Harry M. Salinas

Comparative analysis of processing methods in fat grafting.

Background: Centrifugation is a popular processing method, with an unclear mechanism of action. Hypotheses include fat concentration, reduced inflammatory response by removal of blood, and concentration of adipose-derived stem cells. The authors performed multiple experiments to determine the role of centrifugation and compared it with a different processing method (mesh/gauze technique). Methods: Lipoaspirate components were quantified after centrifugation at increasing speed to determine concentration efficacy. For comparison, the authors quantified the concentration efficacy of mesh/gauze. They also compared the number of adipose-derived stem cells isolated by either method. To determine the effects of each component, they compared fat alone to fat mixed with various spinoff components in a mouse model. They also compared centrifugation to mesh/gauze. Results: The adipocyte fraction remains constant above 5000 g, whereas 1200 g results in 91 percent concentrated fat. Mesh/gauze also results in 90 percent concentrated fat. The number of adipose-derived stem cells in 1 g of fat was 1603 ± 2020 and 1857 ± 1832 in the centrifuge and mesh/gauze groups, respectively (p = 0.86). Five “add-back” groups were created: fat plus oil, fat plus surgical tumescence, fat plus fresh tumescence, fat plus cell pellets and fresh tumescence, and fat plus cell pellets. The fat-only group had better retention than the groups mixed with tumescence, regardless of whether it was surgical, fresh, or had cell pellets. Oil did not affect grafts. Centrifugation at 1200 g was equivalent to mesh/gauze (0.73 ± 0.12 g and 0.72 ± 0.13 g, respectively). Conclusions: Centrifugation improves graft retention by concentration of the adipocyte fraction. The concentration efficacy of mesh/gauze is equivalent to centrifugation at 1200 g, with equivalent in vivo outcomes.

Determining the Need for Radical Surgery in Patients With T1 Rectal Cancer

HYPOTHESIS In the era of modern preoperative staging of patients with rectal cancer, lymph node metastases can be reliably predicted by the histological features of the tumor and preoperative imaging. Local resection can then be safely offered to the patients who are at low risk of having malignant lymph nodes. DESIGN We reviewed the records of 109 consecutive patients with preoperative imaging results suggestive of T1N0 or T2N0 disease who underwent total mesorectal excision. All patients underwent preoperative endorectal ultrasonography or magnetic resonance imaging and computed tomography, with or without positron emission tomography. Final pathologic investigation identified T3 disease in 27 patients. History, physical examination results, and radiologic and pathologic data were evaluated for predictors of positive nodes in the remaining 82 patients. SETTING Tertiary care referral center. PATIENTS Patients with preoperative imaging suggestive of T1N0 or T2N0 rectal cancer. MAIN OUTCOME MEASURES To evaluate different clinical and pathologic tumor features as predictors of positive lymph nodes in T1 and T2 rectal cancers with negative radiographic nodes. BACKGROUND Local resection of T1 and T2 rectal cancer results in lower morbidity compared with radical resection. However, recurrence rates after local resection are higher, likely owing to unresected nodal metastasis. Reports on predictors of lymph node metastasis remain inconsistent in the literature. Although local resection may be appropriate for some rectal cancers, selection criteria remain unclear. RESULTS Despite indications of negative nodes on radiographic examination, 4 of 35 patients with T1 disease (11%) and 13 of 47 with T2 disease (28%) had positive nodes. On univariate analysis, the only significant predictor was depth of invasion: 24 of 65 patients with negative nodes (37%) vs 13 of 17 patients with positive nodes (76%) had tumors invading the lower third of the submucosa and beyond (P = .02). On logistic regression analysis accounting for depth of invasion (lower third of the submucosa and beyond), size, distance from anal verge, differentiation, and lymphovascular and small-vessel invasion, only depth of invasion remained a significant predictor. CONCLUSIONS In all, 89% of patients with T1 disease (31 of 35) and 72% of those with T2 disease (34 of 47) underwent unnecessary radical resection. Endorectal ultrasonography or magnetic resonance imaging and computed tomography, with or without positron emission tomography, for preoperative staging could not identify these patients reliably. In addition, histologic markers of aggressive disease were not helpful. Thus, local resection for T2 rectal cancer is not justified. Local resection should be offered only to patients with superficial T1 tumors who will adhere to aggressive postoperative surveillance.

Penis Transplantation: First Us Experience

Objective: We describe the first successful penis transplant in the United States in a patient with a history of subtotal penectomy for penile cancer. Background: Penis transplantation represents a new paradigm in restoring anatomic appearance, urine conduit, and sexual function after genitourinary tissue loss. To date, only 2 penis transplants have been performed worldwide. Methods: After institutional review board approval, extensive medical, surgical, and radiological evaluations of the patient were performed. His candidacy was reviewed by a multidisciplinary team of surgeons, physicians, psychiatrists, social workers, and nurse coordinators. After appropriate donor identification and recipient induction with antithymocyte globulin, allograft procurement and recipient preparation took place concurrently. Anastomoses of the urethra, corpora, cavernosal and dorsal arteries, dorsal vein, and dorsal nerves were performed, and also inclusion of a donor skin pedicle as the composite allograft. Maintenance immunosuppression consisted of mycophenolate mofetil, tacrolimus, and methylprednisolone. Results: Intraoperative, the allograft had excellent capillary refill and strong Doppler signals after revascularization. Operative reinterventions on postoperative days (PODs) 2 and 13 were required for hematoma evacuation and skin eschar debridement. At 3 weeks, no anastomotic leaks were detected on urethrogram, and the catheter was removed. Steroid resistant-rejection developed on POD 28 (Banff I), progressed by POD 32 (Banff III), and required a repeat course of methylprednisolone and antithymocyte globulin. At 7 months, the patient has recovered partial sensation of the penile shaft and has spontaneous penile tumescence. Our patient reports increased overall health satisfaction, dramatic improvement of self-image, and optimism for the future. Conclusions: We have shown that it is feasible to perform penile transplantation with excellent results. Furthermore, this experience demonstrates that penile transplantation can be successfully performed with conventional immunosuppression. We propose that our successful penile transplantation pilot experience represents a proof of concept for an evolution in reconstructive transplantation.

Photochemical Tissue Passivation Reduces Vein Graft Intimal Hyperplasia in a Swine Model of Arteriovenous Bypass Grafting

Background Bypass grafting remains the standard of care for coronary artery disease and severe lower extremity ischemia. Efficacy is limited by poor long‐term venous graft patency secondary to intimal hyperplasia (IH) caused by venous injury upon exposure to arterial pressure. We investigate whether photochemical tissue passivation (PTP) treatment of vein grafts modulates smooth muscle cell (SMC) proliferation and migration, and inhibits development of IH. Methods and Results PTP was performed at increasing fluences up to 120 J/cm2 on porcine veins. Tensiometry performed to assess vessel elasticity/stiffness showed increased stiffness with increasing fluence until plateauing at 90 J/cm2 (median, interquartile range [IQR]). At 90 J/cm2, PTP‐treated vessels had a 10‐fold greater Youngs modulus than untreated controls (954 [IQR, 2217] vs 99 kPa [IQR, 63]; P=0.03). Each pig received a PTP‐treated and untreated carotid artery venous interposition graft. At 4‐weeks, intimal/medial areas were assessed. PTP reduced the degree of IH by 66% and medial hypertrophy by 49%. Intimal area was 3.91 (IQR, 1.2) and 1.3 mm2 (IQR, 0.97; P≤0.001) in untreated and PTP‐treated grafts, respectively. Medial area was 9.2 (IQR, 3.2) and 4.7 mm2 (IQR, 2.0; P≤0.001) in untreated and PTP‐treated grafts, respectively. Immunohistochemistry was performed to assess alpha‐smooth muscle actin (SMA) and proliferating cell nuclear antigen (PCNA). Objectively, there were less SMA‐positive cells within the intima/media of PTP‐treated vessels than controls. There was an increase in PCNA‐positive cells within control vein grafts (18% [IQR, 5.3]) versus PTP‐treated vein grafts (5% [IQR, 0.9]; P=0.02). Conclusions By strengthening vein grafts, PTP decreases SMC proliferation and migration, thereby reducing IH.

Prevention of vein graft intimal hyperplasia with photochemical tissue passivation.

Objective: Saphenous vein is the conduit of choice for bypass grafting. Saphenous vein grafts have poor long‐term patency rates because of intimal hyperplasia (IH) and subsequent accelerated atherosclerosis. One of the primary triggers of IH is endothelial injury resulting from excessive dilation of the vein after exposure to arterial pressures. Photochemical tissue passivation (PTP) is a technology that cross‐links adventitial collagen by a light‐activated process, which limits dilation by improving vessel compliance. The objective of this study was to investigate whether PTP limits the development of IH in a rodent venous interposition graft model. Methods: PTP is accomplished by coating venous adventitia with a photosensitizing dye and exposing it to light. To assess the degree of collagen cross‐linking after PTP treatment, a biodegradation assay was performed. Venous interposition grafts were placed in the femoral artery of Sprague‐Dawley rats. Rats were euthanized after 4 weeks, and intimal thickness was measured histologically. Vein dilation at the time of the initial procedure was also measured. Results: Time to digestion was 63 ± 7 minutes for controls, 101 ± 2.4 minutes for rose bengal (RB), and 300 ± 0 minutes for PTP (P < .001 PTP vs control). A total of 37 animals underwent the procedure: 12 PTP, 12 RB only, and 13 untreated controls. Dilation of the graft after clamp release was 99% for control, 65% for RB only, and 19% for PTP‐treated (P < .001 PTP vs control). Intimal thickness was 77 ± 59 &mgr;m in controls, 60 ± 27 &mgr;m in RB only, and 33 ± 28 &mgr;m in PTP‐treated grafts. There was a statistically significant 57% reduction in intimal thickness after treatment with PTP compared with untreated controls (P = .03). Conclusions: PTP treatment of venous interposition grafts in a rat model resulted in significant collagen cross‐linking, decreased vessel compliance, and significant reduction in IH. Clinical Relevance: Long‐term patency rates are poor after coronary or lower extremity bypass with autologous vein. This is largely due to intimal hyperplasia (IH), superimposed accelerated atherosclerosis, and graft thrombosis. A key inciting event is graft overdistention and endothelial denudation after exposure to arterial pressure. Limiting overdistention by external mechanical support has been shown to reduce IH. Photochemical tissue passivation involves cross‐linking adventitial collagen, a novel approach to limit overdistention of the vein without an external prosthesis. Photochemical tissue passivation resulted in a 57% reduction of IH. Minimizing vein graft IH would greatly improve long‐term outcomes after arterial bypass.

Abstract 136: Centrifugation Compared to a Combined Mesh/telfa Technique for Fat Grafting: Mechanism, Outcomes and Effect on ADSCs.

PurPose: Fat grafting involves lipoaspirate harvest, isolation of adipocyte fraction, and subsequent injection of processed fat. Centrifugation is cumbersome and the mechanism by which it improves outcomes remains unclear. Hypotheses include fat concentration, reduction of inflammatory response by removal of nonviable components and concentration of adipose-derived stem cells (ADSCs). We performed a series of experiments to compare the process of centrifugation to a faster, simpler, processing method that combines mesh and telfa techniques.

2601: Genitourinary vascularized composite allotransplanation: Preliminary report of first case performed in the United States

2601: Genitourinary vascularized composite allotransplanation: Preliminary report of first case performed in the United States Curtis L. Cetrulo, MD, FACS, Branko Bojovic, MD, Kyle Eberlin, MD, Jonathan Winograd, MD, Francis McGovern, MD, Michael Grant, MD, Cigdem Tanrikut, MD, Adam Feldman, MD, Richard Ehrlichman, MD, Harry Salinas, MD, Matthew Treiser, MD, Jeffrey Lee, MD, Eric Wright, MD, Kai Lee, MD, Ilse Schol, BS, Paul Holzer, MS, William G. Austen, Jr., MD, and Dicken Ko, MD Massachusetts General Hospital, Boston, MA, USA Introduction Vascularized Composite Allotransplantation (VCA) has been a clinical reality in hand transplantation since the late 1990s and in facial transplantation since 2005. VCA has ushered in a very exciting and explosive era of research and new modalities to offer patients in need of options the potential for restorative operative interventions. In addition to upper extremity and facial VCA, much interest has been given to genitourinary VCA, specifically penile transplantation. Recent conflicts that have rendered many wounded warriors with devastating genitourinary injuries, a subset of penile cancer patient survivors previously left with disfiguring or minimal residual penile function, and a newer group of transgender patients interested in more realistic reconstruction than current autologous stateof-the-art techniques can offer, have furthered research and interest in penile VCA. Two prior successful penile VCA cases have been performed to date in the world literature experience. Methods A protocol for penile VCA was approved by the Internal Review Board at Massachusetts General Hospital (MGH) Appropriate candidate screening and selection was approved by the patient selection committee. Preoperative preparation via recipient patient defect-specific cadaveric dissection sessions was performed. The New England Organ Bank (NEOB) facilitated donor patient screening for protocol screened and approved recipient candidates. Results In early May, 2016, a potential donor was identified by the NEOB for a recipient patient accepted by the IRB-approved protocol at MGH. Team mobilization ensued and the recipient patient was informed. Subsequently, the first successful penile VCA in the United States was performed over the course of a 15 hour operation. One week out from the successful procedure, the recipient patient is doing well and meeting expected milestones in recovery. Conclusions We herein present the first successful penile VCA performed in the United States and have demonstrated proof of concept. This now becomes the third case in the world literature experience and opens the discussion of genitourinary VCA to a new geographic focus in the world, possibly leading to further such transplants to now be considered and performed in this important and deserving patient population. CONTACT Curtis L. Cetrulo ccetrulo@mgh.harvard.edu

Abstract 97: Prevention of Vein Intimal Hyperplasia with Photochemical Tissue Passivation in a Porcine Model

PURPOSE: Veins are frequently used in microsurgical reconstruction of extremities, coronary bypass procedures, peripheral arterial revascularization, and vascular access for hemodialysis. Autologous veins are the conduit of choice for arterial reconstruction due to availability, superior patency rates, ease of use, and decreased infection risk compared to synthetic grafts. Despite widespread employment of autologous vein grafts, their effectiveness is limited by poor long-term patency rates compared to arterial grafts. Poor long-term outcomes are due to luminal narrowing caused by intimal hyperplasia (IH), medial thickening, and subsequent superimposed accelerated atherosclerosis. IH is a consequence of intimal injury that ensues after exposure of a vein to arterial pressures. Studies have shown that limiting the distension of the graft reduces the degree of IH, increasing patency rates.

Abstract 108: photochemical tissue passivation for prevention of vein graft intimal hyperplasia.

PurPose: Vein grafts are frequently used as conduits for coronary bypass, peripheral arterial revascularization, and microsurgical reconstruction of the upper extremities. For coronary revascularization, saphenous vein grafts (SVG) are the most commonly used conduit. However, they have poor long term patency rates compared to arterial grafts due to accelerated atherosclerosis in the venous grafts. Accelerated atherosclerosis begins as intimal hyperplasia (IH), which is a consequence of the intimal injury that results from excessive stretching of the vein graft as it is exposed to arterial pressures. Limiting the stretch of the graft reduces the degree of IH. To date, every modality to prevent stretch has been through the application of external sheaths over the vein graft. Photochemical Tissue Passivation (PTP) is a technology that crosslinks surface proteins by a light activated process. PTP offers a simple approach to stiffen venous conduits, thus limiting excessive stretch and the resulting intimal injury.