A randomized crossover study comparing membrane and centrifugal therapeutic plasma exchange procedures.

BACKGROUND: Therapeutic plasma exchange (TPE) can be performed either on a membrane-based system (mTPE) or on a device that separates blood components by centrifugation (cTPE). The number of studies in this field is limited. This randomized study is the first that offers data on the membrane-based Diapact device (B. Braun Medical, Inc.) for TPE procedures and compares it to the centrifuge-based Spectra Optia (Terumo BCT, Inc.). STUDY DESIGN AND METHODS: Twenty-seven patients were enrolled in this randomized prospective head-to-head study comparing the mTPE and cTPE systems. Procedures on both devices were standardized and the plasma removal efficiency (PRE); total procedure time (including setup and priming time); and removal efficiencies of blood cells, immunoglobulin (Ig)G, and fibrinogen for all procedures were analyzed. RESULTS: While both systems removed similar amounts of plasma, it took the cTPE device a mean of 101.5 ± 24.6 minutes to finalize a procedure that was one-third less than procedures on the mTPE device (157 ± 26.2 min; p < 0.0001), due to a difference in PRE between the Spectra Optia (83.0% ± 4.9%) and the Diapact (53.2% ± 6.6%; p < 0.0001). The difference in removal efficiencies of IgG and blood cells were not significantly different but the Spectra Optia was more efficient in removing the larger fibrinogen protein than the Diapact (72.3% ± 8.5% vs. 62.9% ± 16.1%, respectively; p < 0.02). CONCLUSION: This study shows that, although both systems perform adequate and safe TPE procedures, those on the Spectra Optia in comparison to the Diapact are more efficient in terms of plasma removal and significantly shorter.

Scale-up of human embryonic stem cell culture using a hollow fibre bioreactor.

The commercialisation of human embryonic stem cell derived cell therapies for large patient populations is reliant on both minimising expensive and variable manual-handling methods whilst realising economies of scale. The Quantum Cell Expansion System, a hollow fibre bioreactor (Terumo BCT), was used in a pilot study to expand 60 million human embryonic stem cells to 708 million cells. Further improvements can be expected with optimisation of media flow rates throughout the run to better control the cellular microenvironment. High levels of pluripotency marker expression were maintained on the bioreactor, with 97.7 % of cells expressing SSEA-4 when harvested.

Folding properties of the hepatitis B core as a carrier protein for vaccination research.

The hepatitis B core (HBc) protein has been used successfully in numerous experiments as a carrier for heterologous peptides. Folding and capsid formation of the chimeric proteins is not always achieved easily. In silico analyses were performed to provide further comprehension of the feasibility for predicting successful capsid formation. In contrast to previous work, we show that common in silico predictions do not ensure assembly into particles. We included new considerations regarding capsid formation of HBc fusion proteins. Not only the primary sequence and the length of the inserts seem important, also the rigidity, the distance between the N and the C-terminus and the presence of cysteines, which could form disulphide bonds, could influence proper capsid formation. Furthermore, new conformational insights were formulated when linkers were added to create extra flexibility of the chimeric particles. Different hypotheses were suggested to clarify the obtained results. To this extent, the addition of glycine-rich linkers could lower high rigidity of the insert, removal of the strain of the core protein or ease interaction between the HBc and the insert. Finally, we observed specific changes in capsid formation properties when longer linkers were used. These findings have not been reported before in this and other virus-like particle carriers. In this study, we also propose a new high-yield purification protocol for fusion proteins to be used in vaccination experiments with the carrier protein or in comparative studies of particulate or non-particulate HBc fusion proteins.