Original Article Cellular Automata Simulation of Osteoblast Growth on Microfibrous-Carbon-Based Scaffolds Jarema S. Czarnecki, MS, 1,2 Simon Jolivet, MS, 1 Mary E. Blackmore, PhD, 3,4 Khalid Lafdi, DSc, PhD, 1,2 and Panagiotis A. Tsonis, PhD 2,5 The objective of this study was to investigate the use of three fibrous carbon materials (T300, P25, and P120) for bone repair and develop and validate theoretical and computational methods in which bone tissue regen- eration and repair could be accurately predicted. T300 was prepared from polyacrylonitrile precursor while P25 and P120 fibers were prepared from pitch, both common fiber precursors. Results showed that osteoblast growth on carbon scaffolds was enhanced with increased crystallinity, surface roughness, and material orientation. For unidirectional scaffolds at 120 h, there was 33% difference in cell growth between T300 and P25 fibers and 64% difference between P25 and P120 fibers. Moreover, for multidirectional fibers at 120 h, there was 35% dif- ference in cell growth between T300 and P25 fibers and 43% difference between P25 and P120 fibers. Results showed that material alignment was integral to promoting cell growth with multidirectional scaffolds having the capacity for greater growth over unidirectional scaffolds. At 120 h there was 24% increase in cell growth between unidirectional alignment and multidirectional alignment on high-crystalline carbon fibers. Ultimately, data indicated that carbon scaffolds exhibited excellent bioactivity and may be tuned to stimulate unique reactions. Additionally, numerical and computational simulations provided evidence that corroborated exper- imental data with simulations. Results illustrated the capability of cellular automata models for assessing osteoblast cell response to biomaterials. Introduction C urrently, many researchers are working to develop artificial tissues and organs for repair or replacement of damaged or diseased tissue. Groups have explored the use of biomaterials as vehicles for tissue repair and regeneration but results seem to present a variety of in vitro and in vivo responses, indicative of high variability in material design. 1–3 This underlines the challenges that are still present. Lim- ited availability of donor tissue, lack of feasible alternatives, and high potential for patient rejection are critical issues that the healthcare industry has faced in the past. 4 Nevertheless, these challenges have served as a catalyst for innovative research and continue to lead to new technologies, more recently, for simple tissue types. 2,3 However, to date, there are many shortcomings. 4 Additionally, the development of more complex structures that may mimic the properties of native tissues such as tendon or bone has been unsuccess- ful. 5 Current limitations to understanding the relationship between the biological environment (physical and chemical response) and material properties impede success. The structure of the material, its physical and surface properties, and the biological response are all critical issues that govern biomaterial performance. In the past two decades, many materials have been explored as substrates for tissue repair and regeneration. 6–11 Biode- gradable polymers are often limited to applications where the need for high mechanical strength and rigidity is minimal. 12,13 Studies have also shown that because polymer materials tend to degrade, they may yield a negative biological response. 14 In some cases, degradation leads to implant loosening, which then increases the chance of catastrophic failure. Conversely, groups have shown that biodegradable materials may reduce the potential for scar tissue formation and inflammation. Re- searchers have attributed this behavior to contact duration between biomaterial and tissue. 3,15,16 These results support the need for superior materials that enhance bioactivity, maximize cell integration, and support high loads. Carbon-based materials may be ideal materials for bio- mechanical applications where high strength is required. 1 Carbon Research Laboratory, UDRI Carbon Group, Department of Mechanical Engineering, University of Dayton, Dayton, Ohio. 2 Center for Tissue Regeneration and Engineering (TREND), University of Dayton, Dayton, Ohio. 3 Center for Tissue Innovation & Research, Dayton, Ohio. 4 Boonshoft School of Medicine, Wright State University, Dayton, Ohio. 5 Department of Biology, University of Dayton, Dayton, Ohio. TISSUE ENGINEERING: Part A Volume 00, Number 00, 2014 ª Mary Ann Liebert, Inc. DOI: 10.1089/ten.tea.2013.0387 1