Tricalcium phosphate nanoparticles enable rapid purification, increase transduction kinetics, and modify the tropism of mammalian viruses

Adenoviral, adeno-associated viral, and retroviral particles are chosen as gene delivery shuttles in more than 50% of all gene therapy clinical trials. Bulk availability of clinical-grade viral particles and their efficiency to transduce the therapeutic cargo into specific target cells remain the most critical bottlenecks in gene therapy applications to date. Capitalizing on the flame-spray technology for the reproducible economic large-scale production of amorphous tricalcium phosphate nanoparticulate powders (ATCP), we designed a scalable ready-to-use gravity-flow column set-up for the straightforward concentration and purification of transgenic adenoviral, adeno-associated viral, and lentiviral particles. Specific elution buffers enabled rapid release of viral particles from the ATCP matrix of the column and provided high-titer virus preparations in an unsurpassed period of time. The interaction of ATCP with adenoviral, adeno-associated viral, and lentiviral particles in solution increased the transduction kinetics of several mammalian cell lines in culture. The nanoparticles were also able to modify the tropism of murine leukemia virus (MLV) towards transduction of human cells. Based on these findings, we believe that the use of flame-spray tricalcium phosphate nanoparticles will lead to important progress in the development of future gene therapy initiatives. Biotechnol. Bioeng. 2009;102: 1197-1208.