Gene Therapy in Bone Regeneration: A Summary of Delivery Approaches for Effective Therapies - Intracellular Delivery: Fundamentals and Applications - page 818

Fig. 1 Scheme for effective gene delivery. Plasmid DNA coding for a protein is mixed with car-
riers to form a complex for cellular uptake by endocytosis. The newly formed endosome begins
to mature, and the complex must escape before lysosome formation in order to avoid degradation.
Following endosomal escape, the complex is expected to target to nucleus for the plasmid to be
transcribed. The messenger RNA is then translated in the cytoplasm to synthesize the coded
protein
of a lengthy culture period may not possess the same multi-lineage potential as
fresh bone marrow cells.
An alternative to ex-vivo gene transfer is the direct non-viral gene delivery that
offers some advantages with respect to cost and ease-of-use. Direct gene therapy
can be employed immediately after the trauma, and without the issues associated
with cell harvesting and expansion. Many groups are exploring virus-based direct
gene therapy, but a handful of groups are also investigating non-viral carriers due
to safety concerns associated with viruses. Many of the viral therapies are less