The Role of Scleraxis in Fate Determination of Mesenchymal Stem Cells for Tenocyte Differentiation

Mesenchymal stem cells (MSCs) are pluripotent cells that primarily differentiate into osteocytes, chondrocytes, and adipocytes. Recent studies indicate that MSCs can also be induced to generate tenocyte-like cells; moreover, MSCs have been suggested to have great therapeutic potential for tendon pathologies. Yet the precise molecular cascades governing tenogenic differentiation of MSCs remain unclear. We demonstrate scleraxis, a transcription factor critically involved in embryonic tendon development and formation, plays a pivotal role in the fate determination of MSC towards tenocyte differentiation. Using murine C3H10T1/2 pluripotent stem cells as a model system, we show scleraxis is extensively expressed in the early phase of bone morphogenetic protein (BMP)-12-triggered tenocytic differentiation. Once induced, scleraxis directly transactivates tendon lineage-related genes such as tenomodulin and suppresses osteogenic, chondrogenic, and adipogenic capabilities, thus committing C3H10T1/2 cells to differentiate into the specific tenocyte-like lineage, while eliminating plasticity for other lineages. We also reveal that mechanical loading-mediated tenocytic differentiation follows a similar pathway and that BMP-12 and cyclic uniaxial strain act in an additive fashion to augment the maximal response by activating signal transducer Smad8. These results provide critical insights into the determination of multipotent stem cells to the tenocyte lineage induced by both chemical and physical signals

BMP-12 Treatment of Adult Mesenchymal Stem Cells In Vitro Augments Tendon-Like Tissue Formation and Defect Repair In Vivo

We characterized the differentiation of rat bone marrow-derived mesenchymal stem cells (BM-MSCs) into tenocyte-like cells in response to bone morphogenetic protein-12 (BMP-12). BM-MSCs were prepared from Sprague-Dawley rats and cultured as monolayers. Recombinant BMP-12 treatment (10 ng/ml) of BM-MSCs for 12 hours in vitro markedly increased expression of the tenocyte lineage markers scleraxis (Scx) and tenomodulin (Tnmd) over 14 days. Treatment with BMP-12 for a further 12-hour period had no additional effect. Colony formation assays revealed that ∼80% of treated cells and their progeny were Scx- and Tnmd-positive. BM-MSCs seeded in collagen scaffolds and similarly treated with a single dose of BMP-12 also expressed high levels of Scx and Tnmd, as well as type I collagen and tenascin-c. Furthermore, when the treated BM-MSC-seeded scaffolds were implanted into surgically created tendon defects in vivo, robust formation of tendon-like tissue was observed after 21 days as evidenced by increased cell number, elongation and alignment along the tensile axis, greater matrix deposition and the elevated expression of tendon markers. These results indicate that brief stimulation with BMP-12 in vitro is sufficient to induce BM-MSC differentiation into tenocytes, and that this phenotype is sustained in vivo. This strategy of pretreating BM-MSCs with BMP-12 prior to in vivo transplantation may be useful in MSC-based tendon reconstruction or tissue engineering

INTELLIGENT INSTRUMENTS AND VISUAL FORCE FEEDBACK IN LAPAROSCOPIC MINIMALLY INVASIVE SURGERY by

This thesis develops methods to provide the operators of surgical telemanipulators with information about instrument-tissue interactions. It has been shown that the pres-ence of haptic (force and tactile) feedback improves the performance of telemanipulator systems. This may be especially true in robot-assisted minimally invasive surgery. Many tasks involve precise manipulation of delicate tissue, such as cardiac vessels, and the lack of haptic information can result in damaged tissue. In addition, the measurement of blood oxygenation levels in manipulated tissue might serve to further prevent tissue damage. We present a novel augmented reality system that uses ‘intelligent ’ instruments, which sense both forces and blood oxygenation levels within tissue, and visual displays to pro-vide the human operator with information about the instrument-tissue interaction. We show the advantages of the force display system in experimental studies implemented in the da Vinci � Surgical System (Intuitive Surgical, Inc.). This system is intuitive because the force displays track their respective instruments in the stereo endoscopic im

Female Genital Mutilation Reconstruction for Plastic Surgeons—A Call to Arms

Summary:. The practice of female genital mutilation (FGM) is performed for historically engrained cultural beliefs with no recognized health benefits. FGM continues to be practiced secondary to motivating factors based on cultural beliefs, the majority of which aim to maintain the “purity” of the female victim. The World Health Organization has classified FGM into 4 types ranging from partial clitoral resection to complete clitoral excision along with the majority of the vulva. The list of short and long-term complications is extensive and morbid, including injury to the patient’s sexuality and feminine identity. Reconstructive surgery can be an important addition to psychotherapy for these women with the goal of correcting the appearance of the vulva to achieve a more normal appearance, and to restore clitoral function. We suggest that this represents an opportunity for plastic surgeons to use our wealth of reconstructive knowledge to provide restoration of form and function to FGM victims

Effects of visual force feedback on robot-assisted surgical task performance

ObjectiveDirect haptic (force or tactile) feedback is negligible in current surgical robotic systems. The relevance of haptic feedback in robot-assisted performances of surgical tasks is controversial. We studied the effects of visual force feedback, a haptic feedback surrogate, on tying surgical knots with fine sutures similar to those used in cardiovascular surgery.MethodsBy using a modified da Vinci robotic system (Intuitive Surgical, Inc, Sunnyvale, Calif) equipped with force-sensing instrument tips and real-time visual force feedback overlays in the console image, 10 surgeons each tied 10 knots with and 10 knots without visual force feedback. Four surgeons had significant prior da Vinci experience, and the remaining 6 surgeons did not. Performance parameters, including suture breakage and secure knots, peak and standard deviation of applied forces, and completion times using 5-0 silk sutures, were recorded. Chi-square and Student t test analyses determined the differences between groups.ResultsAmong surgeon subjects with robotic experience, no differences in measured performance parameters were found between robot-assisted knot ties executed with and without visual force feedback. Among surgeons without robotic experience, however, visual force feedback was associated with lower suture breakage rates, peak applied forces, and standard deviations of applied forces. Visual force feedback did not impart differences in knot completion times or loose knots for either surgeon group.ConclusionsVisual force feedback resulted in reduced suture breakage, lower forces, and decreased force inconsistencies among novice robotic surgeons, although elapsed time and knot quality were unaffected. In contrast, visual force feedback did not affect these metrics among surgeons experienced with the da Vinci system. These results suggest that visual force feedback primarily benefits novice robot-assisted surgeons, with diminishing benefits among experienced surgeons

Enhanced cell alignment following BMP-12-treatment of scaffolds seeded with BM-MSCs.

<p>Rat BM-MSCs were cultured and implanted as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0017531#pone-0017531-g002" target="_blank">Fig. 2</a>. (<b>A</b>) Toluidine blue staining (20X magnification) revealed increased cell elongation and cellular alignment/organization, within the BMP-12-treated BM-MSCs implants. (<b>B</b>) Nuclear aspect ratio (width <i>vs</i> length of nucleus), and (<b>C</b>) Angular deviation (angle between individual nuclear axis and longitudinal axis based on general alignment). A smaller value of nuclear aspect ratio and nuclear orientation angle indicated greater cellular elongation and alignment in cells treated with BMP-12, as compared to untreated cells. * represents p<0.05.</p