Cationic lipid-mediated gene transfer of cystic fibrosis transmembrane conductance regulator (CFTR) cDNA represents a promising approach for treatment of cystic fibrosis (CF). Here, we report on the structures of several novel cationic lipids that are effective for gene delivery to the lungs of mice. An amphiphile (#67) consisting of a cholesterol anchor linked to a spermine headgroup in a "T-shape" configuration was shown to be particularly efficacious. An optimized formulation of #67 and plasmid vector encoding chloramphenicol acetyl-transferase (CAT) was capable of generating up to 1 microgram of CAT enzyme/lung following intranasal instillation into BALB/c mice. This represents a 1,000-fold increase in expression above that obtained in animals instilled with naked pDNA alone and is greater than 100-fold more active than cationic lipids used previously for CFTR gene expression. When directly compared with adenovirus-based vectors containing similar transcription units, the number of molecules of gene product expressed using lipid-mediated transfer was equivalent to vector administration at multiplicities of infection ranging from 1 to 20. The level of transgene expression in the lungs of BALB/c mice peaked between days 1 and 4 post-instillation, followed by a rapid decline to approximately 20% of the maximal value by day 7. Undiminished levels of transgene expression in the lung could be obtained following repeated intranasal administration of #67:DOPE:pCF1-CAT in nude mice. Transfection of cells with formulations of #67:DOPE:pCF1-CFTR generated cAMP-stimulated CFTR chloride channel and fluid transport activities, two well-characterized defects associated with CF cells. Taken together, the data demonstrate that cationic lipid-mediated gene delivery and expression of CFTR in CF lungs is a viable and promising approach for treatment of the disease.
A continuous fermentation process has been developed in Pichia pastoris (P. pastoris) with the glyceraldehyde-3-phosphate dehydrogenase (GAP) promoter in order to produce large quantities of recombinant human chitinase (rh-chitinase) for preclinical studies as a potential high-dose antifungal drug. Expression levels of about 200 to 400 mg/L have been demonstrated in fed-batch fermentations using strains with either the traditional methanol-inducible or the constitutive GAP promoter. Proteolytic degradation of the enzyme was typically seen in fed-batch fermentations. Continuous production of the enzyme by P. pastoris with the GAP promoter was demonstrated in a 1.5-L working volume fermentor using either glucose or glycerol as the carbon source. The fermentation could be extended for >1 month with a steady-state protein concentration of approximately 300 mg/L. Cell densities were >400 g/L wet cell weight (WCW) (approximately 100 g/L dry cell weight [DCW]) at a dilution rate (D) of 0.83 day(-1) or 1.2 volume exchanges per day (VVD). No proteolytic degradation of the enzyme was seen in the continuous fermentation mode.
Objective-Proof of principle is presented for targeted enzyme supplementation by using lysosomal acid lipase to decrease aortic and coronary wall lipid accumulation in a mouse model of atherosclerosis. Methods and Results-Mice with LDL receptor deficiency were placed on an atherogenic diet and developed predictable aortic and coronary atheroma. ␣-Mannosyl-terminated human lysosomal acid lipase (phLAL) was produced in Pichia pastoris, purified, and administered intravenously to such mice with either early or late lesions. phLAL injections reduced plasma, hepatic, and splenic cholesteryl esters and triglycerides in affected mice. phLAL was detected in hepatic Kupffer cells and in atheromatous foam cells. Repeated enzyme injections were well tolerated, with no obvious adverse effects. In addition, the coronary and aortic atheromatous lesions were (1) eliminated in their early stages and (2) quantitatively and qualitatively reduced in their advanced stages. A therosclerosis is the number 1 cause of mortality and morbidity in the developed countries. A number of interventions or preventions delay the consequences of atherosclerosis, eg, low cholesterol diet and exercise, HMG-CoA reductase inhibitors, and coronary artery bypass. However, they are not suitable for all patients, and few have been shown to promote regression of lesions. Therefore, new approaches are needed for the treatment and prevention of atherosclerosis. Several stages characterize the progression of atherosclerotic lesions. 1,2 The earliest lesion is the "fatty streak," an aggregation of lipid-rich macrophages and T-lymphocytes within the intimae layer of an artery. The fatty streaks evolve into intermediate lesions that have a layer of foamy macrophages and smooth muscle cells. This develops into complex and occlusive lesions, as well as fibrous plaques. These plaques have a dense cap of connective tissue, with embedded smooth muscle cells overlaying a core of lipid and necrotic debris. Macrophages are present at all lesional stages with excessive cholesterol and cholesteryl esters in lysosomes. Continuing development of atherosclerotic plaques requires progressive macrophage processing of cholesteryl esters in and through the lysosomes. Perpetuation and maturation of the plaques depends on additional complex inflammatory and scarring processes. Lysosomal acid lipase (LAL) is the only hydrolase for cleavage of cholesteryl esters delivered to the lysosomes. 3 The receptors that mediate cholesteryl ester uptake into macrophage include those for LDL and oxidized LDL (oxLDL), ie, LDL receptor (LDL-R), the scavenger receptors type AI and AII (SR-AI and SR-AII), 4 -6 the scavenger receptor type B1 (SR-BI), 7-9 CD36, 10 and the LDL receptor related protein (LRP). 11 All of these, except SR-BI, direct associated lipids to the lysosome. 12-15 Furthermore, modification of LDL by oxidation, aggregation, and glycation occurs in the atherosclerotic lesions by histochemical and biochemical studies. 16 -20 The delivery of oxidized LDL to lysosomes of macropha...
The feasibility of large-scale production of recombinant human chitinase using a constitutive Pichia pastoris expression system was demonstrated in a 21-L continuous stirred tank reactor. A steady-state recombinant protein concentration of 250 mg/L in the supernatant was sustained for 1 month at a dilution rate of 0.042 h(-1) (equivalent to one volume exchange per day), enabling a volumetric productivity of 144 mg/L d (240 U/L d). The steady-state dry cell weight concentration in this high cell density culture reached 110 g/L. Considering safety and economical aspects, all large-scale cultivations were conducted without molecular oxygen supplementation. Conventional air sparging was used instead. The oxygen demand of the process was determined by off-gas analysis (OUR = 4.8 g O(2) L(-1) h(-1) with k(L)a = 846 h(-1)) and evaluated with regard to further reactor scale-up.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.