Hickman Catheter Use for Long-Term Vascular Access in a Preclinical Swine Model.

Central venous catheters (CVCs) are invaluable devices in large animal research as they facilitate a wide range of medical applications, including blood monitoring and reliable intravenous fluid and drug administration. Specifically, the tunneled multi-lumen Hickman catheter (HC) is commonly used in swine models due to its lower extrication and complication rates. Despite fewer complications relative to other CVCs, HC-related morbidity presents a significant challenge, as it can significantly delay or otherwise negatively impact ongoing studies. The proper insertion and maintenance of HCs is paramount in preventing these complications, but there is no consensus on best practices. The purpose of this protocol is to comprehensively describe an approach for the insertion and maintenance of a tunneled HC in swine that mitigates HC-related complications and morbidity. The use of these techniques in >100 swine has resulted in complication-free patent lines up to 8 months and no catheter-related mortality or infection of the ventral surgical site. This protocol offers a method to optimize the lifespan of the HC and guidance for approaching issues during use.

Penetrating Trauma in Baltimore: An Analysis of the Effect of a Rise in Localized Violence by Age Group.

BACKGROUND: Incidence of firearm mortality in the United States is increasing. Baltimore, MD saw a substantial increase in violence in April 2015. We analyzed the effect of this localized surge in violence on the pediatric population. METHODS: Using the Maryland Health Services Cost Review Commission database, initial hospital encounters for gunshot wound (GSW) or stab wound (SW) were identified. Baltimore Police Department victim-based crime data and homicide data on GSW and SW assault were used to capture those not seen at hospitals. Changes in incidence rate ratios from before/after April 2015 were analyzed using Poisson regression. RESULTS: No change in mortality was seen in hospital-evaluated GSW patients. The pediatric population showed decreased incidence of SW (P < 0.001) and increase in GSW (P < 0.001) but no change in total penetrating trauma (tPT). The young adult population had decreased SW incidence (P < 0.001) without change in GSW or tPT. The pediatric populations saw no difference in SW/GSW deaths or homicide rate. However, in young adults, there were increased homicides (P < 0.001) and GSW deaths (P < 0.001) with unchanged SW deaths. CONCLUSIONS: After a surge in violence, the shifted mechanism of penetrating trauma in the pediatric population did not increase mortality or tPT. By contrast, GSW incidence is increasing in young adults with more lethal injuries. Intervention could be aimed at gun control and targeted education/intervention in the at-risk younger age group.

Noninvasive evaluation of intragraft immune responses in upper extremity transplantation.

In vascularized composite allotransplantation (VCA), invasive tissue biopsies remain the gold standard in diagnosing rejection carrying significant morbidity. We aimed to show feasibility of tape-stripping for noninvasive immune monitoring in VCA. Tape-stripping was performed on allografts and native skin of upper extremity transplant recipients. Healthy nontransplanted individuals served as controls. The technique was also used in swine on naïve skin in nontransplanted animals, native skin of treated, transplanted swine, nonrejecting VCAs, and rejecting VCAs. Extracted protein was analyzed for differences in cytokine expression using Luminex technology. Significantly decreased levels of INFγ and IL-1Ra were seen between human allograft samples and native skin. In swine, rejecting grafts had increased IL-1Ra compared to naïve and native skin, decreased levels of GM-CSF compared to native skin, and decreased IL-10 compared to nonrejecting grafts. Unsupervised hierarchical clustering revealed rejecting grafts separated from the nonrejecting (P = 0.021). Variable importance in projection scores identified GM-CSF, IL-1Ra, and IL-2 as the most important profiles for group discrimination. Differences in cytokine expression are detectable in human VCA patient native skin and VCA graft skin using a noninvasive tape-stripping method. Swine studies suggest that differences in cytokines between rejecting and nonrejecting grafts are discernable.

Latissimus Dorsi Myocutaneous Flap Procedure in a Swine Model.

BACKGROUND: As surgical research expands in both breadth and scope, translational models become increasingly important. The accessibility, reproducibility, and clinical applicability of translational models is of vital importance to ensure adequate and accurate research. Though different flap models have been described, the literature lacks an in-depth, technical description of an easy large-animal preclinical model. We here describe the procedure for elevation of a latissimus dorsi flap in a swine. This flap contains muscle and skin that can be isolated on a vascular pedicle, transferred as a free flap, perfused, or innervated/denervated as dictated by the needs of the experiment. METHODS: Five different latissimus dorsi flaps were elevated in miniature swine. Careful attention was paid to anatomical landmarks and optimal placement of incision, dissection, and retraction. Temporary ischemia with vascular clamping was performed along with serial digital and infrared imaging both intra- and postoperatively. In three of the flaps with induced ischemia, the animal was observed for a 30-day follow up with daily photodocumentation and intermittent biopsy. RESULTS: A reproducible latissimus flap model was designed with optimized conditions. In the animals in which flaps were followed postoperatively, complete healing was seen within 30 days without evidence of procedure-related ischemia or loss of motor function. CONCLUSION: We have identified and described a pre-clinical large animal flap model that can be easily reproduced for translational studies of multiple scientific areas including flap-based repair, ischemia, ischemia reperfusion, and operative technique. This provides an important model for ready replication in preclinical studies of many varieties.

Efficacy of single-agent immunosuppressive regimens in a murine model of vascularized composite allotransplantation.

We herein investigate the safety and efficacy of single-agent anti-rejection regimens in a mouse vascularized composite allotransplantation (VCA) model. Orthotopic hind-limb transplantations (Balb/c â†’ C57BL/6) were performed using 6- to 8-week-old mice. A thirty-day regimen of either rapamycin, tacrolimus (both 1, 3, 5 mg/kg/day) or cyclosporine (25, 35, 50 mg/kg/day) was used. Primary endpoints were animal and graft survival, and secondary chimerism and regulatory T-cell levels. For rapamycin and tacrolimus given at 1, 3, and 5 mg/kg/day, median graft survival time (MST) was 23 days (18-28 days), 30 days (23-30 days), and 30 d (30-30 days) and 14 days (13-18 days), 30 days (16-30 days), and 30 days (30-30 days), respectively. For cyclosporine dosed at 25 and 35 mg/kg/day, MST was 15 days (12-18 days) and 21 days (14-27 days). Toxicity from CsA 50 mg/kg led to 100% mortality. Mixed chimerism levels were higher in rapamycin-treated animals than in tacrolimus-treated recipients (P = 0.029). Tacrolimus was superior in preventing leukocyte recruitment to the allograft. In murine VCA, no standardized immunosuppressive regimen exists, limiting comparability of outcomes and survival. Our data demonstrate that rapamycin and tacrolimus maintenance treatment at 5 mg/kg/day both yielded allograft survival (

A novel rat microsurgical model to study the immunological characteristics of male genital tissue in the context of penile transplantation.

Penis transplantation represents an exciting new avenue for restoration of male genitalia and function after devastating tissue loss. This animal model is designed to fill a critical void to study immunologic aspects related to reconstructive transplantation of male genitalia. A rat penile graft dissection was designed based on the internal pudendal arteries and dorsal penile vein and includes the skin of the prepuce. A nonsuture cuff technique was used to anastomose the graft vessels to the recipient superficial epigastric and femoral vessels. Seventy-seven penile transplantations were performed. Graft design yields suitable caliber and length of vessels at the radix of the penis. Anastomosis of the dorsal penile vein and the internal pudendal arteries insures optimal graft perfusion. The nonsuture cuff technique allows for successful microvascular anastomosis by a single surgeon with an average overall operative time of 2.5 h. Long-term graft survival (>30 days) was observed in syngeneic transplants. We have established a robust murine model with ideal vascular perfusion of penile tissue to study the unique immunobiology of male genitourinary allotransplantation. Heterotopic inset further allows for visual monitoring of graft viability, while the native penis serves as an optimal control.

Donor cardiac arrest and cardiopulmonary resuscitation: impact on outcomes after simultaneous pancreas-kidney transplantation - a retrospective study.

Donor cardiac arrest and cardiopulmonary resuscitation (CACPR) has been considered critically because of concerns over hypoperfusion and mechanical trauma to the donor organs. We retrospectively analyzed 371 first simultaneous pancreas-kidney transplants performed at the Medical University of Innsbruck between 1997 and 2017. We evaluated short- and long-term outcomes from recipients of organs from donors with and without a history of CACPR. A total of 63 recipients received a pancreas and kidney graft from a CACPR donor. At 1, and 5-years, patient survival was similar with 98.3%, and 96.5% in the CACPR and 97.0%, and 90.2% in the non-CACPR group (log rank P = 0.652). Death-censored pancreas graft survival was superior in the CACPR group with 98.3%, and 91.4% compared to 86.3%, and 77.4% (log rank P = 0.028) in the non-CACPR group, which remained statistically significant even after adjustment [aHR 0.49 (95% CI 0.24-0.98), P = 0.044]. Similar relative risks for postoperative complications Clavien Dindo > 3a, pancreatitis, abscess, immunologic complications, delayed pancreas graft function, and relative length of stay were observed for both groups. Donors with a history of CACPR are, in the current practice, safe for transplantation. Stringent donor selection and short CPR durations may allow for outcomes surpassing those of donors without CACPR.

Outcomes of simultaneous pancreas and kidney transplantation based on donor resuscitation.

It has been hypothesized that transplanting simultaneous pancreas kidney (SPK) grafts from donors with a history of cardiac arrest and cardiopulmonary resuscitation (CACPR) leads to inferior posttransplant outcomes due to organ hypoperfusion during cardiac arrest and mechanical trauma during resuscitation. Using Scientific Registry of Transplant Recipients data, we identified 13 095 SPK transplants from 2000-2018, of which 810 (6.2%) were from donors with a history of CACPR. After inverse probability of treatment weighting on donor and recipient characteristics, we found that 1-, 5-, and 10-year patient (CACPR: 96.4%, 89.9%, and 78.9%; non-CACPR: 96.3%, 88.9%, and 76.0%; P = .3), death-censored pancreas graft survival (CACPR: 89.3%, 82.7%, 75.0%; non-CACPR: 89.9%, 82.7%, 76.3%; P = .7), and death-censored kidney graft survival (CACPR: 97.0%, 89.5%, 78.2%; non-CACPR: 96.9.9%, 88.7%, 80.0%; P = .4) were comparable between the two groups. There were no differences in the risk of pancreatitis (CACPR: 2.9%, non-CACPR: 2.4%; weighted OR = 0.74 1.22 2.02 ; P = .4), anastomotic leak (CACPR: 1.6%, non-CACPR: 2.0%; weighted OR = 0.54 1.02 1.93 ; P > .9), or median length of hospital stay (CACPR: 8 days, non-CACPR: 9 days; P = .6) for recipients of CACPR vs non-CACPR donors. Our findings suggest that CACPR donors could be used to expand the SPK donor pool without compromising short- or long-term outcomes.

Trauma-induced Rejection in Vascularized Composite Allotransplantation.

: Vascularized composite allotransplantation (VCA) is a relatively new field in reconstructive medicine. Likely a result of the unique tissue composition of these allografts-including skin and often a bone marrow component-the immunology and rejection patterns do not always mimic those of the well-studied solid organ transplantations. While the number and type of VCAs performed is rapidly expanding, there is still much to be discovered and understood in the field. With more patients, new findings and patterns emerge and add to our understanding of VCA. Here, we present a case report of an upper extremity transplant recipient with trauma-induced rejection.

Characterization of Clinical and Histological Rejection of Male Genital Tissues Using a Novel Microsurgical Rat Penile Transplantation Model.

BACKGROUND: Penis transplantation represents an exciting new avenue for restoration of male urogenitalia. However, little is known about the specific immunological features of penile transplants, limiting their application in complex urogenital reconstruction. To properly study this emerging form of transplantation, adequate preclinical models are a necessity. The purpose of this study is to establish a clinical and histological rejection classification of urogenital tissue transplants using a new rat heterotopic penile transplant model that includes preputial skin. METHODS: Syngeneic and allogeneic heterotopic penile transplantations were performed on Lewis and Brown Norway rats using a new model designed by our group. Grafts were clinically and histologically monitored at postoperative days (POD) 3-30. RESULTS: Six syngeneic and 25 allogeneic transplants were performed. All syngeneic and tacrolimus-treated grafts survived until endpoint. Allogeneic graft rejection is shown to follow a 4-stage clinical progression with all untreated allografts developing epidermal sloughing at POD7 and full rejecting between POD14 and POD16. Histological samples were used to develop a specific 4-grade rejection classification analogous to the 2007 Banff Criteria for skin-containing allografts. CONCLUSIONS: Graft skin and urethral lining tissue are first rejection targets followed by tunica albuginea and corpora cavernosa in a distal to proximal pattern. We established a robust and reproducible murine model to study the immunobiology of male genital tissue in the context of transplantation and developed a novel 4-grade clinical and histological rejection scale based on graft skin and urethral lining as the main targets of rejection.

Sex matching does not impact the outcome after simultaneous pancreas-kidney transplantation.

BACKGROUND: Several studies in solid organ transplantation have shown a correlation between donor and recipient sex mismatch and risk of graft loss. In this study, we aimed to analyze the impact of donor and recipient sex matching on patient and pancreas graft survival in a large single-center cohort. METHODS: We retrospectively analyzed all first simultaneous pancreas-kidney transplants performed between 1979 and 2017 at the Medical University of Innsbruck. RESULTS: Of 452 patients, 54.6% (247) received a sex-matched transplant. Patient survival (P = .86), death-censored pancreas graft survival (dcPGS, P = .26), and death-censored kidney graft survival (dcKGS, P = .24) were similar between the sex-matched and sex-mismatched groups. Patient survival and dcPGS at 1, 5, and 15 years were 95.9%, 90.0%, and 62.1% and 86.1%, 77.1%, and 56.7% in the sex-matched group and 93.6%, 86.2%, and 62.4% and 83.1%, 73.3%, and 54.3% in the sex-mismatched group. Sex matching led to a lower odds of severe postoperative complications (41.2% vs 49.0%; OR 0.57, 95%CI 0.33-0.97; P = .038); however, no increased odds of other adverse postoperative outcomes was detected. CONCLUSION: Our study demonstrates that sex matching reduced the odds of postoperative complications but did not impact other early and late outcome parameters in our cohort.

A Skin Rejection Grading System for Vascularized Composite Allotransplantation in a Preclinical Large Animal Model.

BACKGROUND: The Banff Criteria have been accepted as a system for grading histological rejection in graft skin in human vascularized composite allotransplantation (VCA). Preclinical swine hindlimb transplantation models have an important role in translational studies in VCA. However, unified grading criteria for rejection in swine skin have not yet been established. METHODS: Two hundred fourteen swine skin biopsy specimens were reviewed, including 88 native skin biopsies and 126 specimens from the skin component of heterotopic swine hindlimb transplants. Thorough review was performed in a blinded fashion by an expert veterinary pathologist with attention paid to the applicability of the Banff criteria as well as specific histologic characteristics and trends. Clinical and histopathologic rejection scores were then directly compared. RESULTS: Two hundred fourteen specimens reviewed showed significant similarities between swine and human skin, as previously published. Notable swine-specific characteristics, including paucicellular infiltration with rare epidermal cell infiltration or necrosis, were accounted for in a proposed grading system that parallels the Banff Criteria. CONCLUSIONS: This comprehensive grading system, based on the Banff Classification for skin rejection in VCA, provides a standardized system for more accurate comparison of rejection in preclinical swine VCA models.

Prosthetic Rehabilitation and Vascularized Composite Allotransplantation following Upper Limb Loss.

BACKGROUND: Upper limb loss is a devastating condition with dramatic physical, psychological, financial, and social consequences. Improvements in the fields of prosthetics and vascularized composite allotransplantation have opened exciting new frontiers for treatment and rehabilitation following upper limb loss. Each modality offers a unique set of advantages and limitations with regard to the restoration of hand function following amputation. METHODS: Presented in this article is a discussion outlining the complex considerations and decisions encountered when determining patient appropriateness for either prosthetic rehabilitation or vascularized composite allotransplantation following upper limb loss. In this review, the authors examine how psychosocial factors, nature of injury, rehabilitation course, functional outcomes, and risks and benefits may affect overall patient selection for either rehabilitative approach. RESULTS: This review summarizes the current state of the literature. Advancements in both prosthetic and biological strategies demonstrate promise with regard to facilitating rehabilitation following upper limb loss. However, there remains a dearth of research directly comparing outcomes in prosthetic rehabilitation to that following upper extremity transplantation. CONCLUSIONS: Few studies have performed a direct comparison between patients undergoing vascularized composite allotransplantation and those undergoing prosthetic rehabilitation. Upper extremity transplantation and prosthetic reconstruction should not be viewed as competing options, but rather as two treatment modalities with different risk-to-benefit profiles and indications.

Chimerism, Transplant Tolerance, and Beyond.

The present review discusses current developments in tolerance induction for solid organ transplantation with a particular emphasis on chimerism-based approaches. It explains the basic mechanisms of chimerism-based tolerance and provides an update on ongoing clinical tolerance trials. The concept of "delayed tolerance" is presented, and ongoing preclinical studies in the nonhuman primate setting-including current limitations and hurdles regarding this approach-are illustrated. In addition, a brief overview and update on cell-based tolerogenic clinical trials is provided. In a critical approach, advantages, limitations, and potential implications for the future of these different regimens are discussed.

Emerging technologies in organ preservation, tissue engineering and regenerative medicine: a blessing or curse for transplantation?

Since the beginning of transplant medicine in the 1950s, advances in surgical technique and immunosuppressive therapy have created the success story of modern organ transplantation. However, today more than ever, we are facing a huge discrepancy between organ supply and demand, limiting the potential for transplantation to save and improve the lives of millions. To address the current limitations and shortcomings, a variety of emerging new technologies focusing on either maximizing the availability of organs or on generating new organs and organ sources hold great potential to eventully overcoming these hurdles. These advances are mainly in the field of regenerative medicine and tissue engineering. This review gives an overview of this emerging field and its multiple sub-disciplines and highlights recent advances and existing limitations for widespread clinical application and potential impact on the future of transplantation.

Feasibility and Outcomes of Femoral Vein Harvest for Dialysis Access and Arterial Reconstruction.

BACKGROUND: We describe the feasibility and long-term outcomes of using femoral vein (FV) for arteriovenous fistula (AVF) and lower extremity bypass (LEB) creation. METHODS: All patients undergoing AVF or LEB using autogenous FV by a single surgeon (April 2006 to September 2013) were reviewed. Perioperative (30-d) complications and long-term outcomes are described. RESULTS: Forty-four patients underwent vascular reconstruction with FV (AVF = 27 and LEB = 17). Perioperative morbidity was 43.2%, including harvest site infection and or seroma in 15.9%. No patients suffered from compartment syndrome or venous thromboembolic event. At median follow-up of 50.0 mon, overall patency was 70.4% for AVF (primary = 37.0% and secondary = 70.3%) and 76.5% for LEB (primary = 70.6% and secondary = 76.5%). Long-term lower extremity swelling occurred in 18.2% of patients. CONCLUSIONS: Perioperative morbidity following FV harvest is high, but long-term patency rates are excellent. FV harvest is feasible and should be considered as a valid conduit in patients without useable great saphenous vein or other more commonly used sources of autogenous vein.

Advances in machine perfusion, organ preservation, and cryobiology: potential impact on vascularized composite allotransplantation.

PURPOSE OF REVIEW: In this review, we discuss novel strategies that allow for extended preservation of vascularized composite allografts and their potential future clinical implications for the field of vascularized composite allotransplantation (VCA). RECENT FINDINGS: The current gold standard in tissue preservation - static cold preservation on ice - is insufficient to preserve VCA grafts for more than a few hours. Advancements in the field of VCA regarding matching and allocation, desensitization, and potential tolerance induction are all within reasonable reach to achieve; these are, however, constrained by limited preservation time of VCA grafts. Although machine perfusion holds many advantages over static cold preservation, it currently does not elongate the preservation time. More extreme preservation techniques, such as cryopreservation approaches, are, however, specifically difficult to apply to composite tissues as the susceptibility to ischemia and cryoprotectant agents varies greatly by tissue type. SUMMARY: In the current scope of extended preservation protocols, high subzero approaches of VCA grafts will be particularly critical enabling technologies for the implementation of tolerance protocols clinically. Ultimately, advances in both preservation techniques and tolerance induction have the potential to transform the field of VCA and eventually lead to broad applications in reconstructive transplantation.

Desensitization and Prevention of Antibody-Mediated Rejection in Vascularized Composite Allotransplantation by Syngeneic Hematopoietic Stem Cell Transplantation.

BACKGROUND: Candidates for vascularized composite allotransplantation (VCA) are frequently sensitized, putting them at risk for antibody-mediated rejection. Current desensitization strategies are imperfect and require a living-donor setting. Here we investigated the impact of sensitization on and the efficacy of a desensitization protocol utilizing syngeneic hematopoietic stem cell transplantation (HSCT) to prevent antibody-mediated rejection in VCA. METHODS: Skin transplants from Dark Agouti to Lewis rats were performed for sensitization. Orthotopic hind limb transplants from Dark Agouti donors were performed to sensitized and nonsensitized recipients, and the animals were treated with either daily tacrolimus or no immunosuppression. A desensitization protocol consisting of total body irradiation, fludarabine, and syngeneic HSCT was applied to sensitized animals. Graft rejection was monitored by clinical assessment and histological analysis. Serum levels of donor-specific antibodies (DSA IgG) were measured using flow cytometry. RESULTS: Sensitized recipients exhibited accelerated rejection by 5.5 ± 1.2 days without immunosuppression and 10.2 ± 3.6 days with daily tacrolimus compared with 8.7 ± 1.2 days and longer than 30 days in nonsensitized recipients, respectively. Serum levels of DSA IgG were markedly elevated (37.3 ± 3.34-fold from baseline) in sensitized recipients after VCA and correlated with histologic evidence of rejection and C4d deposition. Desensitization significantly reduced DSA compared with sensitized controls (2.6 ± 0.5-fold vs 6.0 ± 1.2-fold, P < 0.01) and along with daily tacrolimus led to improved VCA survival longer than 30 days without evidence of C4d deposition (n = 6). CONCLUSIONS: In summary, sensitization leads to accelerated rejection of VCA, and syngeneic HSCT combined with conventional immunosuppression effectively reduces DSA and improves allograft survival in sensitized rats.

Mechanisms of rejection in vascular composite allotransplantation.

PURPOSE OF REVIEW: For patients with devastating injuries in whom standard reconstruction is not an option, vascularized composite allotransplantation (VCA) has become a viable means of restoring form and function. However, immunological rejection continues to be a problem in VCA and has not yet been fully characterized. As the field is relatively new, much of the data on rejection and immunosuppression have been extrapolated from that of solid organ transplantation. In this review, we cover the basic mechanisms of rejection as they relate specifically to VCA with analysis of recent literature and future directions. RECENT FINDINGS: Recent clinical studies have supported previously postulated T-cell-mediated mechanism of acute rejection and have also made strides in differentiating rejection from inflammation from other skin conditions and with different treatment regimens. Antibody-mediated rejection has been described in recent cases as well as treatment of presensitized patients receiving VCAs. With more long-term grafts, chronic changes, including vasculopathy, are being reported. SUMMARY: Clinically observed types of rejection in VCA include mainly cell-mediated, antibody-mediated and chronic rejection. Advances in diagnosis and treatment of rejection have been made, but there is still much to be learned about VCA-specific rejection.