Human cell lines for biopharmaceutical manufacturing: history,status, and future perspectives

Biotherapeutic proteins represent a mainstay of treatment for a multitude of conditions, for example, autoimmune disorders, hematologic disorders, hormonal dysregulation, cancers, infectious diseases and genetic disorders. The technologies behind their production have changed substantially since biotherapeutic proteins were first approved in the 1980s. Although most biotherapeutic proteins developed to date have been produced using the mammalian Chinese hamster ovary and murine myeloma (NS0, Sp2/0) cell lines, there has been a recent shift toward the use of human cell lines. One of the most important advantages of using human cell lines for protein production is the greater likelihood that the resulting recombinant protein will bear post-translational modifications (PTMs) that are consistent with those seen on endogenous human proteins. Although other mammalian cell lines can produce PTMs similar to human cells, they also produce non-human PTMs, such as galactose-α1,3-galactose and N-glycolylneuraminic acid, which are potentially immunogenic. In addition, human cell lines are grown easily in a serum-free suspension culture, reproduce rapidly and have efficient protein production. A possible disadvantage of using human cell lines is the potential for human-specific viral contamination, although this risk can be mitigated with multiple viral inactivation or clearance steps. In addition, while human cell lines are currently widely used for biopharmaceutical research, vaccine production and production of some licensed protein therapeutics, there is a relative paucity of clinical experience with human cell lines because they have only recently begun to be used for the manufacture of proteins (compared with other types of cell lines). With additional research investment, human cell lines may be further optimized for routine commercial production of a broader range of biotherapeutic proteins.     

Simplified Aeroelastic Model for Fluid Structure Interaction between Microcantilever Sensors and Fluid Surroundings

Fluid-structural coupling occurs when microcantilever sensors vibrate in a fluid. Due to the complexity of the mechanical characteristics of microcantilevers and lack of high-precision microscopic mechanical testing instruments, effective methods for studying the fluid-structural coupling of microcantilevers are lacking, especially for non-rectangular microcantilevers. Here, we report fluid-structure interactions (FSI) of the cable-membrane structure via a macroscopic study. The simplified aeroelastic model was introduced into the microscopic field to establish a fluid-structure coupling vibration model for microcantilever sensors. We used the finite element method to solve the coupled FSI system. Based on the simplified aeroelastic model, simulation analysis of the effects of the air environment on the vibration of the commonly used rectangular microcantilever was also performed. The obtained results are consistent with the literature. The proposed model can also be applied to the auxiliary design of rectangular and non-rectangular sensors used in fluid environments.     

Orthogonal test design for optimization of the extraction of polysaccharides from Phascolosoma esulenta and evaluation of its immunity activity

Yield of polysaccharides from Phascolosoma esulenta obtained by phosphate buffer extraction through an orthogonal experiment (L₉(3)⁴) were investigated to get the best extraction conditions. The results showed that extraction temperature, ratio of phosphate buffer to raw material, extraction time, and ratio of trypsinase to raw material were the main four variables that influenced the yields of extracts. The highest yield was obtained when extraction temperature, ratio of phosphate buffer to raw material, extraction time and ratio of trypsinase to raw material were 40 °C, 2, 5.5 h and 1.6, respectively. The immunity-stimulating method showed that polysaccharides from P. esulenta could significantly raise liver, spleen and thymus index of mice and enhance Con A-stimulated mouse spleen cells proliferation. These results indicate that polysaccharides from P. esulenta had significantly higher immunity-stimulating activities.     

Masking effect of different durations of forward masker sound on acoustical responses of mouse inferior collicular neurons to probe sound

To study the effects of different durations of forward masker sound on neuronal firing and rate-intensity function (RIF) of mouse inferior collicular (IC) neurons, a tone relative to 5 dB above the minimum threshold (re MT+5 dB) of the best frequency of recorded neurons was used as forward masker sound under free field stimulation condition. The masker durations used were 40, 60, 80, and 100 ms. Results showed that as masker duration was increased, inhibition in neuronal firing was enhanced (P < 0.000 1, n = 41) and the latency of neurons was lengthened (P<0.01, n = 41). In addition, among 41 inhibited IC neurons, 90.2% (37/41) exhibited narrowed dynamic range (DR) when masker sound duration was increased (P < 0.000 1), whereas the DR of 9.8%(4/41) became wider. These data suggest that masking effects of different durations of forward masker sound might be correlated with the amplitude and duration of inhibitory input to IC neurons elicited by the masker sound. __________ Translated from Journal of Central China Normal University (Nat. Sci.), 2005, 39(2): 236–240 [译自: 华中师范大学学报 (自然科学版), 2005, 39(2): 236–240]