Gene Delivery Using Chemical Methods - Challenges in Delivery of Therapeutic Genomics and Proteomics - page 181

4.7.4 Gelatin
Gelatin is a biocompatible and biodegradable biopolymer obtained by hydrolytic
degradation of porcine or bovine collagen. Troung-Le et al. first described the use
of gelatin as a potential gene delivery vector [380] . Gelatin-plasmid coacervates
were formulated as gelatin nanospheres in the size range of 200-700 nm using salt-
induced coacervation of 5% porcine type A gelatin and plasmid at 55°C under high
stirring [381] . Salt acts as a desolvating agent that facilitates nanosphere formation
by promoting electrostatic interactions between positively charged gelatin and neg-
atively charged DNA. Plasmid can be loaded up to 25-30% w/w at encapsulation
efficiency higher than 98%. Endosomolytic agent chloroquine was added to enhance
gene transfer. Nanospheres displayed improved plasmid stability in serum and nucle-
ase stability as compared to free plasmid. The nanospheres exhibited lower in vitro
transfection efficiency as compared to Lipofectin TM . However, attachment of trans-
ferrin to the surface of gelatin nanospheres tremendously enhanced the transfection
efficiency by 200 times over Lipofectin TM when evaluated against HEK 293 cells.
Another study by the same group employed transferrin along with endosomolytic
agent chloroquine and calcium [382] . The gelatin nanospheres encapsulating chloro-
quine and calcium were surface conjugated with transferrin. The gelatin nanospheres
displayed higher transfection in the presence of transferrin and calcium. Transferrin
is known to facilitate the cellular uptake of nanospheres by means of receptor-
mediated endocytosis, whereas calcium facilitates the release of DNA from the gelatin
matrix by competing with DNA for electrostatic interactions with the gelatin. Gelatin

Table 4.1 Various Nonviral (Chemical) Vectors Used in Gene Therapy Clinical Trials

Delivery Vector Disease Status Reference

PEGylated 30mer PLL Cystic fibrosis Phase 2 [385]

PEI mannose and dextrose HIV Phase 2 [386]

In vivo jetPEI Bladder cancer Phase 2 [387]

CD-based polymer Solid tumors Phase 1 [388]

DOTAP Cystic fibrosis Phase 1 [389]

DC-Chol/DOPE Breast and ovarian cancer Phase 1 [390]

DC-Chol/DOPE Head and neck cancers Phase 2 [391,392]

DC-Chol/DOPE Cystic fibrosis Phase 1 [217]

DC-Chol/DOPE Glioblastoma multiform Phase 2 [393]

EDMPC-Chol Cystic fibrosis Phase 1 [394]

DOSPA/DOPE Solid tumors Phase 1 [395,396]

DMRIE-DOPE Melanoma Phase 3 [397,398]

DMRIE-DOPE Melanoma and renal cell cancer Phase 2 [399]

GL-67-DOPE Cystic fibrosis Phase 1 [400]

GL-67-DOPE-DMPE-
PEG6000

Cystic fibrosis Phase 1 [401]

PEG-PEI-Chol Ovarian cancer Phase 1 [402]

EDMPC: p -ethyl-dimyristoylphosphadityl choline; DMPE: dimyristoylphosphadityl ethanolamine.