Introduction

Type 1 diabetes mellitus (T1DM) is a chronic autoimmune disorder that results in the destruction of insulin-producing pancreatic β-cells, leading to lifelong dependence on exogenous insulin. Patients without adequate glycemic control are at risk for severe complications such as retinopathy, nephropathy, and limb amputation. For these individuals, pancreatic islet transplantation has is a promising therapeutic strategy that can restore endogenous insulin production. However, current transplantation practices typically rely on infusion of islets into the hepatic portal vein—a method associated with significant drawbacks. These include immediate blood-mediated inflammatory reactions (IBMIR), limited insulin release due to the hypoxic environment, and exposure to high levels of immunosuppressants. As a result, multiple donor pancreases are often required to achieve insulin independence, exacerbating the scarcity of donor organs. To overcome these limitations, there is growing interest in identifying alternative, extrahepatic transplantation sites that can provide a more supportive environment for islet engraftment. Human placental cotyledons, which are highly vascularized and readily available following elective cesarean deliveries, represent a novel and potentially advantageous site for islet engraftment. This study explores the feasibility of combining ex vivo placental cotyledon perfusion with islet transplantation to evaluate its potential as a new extrahepatic transplant platform.

Materials and Methods

A novel ex vivo perfusion system for human placental cotyledons was developed through iterative design, focusing on sterility, vasospasm prevention, and optimized tubing. Postcesarean placentas were used to isolate and perfuse a single cotyledon under controlled conditions. After four hours, human pancreatic islets were injected into the intervillous space. Islet function was assessed the next day by a glucose-stimulated insulin secretion (GSIS) measurement as well as functional measurements.

Results

The perfusion setup maintained stable physiological conditions over 23 hours. Insulin secretion increased during high-glucose, showing viable and functional islets after 14 hours of perfusion. Insulin was detected in cotyledon effluent but not fetal venous return, likely due to perfusion flow and placental barriers. Conclusion The 23-hour perfusion demonstrated effective function without infection or tissue damage. Injected islets remained viable and glucose-responsive in the intervillous space. While the setup met several criteria for evaluating extrahepatic transplantation sites, further research is needed to address leakage from the cotyledon and to investigate changes in hormonal secretion of the cotyledon during long-term perfusion.

 

This research addresses the following question: Is it possible to detect vascular obstructions and oedemas or monitor the decellularization process in perfused ex-vivo porcine kidneys using electrical impedance spectroscopy? Patients on the waiting list for kidney transplantation die because of a kidney shortage. A part of this problem can be solved by prolonging the period of preservation between the removal of the kidney from the body and the transplantation. However, oedemas and vascular obstructions are more likely to occur with longer perfusions. The kidney donor risk index doesn’t take this into account so a new technique needs to be established to assess the development of oedema and vascular obstruction. Another approach for increasing the supply of donor kidneys is de- and recellularization of the kidney. Electrical impedance spectroscopy shows promising results in the pancreas and this technique can probably be transferred to the kidney. EIS is a non-invasive, low cost, portable measuring technique that shows the results in real-time. A Spectra Bioimpedance and EIT Complete Kit with the 4-electrode attachment have been used at low frequencies (500 Hz) and high frequencies (70.000 Hz) for the evaluation of the porcine kidneys. Two different measurement techniques will be used, measurements through the renal artery and measurements on the kidney. These techniques are tested during the decellularization process, oedema formation, and vascular obstruction simulation to determine if impedance changes can signal these defects in the kidney. Robust changes have been made to the porcine kidneys in this regard. The sensitivity of the methods is less than expected. Only the decellularization results showed a notable change over time. The conclusion of this research is therefore: The results cannot prove a clear connection between vascular obstruction and oedema detection and electrical impedance changes. There is a probable correlation between electrical impedance and the phase of decellularization in which the kidney is in. Follow-up research is needed to substantiate this further.