Shyam S. Raghavan

The Utility of Endovascular Simulation to Improve Technical Performance and Stimulate Continued Interest of Preclinical Medical Students in Vascular Surgery

OBJECTIVE New training paradigms in vascular surgery allow for early specialization out of medical school. Surgical simulation has emerged as an educational tool for trainees to practice procedures in a controlled environment allowing interested medical students to perform procedures without compromising patient safety. The purpose of this study is to assess the ability of a simulation-based curriculum to improve the technical performance and interest level of medical students in vascular surgery. DESIGN Prospective observational cohort study of medical student performance. SETTING Academic medical center. PARTICIPANTS Forty-one medical students (23 first year, 15 second year, 3 other) enrolled in a vascular surgery elective course. Students completed a survey of their interests and performed a renal stent procedure on an endovascular simulator (pretest). The curriculum consisted of didactic teaching and weekly mentored simulator sessions and concluded with a final renal stent procedure on the simulator (posttest). Objective procedural measures were determined during the pre- and posttest by the simulator, and subjective performance was graded by expert observers utilizing a structured global assessment scale. After the course, the students were surveyed as to their opinions about vascular surgery as a career option. Finally, 1 year after the course, all students were again surveyed to determine continued interest in vascular surgery. RESULTS The objective and subjective criteria measured on the simulator and structured global assessment scale significantly improved from pre- to posttest in terms of performer technical skill, patient safety measures, and structured global assessments. Before beginning the course, 8.5% of the students expressed high interest in vascular surgery, and after completing the course 70% were seriously considering vascular surgery as a career option (p = 0.0001). More than 95% of the students responded that endovascular simulation increased their knowledge and interest in vascular surgery. In the 1-year follow-up survey (n = 23 medical students), 35% had already entered their clinical years. Seventy percent of the students were still considering vascular surgery, while several other career options were still popular including the surgical subspecialties (70%), interventional cardiology (57%), and interventional radiology (48%). Most respondents indicated the major reasons for continued interest in vascular surgery were the ability to practice endovascular procedures on the simulator (100%) and mentorship from vascular surgery faculty (78%). CONCLUSIONS The use of high fidelity endovascular simulation within an introductory vascular surgery course improves medical student performance with respect to technical skill, patient safety parameters, and global performance assessment. Mentored exposure to endovascular procedures on the simulator positively impacts long term medical student attitudes towards vascular surgery. Simulator-based courses may have the potential to be an important component in the assessment and recruitment of medical students for future surgical training programs.

Major blood vessel reconstruction during sarcoma surgery.

OBJECTIVE To evaluate the outcomes of major vessel reconstruction as part of surgery to remove sarcomas. DESIGN Retrospective review. SETTING Tertiary academic medical center. PATIENTS Fourteen patients (10 female) with retroperitoneal or extremity sarcomas and major blood vessel involvement who underwent surgery to remove the tumor and had blood vessel reconstruction between 2003 and 2008. Each patient underwent computed tomography angiography. MAIN OUTCOME MEASURES Early (<30 days) and late (>30 days) operative morbidity and mortality, freedom from disease, and graft patency. RESULTS Seven patients had retroperitoneal sarcomas and 7, extremity sarcomas. Thirteen tumors were malignant (7 high grade and 6 low grade) and 1, benign (leiomyoma). Seven patients had replacement of artery and vein; 5, artery only; and 2, vein only. In all, 16 arteries were reconstructed (2 common femoral; 5 iliac; 2 superficial femoral; 1 brachial; 1 popliteal; and 2 aorta, one with implantation of both iliac arteries and the other with implantation of the left renal, superior mesenteric, and hepatic arteries). Eight patients (57%) had 9 veins reconstructed (3 external iliac, 3 superficial femoral, 2 vena cava, and 1 popliteal). Primary arterial patency was 58% and primary-assisted patency was 83%. Venous patency was 78%. Local recurrence occurred in 3 patients (21%). Five-year disease-free and overall survival were 52% and 68%, respectively. Limb salvage was achieved in 93%. CONCLUSION Involvement of vascular structures is not a contraindication for resection of sarcomas, but appropriate planning is necessary to optimize outcome.

Co-culture of human adipose-derived stem cells with tenocytes increases proliferation and induces differentiation into a tenogenic lineage.

Background: Seeding acellularized tendons with cells is an approach for creating tissue-engineered tendon grafts with favorable biomechanical properties. It was the authors’ aim to evaluate whether human adipose-derived stem cells could replace tenocytes for scaffold seeding. Methods: Adipose-derived stem cells and tenocytes were co-cultured in different ratios (3:1, 1:1, and 1:3) and with three different methods: (1) direct co-culture, (2) tenocyte-conditioned media on adipose-derived stem cells, and (3) an insert system to keep both cell types in the same media without contact. Proliferation, collagen production, and tenogenic marker expression were measured by hematocytometry, immunocytochemistry, enzyme-linked immunosorbent assay, and real-time polymerase chain reaction. Results: Proliferation and collagen production were similar for tenocytes and adipose-derived stem cells alone. Phenotype difference between adipose-derived stem cells and tenocytes was indicated by higher tenascin C and scleraxis expression in tenocytes. Proliferation was increased in direct co-cultures, especially at an adipose-derived stem cells–to-tenocyte ratio of 3:1, and for tenocytes in adipose-derived stem cell–conditioned media. Direct co-culture caused significant up-regulation in tenascin C expression in adipose-derived stem cells (4.0-fold; p < 005). In tenocyte-conditioned media, tenascin C expression was up-regulated 2.5-fold (p < 0.05). In the insert system, tenascin C expression was up-regulated 2.3-fold (p < 0.05). Conclusions: Adipose-derived stem cells are good candidates for tendon tissue engineering because they are similar to tenocytes in proliferation and collagen production. With an optimal ratio of 3:1, they increase proliferation in co-culture and change their phenotype toward a tenogenic direction.

Optimization of human tendon tissue engineering: synergistic effects of growth factors for use in tendon scaffold repopulation.

Background: Tissue-engineered flexor tendon grafts may allow reconstruction of severe tendon losses. One critical factor is the optimization of cell proliferation and reseeding. Use of growth factors—basic fibroblast growth factor (bFGF), insulin-like growth factor (IGF)-1, and platelet-derived growth factor (PDGF)-BB—may improve culture conditions for human fibroblasts, tenocytes, and adipose-derived stem cells and increase repopulation of a tendon scaffold. Methods: All cell types were plated at a density of 10,000 cells per well and cultured in F12 media supplemented with varying concentrations of bFGF, IGF-1, and PDGF-BB. After 72 hours, cell proliferation was determined using the CellTiter assay. Human flexor tendon segments were acellularized and reseeded in a cell suspension of 5 × 105 cells/ml. After 5 days, tendon repopulation was determined using the MTS assay and histology. Statistical significance was determined with analysis of variance and a t test. Results: For all cell types, there was enhanced proliferation with growth factors. Among single growth factors, PDGF-BB at 50 ng/ml was the most efficient stimulator of proliferation. With multiple growth factors, the optimal concentration was determined to be 5 ng/ml bFGF, 50 ng/ml IGF-1, and 50 ng/ml PDGF-BB (increase when compared with control: fibroblasts, 2.92-fold; tenocytes, 2.3-fold; and adipose-derived stem cells, 2.4-fold; p < 0.05). Tendons reseeded with this optimal combination of growth factors showed improved reseeding compared with the control group (fibroblasts, 2.01-fold; tenocytes, 1.78-fold; and adipose-derived stem cells, 1.76-fold; p < 0.05). Conclusions: bFGF, IGF-1, and PDGF-BB can be used to improve cellular proliferation and repopulation of an acellularized scaffold. The use of growth factors may be an important step in the tissue engineering of human flexor tendons.

Flexor Tendon Sheath Engineering Using Decellularized Porcine Pericardium

Background: The flexor tendon sheath is an ideal target for tissue engineering because it is difficult to reconstruct by conventional surgical methods. The authors hypothesized that decellularized porcine pericardium can be used as a scaffold for engineering a biologically active tendon sheath. Methods: The authors’ protocol removed cellular material from the pericardium and preserved the structural architecture in addition to the collagen and glycosaminoglycan content. The scaffold was successfully reseeded with human sheath synoviocytes and human adipose-derived stem cells. Cells were evaluated for 8 weeks after reseeding. Results: The reseeded construct demonstrated continuous production of hyaluronic acid, the main component of synovial fluid. After being seeded on the membrane, adipose-derived stem cells demonstrated down-regulation of collagen I and III and up-regulation of hyaluronan synthase 2. Conclusion: The results indicate that decellularized porcine pericardium may be a potential scaffold for engineering a biologically active human tendon sheath.

Histopathologic approach to epidermotropic lymphocytic infiltrates

Mycosis fungoides is the most common and therefore quintessential cutaneous lymphoma and is typically characterized by an epidermotropic infiltrate of atypical monoclonal CD4+ lymphocytes. Classical histopathologic findings include epidermotropism, lymphocytes with convoluted nuclear contours and surrounding perinuclear “halos,” and papillary dermal fibrosis. Atypical lymphocytes may occasionally form Pautrier’s microabscesses with tagging of lymphocytes along the basal keratinocytes. Unfortunately, a variety of benign inflammatory infiltrates, as well as other cutaneous lymphomas, may demonstrate some similar histopathologic findings. Herein, we review the wide array of epidermotropic T-cell lymphomas and discuss distinguishing features between these entities. We also offer an algorithmic approach utilizing histopathologic, immunophenotypic, and molecular techniques that can be used for analyzing an epidermotropic T-cell infiltrate in order to render a specific diagnosis.

Utility of CD30, Ki67 and p53 in assisting with the diagnosis Mycosis Fungoides with Large Cell Transformation

Mycosis fungoides (MF) with large cell transformation (LCT) is an advanced stage of cutaneous lymphoma with a poor prognosis. Identification of LCT is critical and especially challenging when the number of large abnormal lymphocytes is near but below 25%. We propose that Ki‐67 and p53 may be useful in making this diagnosis.