A low-cost, accurate method for detecting reticulocytes at different maturation stages based on changes in the mitochondrial membrane potential.

In the clinical setting, reticulocytes are used as an index for the hematopoietic function of the bone marrow. Different maturation stages of reticulocytes are early markers for bone marrow hematopoietic stem cell transplantation and bone marrow regeneration after chemotherapy. Therefore, we aimed to establish a method for detecting the different reticulocyte maturation stages. Based on the decreases in mitochondrial membrane potential during reticulocyte maturation, we used MitoTracker Green (MTG)/tetramethylrhodamine, ethylester (TMRE) to identify the different reticulocyte maturation stages and used Hoechst33342 to exclude nucleated cells. The results show that this method was universal and could be applied to detect the proportions of reticulocytes in different samples. Their proportion in normal peripheral blood, a blood deficiency model, bone marrow, and spleen were (6 ± 2)%, (38 ± 4)%, (14 ± 4)%, and (3 ± 1)%, respectively. The results obtained using this method were similar to those obtained using the manual counting method (methylene blue); the correlation was good (R = 0.817; p < .01) and the coefficient of variation was lower for the method established. Moreover, reticulocytes in peripheral blood could be further divided into three distinct maturation stages: R1 (MTGneg/TMREhigh), R2 (MTGhigh/TMREhigh), and R3 (MTGhigh/TMREneg). Reticulocytes in the bone marrow and spleen could be further divided into four distinct maturation stages: R1 (MTGneg/TMREhigh), R2-1 (MTGhigh/TMREhigh/FSbig), R2-2 (MTGhigh/TMREhigh/FSsmall), and R3 (MTGhigh/TMREneg). Based on changes in mitochondrial membrane potential, MTG/TMRE/Hoechst33342 staining could be used to detect reticulocytes in different samples and at different maturation stages with low cost and high accuracy.

Using a single hydrophobic-interaction chromatography to purify pharmaceutical-grade supercoiled plasmid DNA from other isoforms.

CONTEXT: The recent developments in non-viral gene therapy and DNA vaccine have fostered the development of efficient plasmid DNA (pDNA) purification processes. OBJECTIVES: This work aimed to establish a cost-effective purification process for the large-scale production of plasmid DNA for gene therapy and DNA vaccine. MATERIALS AND METHODS: E. coli DH5α harboring pCDNA3.1-GFP (7200 base pairs) was used as a model plasmid. Hydrophobic-interaction chromatography (HIC) was employed to purify supercoiled plasmid DNA (sc pDNA). RESULTS: With this method, not only host contaminants, but also open circular plasmid DNA (oc pDNA) could be removed from sc pDNA. Anion-exchange HPLC analysis proved that the recovery of HIC could reach 75%. The plasmid DNA exhibited high purity with supercoiled percentage of 98 ± 1.2% and undetectable residual endotoxins, genomic DNA, RNA and protein. The purity of pDNA had nothing to do with the flow rate in the range at least up to 400 cm/h. Liposomes transfection experiment prove that the purified pDNA in this article had higher transfection efficiency than the control pDNA. DISCUSSION AND CONCLUSION: In the present work, we confirmed the possibility of separation of sc pDNA from oc pDNA and other host contaminants using a single HIC chromatography.