Manufacturing Therapeutic Exosomes: from Bench to Industry.

Process of manufacturing therapeutics exosome development for commercialization. The development of exosome treatment starts at the bench, and in order to be commercialized, it goes through the manufacturing, characterization, and formulation stages, production under Good Manufacturing Practice (GMP) conditions for clinical use, and close consultation with regulatory authorities. Exosome, a type of nanoparticles also known as small extracellular vesicles are gaining attention as novel therapeutics for various diseases because of their ability to deliver genetic or bioactive molecules to recipient cells. Although many pharmaceutical companies are gradually developing exosome therapeutics, numerous hurdles remain regarding manufacture of clinical-grade exosomes for therapeutic use. In this mini-review, we will discuss the manufacturing challenges of therapeutic exosomes, including cell line development, upstream cell culture, and downstream purification process. In addition, developing proper formulations for exosome storage and, establishing good manufacturing practice facility for producing therapeutic exosomes remains as challenges for developing clinicalgrade exosomes. However, owing to the lack of consensus regarding the guidelines for manufacturing therapeutic exosomes, close communication between regulators and companies is required for the successful development of exosome therapeutics. This review shares the challenges and perspectives regarding the manufacture and quality control of clinical grade exosomes.

Dysregulation of bile acids increases the risk for preterm birth in pregnant women.

Preterm birth (PTB) is the leading cause of perinatal mortality and newborn complications. Bile acids are recognized as signaling molecules regulating a myriad of cellular and metabolic activities but have not been etiologically linked to PTB. In this study, a hospital-based cohort study with 36,755 pregnant women is conducted. We find that serum total bile acid levels directly correlate with the PTB rates regardless of the characteristics of the subjects and etiologies of liver disorders. Consistent with the findings from pregnant women, PTB is successfully reproduced in mice with liver injuries and dysregulated bile acids. More importantly, bile acids dose-dependently induce PTB with minimal hepatotoxicity. Furthermore, restoring bile acid homeostasis by farnesoid X receptor activation markedly reduces PTB and dramatically improves newborn survival rates. The findings thus establish an etiologic link between bile acids and PTB, and open an avenue for developing etiology-based therapies to prevent or delay PTB.

Dysregulation of Δ4-3-oxosteroid 5ß-reductase in diabetic patients: Implications and mechanisms.

Aldo-keto reductase family 1 member D1 (AKR1D1) is a Δ4-3-oxosteroid 5ß-reductase required for bile acid synthesis and steroid hormone metabolism. Both bile acids and steroid hormones, especially glucocorticoids, play important roles in regulating body metabolism and energy expenditure. Currently, our understanding on AKR1D1 regulation and its roles in metabolic diseases is limited. We found that AKR1D1 expression was markedly repressed in diabetic patients. Consistent with repressed AKR1D1 expression, hepatic bile acids were significantly reduced in diabetic patients. Mechanistic studies showed that activation of peroxisome proliferator-activated receptor-α (PPARα) transcriptionally down-regulated AKR1D1 expression in vitro in HepG2 cells and in vivo in mice. Consistently, PPARα signaling was enhanced in diabetic patients. In summary, dysregulation of AKR1D1 disrupted bile acid and steroid hormone homeostasis, which may contribute to the pathogenesis of diabetes. Restoring bile acid and steroid hormone homeostasis by modulating AKR1D1 expression may represent a new approach to develop therapies for diabetes.

Differential Feedback Regulation of Δ4-3-Oxosteroid 5ß-Reductase Expression by Bile Acids.

Δ4-3-oxosteroid 5ß-reductase is member D1 of the aldo-keto reductase family 1 (AKR1D1), which catalyzes 5ß-reduction of molecules with a 3-oxo-4-ene structure. Bile acid intermediates and most of the steroid hormones carry the 3-oxo-4-ene structure. Therefore, AKR1D1 plays critical roles in both bile acid synthesis and steroid hormone metabolism. Currently our understanding on transcriptional regulation of AKR1D1 under physiological and pathological conditions is very limited. In this study, we investigated the regulatory effects of primary bile acids, chenodeoxycholic acid (CDCA) and cholic acid (CA), on AKR1D1 expression. The expression levels of AKR1D1 mRNA and protein in vitro and in vivo following bile acid treatments were determined by real-time PCR and Western blotting. We found that CDCA markedly repressed AKR1D1 expression in vitro in human hepatoma HepG2 cells and in vivo in mice. On the contrary, CA significantly upregulated AKR1D1 expression in HepG2 cells and in mice. Further mechanistic investigations revealed that the farnesoid x receptor (FXR) signaling pathway was not involved in regulating AKR1D1 by bile acids. Instead, CDCA and CA regulated AKR1D1 through the mitogen-activated protein kinases/c-Jun N-terminal kinases (MAPK/JNK) signaling pathway. Inhibition of the MAPK/JNK pathway effectively abolished CDCA and CA-mediated regulation of AKR1D1. It was thus determined that AKR1D1 expression was regulated by CDCA and CA through modulating the MAPK/JNK signaling pathway. In conclusion, AKR1D1 expression was differentially regulated by primary bile acids through negative and positive feedback mechanisms. The findings indicated that both bile acid concentrations and compositions play important roles in regulating AKR1D1 expression, and consequently bile acid synthesis and steroid hormone metabolism.

Estrogen and Estrogen Receptor-α-Mediated Transrepression of Bile Salt Export Pump.

Among diseases unique to pregnancy, intrahepatic cholestasis of pregnancy is the most prevalent disorder with elevated serum bile acid levels. We have previously shown that estrogen 17ß-estradiol (E2) transrepresses bile salt export pump (BSEP) through an interaction between estrogen receptor (ER)-α and farnesoid X receptor (FXR) and transrepression of BSEP by E2/ERα is an etiological contributing factor to intrahepatic cholestasis of pregnancy. Currently the mechanistic insights into such transrepression are not fully understood. In this study, the dynamics of coregulator recruitment to BSEP promoter after FXR activation and E2 treatment were established with quantitative chromatin immunoprecipitation assays. Coactivator peroxisome proliferator-activated receptor-γ coactivator-1 was predominantly recruited to the BSEP promoter upon FXR activation, and its recruitment was decreased by E2 treatment. Meanwhile, recruitment of nuclear receptor corepressor was markedly increased upon E2 treatment. Functional evaluation of ERα and ERß chimeras revealed that domains AC of ERα are the determinants for ERα-specific transrepression on BSEP. Further studies with various truncated ERα proteins identified the domains in ERα responsible for ligand-dependent and ligand-independent transrepression. Truncated ERα-AD exhibited potent ligand-independent transrepressive activity, whereas ERα-CF was fully capable of transrepressing BSEP ligand dependently in vitro in Huh 7 cells and in vivo in mice. Both ERα-AD and ERα-CF proteins were associated with FXR in the coimmunoprecipitation assays. In conclusion, E2 repressed BSEP expression through diminishing peroxisome proliferator-activated receptor-γ coactivator-1 recruitment with a concurrent increase in nuclear receptor corepressor recruitment to the BSEP promoter. Domains AD and CF in ERα mediated ligand-independent and ligand-dependent transrepression on BSEP, respectively, through interacting with FXR.

Speciation of the products of and establishing the role of water in the reaction of TNT with hydroxide and amines: structure, kinetics, and computational results.

The reaction of trinitrotoluene (TNT) with bases has been investigated by NMR and visible spectroscopy methods. Hydroxide ion was found to react in one of two ways, either by deprotonation of the methyl group or by nucleophilic attack on the aromatic ring to form a σ adduct. The rate of each mode of reaction depends upon the polarity of the solvent. In tetrahydrofuran (THF), σ adduct formation is rapid and the long-term equilibrium product is deprotonation of the methyl group. When the solvent is methanol (MeOH), the two reactions have similar rates and the σ adduct becomes the majority product. Amines were found to be ineffective in directly deprotonating TNT or in forming σ adducts. Rather, the amines react with ambient water to generate hydroxide ion, which then reacts with TNT. The solvent choice and water content are crucial to understanding the reactivity of bases with TNT. To assist in the interpretation of the experimental results, computational analysis was performed at the B3LYP/6-311+G**//HF/6-311+G** level to determine the thermodynamics of the reactions of TNT. The SM8 implicit solvation model was applied to converged geometries and suggested a strong solvation effect upon product formation. Thermodynamic analysis suggested a significant preference of alkoxide or hydroxide attack versus amine attack in any modeled dielectric, consistent with the experimental observations.

Fluorescent species formed by reaction of trinitroaromatics with N,N-dimethylformamide and hydroxide.

Trinitrobenzene (TNB) and trinitrotoluene (TNT) react in N,N-dimethylformamide (DMF) to form multiple species in solution. Despite structural similarities, electronic spectra show that the reactivity is different for TNB and TNT. In addition to reaction with the DMF solvent, residual water in nominally dry DMF generates sufficient hydroxide for reaction with TNB and TNT. Multiple sigma adducts are formed and observed to be fluorescent, which has not been previously reported. Both TNB and TNT show the capacity to form sigma adducts with hydroxide and DMF, while methyl hydrogens of TNT can be deprotonated by hydroxide.