Lejeboca
Member
- Joined
- Jun 19, 2017
- Messages
- 1,039
Thanks for the "in vivo SLN" paper @schultz ! It is clear that LNPs are dangerous
The paper Cationic lipid saturation influences intracellular delivery of encapsulated nucleic acids (which I cited earlier in thread) gives some answers to your questions, in an "objective" way.
I couldn't decipher all the ideas but, basically, LNPs for the RNA-type therapies is not an adjuvant---in the sense that their main purpose is to promote immune response---but rather as effective RNA (i.e., payload) transporter into the cell and delivery inside the cell.
Abstract for the paper:
An analogous series of cationic lipids (1,2-distearyloxy-N,N-dimethyl-3-aminopropane (DSDMA), 1,2-dioleyloxy-N,N-dimethyl-3-aminopropane (DODMA), 1,2-dilinoleyloxy-N,N-dimethyl-3-aminopropane (DLinDMA) and 1,2-dilinolenyloxy-N,N-dimethyl-3-aminopropane (DLenDMA)) possessing 0, 1, 2 or 3 double bonds per alkyl chain respectively, was synthesized to determine the correlation between lipid saturation, fusogenicity and efficiency of intracellular nucleic acid delivery. 31P-NMR analysis suggests that as saturation increases, from 2 to 0 double bonds, lamellar (Lα) to reversed hexagonal (HII) phase transition temperature increases, indicating decreasing fusogenicity. This trend is largely reflected by the efficiency of gene silencing observed in vitro when the lipids are formulated as Stable Nucleic Acid Lipid Particles (SNALPs) encapsulating small inhibitory RNA (siRNA). Uptake experiments suggest that despite their lower gene silencing efficiency, the less fusogenic particles are more readily internalized by cells. Microscopic visualization of fluorescently labelled siRNA uptake was supported by quantitative data acquired using radiolabelled preparations. Since electrostatic binding is a precursor to uptake, the pKa of each cationic lipid was determined. The results support a transfection model in which endosomal release, mediated by fusion with the endosomal membrane, results in cytoplasmic translocation of the nucleic acid payload.
Cationic lipid nano particles are quite inflammatory and probably cause damage all on their own. It would definitely be acting as an adjuvant, even if it wasn't intended as such.
I am unaware of how the lipid acts once in cells. Is it cleared quickly? Does it interact with proteins and metals?
The paper Cationic lipid saturation influences intracellular delivery of encapsulated nucleic acids (which I cited earlier in thread) gives some answers to your questions, in an "objective" way.
I couldn't decipher all the ideas but, basically, LNPs for the RNA-type therapies is not an adjuvant---in the sense that their main purpose is to promote immune response---but rather as effective RNA (i.e., payload) transporter into the cell and delivery inside the cell.
Abstract for the paper:
An analogous series of cationic lipids (1,2-distearyloxy-N,N-dimethyl-3-aminopropane (DSDMA), 1,2-dioleyloxy-N,N-dimethyl-3-aminopropane (DODMA), 1,2-dilinoleyloxy-N,N-dimethyl-3-aminopropane (DLinDMA) and 1,2-dilinolenyloxy-N,N-dimethyl-3-aminopropane (DLenDMA)) possessing 0, 1, 2 or 3 double bonds per alkyl chain respectively, was synthesized to determine the correlation between lipid saturation, fusogenicity and efficiency of intracellular nucleic acid delivery. 31P-NMR analysis suggests that as saturation increases, from 2 to 0 double bonds, lamellar (Lα) to reversed hexagonal (HII) phase transition temperature increases, indicating decreasing fusogenicity. This trend is largely reflected by the efficiency of gene silencing observed in vitro when the lipids are formulated as Stable Nucleic Acid Lipid Particles (SNALPs) encapsulating small inhibitory RNA (siRNA). Uptake experiments suggest that despite their lower gene silencing efficiency, the less fusogenic particles are more readily internalized by cells. Microscopic visualization of fluorescently labelled siRNA uptake was supported by quantitative data acquired using radiolabelled preparations. Since electrostatic binding is a precursor to uptake, the pKa of each cationic lipid was determined. The results support a transfection model in which endosomal release, mediated by fusion with the endosomal membrane, results in cytoplasmic translocation of the nucleic acid payload.