NDP-MSH (Melanotan I) treatment recovers marginal lungs during ex vivo lung perfusion
Background
The demand for lung transplants far exceeds the supply of suitable donor organs, forcing clinicians to consider using 'marginal' lungs, which are more susceptible to injury and have poorer outcomes. Ex vivo lung perfusion (EVLP) is a technique used to assess and recondition these lungs outside the body before transplantation. However, significant challenges remain in mitigating inflammation and injury sustained during events like ischemia/reperfusion (IR) or cardiac death (CD). The melanocortin system, particularly receptors like MC1R and MC5R, is known to exert potent anti-inflammatory effects in the lungs. This study investigates if a synthetic melanocortin analogue can leverage this pathway to improve the quality of marginal lungs during EVLP.
Study Design
Researchers subjected rats to either ischemia/reperfusion (IR) injury or cardiac death (CD) protocols (N=10 each). Within each protocol, half the rats (N=5) received the synthetic α-MSH analogue NDP-MSH, administered before lung procurement and during the subsequent ex vivo lung perfusion (EVLP) period. The control groups (N=5 each) underwent the same injury protocols and EVLP without the peptide treatment. Throughout the perfusion, the team assessed pulmonary function and analyzed perfusate for gases, electrolytes, metabolites, nitric oxide, inflammatory mediators, and cells. Finally, lung tissue was analyzed for ATP content and the expression of specific melanocortin receptors (MCRs).
Results
NDP-MSH treatment significantly improved outcomes in both injury models. In both IR and CD groups, the peptide reduced the release of inflammatory mediators and lactate production (p=0.010 for IR; p=0.008 for CD). It also lowered the amount of leukocytes in the perfusate (p=0.034 for IR; p=0.002 for CD). In the IR group specifically, NDP-MSH led to increased lung ATP content (p=0.040) compared to controls, indicating better energy preservation. The most dramatic improvements were seen in the cardiac death model.
In lungs from the cardiac death (CD) group, NDP-MSH treatment resulted in significant improvement of vascular parameters (p=0.002), peak airway pressure (p<0.001), lung compliance (p<0.050), and oxygenation (pO2, p<0.001). Analysis of lung tissue confirmed the expression of
MC1RandMC5Rin both native and perfused lungs, providing a mechanistic target for NDP-MSH's action.
Key Findings
- In cardiac death (CD) lungs, NDP-MSH improved vascular parameters (p=0.002), airway pressure (p<0.001), and oxygenation (pO2, p<0.001).
- NDP-MSH treatment reduced lactate production in both ischemia/reperfusion (IR) (p=0.010) and CD (p=0.008) groups.
- Leukocyte count in the perfusate was significantly lower in NDP-MSH treated lungs for both IR (p=0.034) and CD (p=0.002) models.
- In the IR injury model, NDP-MSH treatment was associated with increased lung ATP content (p=0.040) compared to controls.
- Melanocortin receptors MC1R and MC5R were confirmed to be expressed in both native and ex vivo-perfused rat lungs.
Why It Matters
These findings suggest that administering NDP-MSH during EVLP could be a powerful strategy for reconditioning and recovering marginal donor lungs, potentially expanding the pool of organs available for transplantation. For clinicians and transplant teams, this introduces a novel pharmacological approach to improve graft quality right before surgery. The exploitation of the melanocortin system could become a key part of future EVLP protocols to salvage lungs that would otherwise be discarded. While promising, this is a preclinical rat study. The protocol would need to be validated in larger animal models and eventually human clinical trials to determine optimal dosing, timing, and safety before it could be applied in transplant centers. This opens the door to using melanocortins not just for inflammation, but specifically for organ preservation and reconditioning.
