Compositions and methods for targeted delivery to cells

An aerosol composition comprising aerosol droplets, wherein the aerosol droplets comprise an mRNA assembled with a lipid composition, wherein the mRNA expresses a CFTR protein, and wherein the lipid composition comprises:

• (i) a compound that is a compound of Formula (I-1):
• Core-Repeating Unit-Terminating Group (I-1),
• or a pharmaceutically acceptable salt thereof,
• wherein the core is linked to two to six repeating units;
• and
• wherein:
• the core has the formula:
• wherein:
• X3 is —NR6— or heterocycloalkanediylC≤8, wherein R6 is hydrogen or alkylC≤8;
• R3 and R4 are each independently amino, alkylaminoC≤12, or dialkylaminoC≤12;
• wherein the alkylamino or dialkylamino are each optionally substituted with amino;
• each repeating unit comprises a degradable diacyl having the formula:
• wherein:
• A1 and A2 are each independently —O—,
• Y3 is —CH2CH2—, and
• R9 is —CH3;
• and
• the terminating group is selected from the group consisting of:
• (ii) 1,2-dioleoyl-3-dimethylammonium-propane (DODAP);
• (iii) a phospholipid;
• (iv) a cholesterol;
• and
• (v) a polyethylene glycol-conjugated lipid (PEG-lipid).