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Maxson S.,Institute for Biological Interfaces of Engineering | Burg K.J.L.,Institute for Biological Interfaces of Engineering
Cellular and Molecular Bioengineering | Year: 2012

The objective of this study was to investigate the effect of mechanical stimuli in combination with conditioned media (CM) on the osteogenic and chondrogenic differentiation of mesenchymal stem cells (MSCs). Two "opposing" groups were defined for the study. The first, designated the bone group, was formed by seeding MSCs onto porous poly(L-lactide-co-e- caprolactone)/hydroxyapatite scaffolds. The second group, designated the cartilage group, was formed by encapsulating MSCs in 2% agarose. The samples were either subjected to hydrostatic pressure (HP), administered CM from the opposing group at a concentration of 50%, or given a combination of the two stimuli. The sulfated glycosaminoglycan (sGAG) content and SOX9, aggrecan, and collagen type II expressions suggest that both osteoblast CM and intermittent HP individually enhanced the chondrogenic differentiation of MSCs. In addition, there is evidence of a synergistic interaction between CM and HP on chondrogenic differentiation. The alkaline phosphatase (ALP) activity and osteocalcin and bone sialoprotein expression suggest that the combination of chondrocyte CM and HP significantly enhanced the osteogenic differentiation of MSCs. However, the individual stimuli did not have a significant effect on osteogenic differentiation. Enzymelinked immunosorbent assay (ELISA) results revealed that both the chondrocyte CM and osteoblast CM contained considerable amounts of TGF-b1 and BMP-2. © 2012 Biomedical Engineering Society.


Singapogu R.B.,Institute for Biological Interfaces of Engineering | Singapogu R.B.,Greenville Hospital System University Medical Center | Burg T.C.,Institute for Biological Interfaces of Engineering | Burg T.C.,Clemson University | And 5 more authors.
Critical Reviews in Biomedical Engineering | Year: 2014

Laparoscopic surgery is a minimally invasive surgical technique with significant potential benefits to the patient, including shorter recovery time, less scarring, and decreased costs. There is a growing need to teach surgical trainees this emerging surgical technique. Simulators, ranging from simple “box” trainers to complex virtual reality (VR) trainers, have emerged as the most promising method for teaching basic laparoscopic surgical skills. Current box trainers require oversight from an expert surgeon for both training and assessing skills. VR trainers decrease the dependence on expert teachers during training by providing objective, real-time feedback and automatic skills evaluation. However, current VR trainers generally have limited credibility as a means to prepare new surgeons and have often fallen short of educators’ expectations. Several researchers have speculated that the missing component in modern VR trainers is haptic feedback, which refers to the range of touch sensations encountered during surgery. These force types and ranges need to be adequately rendered by simulators for a more complete training experience. This article presents a perspective of the role and utility of haptic feedback during laparoscopic surgery and laparoscopic skills training by detailing the ranges and types of haptic sensations felt by the operating surgeon, along with quantitative studies of how this feedback is used. Further, a number of research studies that have documented human performance effects as a result of the presence of haptic feedback are critically reviewed. Finally, key research directions in using haptic feedback for laparoscopy training simulators are identified. © 2014 by Begell House, Inc.


Singapogu R.B.,Institute for Biological Interfaces of Engineering | Singapogu R.B.,Clemson University | Smith D.E.,Institute for Biological Interfaces of Engineering | Smith D.E.,Clemson University | And 8 more authors.
Journal of Surgical Education | Year: 2012

Background: There is a growing need for effective surgical simulators to train the novice resident with a core skill set that can be later used in advanced operating room training. The most common simulator-based laparoscopic skills curriculum, the Fundamentals of Laparoscopic Skills (FLS), has been demonstrated to effectively teach basic surgical skills; however, a key deficiency in current surgical simulators is lack of validated training for force-based or haptic skills. In this study, a novel haptic simulator was examined for construct validity by determining its ability to differentiate between the force skills of surgeons and novices. Methods: A total of 34 participants enrolled in the study and were divided into two groups: novices, with no previous surgical experience and surgeons, with some level of surgical experience (including upper level residents and attendings). All participants performed a force-based task using grasping, probing, or sweeping motions with laparoscopic tools on the simulator. In the first session, participants were given 3 trials to learn specific forces associated with locations on a graphic; after this, they were asked to reproduce forces at each of the locations in random order. A force-based metric (score) was used to record performance. Results: On probing and grasping tasks, novices applied significantly greater overall forces than surgeons. When analyzed by force levels, novices applied greater forces on the probing task at lower and mid-range forces, for grasping at low-range forces ranges and, for sweeping at high-range forces. Conclusions: The haptic simulator successfully differentiated between novice and surgeon force skill level at specific ranges for all 3 salient haptic tasks, establishing initial construct validity of the haptic simulator. Based on these results, force-based simulator metrics may be used to objectively measure haptic skill level and potentially train residents. Haptic simulator development should focus on the 3 salient haptic skills (grasping, probing, and sweeping) where precise force application is necessary for successful task outcomes. © 2012 Association of Program Directors in Surgery.

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