Shehan Hettiaratchy

Tolerance to composite tissue allografts across a major histocompatibility barrier in miniature swine

Background. Tolerance to composite tissue allografts might allow the widespread clinical use of reconstructive allotransplantation if protocols to achieve this could be rendered sufficiently nontoxic. The authors investigated whether tolerance could be generated in miniature swine to composite tissue allografts across a major histocompatibility (MHC) barrier. A clinically relevant tolerance protocol involving hematopoietic cell transplantation without the need for irradiation or myelosuppressive drugs was tested. Methods. Seven recipient animals were transiently T-cell depleted and a short course of cyclosporine was initiated. Twenty-four hours later, a donor hematopoietic cell transplant consisting of cytokine-mobilized peripheral blood mononuclear cells or bone marrow cells and a heterotopic limb transplant were performed. In vitro anti-donor responsiveness was assessed by mixed-lymphocyte reaction and cell-mediated lympholysis assays. Acceptance of the limb allografts was determined by gross and histologic appearance. Chimerism in the peripheral blood and lymphohematopoietic organs was assessed by flow cytometry. Results. All seven experimental animals accepted the musculoskeletal elements but rejected the skin of the allografts. All but one of the animals displayed donor-specific unresponsiveness in vitro. The animals that received cytokine mobilized-peripheral blood mononuclear cells showed chimerism but had clinical evidence of graft-versus-host disease (GVHD). None of the animals that received bone marrow cells showed stable chimerism and none developed GVHD. Conclusions. This protocol can achieve tolerance to the musculoskeletal elements of composite tissue allografts across an MHC barrier in miniature swine. Stable chimerism does not appear to be necessary for tolerance and may not be desirable because of the risk of GVHD.

Composite tissue allotransplantation and reconstructive surgery : first clinical applications

ObjectiveTo review the first clinical cases of composite tissue allotransplantation (CTA) for reconstructive surgery and to discuss the outcome of and indications for these procedures in the context of chronic immunosuppression. Summary Background DataThe first human hand transplant was performed in 1998. This procedure, as well as other composite tissue transplants, offers the potential for correcting untreatable large tissue defects. However, concerns remain regarding obligatory chronic immunosuppression and long-term functional results. MethodsAll the CTAs performed in humans that have been published or documented were reviewed. The preexisting clinical conditions and surgical procedures and the immunosuppressive therapy are described. The functional results and the complications or side effects of the treatment are detailed. ResultsVascularized tendons (two cases), vascularized femoral diaphyses (three cases), knees (five cases), hands (four bilateral and seven unilateral cases), larynx (one case), and nonvascularized peripheral nerves (seven cases) have been transplanted in humans in the past decade. Rejection was prevented in most cases without difficulty. Early results are encouraging, particularly for hand and larynx transplants, but will need to be evaluated in the long term and in a larger number of patients. ConclusionsCTA holds great potential for reconstructive surgery but is at present restricted by the risks of chronic immunosuppression and uncertain long-term results.

Prolongation of skin allograft survival after neonatal injection of donor bone marrow and epidermal cells.

Composite-tissue (e.g., hand allograft) allotransplantation is currently limited by the need for immunosuppression to prevent graft rejection. Inducing a state of tolerance in the recipient could potentially eliminate the need for immunosuppression but requires reprogramming of the immunological repertoire of the recipient. Skin is the most antigenic tissue in the body and is consistently refractory to tolerance induction regimens using bone marrow transplantation alone. It was hypothesized that tolerance to skin allografts could be induced in rats by injecting epidermal cells with bone marrow cells during the first 24 hours of life of the recipients. Brown Norway rats (RT1n) served as donors for the epidermal cells, bone marrow cells, and skin grafts. Epidermal cells were injected intraperitoneally and bone marrow cells were injected intravenously into Lewis (RT1l) newborn recipient rats. In control groups, recipients received saline solution with no cells (group I, n = 12), bone marrow cells only (group II, n = 15), or epidermal cells only (group III, n = 15). In the experimental group (group IV, n = 18), recipients received epidermal and bone marrow cells simultaneously. Skin grafts were transplanted from Brown Norway (RT1n) rats to the Lewis (RT1l) rats 8 weeks after cell injections. Skin grafts survived an average of 8.5 days in group I (10 grafts), 9.2 days in group II (12 grafts), and 12 days in group III (14 grafts). Grafts survived 15.5 days (8 to 26 days) in group IV (15 grafts). The difference was statistically significant (p < 0.05). Hair growth was observed in some accepted grafts in group IV but never in the control groups. This is the first report of prolonged survival of skin allografts in a rat model after epidermal and bone marrow cell injections. Survival prolongation was achieved across a major immunological barrier, without irradiation, myeloablation, or immunosuppression. It is concluded that the presentation of skin-specific antigens generated a temporary state of tolerance to the skin in the recipients that could have delayed the rejection of skin allografts.

Experience of an orthoplastic limb salvage team after the Haiti earthquake: analysis of caseload and early outcomes.

Background: After the devastating earthquake in Haiti on January 12, 2010, a British orthoplastic limb salvage team was mobilized. The team operated in a suburb of Port-au-Prince from January 20, 2010. This analysis gives an overview of the caseload and early outcomes. Methods: A retrospective analysis of operative data from the log book was performed from the opening of the facility on January 20, 2010, until March 12, 2010. Results: In total, 348 operations were carried out on 158 patients, at an average of 47 cases per week. Seventy-three percent of the cases were soft-tissue cases and 25 percent were bony or combined soft-tissue and bony cases. The majority of bony procedures (n = 26; 16 percent) and flap procedures (n = 16; 10 percent) took place in the early weeks (weeks 1 through 4). Combined orthoplastic cases accounted for 37 percent of cases (16 of 44) in week 2 but only 7 percent (three of 43) in week 7. General anesthetic cases accounted for 89 percent of cases (39 of 44) in week 2 but only 40 percent (17 of 43) in week 7. Only six patients (4 percent) underwent amputation, but 36 operations (10 percent) dealt with the sequelae of amputation. Sixteen patients (10 percent) suffered complications, including two amputations for failed limb salvage. Conclusions: This article reports the outcomes of a limb salvage team in the acute response after an earthquake disaster with a favorable amputation rate and highlights the potential benefit of mobilizing this type of team. Detailing the changing caseload over time will allow for more efficient planning in case of a similar future disaster.

Risk factors for the development of post-transplant lymphoproliferative disorder in a large animal model.

A high incidence of a post‐transplant lymphoproliferative disorder (PTLD) is observed in miniature swine conditioned for allogeneic hematopoietic cell transplantation using a protocol involving T‐cell depletion and cyclosporine therapy. This study was designed to assess contributing factors to disease development. Forty‐six animals were studied including 12 (26%) that developed PTLD. A number of risk factors for PTLD were examined, including degree of immunosuppression, degree of MHC mismatch and infection by a porcine lymphotrophic herpesvirus (PLHV‐1). Flow cytometry was used to measure host and donor T‐ and B‐cell levels in the peripheral blood. Porcine lymphotrophic herpesvirus viral load was determined by quantitative PCR. Animals developing PTLD had significantly lower levels of T cells on the day of transplant. Cyclosporine levels did not differ significantly between animals with and without PTLD. Animals receiving transplants across a two‐haplotype mismatch barrier showed an increased incidence of PTLD. All animals with PTLD had significant increases in PLHV‐1 viral loads. Porcine lymphotrophic herpesvirus viral copy numbers remained at low levels in the absence of disease. The availability of a preclinical large‐animal model with similarities to PTLD of humans may allow studies of the pathogenesis and treatment of that disorder.

Outcomes of anterolateral thigh free flap thinning using liposuction following lower limb trauma

BACKGROUND Whilst soft tissue closure is the priority to prevent infection in open fractures of the lower limb, some patients find that bulky flaps interfere with function and dislike the appearance. We report the outcomes of delayed free anterolateral thigh flap thinning with liposuction. MATERIAL AND METHODS 38 patients treated between 2006 and 2009 were offered flap contouring. 23 chose flap thinning and 15 did not. We measured outcomes using the SF-36v2 questionnaire and cosmetic outcome scores pre and postoperatively at a mean follow up of 12 weeks (range 10-16 weeks). RESULTS SF-36v2 physical health (PH) scores improved from a mean of 67 preoperatively to 80 postoperatively (p = 0.01) in the thinned group, while mental health (MH) scores remained unchanged (74-72). The mean SF-36v2 scores for the non-thinned group were 77 (PH) and 86 (MH). Following liposuction the median cosmetic outcome scores out of 5 improved from 1 (not at all satisfied) to 4 (very satisfied) postoperatively (p = 0.0005), which was also higher than the non-thinned group (3) [moderately satisfied], p = 0.004). There was no difference in sex, age, BMI and region on the leg of free flap reconstruction between the non-thinned and thinned groups. CONCLUSIONS Delayed contouring of free ALT flaps used for lower limb reconstruction results in improvements in physical health measures and cosmetic outcomes. Patients not requesting thinning are generally satisfied with their reconstruction.

Modular and Versatile Spatial Functionalization of Tissue Engineering Scaffolds through Fiber-Initiated Controlled Radical Polymerization

Native tissues are typically heterogeneous and hierarchically organized, and generating scaffolds that can mimic these properties is critical for tissue engineering applications. By uniquely combining controlled radical polymerization (CRP), end‐functionalization of polymers, and advanced electrospinning techniques, a modular and versatile approach is introduced to generate scaffolds with spatially organized functionality. Poly‐ε‐caprolactone is end functionalized with either a polymerization‐initiating group or a cell‐binding peptide motif cyclic Arg‐Gly‐Asp‐Ser (cRGDS), and are each sequentially electrospun to produce zonally discrete bilayers within a continuous fiber scaffold. The polymerization‐initiating group is then used to graft an antifouling polymer bottlebrush based on poly(ethylene glycol) from the fiber surface using CRP exclusively within one bilayer of the scaffold. The ability to include additional multifunctionality during CRP is showcased by integrating a biotinylated monomer unit into the polymerization step allowing postmodification of the scaffold with streptavidin‐coupled moieties. These combined processing techniques result in an effective bilayered and dual‐functionality scaffold with a cell‐adhesive surface and an opposing antifouling non‐cell‐adhesive surface in zonally specific regions across the thickness of the scaffold, demonstrated through fluorescent labelling and cell adhesion studies. This modular and versatile approach combines strategies to produce scaffolds with tailorable properties for many applications in tissue engineering and regenerative medicine.

The surgical management of injectional anthrax

Anthrax is caused by the spore forming, gram-positive aerobic organism Bacillus anthracis. Three clinical forms of anthrax are recognised; respiratory, gastrointestinal and cutaneous, with the latter being the most common. An isolated fatal case of injectional anthrax as a result of heroin use has been previously reported. Recently, there has been an outbreak of injectional anthrax in Europe (www.hps.scot.nhs.uk/anthrax) and we describe our experience of the surgical management of two cases.

Hair-tourniquet syndrome--multiple toes and bilaterality.

The hair-tourniquet syndrome involves circumferential strangulation of an appendage by a human hair or fibre and usually affects infants under the age of 2. It is an emergency condition that induces progressive oedema, ischaemia and tissue necrosis and can lead to the autoamputation of digits or other strangulated structures. Though the majority of cases are accidental, a proportion may be due to nonaccidental injury. The prompt diagnosis and treatment of the condition is vital to attain a good outcome and prevent further harm to the child. We report a case of hair-tourniquet syndrome affecting multiple toes of an infant, and suggest that awareness of the condition should be increased to help prevent its potential complications.

Spontaneous compartment syndrome after thrombolytic therapy.

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