Surface Patterning: Tool to Modulate Stem Cell Differentiation in an Adipose System Aditya Chaubey, 1 Kevin J. Ross, 2 Ross M. Leadbetter, 2 Karen J. L. Burg 1 1 Department of Bioengineering, 401 Rhodes Engineering Research Center, Clemson University, Clemson, South Carolina 29634 2 Statistics Department, New West CB 3260, 3260 Cameron Avenue, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599 Received 2 October 2006; revised 7 March 2007; accepted 7 March 2007 Published online 23 April 2007 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jbm.b.30846 Abstract: There are several issues that need to be better understood before breast tissue- engineering becomes viable clinically. One of the key issues is the interaction between cells and the microtopography of the implant surface. The aim of this study was to evaluate the efficacy of D1 cells, multipotent mouse bone marrow stromal precursors, in differentiating to fat and to characterize their metabolic activity (lactic acid released and glucose consumed) and lipid production when cultured on patterned poly-L-lactide (PLLA) films. It was determined that, with appropriate stimulation, the D1 cells displayed morphological characteristics of adipocytes and produced lipid. The results show that the patterned surfaces did affect the rate of lipid production. Polynomial models were proposed to predict the metabolic activity of the cells over a period of time. ' 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 84B: 70–78, 2008 Keywords: adipocytes; D1 cells; lipid; microtopography; poly-L-lactide INTRODUCTION The need for soft tissue reconstruction or augmentation has increased continuously over the years. Breast cancer is the most common form of cancer affecting women. 1 The treatment options for breast cancer include lumpectomy, mastectomy, and therapeutic treatments. Soft-tissue recon- struction is also crucial for the treatment of post-traumatic repair and congenital deformities. Current reconstruction procedures include implants, tissue flaps, and tissue trans- plantation. There are inherent problems associated with each existing option. The survival of grafted fat is low, generally grafting results in necrosis due to insufficient vascularization and results in resorption of the graft over time. 2 Also, the volume of fat available for grafting may be limited. Longevity and leaching of the constituent particles is of utmost concern for synthetic replacement devices such as silicone implants, as is immune response to bulk and degradants. Tissue engineering holds considerable promise as an al- ternative to existing options, by providing a biologically based solution. However, for any medical implant to be successful in the long-term, it must be successfully inte- grated into the body. Many strategies have been formulated to influence tissue–biomaterial interactions. For example, it has been shown that geometrical configuration of an implant 3 or the pore size employed 4 can influence the level of development of a capsule or an oriented fibrous attach- ment or its better integration with the body. It is well known that cells respond to surface features and react to them, leading to what is termed as \contact guidance." It has also been shown that the roughness of an implant can alter the affinity of cell types to hydrophobic and hydro- philic surfaces. 5 Porous surfaces can enhance tissue integra- tion with the implant surface thus providing long term stability in vivo 6 ; the results of several studies detailed in the literature suggest that surfaces with microgrooves affect the orientation and migration of cells. 7,8 Wan et al. 9 used microtopography to study the adhesion behavior of cells and found that cell adhesion was enhanced on poly-L-lactide (PLLA) and polystyrene (PS) surface with nanoscale and microscale roughness compared to the smooth surfaces of the PLLA and PS. Parker et al. 10 evaluated tissue reaction around implants with different surface topographies and found that the application of microgrooves or random sur- face roughness to polymer implants apparently does not have beneficial effects on peri-implant tissue healing in vivo. This indicates the contradictory results present in the literature regarding the role of microtopography. Correspondence to: K. J. L. Burg (e-mail: kburg@clemson.edu) ' 2007 Wiley Periodicals, Inc. 70