Preserving and rejuvenating old organs for transplantation: novel treatments including the potential of senolytics

Abstract

Purpose of review: Older donors have the potential to close the gap between demand and supply in solid organs transplantation. Utilizing older organs, at the same time, has been associated with worse short- and long-term outcomes. Here, we introduce potential mechanisms on how treatments during machine perfusion (MP) may safely improve the utilization of older organs.

Recent findings: Consequences of ischemia reperfusion injury (IRI), a process of acute, sterile inflammation leading to organ injury are more prominent in older organs. Of relevance, organ age and IRI seem to act synergistically, leading to an increase of damage associated molecular patterns that trigger innate and adaptive immune responses. While cold storage has traditionally been considered the standard of care in organ preservation, accumulating data support that both hypothermic and normothermic MP improve organ quality, particularly in older organs. Furthermore, MP provides the opportunity to assess the quality of organs while adding therapeutic agents. Experimental data have already demonstrated the potential of applying treatments during MP. New experimental show that the depletion of senescent cells that accumulate in old organs improves organ quality and transplant outcomes.

Summary: As the importance of expanding the donor pool is increasing, MP and novel treatments bear the potential to assess and regenerate older organs, narrowing the gap between demand and supply.

Figure 1:. Mechanisms through which senolytics interfere with aging.

Mechanisms of actions of different senolytics (Dasatinib, Fisetin, Quercetin, Curcumin, PCC1, 17-AAG, 17-DMAG, Geldanamycin, UBC-1325, A-1331852, A1155463) are shown. Interfering with distinct signaling pathways, senolytics facilitate the apoptosis of senescent cells, thereby reducing the secretion of the senescence-associated secretory phenotype. Arrows represent activation; bars represent inhibition; yellow/red particles symbolize the senescence-associated secretory phenotype. Abbreviations: RTK, receptor tyrosine kinase; PI3K, Phosphatidylinositol 3-kinase; Akt, Protein kinase B; HSP90, heat shock protein 90; mTOR, mammalian target of rapamycin; NF-κB, nuclear factor kappa-light-chain-enhancer of activated B cells; bad, BCL2 associated agonist of cell death; Bax, Bcl-2-associated X protein; Bcl-xL, B-cell lymphoma-extra-large; FoxO4, Forkhead box protein O4; p21, cyclin-dependent kinase inhibitor 1; p53, tumor suppressor p53; PCC1, procyanidin C1; 17-AAG, 17-N-allylamino-17-demethoxygeldanamycin; 17-DMAG, 17-Dimethylaminoethylamino- 17-demethoxygeldanamycin; A-1331852 & A-1155463, both selective Bcl-xL inibitors.