Actively regulating bioengineered tissue and organ formation DJ Mooney T Boontheekul R Chen K Leach Authors' affiliations: David J. Mooney, K. Leach, Division of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA T. Boontheekul, Department of Chemical Engineering, University of Michigan, MI, USA Ruth Chen, Department of Biomedical Engineering, University of Michigan, MI, USA Correspondence to: David J. Mooney DEAS, Harvard University 29 Oxford St., 325 Pierce Hall Cambridge, MA 02138, USA Tel.: +617 384 9624 Fax: +617 495 8543 E-mail: mooneyd@deas.harvard.edu Structured Abstract Authors – Mooney DJ, Boontheekul T, Chen R, Leach K Objectives – Describe current and future approaches to tissue engineering, specifically in the area of bone regeneration. These approaches will allow one to actively regulate the cellular populations participating in this process. Design – Many approaches to actively regulate cellular phenotype are under exploration, and these typically exploit known signal transduction pathways via presentation of specific receptor-binding ligands, and may also deliver mechanical information via the physical bridge formed by the receptor-ligand interactions. Cellular gene expression may also be directly modulated utilizing gene therapy approaches to control tissue regeneration. Conclusions – Significant progress has been made to date in bone regeneration using inductive molecules and transplanted cells, and FDA approved therapies have resulted. While approaches to date have focused on delivery of single stimuli (e.g. one growth factor), future efforts will likely attempt to more closely mimic developmental processes by the delivery of multiple inputs to the cells in spatially and temporally regulated fashions. Key words: biomaterials; extracellular matrix; growth factors; peptides Introduction Limitations to the current therapies available for the reconstruction and replacement of craniofacial tissues has led to significant interest in tissue engineering approaches to these challenges (1). The tissue engin- eering approaches include conductive, inductive, and cell transplantation approaches. All three approaches have been successful in various animal models (1), and some have progressed to clinical application (e.g. Dates: Accepted 10 April 2005 To cite this article: Orthod Craniofacial Res 8, 2005; 141–144 Mooney DJ, Boontheekul T, Chen R, Leach K: Actively regulating bioengineered tissue and organ formation Copyright Ó Blackwell Munksgaard 2005