Scalability and process transfer of mesenchymal stromal cell production from monolayer to microcarrier culture using human platelet lysate.

BACKGROUND AIMS: The selection of medium and associated reagents for human mesenchymal stromal cell (hMSC) culture forms an integral part of manufacturing process development and must be suitable for multiple process scales and expansion technologies. METHODS: In this work, we have expanded BM-hMSCs in fetal bovine serum (FBS)- and human platelet lysate (HPL)-containing media in both a monolayer and a suspension-based microcarrier process. RESULTS: The introduction of HPL into the monolayer process increased the BM-hMSC growth rate at the first experimental passage by 0.049 day and 0.127/day for the two BM-hMSC donors compared with the FBS-based monolayer process. This increase in growth rate in HPL-containing medium was associated with an increase in the inter-donor consistency, with an inter-donor range of 0.406 cumulative population doublings after 18 days compared with 2.013 in FBS-containing medium. Identity and quality characteristics of the BM-hMSCs are also comparable between conditions in terms of colony-forming potential, osteogenic potential and expression of key genes during monolayer and post-harvest from microcarrier expansion. BM-hMSCs cultured on microcarriers in HPL-containing medium demonstrated a reduction in the initial lag phase for both BM-hMSC donors and an increased BM-hMSC yield after 6 days of culture to 1.20 ± 0.17 × 10(5) and 1.02 ± 0.005 × 10(5) cells/mL compared with 0.79 ± 0.05 × 10(5) and 0.36 ± 0.04 × 10(5) cells/mL in FBS-containing medium. CONCLUSIONS: This study has demonstrated that HPL, compared with FBS-containing medium, delivers increased growth and comparability across two BM-hMSC donors between monolayer and microcarrier culture, which will have key implications for process transfer during scale-up.

Serum-free process development: improving the yield and consistency of human mesenchymal stromal cell production.

BACKGROUND AIMS: The cost-effective production of human mesenchymal stromal cells (hMSCs) for off-the-shelf and patient specific therapies will require an increasing focus on improving product yield and driving manufacturing consistency. METHODS: Bone marrow-derived hMSCs (BM-hMSCs) from two donors were expanded for 36 days in monolayer with medium supplemented with either fetal bovine serum (FBS) or PRIME-XV serum-free medium (SFM). Cells were assessed throughout culture for proliferation, mean cell diameter, colony-forming potential, osteogenic potential, gene expression and metabolites. RESULTS: Expansion of BM-hMSCs in PRIME-XV SFM resulted in a significantly higher growth rate (P < 0.001) and increased consistency between donors compared with FBS-based culture. FBS-based culture showed an inter-batch production range of 0.9 and 5 days per dose compared with 0.5 and 0.6 days in SFM for each BM-hMSC donor line. The consistency between donors was also improved by the use of PRIME-XV SFM, with a production range of 0.9 days compared with 19.4 days in FBS-based culture. Mean cell diameter has also been demonstrated as a process metric for BM-hMSC growth rate and senescence through a correlation (R(2) = 0.8705) across all conditions. PRIME-XV SFM has also shown increased consistency in BM-hMSC characteristics such as per cell metabolite utilization, in vitro colony-forming potential and osteogenic potential despite the higher number of population doublings. CONCLUSIONS: We have increased the yield and consistency of BM-hMSC expansion between donors, demonstrating a level of control over the product, which has the potential to increase the cost-effectiveness and reduce the risk in these manufacturing processes.

Expansion, harvest and cryopreservation of human mesenchymal stem cells in a serum-free microcarrier process.

Human mesenchymal stem cell (hMSC) therapies are currently progressing through clinical development, driving the need for consistent, and cost effective manufacturing processes to meet the lot-sizes required for commercial production. The use of animal-derived serum is common in hMSC culture but has many drawbacks such as limited supply, lot-to-lot variability, increased regulatory burden, possibility of pathogen transmission, and reduced scope for process optimization. These constraints may impact the development of a consistent large-scale process and therefore must be addressed. The aim of this work was therefore to run a pilot study in the systematic development of serum-free hMSC manufacturing process. Human bone-marrow derived hMSCs were expanded on fibronectin-coated, non-porous plastic microcarriers in 100 mL stirred spinner flasks at a density of 3 × 10(5) cells.mL(-1) in serum-free medium. The hMSCs were successfully harvested by our recently-developed technique using animal-free enzymatic cell detachment accompanied by agitation followed by filtration to separate the hMSCs from microcarriers, with a post-harvest viability of 99.63 ± 0.03%. The hMSCs were found to be in accordance with the ISCT characterization criteria and maintained hMSC outgrowth and colony-forming potential. The hMSCs were held in suspension post-harvest to simulate a typical pooling time for a scaled expansion process and cryopreserved in a serum-free vehicle solution using a controlled-rate freezing process. Post-thaw viability was 75.8 ± 1.4% with a similar 3 h attachment efficiency also observed, indicating successful hMSC recovery, and attachment. This approach therefore demonstrates that once an hMSC line and appropriate medium have been selected for production, multiple unit operations can be integrated to generate an animal component-free hMSC production process from expansion through to cryopreservation.

Human hair follicle dermal sheath and papilla cells support keratinocyte growth in monolayer coculture.

Traditional skin grafting techniques are effective but limited methods of skin replacement. Autologous transplantation of rapidly cultured keratinocytes is successful for epidermal regeneration, but the current gold-standard technique requires mouse fibroblast feeders and serum-rich media, with serum-free systems and dermal fibroblast (DF) feeders performing relatively poorly. Here, we investigated the capacity of human hair follicle dermal cells to act as alternative supports for keratinocyte growth. Dermal papilla (DP) dermal sheath (DS), DF and 3T3 cells were used as inactivated feeder cells for human keratinocyte coculture. Under conditions favouring dermal cells, proliferation of keratinocytes in the presence of either DS or DP cells was significantly enhanced compared with DF cells, at levels comparable to keratinocytes cultured under gold-standard conditions. Secreted protein acidic and rich in cysteine (SPARC) expression increased DS and DP cells relative to DFs; however, further experiments did not demonstrate a role in keratinocyte support.

Assessment of Protocol Impact on Subjectivity Uncertainty When Analyzing Peripheral Blood Mononuclear Cell Flow Cytometry Data Files.

Measured variability of product within Cell and Gene Therapy (CGT) manufacturing arises from numerous sources across pre-analytical to post-analytical phases of testing. Operators are a function of the manufacturing process and are an important source of variability as a result of personal differences impacted by numerous factors. This research uses measurement uncertainty in comparison to Coefficient of Variation to quantify variation of participants when they complete Flow Cytometry data analysis through a 5-step gating sequence. Two study stages captured participants applying gates using their own judgement, and then following a diagrammatical protocol, respectively. Measurement uncertainty was quantified for each participant (and analysis phase) by following Guide to the Expression of Uncertainty in Measurement protocols, combining their standard deviations in quadrature from each gating step in the respective protocols. When participants followed a diagrammatical protocol, variation between participants reduced by 57%, increasing confidence in a more uniform reported cell count percentage. Measurement uncertainty provided greater resolution to the analysis processes, identifying that most variability contributed in the Flow Cytometry gating process is from the very first gate, where isolating target cells from dead or dying cells is required. This work has demonstrated the potential for greater usage of measurement uncertainty within CGT manufacturing scenarios, due to the resolution it provides for root cause analysis and continuous improvement.

Quantifying Operator Subjectivity within Flow Cytometry Data Analysis as a Source of Measurement Uncertainty and the Impact of Experience on Results.

Flow cytometry is a complex measurement characterization technique, utilized within the manufacture, measurement, and release of cell and gene therapy products for rapid, high-content, and multiplexed discriminatory cell analysis. A number of factors influence the variability in the measurement reported including, but not limited to, biological variation, reagent variation, laser and optical configurations, and data analysis methods. This research focused on understanding the contribution of manual operator variability within the data analysis phase. Thirty-eight participants completed a questionnaire, providing information about experience and motivational factors, before completing a simple gating study. The results were analyzed using gauge repeatability and reproducibility techniques to quantify participant uncertainty. The various stages of the gating sequence were combined through summation in quadrature and expanded to give each participant a representative uncertainty value. Of the participants surveyed, 85% preferred manual gating to automated data analysis, with the primary reasons being legacy ("it's always been done that way") and accuracy, not in the metrological sense but in the clear definition of the correct target population. The median expanded uncertainty was calculated as 3.6% for the population studied, with no significant difference among more or less experienced users. Operator subjectivity can be quantified to include within measurement uncertainty budgets, required for various standards and qualifications. An emphasis on biomanufacturing measurement terminology is needed to help understand future and potential solutions, possibly looking at translational clinical models to engage and enhance better training and protocols within industrial and research settings.

Multivariate data analysis in cell gene therapy manufacturing.

The emergence of cell gene therapy (CGT) as a safe and efficacious treatment for numerous severe inherited and acquired human diseases has led to growing interest and investment in new CGT products. The most successful of these have been autologous viral vector-based treatments. The development of viral vector manufacturing processes and ex vivo patient cell processing capabilities is a pressing issue in the advancement of autologous viral vector-based CGT treatments. In viral vector production, scale-up is a critical task due to the limited scalability of traditional laboratory systems and the demand for high volumes of viral vector manufactured in accordance with current good manufacturing practice. Ex vivo cell processing methods require optimisation and automation before they can be scaled out, and several other manufacturing challenges are prevalent such as high levels of raw material and process variability, difficulty characterising complex materials, and a lack of knowledge of critical process parameters and their effect on critical quality attributes of the viral vector and cell drug products. Multivariate data analysis (MVDA) has been leveraged successfully in a variety of applications in the chemical and biochemical industries, including for tasks such as bioprocess monitoring, identification of critical process parameters and assessment of process variability and comparability during process development, scale-up and technology transfer. Henceforth, MVDA is reviewed here as a suitable tool for tackling some of the challenges faced in the development of CGT manufacturing processes. A summary of some key CGT manufacturing challenges is provided along with a review of MVDA applications to mammalian and microbial processes, and an exploration of the potential benefits, requirements and pre-requisites of MVDA applications in the development of CGT manufacturing processes.

Studies related to antibody fragment (Fab) production in Escherichia coli W3110 fed-batch fermentation processes using multiparameter flow cytometry.

Microbiology is important to industry therefore rapid and statistically representative measurements of cell physiological state, proliferation, and viability are essential if informed decisions about fermentation bioprocess optimization or control are to be made, because process performance will depend largely on the number of metabolically active viable cells. Samples of recombinant Escherichia coli W3110, containing the gene for the D1.3 anti-lysozyme Fab fragment under the control of the lac-based expression system, were taken at various stages from fed-batch fermentation processes and stained with a mixture of bis-(1,3-dibutylbarbituric acid) trimethine oxonol and propidium iodide (PI/BOX). Where appropriate, measurements of dissolved oxygen tension (DOT), OD600nm and Fab concentration were made. Depending on time of induction the maximum amount of Fab accumulating in the supernatant varied quite markedly from 1 to 4 microg ml(-1) as did subsequent cell physiological state with respect to PI/BOX staining with a concomitant drop in maximum biomass concentration. Depending on point of induction a fourfold increase in Fab production could be achieved accompanied by a approximately 50% drop in maximum biomass concentration but with a higher proportion of viable cells as measured by multiparameter flow cytometry.

The translation of cell-based therapies: clinical landscape and manufacturing challenges.

Cell-based therapies have the potential to make a large contribution toward currently unmet patient need and thus effective manufacture of these products is essential. Many challenges must be overcome before this can become a reality and a better definition of the manufacturing requirements for cell-based products must be obtained. The aim of this study is to inform industry and academia of current cell-based therapy clinical development and to identify gaps in their manufacturing requirements. A total of 1342 active cell-based therapy clinical trials have been identified and characterized based on cell type, target indication and trial phase. Multiple technologies have been assessed for the manufacture of these cell types in order to facilitate product translation and future process development.

Generation and characterization of multipotent stem cells from established dermal cultures.

Human multipotent skin derived precursor cells (SKPs) are traditionally sourced from dissociated dermal tissues; therefore, donor availability may become limiting. Here we demonstrate that both normal and diseased adult human dermal fibroblasts (DF) pre-cultured in conventional monolayers are capable of forming SKPs (termed m-SKPs). Moreover, we show that these m-SKPs can be passaged and that cryopreservation of original fibroblast monolayer cultures does not reduce m-SKP yield; however, extensive monolayer passaging does. Like SKPs generated from dissociated dermis, these m-SKPs expressed nestin, fibronectin and versican at the protein level. At the transcriptional level, m-SKPs derived from normal adult human DF, expressed neural crest stem cell markers such as p75NTR, embryonic stem cell markers such as Nanog and the mesenchymal stem cell marker Dermo-1. Furthermore, appropriate stimuli induced m-SKPs to differentiate down either mesenchymal or neural lineages resulting in lipid accumulation, calcification and S100ß or ß-III tubulin expression (with multiple processes). m-SKP yield was greater from neonatal foreskin cultures compared to those from adult DF cultures; however, the former showed a greater decrease in m-SKP forming capacity after extensive monolayer passaging. m-SKP yield was greater from adult DF cultures expressing more alpha-smooth muscle actin (αSMA). In turn, elevated αSMA expression correlated with cells originating from specimens isolated from biopsies containing more terminal hair follicles; however, αSMA expression was lost upon m-SKP formation. Others have shown that dissociated human hair follicle dermal papilla (DP) are a highly enriched source of SKPs. However, conversely and unexpectedly, monolayer cultured human hair follicle DP cells failed to form m-SKPs whereas those from the murine vibrissae follicles did. Collectively, these findings reveal the potential for using expanded DF cultures to produce SKPs, the heterogeneity of SKP forming potential of skin from distinct anatomical locations and ages, and question the progenitor status of human hair follicle DP cells.