ABSTRACT
BACKGROUND: Previous studies have found that the culture supernatant of the olfactory ensheathing cells is capable of promoting axonal regeneration and functional recovery after spinal cord injury, but there is a lack of research in the field of peripheral nerve. OBJECTIVE: To investigate whether olfactory ensheathing cell culture supernatant is beneficial for nerve repair after peripheral nerve injury. METHODS: Olfactory ensheathing cells were isolated and purified, to prepare the supernatant. The olfactory ensheathing cell culture supernatant was applied to the dorsal root ganglion tissue block in vitro to observe the axon growth of the dorsal root ganglion. The olfactory ensheathing cell culture supernatant was applied to a rat sciatic nerve defect model in vivo to examine its effect on axonal regeneration and myelinization of the injured nerve. RESULTS AND CONCLUSION: The purity of olfactory ensheathing cells was (94.4±3.1)%. Compared with the blank control and low dose olfactory ensheathing cell culture groups, the average length of five longest axons in dorsal root ganglion tissue mass in the high dose olfactory ensheathing cells culture group was significantly increased (P < 0.05). Immunofluorescence showed that the regenerated nerve penetrated through the defect area and the regenerated nerve was arranged orderly in the olfactory ensheathing cell culture and the autologous nerve groups, which was significantly superior to that in the blank control group. Transmission electron microscope observed that the number of regenerated nerve axons and the thickness of myelin sheath in the olfactory ensheathing cell culture group were significantly higher than those in the blank control group (P < 0.05). These results indicate that the supernatant of the olfactory ensheathing cells can promote axonal regeneration after peripheral nerve injury and the myelination of the regenerated axons, which provides a new olfactory ensheathing cells-based acellular therapy for peripheral nerve injury.
ABSTRACT
Therapeutic monoclonal antibodies become the major product class within the biopharmaceutical market. Protein A as the first capture step is still dominant in current platforms for purification of monoclonal antibodies. In this study, we developed a new antibody harvest process that incorporates acidic treatment of cell harvest, demonstrating high process yield, improved clearance of host cell associated contaminants, like non-histone host cell protein, histone, DNA and heteroaggregates. Host protein contamination was reduced about 10-fold compared to protein A loaded with harvest clarified by centrifugation and microfiltration. Turbidity increase of eluted IgG upon pH neutralization was nearly eliminated. Residual levels of impurities in the protein A eluate were achieved that potentially meet requirements of drug substance and thus alleviate the burden for further impurities removal in subsequent chromatography steps. The mechanism of host cell associated contaminants removal during acidic treatment was also explored. After a polishing step by Capto adhere, host cell protein was reduced to less than 5 ppm, DNA less than 1 ppb, histone to undetectable level, heteroaggregates less than 0.01% with total IgG recovery around 87%. This efficient process can be easily integrated into current IgG purification platforms, and may overcome downstream processing challenges.