Current strategies to prevent ishcemia reperfusion injury in organ transplantation

Solid organ transplantation is inherently associated to ischemia reperfusion injury (IRI) since the operative procedure always impliesthe harvesting, preservation and implantation of the organ,whichresult in several hours of ischemia followed by reperfusion. Several strategies have been proposed to mitigate IRI in organ transplantation.However, most of them are in experimental phases and currently few are implemented in the clinical field. These strategies can be applied in 3 different stages of the transplantation procedure: on the organ donor, known as donor pre-treatment; during preservation, when ischemic organ is waiting to be implanted in the recipient or on the transplant recipient. In the present review, we will discuss the different approaches to control IRI damage in solid organ transplantation and the rationale behind them.Facultad de Ciencias ExactasInstituto de Estudios Inmunológicos y Fisiopatológico

Inmunosupresión en donantes renales

La lesión por isquemia y reperfusión (IRI) es uno de los principales problemas en el trasplante. Nuestro objetivo fue evaluar el efecto del pre - acondicionamiento al donante con rapamicina y tacrolimus para prevenir la lesión por IRI. Las ratas Wistar donantes, 12 horas antes de la nefrectomía, recibieron fármacos inmunosupresores. La muestra se dividió en cuatro grupos experimentales: un grupo con intervención simulada (sham), un grupo control sin tratamiento, otro tratado con rapamicina (2 mg/kg) y el restante tratado con tacrolimus (0.3 mg/kg). Se retiró el riñón izquierdo y después de tres horas de isquemia fría, se lo trasplantó. Veinticuatro horas después, el órgano trasplantado se recuperó para el análisis histológico y la evaluación de la expresión de citoquinas. El tratamiento de pre-acondicionamiento con rapamicina o con tacrolimus redujo significativamente el nitrógeno ureico en sangre y los niveles de creatinina en comparación con el control (BUN: p < 0.001; creatinina: p < 0.001). La necrosis tubular aguda fue significativamente menor en las ratas donantes tratadas con inmunosupresores en comparación con el grupo control (p < 0.001). Finalmente, las citoquinas inflamatorias, como TNF-α, IL-6 y rIL-21, mostraron niveles más bajos en el injerto de los animales que recibieron tratamiento. Este estudio experimental exploratorio muestra que el pre-acondicionamiento en donantes con rapamicina y tacrolimus en dos grupos distintos mejora los resultados clínicos y anatomopatológicos en receptores, con una reducción in situ de citoquinas pro-inflamatorias relacionadas con la diferenciación Th17, y de este modo crea un ambiente favorable para la diferenciación de células T regulatorias (Tregs).The ischemia-reperfusion injury (IRI) remains a major problem in transplantation. The objective of this study was to evaluate the effects of preconditioning a donor group with rapamycin and another donor group with tacrolimus to prevent IRI. Twelve hours before nephrectomy, donor Wistar rats received immunosuppressive drugs. The sample was divided into four experimental groups: a sham group, an untreated control group, a group treated with rapamycin (2 mg/kg) and a group treated with tacrolimus (0.3 mg/kg). Left kidneys were removed and, after three hours of cold ischemia, grafts were transplanted. Twenty-four hours later, the transplanted organs were recovered for histological analysis and evaluation of cytokine expression. The pre-conditioning treatment with rapamycin or tacrolimus significantly reduced donor blood urea nitrogen and creatinine levels compared with control group (BUN: p < 0.001 vs. control and creatinine: p < 0.001 vs. control). Acute tubular necrosis was significantly lower in donors treated with immunosuppressant drugs compared with the control group (p < 0.001). Finally, inflammatory cytokines such as TNF-α, IL-6 and rIL-21 showed lower levels in the graft of pre-treated animals. This exploratory experimental study shows that preconditioning donors with rapamycin and tacrolimus in different groups improves clinical outcome and pathology in recipients and reduces in situ pro-inflammatory cytokines associated with Th17 differentiation, creating a favorable environment for the differentiation of regulatory T cells (Tregs)

Tratamento prévio com adalimumabe reduz lesão pulmonar induzida por ventilação mecânica em um modelo experimental

Objective: To determine whether adalimumab administration before mechanical ventilation reduces ventilator- -induced lung injury (VILI). Methods: Eighteen rats randomized into 3 groups underwent mechanical ventilation for 3 hours with a fraction of inspired oxygen = 0.40% including a low tidal volume group (n = 6), where tidal volume = 8mL/kg and positive end-expiratory pressure = 5cmH2O; a high tidal volume group (n = 6), where tidal volume = 35mL/kg and positive end-expiratory pressure = 0; and a pretreated + high tidal volume group (n = 6) where adalimumab (100ug/kg) was administered intraperitoneally 24 hours before mechanical ventilation + tidal volume = 35mL/ kg and positive end-expiratory pressure = 0. ANOVA was used to compare histological damage (ATS 2010 Lung Injury Scoring System), pulmonary edema, lung compliance, arterial partial pressure of oxygen, and mean arterial pressure among the groups. Results: After 3 hours of ventilation, the mean histological lung injury score was higher in the high tidal volume group than in the low tidal volume group (0.030 versus 0.0051, respectively, p = 0.003). The high tidal volume group showed diminished lung compliance at 3 hours (p = 0.04) and hypoxemia (p = 0,018 versus control). Pretreated HVt group had an improved histological score, mainly due to a significant reduction in leukocyte infiltration (p = 0.003). Conclusion: Histological examination after 3 hours of injurious ventilation revealed ventilator-induced lung injury in the absence of measurable changes in lung mechanics or oxygenation; administering adalimumab before mechanical ventilation reduced lung edema and histological damage.Facultad de Ciencias Médica

Defining the nonreturn time for intestinal ischemia reperfusion injury in mice

Among the abdominal organs, the intestine is probably the most sensitive to ischemia reperfusion injury (IRI), a phenomenon that occurs in many intestinal disorders. Few studies have reported in detail the impact of intestinal ischemia time in mice. We evaluated the effect of various warm intestinal ischemia times in an intestinal IRI model in mice. Adult male Balb/c mice were divided into 4 groups that differed in intestinal ischemia time: G1, 30; minutes; G2, 35 minutes; G3, 40 minutes; and G4, 45 minutes. Histological evaluation showed average Park scores as follows: G1 0.6 ± 0.55; G2 1.8 ± 0.45; G3 4.8 ± 2.25; and G4 5 ± 1.79. All animals from G1 survived 30 hours. G2 animals showed intermediate behavior with all succumbing between 18 and 30 hours postprocedure. G3 and G4 displayed similar survival results with animals succumbing before 6 hours after intestinal reperfusion. These data showed that Park index scores of 3 or higher were related to early death. We concluded that the 5 minutes between 35 and 40 minutes is the critical limit, after which all mice die after reperfusion. This result may represent a valuable tool for future research in mice.Fil: Stringa, Pablo Luis. Universidad Favaloro; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Laboratorio de Transplante de Órganos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lausada, Natalia Raquel. Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Laboratorio de Transplante de Órganos; Argentina. Universidad Favaloro; ArgentinaFil: Romanin, David Emmanuel. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Machuca, Mariana Alejandra. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Cátedra de Patología Especial; ArgentinaFil: Cabanne, Ana. Universidad Favaloro; ArgentinaFil: Rumbo, Martín. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; ArgentinaFil: Gondolesi, Gabriel Eduardo. Universidad Favaloro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Trasplante heterotópico de intestino en ratones: descripción de la técnica quirúrgica y análisis histopatológico en diferentes etapas del procedimiento

El trasplante intestinal (TI) se ha constituido en una alternativa terapéutica para pacientes con insuficiencia intestinal y falla de la nutrición parenteral. Los resultados clínicos después del TI todavía representan un desafío frente a otros órganos sólidos. Por lo tanto, los modelos animales son fundamentales para comprender mejor la inmunología y la fisiología de estos injertos. Pese a su complejidad quirúrgica, los modelos de trasplante (Tx) en ratones brindan la ventaja de disponer de cepas manipuladas genéticamente.Facultad de Ciencias Médica

Modelo experimental murino de isquemia-reperfusión intestinal y su impacto en órganos remotos

La falla multiorgánica es una de las causas de morbi-mortalidad en pacientes con trasplante intestinal. La lesión por isquemia-reperfusión intestinal (IRI) provoca ruptura de la barrera del intestino con impacto en órganos distantes, ya sea por sepsis, traslocación bacteriana o por activar una respuesta inflamatoria sistémica Objetivos: evaluar la respuesta histológica del tejido intestinal, pulmonar y hepático luego de un período de 35 minutos de isquemia intestinal por clampeo de la arteria mesentérica superior (AMS) seguidos de 60 minutos de reperfusión.Facultad de Ciencias Médica

Protective effect of immunosuppressive treatment before orthotopic kidney autotransplantation

Background: Ischemia reperfusion injury (IRI) is one of the risk factors for delayed graft function, acute rejection and long term allograft survival after kidney transplantation. IRI is an independent antigen inflammatory process that produces tissue damage. Our objective was to study the impact of immunosuppressive treatment (IS) on IRI applying only one dose of IS before orthotopic kidney autotransplantation. Methods: Twenty-four rats allocated in four groups were studied. One group served as control (G1: autotransplanted rats without IS) and the rest received IS 12. h before kidney autotransplantation (G2: Rapamycin, G3: Mycophenolate mofetil and G4: Tacrolimus). Results: Improved renal function and systemic inflammatory response were found among IS groups compared to the control group (Delta Urea p < 0.0001; Delta Creatinine p < 0.0001; Delta C3 p < 0.001). The number of apoptotic nuclei in renal medulla in G1 was higher than in IS groups (p < 0.0001). Tubular damage was less severe in IS groups respecting G1 (p < 0.001). C3, TNF-γ and IL-6 expression in kidney samples was reduced when IS was used compared to the control group. No differences were observed among the different immunosuppressive drugs tested. However, Heme oxygenase-1(HO-1) was increased only in Rapamycin treatment. Conclusions: These data suggest that the use of IS administered before transplant attenuates the IRI process after kidney transplantation in an animal model.Fil: Cicora, Federico. Universidad Nacional de La Plata. Facultad de Ciencias Médicas; Argentina. Hospital Alemán; Argentina. Fundación Para la Investigación y Asistencia de la Enfermedad Renal; ArgentinaFil: Lausada, Natalia Raquel. Universidad Nacional de La Plata. Facultad de Ciencias Médicas; ArgentinaFil: Vasquez, Daniela Noris. Fundación Para la Investigación y Asistencia de la Enfermedad Renal; ArgentinaFil: Cicora, Paola. Fundación Para la Investigación y Asistencia de la Enfermedad Renal; ArgentinaFil: Guerrieri, Diego. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Farmacología; ArgentinaFil: Gonzalez, Pedro. Universidad Nacional de La Plata. Facultad de Ciencias Médicas; ArgentinaFil: Zalazar, Gustavo. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; ArgentinaFil: Stringa, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Médicas; ArgentinaFil: Raimondi, Jorge Clemente. Universidad Nacional de La Plata. Facultad de Ciencias Médicas; Argentin

Injuria por isquemia-reperfusión intestinal : Impacto del tiempo de isquemia en el daño tisular y en la supervivencia post-quirúrgica

El intestino es uno de los órganos más sensibles a la injuria por isquemia-reperfusión (IRI), fenómeno presente en diversas situaciones clínicas como hernias estranguladas, vólvulo, enterocolitis necrotizante y trasplante intestinal. Pese a que se sabe que la duración de la isquemia es determinante en el daño tisular luego de un evento de isquemia-reperfusión, no está claramente dilucidado cual es el tiempo de isquemia intestinal que provoca una lesión letal para el órgano en cuestión y para la supervivencia pos reperfusión.Facultad de Ciencias Médica

Glycerol-3-phosphate acyltransferase 2 is essential for normal spermatogenesis

Glycerol-3-phosphate acyltransferases (GPATs) catalyze the first and rate-limiting step in the de novo glycerolipid synthesis. The GPAT2 isoform differs from the other isoforms because its expression is restricted to male germ cells and cancer cells. It has been recently reported that GPAT2 expression in mouse testis fluctuates during sexual maturation and that it is regulated by epigenetic mechanisms in combination with vitamin A derivatives. Despite progress made in this field, information about GPAT2 role in the developing male germ cells remains unclear. The aim of the present study was to confirm the hypothesis that GPAT2 is required for the normal physiology of testes and male germ cell maturation. The gene was silenced in vivo by inoculating lentiviral particles carrying the sequence of a short-hairpin RNA targeting Gpat2 mRNA into mouse testis. Histological and gene expression analysis showed impaired spermatogenesis and arrest at the pachytene stage. Defects in reproductive fitness were also observed, and the analysis of apoptosis-related gene expression demonstrated the activation of apoptosis in Gpat2-silenced germ cells. These findings indicate that GPAT2 protein is necessary for the normal development of male gonocytes, and that its absence triggers apoptotic mechanisms, thereby decreasing the number of dividing germ cells.Instituto de Investigaciones Bioquímicas de La PlataFacultad de Ciencias MédicasCentro de Investigaciones Inmunológicas Básicas y Aplicada

Modelo de donante cadavérico con criterio neurológico de muerte en la rata de laboratorio

El modelo experimental de trasplante de órganos y tejidos en la rata, se ha llevado a cabo tradicionalmente con donante vivo. La complejidad de lograr un donante cadavérico en roedores de laboratorio, ha restringido su utilización. Esta situación limita la extrapolación de los resultados a la realidad clínica, donde mayoritariamente se utilizan órganos extraídos de donantes cadavéricos. La necesidad de poseer resultados experimentales, tanto en donante vivo como cadavérico, nos ha llevado a optimizar el modelo de donante de órganos en rata con criterio neurológico de muerte y asistencia respiratoria mecánica.Facultad de Ciencias Médica