Application of a simple unstructured kinetic and cost of goods models to support T-cell therapy manufacture.

Manufacturing of cell therapy products requires sufficient understanding of the cell culture variables and associated mechanisms for adequate control and risk analysis. The aim of this study was to apply an unstructured ordinary differential equation-based model for prediction of T-cell bioprocess outcomes as a function of process input parameters. A series of models were developed to represent the growth of T-cells as a function of time, culture volumes, cell densities, and glucose concentration using data from the Ambr®15 stirred bioreactor system. The models were sufficiently representative of the process to predict the glucose and volume provision required to maintain cell growth rate and quantitatively defined the relationship between glucose concentration, cell growth rate, and glucose utilization rate. The models demonstrated that although glucose is a limiting factor in batch supplied medium, a delivery rate of glucose at significantly less than the maximal specific consumption rate (0.05 mg 1 × 106  cell h-1 ) will adequately sustain cell growth due to a lower glucose Monod constant determining glucose consumption rate relative to the glucose Monod constant determining cell growth rate. The resultant volume and exchange requirements were used as inputs to an operational BioSolve cost model to suggest a cost-effective T-cell manufacturing process with minimum cost of goods per million cells produced and optimal volumetric productivity in a manufacturing settings. These findings highlight the potential of a simple unstructured model of T-cell growth in a stirred tank system to provide a framework for control and optimization of bioprocesses for manufacture.

Immobilisation of Delta-like 1 ligand for the scalable and controlled manufacture of hematopoietic progenitor cells in a stirred bioreactor.

BACKGROUND: Umbilical cord blood provides a source of hematopoietic stem cells for transplantation with immunological and availability advantages over conventional bone marrow sources. Limited cell numbers and slower engraftment from umbilical cord blood units has led to the clinical development of immobilised Notch ligand Delta-Like 1 to promote ex vivo expansion of a rapidly engrafting cell population. However, current immobilisation methods are not simple to scale in a controlled manner. RESULTS: Delta-Like 1 was immobilised onto streptavidin coated magnetic particles via a heterobifunctionalised polyethylene glycol linker molecule to provide an easily manipulated format of surface protein presentation. CD34+ enriched cord blood cells were treated with Delta-Like 1 immobilised particles, and immunophenotypic markers measured to monitor population distributions using cluster identification, characterization, and regression software. The amenability of the approach to scalability was evaluated in a micro-scale stirred tank bioreactor. Surface concentration of Delta-Like 1 was well controlled used differing stoichiometric reagent ratios. Protein immobilisation was a cost effective process and particles were efficiently removed from the final cell product. Immobilised Delta-Like 1 is functional and stimulates qualitatively similar CD34hi, CD38lo, CD90lo, CD133hi, CD135hi progenitor expansion in both static culture and scalable stirred culture platforms. CONCLUSIONS: Immobilised Delta-Like 1 in this form has the potential to improve the manufacturing efficiency and control of final ex vivo expanded cell product through compatibility with highly controlled and characterised suspension culture systems.

Immobilized hematopoietic growth factors onto magnetic particles offer a scalable strategy for cell therapy manufacturing in suspension cultures.

Hematopoietic therapies require high cell dosages and precise phenotype control for clinical success; scalable manufacturing processes therefore need to be economic and controllable, in particular with respect to culture medium and growth factor (GF) strategy. The aim of this work was to demonstrate the biological function, and integration within scalable systems, of a highly controllable immobilized growth factor (iGF) approach. GFs were biotinylated and attached to streptavidin coated magnetic particles. GF concentration during biotinylation, GF-biotin ratio, and GF lysine content were shown to control iGF surface concentration and enable predictable co-presentation of multiple GF on a single bead. Function was demonstrated for immobilized GMCSF, SCF, TPO and IL-3 in GF dependent cell lines TF-1 and M-07e. Immobilized GMCSF (iGMCSF) was analyzed to show sustained activity over 8 days of culture, a 2-3 order of magnitude potency increase relative to soluble factor, and retained functionality under agitation in a micro-scale stirred tank bioreactor. Further, short exposure to iGMCSF demonstrated prolonged growth response relative to soluble factor. This immobilization approach has the potential to reduce the manufacturing costs of scaled cell therapy products by reducing GF quantities and offers important process control opportunities through separation of GF treatments from the bulk media.

Discovery and Characterization of a Potent Interleukin-6 Binding Peptide with Neutralizing Activity In Vivo.

Interleukin-6 (IL-6) is an important member of the cytokine superfamily, exerting pleiotropic actions on many physiological processes. Over-production of IL-6 is a hallmark of immune-mediated inflammatory diseases such as Castleman's Disease (CD) and rheumatoid arthritis (RA). Antagonism of the interleukin IL-6/IL-6 receptor (IL-6R)/gp130 signaling complex continues to show promise as a therapeutic target. Monoclonal antibodies (mAbs) directed against components of this complex have been approved as therapeutics for both CD and RA. To potentially provide an additional modality to antagonize IL-6 induced pathophysiology, a peptide-based antagonist approach was undertaken. Using a combination of molecular design, phage-display, and medicinal chemistry, disulfide-rich peptides (DRPs) directed against IL-6 were developed with low nanomolar potency in inhibiting IL-6-induced pSTAT3 in U937 monocytic cells. Targeted PEGylation of IL-6 binding peptides resulted in molecules that retained their potency against IL-6 and had a prolongation of their pharmacokinetic (PK) profiles in rodents and monkeys. One such peptide, PN-2921, contained a 40 kDa polyethylene glycol (PEG) moiety and inhibited IL-6-induced pSTAT3 in U937 cells with sub-nM potency and possessed 23, 36, and 59 h PK half-life values in mice, rats, and cynomolgus monkeys, respectively. Parenteral administration of PN-2921 to mice and cynomolgus monkeys potently inhibited IL-6-induced biomarker responses, with significant reductions in the acute inflammatory phase proteins, serum amyloid A (SAA) and C-reactive protein (CRP). This potent, PEGylated IL-6 binding peptide offers a new approach to antagonize IL-6-induced signaling and associated pathophysiology.

Current status and perspectives on stem cell-based therapies undergoing clinical trials for regenerative medicine: case studies.

BACKGROUND: Apart from haematopoietic stem cell transplantation for haematological disorders many stem cell-based therapies are experimental. However, with only 12 years between human embryonic stem cell isolation and the first clinical trial, development of stem cell products for regenerative medicine has been rapid and numerous clinical trials have begun to investigate their therapeutic potential. SOURCE OF DATA: This review summarizes key clinical trial data, current and future perspectives on stem cell-based products undergoing clinical trials, based on literature search and author research. AREAS OF AGREEMENT: It is widely recognized that the ability to stimulate stem cell differentiation into specialized cells for use as cellular therapies will revolutionize health care and offer major hope for numerous diseases for which there are limited or no therapeutic options. AREAS OF CONTROVERSY: Stem cell-based products are unique and cover a large range of disorders to be treated; therefore, there is significant potential for variation in cell source, type, processing manipulation, the bioprocessing approach and scalability, the cost and purity of manufacture, final product quality and mode of action. As such there are gaps in regulatory and manufacturing frameworks and technologies, only a small number of products are currently within late phase clinical trials and few products have achieved commercialization. GROWING POINTS: Recent developments are encouraging acceleration through the difficulties encountered en route to clinical trials and commercialization of stem cell therapies. AREAS TIMELY FOR DEVELOPING RESEARCH: The field is growing year on year with the first clinical trial using induced pluripotent stem cells anticipated by end 2013.

Production of erythrocytes from directly isolated or Delta1 Notch ligand expanded CD34+ hematopoietic progenitor cells: process characterization, monitoring and implications for manufacture.

BACKGROUND AIMS: Economic ex vivo manufacture of erythrocytes at 10(12) cell doses requires an efficiently controlled bio-process capable of extensive proliferation and high terminal density. High-resolution characterization of the process would identify production strategies for increased efficiency, monitoring and control. METHODS: CD34(+) cord blood cells or equivalent cells that had been pre-expanded for 7 days with Delta1 Notch ligand were placed in erythroid expansion and differentiation conditions in a micro-scale ambr suspension bioreactor. Multiple culture parameters were varied, and phenotype markers and metabolites measured to identify conserved trends and robust monitoring markers. RESULTS: The cells exhibited a bi-modal erythroid differentiation pattern with an erythroid marker peak after 2 weeks and 3 weeks of culture; differentiation was comparatively weighted toward the second peak in Delta1 pre-expanded cells. Both differentiation events were strengthened by omission of stem cell factor and dexamethasone. The cumulative cell proliferation and death, or directly measured CD45 expression, enabled monitoring of proliferative rate of the cells. The metabolic activities of the cultures (glucose, glutamine and ammonia consumption or production) were highly variable but exhibited systematic change synchronized with the change in differentiation state. CONCLUSIONS: Erythroid differentiation chronology is partly determined by the heterogeneous CD34(+) progenitor compartment with implications for input control; Delta1 ligand-mediated progenitor culture can alter differentiation profile with control benefits for engineering production strategy. Differentiation correlated changes in cytokine response, markers and metabolic state will enable scientifically designed monitoring and timing of manufacturing process steps.

Integrin-substrate interactions underlying shear-induced inhibition of the inflammatory response of endothelial cells.

Conditioning of endothelial cells by shear stress suppresses their response to inflammatory cytokines. We questioned whether signalling through different integrin-matrix interactions, previously associated with the pathogenic effects of disturbed flow, supported the anti-inflammatory action of steady shear. Primary human endothelial cells were cultured on different substrates and exposed to shear stress (2.0Pa) for varying periods before stimulation with tumour necrosis factor-α (TNF). Shear-conditioning inhibited cytokine-induced recruitment of flowing neutrophils. However, the effect was similar for culture on collagen, laminin or fibronectin, even when seeding was reduced to 2 hours, and shear to 3 hours before TNF treatment (to minimise deposition of endothelial matrix). Nevertheless, in short- or longer-term cultures, reduction in expression of ß(1)-integrin (but not ß(3)-integrin) using siRNA essentially ablated the effect of shear-conditioning on neutrophil recruitment. Studies of focal adhesion kinase (FAK) phosphorylation, siRNA against FAK and a FAK-inhibitor (PF573228) indicated that FAK activity was an essential component downstream of ß(1)-integrin. In addition, MAP-kinase p38 was phosphorylated downstream of FAK and also required for functional modification. Mechanotransduction through ß(1)-integrins, FAK and p38 is required for anti-inflammatory effects of steady shear stress. Separation of the pathways which underlie pathological versus protective responses of different patterns of flow is required to enable therapeutic modification or mimicry, respectively.