Procedure for Decellularization of Rat Livers in an Oscillating-pressure Perfusion Device

Decellularization and recellularization of parenchymal organs may enable the generation of functional organs in vitro, and several protocols for rodent ...

Charité – Universitätsmedizin Berlin

Despite improved immunosuppression, intestinal transplantation is still complicated by severe rejection episodes. To further improve immunosuppressive concepts, we evaluated an anti-CD4 antibody and an anti-tumor necrosis factor (TNF)-alpha monoclonal antibody for their immunosuppressive efficacy in the standard rat model of intestinal transplantation.

Short-term anti-CD4 plus anti-TNF-alpha receptor treatment in allogeneic small bowel transplantation results in long-term survival.

Because of the limited tolerance to portal venous clamping, the model of liver transplantation in rats represents a difficult task, which requires a great proportion of experience. Since techniques that include the introduction of an artificial stent increase the risk of thrombosis, it was our goal to modify the classical vascular hand-sewn venous anastomosis technique by using a modified end-to-end knotless procedure.

Improvement of microsurgical techniques in orthotopic rat liver transplantation.

Mesenchymal stromal cells (MSC) have shown immunomodulatory and tissue repair potential including partial tolerance induction by pre-treatment of donor-specific cells in a rat heart transplantation model. Very recently, we could show that autologous MSC attenuated ischemia reperfusion injury in a highly mismatched donor-recipient rat kidney transplant model. Therefore, we investigated donor-specific MSC pre-treatment in this rat kidney transplantation model to study whether graft function could be improved, or if tolerance could be induced. Donor- and recipient-type MSC or phosphate buffered saline (PBS) as a control was injected i.v. 4 days before kidney transplantation. Mycophenolate mofetil immunosuppression (20mg/kg body weight) was applied for 7 days. Kidney grafts and spleens were harvested between days 8 and 10 and analyzed by quantitative RT-PCR and immunohistology. In addition, creatinine levels in the blood were measured and serum was screened for the presence of donor-specific antibodies. Surprisingly, application of both donor- and recipient-specific MSC resulted in enhanced humoral immune responses verified by intragraft B cell infiltration and complement factor C4d deposits. Moreover, signs of inflammation and rejection were generally enhanced in both MSC-treated groups relative to PBS control group. Additionally, pre-treatment with donor-specific MSC significantly enhanced the level of donor-specific antibody formation when compared with PBS- or recipient MSC-treated groups. Pre-treatment with both MSC types resulted in a higher degree of kidney cortex tissue damage and elevated creatinine levels at the time point of rejection. Thus, MSC pre-sensitization in this model impairs the allograft outcome. Our data from this pre-clinical kidney transplantation model indicate that pre-operative MSC administration may not be optimal in kidney transplantation and caution must be exerted before moving forward with clinical studies in order to avoid adverse effects.

Detrimental effects of rat mesenchymal stromal cell pre-treatment in a model of acute kidney rejection.

Tumor necrosis factor (TNF)-α inhibition was shown to reduce ischemia/reperfusion injury (IRI) after intestinal transplantation (ITX). We studied the effects of different TNFα inhibitors on acute IRI and long-term inflammatory responses in experimental ITX.

Short-term TNF-alpha inhibition reduces short-term and long-term inflammatory changes post-ischemia/reperfusion in rat intestinal transplantation.

One approach of regenerative medicine to generate functional hepatic tissue in vitro is decellularization and recellularization, and several protocols for the decellularization of livers of different species have been published. This appears to be the first report on rat liver decellularization by perfusion under oscillating pressure conditions, intending to optimize microperfusion and minimize damage to the ECM. Four decellularization protocols were compared: perfusion via the portal vein (PV) or the hepatic artery (HA), with (+P) or without (-P) oscillating pressure conditions. All rat livers (n = 24) were perfused with 1% Triton X-100 and 1% sodium dodecyl sulphate, each for 90 min with a perfusion rate of 5 ml/min. Perfusion decellularization was observed macroscopically and the decellularized liver matrices were analysed by histology and biochemical analyses (e.g. levels of DNA, glycosaminoglycans and hepatocyte growth factor). Livers decellularized via the hepatic artery and under oscillating pressure showed a more homogeneous decellularization and less remaining DNA, compared with the livers of the other experimental groups. The novel decellularization method described is effective, quick (3 h) and gentle to the extracellular matrix and thus represents an improvement of existing methodology. Copyright © 2014 John Wiley & Sons, Ltd.

Improved rat liver decellularization by arterial perfusion under oscillating pressure conditions.

Particle-based delivery systems for therapeutic manipulation and tracking of transplanted cells by magnetic resonance imaging (MRI) are commonly based on nanometer-sized superparamagnetic iron oxide particles (SPIOs). Here, we present a proof of concept for multifunctional, silica based micron-sized iron oxide-containing particles (sMPIO) that combine fluorescence imaging, MRI tracking, and on-the-spot targeting of specific microRNAs on a particle surface for therapeutic manipulation by RNA interference. Antisense locked nucleic acids (α-LNA) were covalently bound to the surface of silica-based, DAPI-integrated, micron-sized iron oxide particles (sMPIO-α-LNA). In vitro studies using primary human hepatocytes showed rapid particle uptake (4 h) that was accompanied by significant depletion of the targeted microRNA Let7g (80%), up-regulation of the target proteins Cyclin D1 and c-Myc, and specific proteome changes. sMPIO-α-LNA-labeled cells were successfully detected by fluorescence imaging and could be visualized by MRI after intrasplenic transplantation in rats. This new theranostic particle provides a promising tool for cell transplantation where cellular imaging and microRNA-based manipulation is needed. [165].

Dietrich Polenz

General,
Visceral,
and Transplantation Surgery,
General, Visceral, and Transplantation Surgery

Charité – Universitätsmedizin Berlin

Procedure for Decellularization of Rat Livers in an Oscillating-pressure Perfusion Device

Dietrich Polenz

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Charité – Universitätsmedizin Berlin

Procedure for Decellularization of Rat Livers in an Oscillating-pressure Perfusion Device

General,
Visceral,
and Transplantation Surgery,
General, Visceral, and Transplantation Surgery