathways that influence differentiation and enhance regenerative potential. In this study, we employed the NanoString nCounter technology, an advanced multiplexed digital counting method of RNA molecules, to comprehensively characterize differentially expressed transcripts involved in metabolic pathways at distinct time points in osteogenically differentiating ASCs treated with or without the pan-DNMT inhibitor RG108. In silico annotation and gene ontology analysis highlighted the activation of ethanol oxidation, ROS regulation, retinoic acid metabolism, and steroid hormone metabolism, as well as in the metabolism of lipids, amino acids, and nucleotides, and pinpointed potential new osteogenic drivers like AOX1 and ADH1A. RG108-treated cells, in addition to the upregulation of the osteogenesis-related markers RUNX2 and ALPL, showed statistically significant alterations in genes implicated in transcriptional control (MYCN, MYB, TP63, and IRF1), ethanol oxidation (ADH1C, ADH4, ADH6, and ADH7), and glucose metabolism (SLC2A3). These findings highlight the complex interplay of the metabolic, structural, and signaling pathways that orchestrate osteogenic differentiation. Furthermore, this study underscores the potential of epigenetic drugs like RG108 to enhance ASC properties, paving the way for more effective and personalized cell-based therapies for bone regeneration.

Met-Flow analyses of the metabolic heterogeneity associated with different stages of cord blood-derived hematopoietic cell differentiation

Background

The differentiation of hematopoietic cells is significantly affected by cell metabolic activity. However, despite increasing interest in this field, there has been no comprehensive investigation of the metabolic functions of human hematopoietic cells during specific phases of differentiation. Thus, this study was conducted to develop a method for comparing hematopoietic cell lineage differentiation based on the metabolic functions of the cell. The metabolic activity of human umbilical cord-derived hematopoietic cells was examined during various phases of differentiation, specifically, hematopoietic stem cells (HSCs), hematopoietic progenitor cells, and differentiated blood cells. This approach was used to develop comprehensive metabolic maps corresponding to the different stages.

Results

HSCs were found to have robust fatty acid (FA) synthesis, FA oxidation, pentose phosphate pathway (PPP) activity, and glucose uptake, shown by their significantly higher expression of ACAC, CPT1A, G6PD, and GLUT1 as compared to differentiated pluripotent progenitor cells, common myeloid progenitors, megakaryocyte erythroid progenitors, lympho-myeloid primed progenitors, and granulocyte-macrophage progenitor cell populations. In monocytic differentiation, higher levels of ACAC, ASS1, ATP5A, CPT1A, G6PD, GLUT1, IDH2, PRDX2, and HK1 protein expression were evident in classical and intermediate monocytes relative to non-classical monocytes, consistent with high anabolic and catabolic levels. Compared with myelocytes and mature cells, the meta-myelocyte and pro-myelocyte populations of granulocytes show significantly elevated levels of ACAC, ASS1, ATP5A, CPT1A, G6PD, IDH2, PRDX2, and HK. In contrast to naïve and regulatory B cells, pro-B cells had higher levels of oxidative phosphorylation, while regulatory B cells showed greater PPP activity, glucose uptake, and tricarboxylic acid cycle activity. The analyses of T cells also indicated significantly higher ACAC, ASS1, ATP5A, CPT1A, G6PD, GLUT1, IDH2, PRDX2, and HK1 expression levels in CD4+ populations compared with CD8+ populations.

Conclusions

The results provide comprehensive analytical methods and reference values for future systematic studies into the metabolic functions of various cord blood-derived hematopoietic cell populations in different pathological or physiological conditions. These findings could also contribute to research on the connection between cellular metabolism and cancer or aging.

Research progress of gene therapy combined with tissue engineering to promote bone regeneration

Gene therapy has emerged as a highly promising strategy for the clinical treatment of large segmental bone defects and non-union fractures, which is a common clinical need. Meanwhile, many preclinical data have demonstrated that gene and cell therapies combined with optimal scaffold biomaterials could be used to solve these tough issues. Bone tissue engineering, an interdisciplinary field combining cells, biomaterials, and molecules with stimulatory capability, provides promising alternatives to enhance bone regeneration. To deliver and localize growth factors and associated intracellular signaling components into the defect site, gene therapy strategies combined with bioengineering could achieve a uniform distribution and sustained release to ensure mesenchymal stem cell osteogenesis. In this review, we will describe the process and cell molecular changes during normal fracture healing, followed by the advantages and disadvantages of various gene therapy vectors combined with bone tissue engineering. The growth factors and other bioactive peptides in bone regeneration will be particularly discussed. Finally, gene-activated biomaterials for bone regeneration will be illustrated through a description of characteristics and synthetic methods.

Functional variation among mesenchymal stem cells derived from different tissue sources

Background

Mesenchymal stem cells (MSCs) are increasingly recognized for their regenerative potential. However, their clinical application is hindered by their inherent variability, which is influenced by various factors, such as the tissue source, culture conditions, and passage number.

Methods

MSCs were sourced from clinically relevant tissues, including adipose tissue-derived MSCs (ADMSCs, n = 2), chorionic villi-derived MSCs (CMMSCs, n = 2), amniotic membrane-derived MSCs (AMMSCs, n = 3), and umbilical cord-derived MSCs (UCMSCs, n = 3). Passages included the umbilical cord at P0 (UCMSCP0, n = 2), P3 (UCMSCP3, n = 2), and P5 (UCMSCP5, n = 2) as well as the umbilical cord at P5 cultured under low-oxygen conditions (UCMSCP5L, n = 2).

Results

We observed that MSCs from different tissue origins clustered into six distinct functional subpopulations, each with varying proportions. Notably, ADMSCs exhibited a higher proportion of subpopulations associated with vascular regeneration, suggesting that they are beneficial for applications in vascular regeneration. Additionally, CMMSCs had a high proportion of subpopulations associated with reproductive processes. UCMSCP5 and UCMSCP5L had higher proportions of subpopulations related to female reproductive function than those for earlier passages. Furthermore, UCMSCP5L, cultured under low-oxygen (hypoxic) conditions, had a high proportion of subpopulations associated with pro-angiogenic characteristics, with implications for optimizing vascular regeneration.

Conclusions

This study revealed variation in the distribution of MSC subpopulations among different tissue sources, passages, and culture conditions, including differences in functions related to vascular and reproductive system regeneration. These findings hold promise for personalized regenerative medicine and may lead to more effective clinical treatments across a spectrum of medical conditions.

Umbilical cord mesenchymal stromal cells in serum-free defined medium display an improved safety profile

BACKGROUND

Safety evaluations in preclinical studies are needed to confirm before translating a cell-based product into clinical application. We previously developed a serum-free, xeno-free, and chemically defined media (S&XFM-CD) for the derivation of clinical-grade umbilical cord-derived MSCs (UCMSCs), and demonstrated that intraperitoneal administration of UCMSCs in S&XFM-CD (UCMSCS&XFM-CD) exhibited better therapeutic effects than UCMSCs in serum-containing media (SCM, UCMSCSCM). However, a comprehensive investigation of the safety of intraperitoneal UCMSCS&XFM-CD treatment should be performed before clinical applications.

METHODS

In this study, the toxicity, immunogenicity and biodistribution of intraperitoneally transplanted UCMSCS&XFM-CD were compared with UCMSCSCM in rats via general vital signs, blood routine, blood biochemistry, subsets of T cells, serum cytokines, pathology of vital organs, antibody production and the expression of human-specific gene. The tumorigenicity and tumor-promoting effect of UCMSCS&XFM-CD were compared with UCMSCSCM in nude mice.

RESULTS

We confirmed that intraperitoneally transplanted UCMSCS&XFM-CD or UCMSCSCM did not cause significant changes in body weight, temperature, systolic blood pressure, diastolic blood pressure, heart rate, blood routine, T lymphocyte subsets, and serum cytokines, and had no obvious histopathology change on experimental rats. UCMSCS&XFM-CD did not produce antibodies, while UCMSCSCM had very high chance of antibody production to bovine serum albumin (80%) and apolipoprotein B-100 (60%). Furthermore, intraperitoneally injected UCMSCS&XFM-CD were less likely to be blocked by the lungs and migrated more easily to the kidneys and colon tissue than UCMSCSCM. In addition, UCMSCS&XFM-CD or UCMSCSCM showed no obvious tumorigenic activity. Finally, UCMSCS&XFM-CD extended the time of tumor formation of KM12SM cells, and decreased tumor incidence than that of UCMSCSCM.

CONCLUSIONS

Taken together, our data indicate that UCMSCS&XFM-CD display an improved safety performance and are encouraged to use in future clinical trials.

Pediatric Drug Development: Reviewing Challenges and Opportunities by Tracking Innovative Therapies

The paradigm of pediatric drug development has been evolving in a "carrot-and-stick"-based tactic to address population-specific issues. However, the off-label prescription of adult medicines to pediatric patients remains a feature of clinical practice, which may compromise the age-appropriate evaluation of treatments. Therefore, the United States and the European Pediatric Formulation Initiative have recommended applying nanotechnology-based delivery systems to tackle some of these challenges, particularly applying inorganic, polymeric, and lipid-based nanoparticles. Connected with these, advanced therapy medicinal products (ATMPs) have also been highlighted, with optimistic perspectives for the pediatric population. Despite the results achieved using these innovative therapies, a workforce that congregates pediatric patients and/or caregivers, healthcare stakeholders, drug developers, and physicians continues to be of utmost relevance to promote standardized guidelines for pediatric drug development, enabling a fast lab-to-clinical translation. Therefore, taking into consideration the significance of this topic, this work aims to compile the current landscape of pediatric drug development by (1) outlining the historic regulatory panorama, (2) summarizing the challenges in the development of pediatric drug formulation, and (3) delineating the advantages/disadvantages of using innovative approaches, such as nanomedicines and ATMPs in pediatrics. Moreover, some attention will be given to the role of pharmaceutical technologists and developers in conceiving pediatric medicines.

Stem cell-derived exosome versus stem cell therapy

Stem cell therapies are being explored for the treatment of various diseases, including haematological disease, immune disease, neurodegenerative disease, and tissue injuries. Alternatively, stem cell-derived exosomes may provide similar clinical benefits without the biosafety concerns associated with the transplantation of living cells. However, large-scale manufacturing and purification, batch-to-batch variation, and analysis of the complex cargos of exosomes will need to be addressed to enable their clinical translation.

Developing standards to support the clinical translation of stem cells

Stem cells, which could be developed as starting or raw materials for cell therapy, hold tremendous promise for regenerative medicine. However, despite multiple fundamental and clinical studies, clinical translation of stem cells remains in the early stages. In contrast to traditional chemical drugs, cellular products are complex, and efficacy can be altered by culture conditions, suboptimal cell culture techniques, and prolonged passage such that translation of stem cells from bench to bedside involves not only scientific exploration but also normative issues. Establishing an integrated system of standards to support stem cell applications has great significance in efficient clinical translation. In recent years, regulators and the scientific community have recognized gaps in standardization and have begun to develop standards to support stem cell research and clinical translation. Here, we discuss the development of these standards, which support the translation of stem cell products into clinical therapy, and explore ongoing work to define current stem cell guidelines and standards. We also introduce general aspects of stem cell therapy and current international consensus on human pluripotent stem cells, discuss standardization of clinical-grade stem cells, and propose a framework for establishing stem cell standards. Finally, we review ongoing development of international and Chinese standards supporting stem cell therapy.