title: How controlled release technology can aid gene delivery.
abstract: BACKGROUND
  Many types of gene delivery systems have been developed to enhance the level of gene expression. Controlled release technology is a feasible gene delivery system which enables genes to extend the expression duration by maintaining and releasing them at the injection site in a controlled manner. This technology can reduce the adverse effects by the bolus dose administration and avoid the repeated administration. Biodegradable biomaterials are useful as materials for the controlled release-based gene delivery technology and various biodegradable biomaterials have been developed.
  
  
  METHODS
  Controlled release-based gene delivery plays a critical role in a conventional gene therapy and genetic engineering. In the gene therapy, the therapeutic gene is released from biodegradable biomaterial matrices around the tissue to be treated. On the other hand, the intracellular controlled release of gene from the sub-micro-sized matrices is required for genetic engineering. Genetic engineering is feasible for cell transplantation as well as research of stem cells biology and medicine.
  
  
  CONCLUSIONS
  DNA hydrogel containing a sequence of therapeutic gene and the exosome including the individual specific nucleic acids may become candidates for controlled release carriers. Technologies to deliver genes to cell aggregates will play an important role in the promotion of regenerative research and therapy.
authors.affiliation: a Department of Biomaterials, Field of Tissue Engineering, Institute for Frontier Medical Sciences, Kyoto University , 53 Kawara-cho Shogoin, Sakyo-ku Kyoto 606-8507, Japan +81 75 751 4121 ; +81 75 751 4646 ; yasuhiko@frontier.kyoto-u.ac.jp.
authors.forename: Jun-Ichiro
authors.initials: J
authors.lastname: Jo
authors.affiliation: a Department of Biomaterials, Field of Tissue Engineering, Institute for Frontier Medical Sciences, Kyoto University , 53 Kawara-cho Shogoin, Sakyo-ku Kyoto 606-8507, Japan +81 75 751 4121 ; +81 75 751 4646 ; yasuhiko@frontier.kyoto-u.ac.jp.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Tabata
mesh_terms: D000818:Animals; D003692:Delayed-Action Preparations; D016503:Drug Delivery Systems; D018014:Gene Transfer Techniques; D005818:Genetic Engineering; D015316:Genetic Therapy / Q000379:methods*; D006801:Humans; D044968:Regenerative Medicine
chemical_list: D003692:Delayed-Action Preparations
keywords: biodegradable biomaterials; drug delivery system; intracellular controlled release; regenerative medicine