Executive Summary
1 Project Background and motivation
Currently, organ transplantation remains the only viable option for patients suffering from end stage organ failure. There is a steady increase in the need for donor organs with more than 46 000 organs transplanted in 2023 and more than 103 000 patients still on the transplant waiting list. There are three research directions that can result in an increase in avaible high-quality organs for transplant, i.e. organ preservation, organ transportation systems and organ printing.
Organ preservation fluids together with perfusion systems has been the focus in recent years. The quality of the transplanted organ plays a crucial role in patient morbidity and development of post-transplant implications. The most urgent limitations with current methods, which is static cold storage (SCS), are the preservation time before the onset of permanent tissue damage as well as limited time to assess organ viability and affect necessary repairs. The limited available organ pool can be extended by using extended criteria donor (RCD) organs if the preservation method can be improved. Organ perfusion has been shown to increase organ viability during transport and consequently, there has been great progress made in optimising liquid formulations as well as perfusion conditions and equipment. The hypothermic conditions and the perfusion solution both slow down cellular metabolism. The perfusion solution also lessens cyto-destructive inflammation caused by solid organ transplant by creating a matrix within which the donor T-cells are activated to promote graft acceptance and tolerance. (Hadziar and Koulmanda, 2011). A modified histidine-tryptophan-ketoglutarate (HTK) solution to which additional mano acids and chemicals have been added are currently undergoing clinical trials (Pzanis et al., 2012). State-of-the art organ preservation systems, such as the Organ Care System (OCS) uses glucose as primary energy source in their organ perfusion-during-transport system. Oxygen carriers with oxygen transport properties like that of human haemoglobin are being investigated to limit the use of donated human blood during organ perfusion.
Bioprinting of organs holds the greatest promise in solving the shortage of transplantable organs but has the largest challenges towards commercial translation. A viable biopriming process that results in viable human cells is the holy grail of future medicine. Some of the largest challenges to be overcome is scaffold rigidity and integrity as well as survival of human cells outside of the body to affect organ growth. Also, a human organ comprises of many different types of cells that has different functions, making printing of human organ tissue not a straightforward process. A step Development of an affordable and effective preservation/perfusion that prolongs organ viability and can be further developed into a possible bio-ink for organ 3-D printing holds great promise for the future.
Various poly-saccharide macromolecules have been used in hydrogels for synthesis of drug delivery systems (Farhat et al., 2017). Lignin specifically is attractive because of its conductive surfaces for cell attachment and proliferation (Kaur et al., 2021). Mechanically stable hydrogels require large molecules with cross-linking to ensure stable biofilms and scaffolds. Lignin has attracted attention in the medical research field because of its renewable nature, but also because of its anti-inflammatory; (Wamg et al., 2016), antioxidant, anti-fungal, anti-viral and anti-bacterial properties (Chakar and Ragauskas., 2004; Matović et al, 2018)). Furthermore, lignin has also been shown to exhibit anticoagulation, cholesterol reduction, and anti-hyperglycaemic effects which makes it ideal for medical applications (Henry et al, 2011; 2014). (Ravishankar et al. 2019) proofed adhesion of mesenchymal stem cells to a lignin-chitosan based hydrogel with cell proliferation. Lignin crosslinks with chitosan by hydrogen boding between the hydroxyl groups of lignin and the amino groups of chitosan. The pH of the lignin determine the orientation of the, molecule’s hydroxyl groups allowing for a precise manipulation of rheological properties of the hydrogel through the cross-linking conditions. This implies that the rheological properties of haemoglobin can be matched using a lignin-chitosan hydrogel preventing infections and inflammation that can affect the organ viability. Also, since the liquid is completely natural and the human body knows how to deal with it, the impact to the organ recipient is reduced and the new organ is protected while the body copes with the biological changes. It is thus worthwhile exploring this avenue for improving perfusion solutions for organ transportation.
References
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2 Researchers involved.
| Researchers | Affiliation | Highest Qualification | Role | Abbreviation |
|---|---|---|---|---|
| Prof Sanette Marx | Previous from Northwest University | PhD | Project initiator and research consultant | SM |
| Prof Annemarie Wentzel | Northwest University | PhD | Biochemical and cell analysis | AW |
| Agnieszka Brand-Talbot | Imperial College | PhD | Co-researcher | ABT |
| Angélique Lewies | University of the Free Sate | PhD | Co-researcher | AL |
| Netcare Transplant team | Milpark Hospital | TPT |
3 Project Aim
The development of a fit for purpose, cost-effective lignin-chitosan hydrogel for use as a transplant perfusion liquid.
4 Project objectives
Establishing a continuous, independent source of lignin for the project and the perceived industrialization of the project results through optimization of lignin vaporization from various waste sources that are not linked to current industrial processes.
Establish a continuous independent source of chitin from which chitosan can be produced locally to demonstrate the concept on a prototype scale.
Formulate and quantify a lignin-chitosan-based hydrogel that has rheological properties comparable to human haemoglobin
Gain-of-function research on additives to optimise the formulated hydrogel for use in state-of-the-art organ transport perfusion systems.
Evaluate performance of formulation with commercially available liquids in terms of organ Viability with perfusion time.
Animal trials to test the new perfusion formulation.
Human trials using donated organs that are not deemed viable for organ transplantation.
5 Research Plan
The research plan has four phases.
Firstly, the lignin-chitosan hydrogel needs to be formulated and the rheology matched to that of human haemoglobin and the results verified by a third party.
During the second phase, the solubility and addition of additives currently used in perfusion liquids in the rheological correct hydrogel needs to be verified.
In stage three, the compatibility of the developed perfusion liquid (product) with currently used state-of-the-art equipment needs to be verified.
Lastly, animal and human trials need to be conducted by authorized laboratories to establish the efficacy of the developed product compared to commercially available products and monitor any side-effects.
Action 1
Specific Aim 1
Determine the gel formulation that will result in a liquid that is rheological like human blood within a very small margin of variability.
Specific Objectives 1
Determine the most critical rheological properties of human haemoglobin that determines proper biological function.
Determine the most optimal way of measuring the pertinent rheological properties within the smallest margin of error.
Formulate hydrogels by crosslinking lignin with chitosan and determine the rheological properties of the hydrogels at different lignin concentrations.
Verify results with third party analysis.
Optimised the gel formulation to match the rheological properties of human blood.
Action 2
Specific Aim 2
Identify and quantify the additives required in a perfusion liquid and formulate a suitable perfusion liquid.
Specific Objectives 2
2.1 Identify the additives currently being used in perfusion liquids and verify their solubility in the optimised hydrogel.
2.2 Formulate an optimise s perfusion liquid containing all the necessary additives.
2.3 Test and verify if the optimised perfusion liquid shows any enhanced antimicrobial, anti-viral and anti-fungal properties.
Action 3
Specific Aim 3
Verification of compatibility of developed perfusion liquid with current preservation methods such a static cold storage (SCS) as well as state-of-the-art perfusion systems such as the Organ Care System (OCS).
Specific Objectives 3
3.1 Determine critical parameters and criteria that indicate optimal organ preservation during organ transport.
3.2 Simulate organ transport using the different preservation/perfusion systems (using animal organs such as pig hearts) and compare effectiveness based on the criteria identified in Objective 3.1.
3.3 Identify critical flaws in the developed perfusion liquid that needs to be addressed.
Action 4
Specific Aim 4
Perform clinical animal trials as first step towards registering the developed product for use in transplantation.
Specific Objectives 4
4.1 Obtain necessary ethical clearance and certificates for clinical trials
4.2 Clinial animal trials using mice.
4.3 Clinical trials using pigs.
Action 5
Specific aim 5
Perform clinical test on human subjects.
Specific objectives 5
5.1 Obtain ethical clearance and certificates for trials.
5.2 Clinical trials using human organ rejected for organ transplant.
5.3 If all prior tests have been proven to be successful, human trials using actual transplant patients should be performed as the final validation that the perfusion liquid is safe and effective.
7 Work Packages (WP)