Safety assessment of biolistic DNA vaccination.

DNA-based vector systems have been widely studied as new modalities for the prevention and treatment of human diseases. As for all other medicinal products, safety is an important aspect in the evaluation of such products. In this chapter we reflect on the basic safety issues which have been raised with respect to preventive and therapeutic DNA vaccines, including insertional mutagenesis in case of chromosomal integration, possible formation of anti-DNA antibodies, induction of autoimmune responses and/or immunological tolerance. In addition, local reactions at the site of administration and adverse effects resulting from plasmid DNA spread to nontarget tissues are discussed. Most importantly, however, the benefit-risk profile of a medicinal product is crucial for a decision on providing marketing authorization or not. A product has an acceptable benefit-risk profile if the benefits of the product outweigh its risks for the treated patient.

Particle-mediated gene delivery and human skin: ultrastructural observations on stratum corneum barrier structures.

The particle-mediated delivery systems are becoming a clinically relevant tool in dermatology and immunology. We investigated the qualitative ultrastructural morphology of skin following pressure-driven delivery of gold particles to ex vivo human breast skin, at different pressures ranging from 350 to 1,000 psi. Pressures of 800 and 1,000 psi appear to be more effective, as indicated by distribution of particles in the viable epidermis and dermis. Particle bombardment of the skin with gold beads caused microwounds that spanned the stratum corneum (SC). The SC lipids did not reseal these wounds in the SC after 24 h in organ culture. The implications of particle-mediated delivery to permeability barrier functions of the SC are discussed.

[Activity of exogenous genetic designs, introduced into cells by a ballistic transfection method, in murine ontogenesis]. / Aktivnost' ékzogennykh geneticheskikh konstruktsii, vvedennykh v kletki metodom ballisticheskoi transfektsii, v ontogeneze myshi.

We used the method of particle bombardment (ballistic transfection) to introduce beta-galactosidase and human dystrophin genes into mouse embryos and skeletal muscles of adult mice. We examined the mechanisms of DNA transfer into skeletal muscle cells, the biological processes accompanying and following this transfer, the susceptibility of various types of muscle cells to transfection, and the duration of expression of and conditions affecting the introduced genes. We have also developed an effective, convenient, and practical methods of skeletal muscles transfection.

Safe and effective regulation of hematocrit by gene gun administration of an erythropoietin-encoding DNA plasmid.

This work examines the effect of delivering a DNA plasmid encoding murine erythropoietin (pVRmEpo) to BALB/c mice by gene gun. Whereas intramuscular injection elicits a rise in hematocrit persisting >8 months, intradermal delivery triggers the dose-dependent secretion of biologically active erythropoietin (Epo) for approximately 1 month. Repeated administration of pVRmEpo by gene gun elicits a stable increase in hematocrit. The source of the Epo produced following gene gun delivery was analyzed by periodically grafting the site of injection onto naive recipients. Results indicate that both stationary cells (presumably keratinocytes) and migratory (presumably dendritic) cells were transfected and secreted biologically active Epo in vivo. Gene gun administration of plasmid DNA appears to be safe, and provides an additional strategy for achieving the regulated secretion of an exogenous gene product.