Bio-Rad Helios® Gene Gun System - Manual (Page 7)

Table 1. Advantages of particle bombardment for in vitro and
in vivo gene transfer.
• Easy to use, rapid, versatile gene delivery system
• Independent of target cell type
• Useful for both transient and stable expression
• Requires only small amounts of DNA
• No carrier DNA is needed
• Requires only small numbers of cells
• May obtain high levels of co-transformation
• Large DNA fragments may be transferred
• Direct intracellular delivery to many cells in the target area
• Applicable to both in vitro and in vivo transformation
• No extraneous genes or proteins are delivered
2.2 The Helios Gene Gun
The Helios Gene Gun is the second instrument in Bio-Rad’s particle delivery product
line. In contrast to the PDS-1000/He instrument where the overall size of the target to be
transformed is limited by the size of the chamber and the target tissue is subjected to a vacu-
um during bombardment, the Helios Gene Gun requires no vacuum and any target accessible
to the barrel can be transformed. Consequently, the Helios Gene Gun may be used in a much
wider variety of gene transfer applications and provides a tool for both in vitro and in vivo
transformations in the research lab. Essentially any type of cells which can be made accessi-
ble to its nozzle may be transformed.
Gene gun models have also been developed by Auragen, Inc., a Bio-Rad collabo-
rator. Cell penetration, gene expression and other measures of performance vary with
the model of gene gun used. Users must be careful to select operating parameters
optimized for their particular model. The Accell
® model used by Auragen Inc. may
include modifications to be included in the future Helios models. The current Helios
Gene Gun has been designed to serve a wide range of research uses.
In vertebrates, the epidermal cells of the skin are the most obvious target (Yang et al.,
1990; Williams et al., 1991). In vivo experimental systems have targeted the skin for vacci-
nation studies (Tang et al., 1992; Fynan et al., 1993; Eisenbraun et al., 1993), and wound
healing (Andree, et al., 1994), and cytokine gene therapy studies in mouse tumor models
(Sun et al., 1995; Keller et al., 1996; Rakhmilevich et al., 1996). In addition to skin, muscle
and internal organs, including liver, pancreas, spleen, kidney, etc., when appropriately exposed
surgically, can also be targeted in vivo (Yang et al., 1990; William et al., 1991; Cheng et al.,
1993). Using the Accell Gene Gun, both primary and established cultures of mammalian cells
have been transfected in vitro and ex vivo (Albertini et al., 1996; Mahvi et al., 1996;
Rakhmilevich et al., 1996). Additionally, transgenic expression of
β
-galactosidase, luciferase,
IL-12, granulocyte macrophage-colony stimulating factor and a nuclear papillomavirus pro-
tein has been demonstrated following in vivo transformation (Sundaram et al., 1996; Keller
et al., 1996; Rakhmilevich et al., 1996). Meristematic tissues and leaves are obvious target cells
for in vivo transformation of plants.
2.3 Operating Principle of the Helios Gene Gun System
The Helios Gene Gun System consists of all of the components needed to prepare DNA-
coated microcarriers, coat the DNA-microcarrier suspension onto the inner surface of the
Gold-Coat
™ tubing, cut the tubing into cartridges which are used in the Helios Gene Gun, and
finally propel the microcarriers and their associated DNA into cells.
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