X-Message-Number: 9770
Date: Sun, 24 May 1998 09:13:31 -0700 (PDT)
From: Doug Skrecky <>
Subject: freeze-drying lipid/DNA

Authors
  Anchordoquy TJ.  Carpenter JF.  Kroll DJ.
Institution
  Department of Pharmaceutical Sciences, University of Colorado Health Sciences
  Center, Denver 80262, USA.
Title
  Maintenance of transfection rates and physical characterization of lipid/DNA
  complexes after freeze-drying and
  rehydration.
Source
  Archives of Biochemistry & Biophysics.  348(1):199-206, 1997 Dec 1.
Abstract
  It is well established that cationic liposomes form complexes with DNA and
  effectively transfect cells in vivo and ex vivo. Lipid/DNA complexes have
  proven safe and nonimmunogenic in clinical trials; however, they are known to
  aggregate readily in liquid formulations. This physical instability requires
  clinicians to prepare lipid/DNA complexes immediately prior to injection. In
  order to eliminate problems associated with this temporal requirement, we
  investigated the feasibility of preserving complexes as a dried preparation
  that could be tested, stored, and rehydrated as needed. To this end, our
  study evaluated the ability of different stabilizers to preserve transfection
  rates of complexes during acute
  freeze-drying stress. Our data show that
  complexes lyophilized in 0.5 M sucrose or trehalose possessed transfection
  rates similar to those of fresh preparations. In addition, dried complexes
  that exhibited full transfection activity upon rehydration had sizes
  comparable to nonlyophilized controls. Our work demonstrates that lipid/DNA
  complexes can be stabilized as dried powders that offer significant
  advantages over current liquid formulations. Furthermore, the correlation of
  transfection rates with maintenance of complex diameter suggests that size
  plays a critical role in lipid-based DNA delivery.

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