Optimizing the synthesis and purification of MS2 virus like particles

Introducing bacteriophage MS2 virus-like particles (VLPs) as gene and drug delivery tools increases the demand for optimizing their production and purification procedure. PEG precipitation method is used efficiently to purify VLPs, while the effects of pH and different electrolytes on the stability, size, and homogeneity of purified MS2 VLPs, and the encapsulated RNA sequences remained to be elucidated. In this regard, a vector, capable of producing VLP with an shRNA packed inside was prepared. The resulting VLPs in different buffers/solutions were assessed for their size, polydispersity index, and ability to protect the enclosed shRNA. We report that among Tris, HEPES, and PBS, with or without NaNO3, and also NaNO3 alone in different pH and ionic concentrations, the 100 mM NaNO3-Tris buffer with pH:8 can be used as a new and optimal MS2 VLP production buffer, capable of inhibiting the VLPs aggregation. These VLPs show a size range of 27-30 nm and suitable homogeneity with minimum 12-month stability at 4 °C. Moreover, the resulting MS2 VLPs were highly efficient and stable for at least 48 h in conditions similar to in vivo. These features of MS2 VLPs produced in the newly introduced buffer make them an appropriate candidate for therapeutic agents’ delivery.

MS2 Virus-like Particle as an Efficient Drug Delivery Tool: Optimizing the Synthesis and Purification Protocol

Introducing bacteriophage MS2 virus-like particles (VLPs) as gene and drug delivery tools increases the demand for optimizing their production and purification procedure. PEG precipitation method is used efficiently to purify VLPs, while the effects of pH and different electrolytes on the stability, size, and homogeneity of purified MS2 VLPs, and the encapsulated RNA sequences remained to be elucidated.In this regard, a vector, capable of producing VLP with an shRNA packed inside was prepared. The resulting VLPs in different buffers/solutions were assessed for their size, polydispersity index, and ability to protect the enclosed shRNA. We report that among Tris, HEPES, and PBS, with or without NaNO3, and also NaNO3 alone in different pH and ionic concentrations, the 100mM NaNO3-Tris buffer with pH:8 can be used as a new and optimal MS2 VLP production buffer, capable of inhibiting the VLPs aggregation. These VLPs show a size range of 27-30nm and suitable homogeneity with minimum 12-month stability at 4◦C. Moreover, the resulting MS2 VLPs were highly efficient and stable for at least 48 hours in conditions similar to in vivo. These features of MS2 VLPs produced in the newly introduced buffer make them an appropriate candidate for therapeutic agents’ delivery.

Extraction and quality evaluation of exosomes from joint effusion

Objective: The aim of this study was to compare the quality and efficiency of exosomes extracted from knee joint effusion by different methods, laying a foundation for further research on exosomes from knee joint effusion. Methods:To separate and extract joint exosomes by 8% polyethylene glycol (PEG) precipitation method, ultracentrifugation method (UC) and ultrafiltration with exclusion chromatography (SECF). Transmission electron microscopy (TEM) and nanoparticle tracing technology (NTA) were used to detect particle morphology and particle size, and Western Blot (WB) was used to detect marker proteins of granule surface (CD9, CD63, Flotillin-1 and calnexin).Results: Three methods separated vesicle-like round particles from joint effusion successfully. The results of TEM show that the particles obtained by the three extraction methods are round or oval vesicles, the plasma membrane is intact, the size is different, and the diameter is distributed between 30 and 150 nm. Compared with SECF group, PEG group had more background particle impurities. and the broken vesicle fragments can be seen in the UC group; The results of NTA show that the main peaks of the three groups of particles are between 100-120nm, and the particle concentration is greater than 1×1010/ml; The results of WB show that the protein expressions of CD9, CD63 and Flotillin-1 in the suspension extracted by the three methods were higher, the expression of calnexin protein in the PEG group was higher than the UC group and SECF group.Conclusion: The three extraction methods can extract the exosomes of joint effusion successfully. The quality of exosomes obtained by the SECF method is relatively high, while the PEG precipitation method contains a small amount of impurity particles. UC method does not guarantee the integrity of exosomes. In summary, we recommend the SECF method to extract and isolate joint effusion exudates-derived exosomes when further studying the role of exosomes in the pathogenesis of knee osteoarthritis.

Extraction And Quality Evaluation of Exosomes From Joint Effusion

Objective: The aim of this study was to compare the quality and efficiency of exosomes extracted from knee joint effusion by different methods, laying a foundation for further research on exosomes from knee joint effusion. Methods: Separate and extract joint exosomes by 8% polyethylene glycol (PEG) precipitation method, ultracentrifugation method (UC) and ultrafiltration with exclusion chromatography (SECF). Transmission electron microscopy (TEM) and nanoparticle tracing technology (NTA) were used to detect particle morphology and particle size, and Western Blot (WB) was used to detect granule protein surface marker proteins (CD9, CD63, Flotillin-1 and calnexin).Results: All three methods successfully separated vesicle-like round particles from joint effusion. TEM results show that the particles obtained by the three extraction methods are round or oval vesicles, the plasma membrane is intact, the size is different, and the diameter is distributed between 30 and 150 nm. Compared with SECF group, PEG group had more background particle impurities. and the broken vesicle fragments can be seen in the UC group; NTA results show that the main peaks of the three groups of particles are between 100-120nm, and the particle concentration is greater than 1×1010/ml; WB results show that the expressions of CD9, CD63 and Flotillin-1 protein in the suspension extracted by the three methods were all higher, the expression of calnexin protein was higher in the PEG group than the UC group and SECF group.Conclusion: The three extraction methods can successfully extract the exosomes of joint effusion. The quality of exosomes obtained by the SECF method is relatively high, while the PEG precipitation method contains a small amount of impurity particles. UC method does not guarantee the integrity of exosomes. In summary, when further studying the role of exosomes in the pathogenesis of knee osteoarthritis, we recommend the SECF method to extract and isolate joint exudates.

Extraction And Quality Evaluation of Exosomes From Joint Effusion

Objective: The aim of this study was to compare the quality and efficiency of exosomes extracted from knee joint effusion by different methods, laying a foundation for further research on exosomes from knee joint effusion. Methods: Separate and extract joint exosomes by 8% polyethylene glycol (PEG) precipitation method, ultracentrifugation method (UC) and ultrafiltration with exclusion chromatography (SECF). Transmission electron microscopy (TEM) and nanoparticle tracing technology (NTA) were used to detect particle morphology and particle size, and Western Blot (WB) was used to detect granule protein surface marker proteins (CD9, CD63, Flotillin-1 and calnexin).Results: All three methods successfully separated vesicle-like round particles from joint effusion. TEM results show that the particles obtained by the three extraction methods are round or oval vesicles, the plasma membrane is intact, the size is different, and the diameter is distributed between 30 and 150 nm. Compared with SECF group, PEG group had more background particle impurities. and the broken vesicle fragments can be seen in the UC group; NTA results show that the main peaks of the three groups of particles are between 100-120nm, and the particle concentration is greater than 1×1010/ml; WB results show that the expressions of CD9, CD63 and Flotillin-1 protein in the suspension extracted by the three methods were all higher, the expression of calnexin protein was higher in the PEG group than the UC group and SECF group.Conclusion: The three extraction methods can successfully extract the exosomes of joint effusion. The quality of exosomes obtained by the SECF method is relatively high, while the PEG precipitation method contains a small amount of impurity particles. UC method does not guarantee the integrity of exosomes. In summary, when further studying the role of exosomes in the pathogenesis of knee osteoarthritis, we recommend the SECF method to extract and isolate joint exudates.

Optimizing laboratory defined macroprolactin algorithm

Introduction: Macroprolactinaemia is a well-known analytical problem in diagnostics of hyperprolactinaemia usually detected with polyethylene glycol (PEG) precipitation method. Since there is no harmonization in macroprolactin detection and reporting results, this study proposes and evaluates the usefulness of in-house developed algorithm. The aims were to determine the most suitable way of reporting results after PEG treatment and the possibilities of rationalizing the precipitation procedure. Materials and methods: This is a retrospective study based on extracted data for 1136 patients. Prolactin concentrations were measured before and after PEG precipitation on Roche cobas e601. Macroprolactinaemia was defined by percentage recovery and post-PEG prolactin concentrations. Results: Prevalence of macroprolactinaemia using recovery criteria of ≤ 40%, ≤ 60%, and post-PEG prolactin concentrations was 3.3%, 8.8% and 7.8%, respectively. Raising the cut-off value from the upper limit of the manufacturer’s reference interval to 32.9 μg/L does not drastically change detected macroprolactinaemia with recovery criteria. Post-PEG prolactin concentrations showed more than half of the patients with macroprolactinaemia would be overlooked. Regardless of the criteria, a cut-off of 47.0 μg/L would miss most of the macroprolactinaemic patients. Repeated recovery measurements of follow-up patients showed there is a significant difference with mean absolute bias of 9%. Conclusions: Post-PEG prolactin concentration with corresponding reference interval is the most suitable way of reporting results. All samples with prolactin concentration above the upper limit of the manufacturer’s reference interval should be submitted to PEG precipitation. Follow-up period could be prolonged since the difference between the recoveries of repeated measurements is not clinically significant.