Production via good manufacturing practice of exofucosylated human mesenchymal stromal cells for clinical applications.

BACKGROUND: The regenerative and immunomodulatory properties of human mesenchymal stromal cells (hMSCs) have raised great hope for their use in cell therapy. However, when intravenously infused, hMSCs fail to reach sites of tissue injury. Fucose addition in α(1,3)-linkage to terminal sialyllactosamines on CD44 creates the molecule known as hematopoietic cell E-/L-selectin ligand (HCELL), programming hMSC binding to E-selectin that is expressed on microvascular endothelial cells of bone marrow (BM), skin and at all sites of inflammation. Here we describe how this modification on BM-derived hMSCs (BM-hMSCs) can be adapted to good manufacturing practice (GMP) standards. METHODS: BM-hMSCs were expanded using xenogenic-free media and exofucosylated using α(1,3)-fucosyltransferases VI (FTVI) or VII (FTVII). Enforced fucosylation converted CD44 into HCELL, and HCELL formation was assessed using Western blot, flow cytometry and cell-binding assays. Untreated (unfucosylated), buffer-treated and exofucosylated BM-hMSCs were each analyzed for cell viability, immunophenotype and differentiation potential, and E-selectin binding stability was assessed at room temperature, at 4°C, and after cryopreservation. Cell product safety was evaluated using microbiological testing, karyotype analysis, and c-Myc messenger RNA (mRNA) expression, and potential effects on genetic reprogramming and in cell signaling were analyzed using gene expression microarrays and receptor tyrosine kinase (RTK) phosphorylation arrays. RESULTS: Our protocol efficiently generates HCELL on clinical-scale batches of BM-hMSCs. Exofucosylation yields stable HCELL expression for 48 h at 4°C, with retained expression after cell cryopreservation. Cell viability and identity are unaffected by exofucosylation, without changes in gene expression or RTK phosphorylation. DISCUSSION: The described exofucosylation protocol using xenogenic-free reagents enforces HCELL expression on hMSCs endowing potent E-selectin binding without affecting cell viability or native phenotype. This described protocol is readily scalable for GMP-compliant clinical production.

Assessment of biodistribution using mesenchymal stromal cells: Algorithm for study design and challenges in detection methodologies.

BACKGROUND AIMS: Biodistribution of candidate cell-based therapeutics is a critical safety concern that must be addressed in the preclinical development program. We aimed to design a decision tree based on a series of studies included in actual dossiers approved by competent regulatory authorities, noting that the design, execution and interpretation of pharmacokinetics studies using this type of therapy is not straightforward and presents a challenge for both developers and regulators. METHODS: Eight studies were evaluated for the definition of a decision tree, in which mesenchymal stromal cells (MSCs) were administered to mouse, rat and sheep models using diverse routes (local or systemic), cell labeling (chemical or genetic) and detection methodologies (polymerase chain reaction [PCR], immunohistochemistry [IHC], fluorescence bioimaging, and magnetic resonance imaging [MRI]). Moreover, labeling and detection methodologies were compared in terms of cost, throughput, speed, sensitivity and specificity. RESULTS: A decision tree was defined based on the model chosen: (i) small immunodeficient animals receiving heterologous MSC products for assessing biodistribution and other safety aspects and (ii) large animals receiving homologous labeled products; this contributed to gathering data not only on biodistribution but also on pharmacodynamics. PCR emerged as the most convenient technique despite the loss of spatial information on cell distribution that can be further assessed by IHC. DISCUSSION: This work contributes to the standardization in the design of biodistribution studies by improving methods for accurate assessment of safety. The evaluation of different animal models and screening of target organs through a combination of techniques is a cost-effective and timely strategy.

Intraarticular and intravenous administration of 99MTc-HMPAO-labeled human mesenchymal stem cells (99MTC-AH-MSCS): In vivo imaging and biodistribution.

INTRODUCTION: Therapeutic application of intravenous administered (IV) human bone marrow-derived mesenchymal stem cells (ahMSCs) appears to have as main drawback the massive retention of cells in the lung parenchyma, questioning the suitability of this via of administration. Intraarticular administration (IAR) could be considered as an alternative route for therapy in degenerative and traumatic joint lesions. Our work is outlined as a comparative study of biodistribution of 99mTc-ahMSCs after IV and IAR administration, via scintigraphic study in an animal model. METHODS: Isolated primary culture of adult human mesenchymal stem cells was labeled with 99mTc-HMPAO for scintigraphic study of in vivo distribution after intravenous and intra-articular (knee) administration in rabbits. RESULTS: IV administration of radiolabeled ahMSCs showed the bulk of radioactivity in the lung parenchyma while IAR images showed activity mainly in the injected cavity and complete absence of uptake in pulmonary bed. CONCLUSIONS: Our study shows that IAR administration overcomes the limitations of IV injection, in particular, those related to cells destruction in the lung parenchyma. After IAR administration, cells remain within the joint cavity, as expected given its size and adhesion properties. ADVANCES IN KNOWLEDGE: Intra-articular administration of adult human mesenchymal stem cells could be a suitable route for therapeutic effect in joint lesions. IMPLICATIONS FOR PATIENT CARE: Local administration of adult human mesenchymal stem cells could improve their therapeutic effects, minimizing side effects in patients.