Plasminogen activator inhibitor type-1 (PAI-1) is a protein with multiple jobs within the body. PAI-1 is a serpin, or serine protease inhibitor, and is a regulator of the plasminogen activation system (Sillen and Declerck, 2021). Not only is PAI-1 responsible for inhibiting plasminogen activators, but PAI-1 regulates the plasminogen activation system by inhibiting the plasminogen activators urokinase (uPA) and tissue-type plasminogen activator (tPA), and is important in regulating cell proliferation, adhesion, migration, and signal transduction pathways. Studies have shown that PAI-1 also plays an important role in regulating proliferation, migration, and apoptosis of vascular smooth muscle cells (VSMC) and endothelial cells (EC) (Balsara and Ploplis, 2008). Cardiologists also have an interest in PAI-1, as it plays a role in blood-clot regulation, and researchers studying longevity and healthy aging in humans also frequently study PAI-1 (Mosbergen, 2025).
PAI-1 in Cell Death
Programmable cell death or apoptosis of vascular cells is an important process that regularly occurs during blood vessel remodeling both in pathological situations and during normal physiological events. This process is important in both forming atherosclerotic plaques as well as determining the fate of tumor growth. Studies have shown that parts of the plasminogen-plasminogen activator system play an important role in cell death by facilitating extracellular matrix (ECM) remodeling. Specifically, both VSMC and EC exhibit significant fibrinolytic activity, where inactive plasminogen is converted to active plasmin by uPA and tPA. Interestingly, studies have suggested that this plasmin-generating cascade may partially serve a neuro-protective role in the body (Balsara and Ploplis, 2008).
In an Alzheimer’s disease model, researchers observed that the activation of plasminogen by uPA or tPA was accompanied by an increase in the viability of cerebrovascular smooth muscle cells. However, it was also observed that chronic expression of uPA and plasminogen activation led to increased levels of cell detachment. Further, researchers have noted that, in some cases, tPA synthesis increases the triggering of neuronal death – something that may be prevented by the presence of PAI-1. These findings suggest to researchers the importance of tight control over plasmin generation within the body (Balsara and Ploplis, 2008).
PAI-1 in Aging
Researchers studying healthy aging and longevity research also work with PAI-1. Researchers that study aging are interested in studying “biological age,” which is the cumulative expression of aging on a person’s organs and body. About 10 years ago, cardiologists working with Dr. Douglas Vaughan of the Northwestern University’s Potocsnak Longevity Institute found a genetic mutation in the gene that codes for PAI-1 which results in protection from aging in a variety of ways (Mosbergen, 2025).
While studying an Amish community in Indiana, the researchers found that carriers of the mutation on the PAI-1 encoding gene typically lived on average 10 years longer than other members of their community, don’t get diabetes, have “younger” cardiovascular systems, and have longer telomeres than those that don’t have the mutation (Mosbergen, 2025). After further study, the researchers concluded that extremely low levels of PAI-1 were the underlying cause of the health benefits carriers of the mutation exhibited. Researchers now are planning clinical trials to determine whether PAI-1 inhibition can help lower biological age (Longevity Research You Can Use Today, 2026).
Other Applications of PAI-1
As a protein involved in the fibrinolytic system, PAI-1 has been shown to have a role in various pathologies in the body like fibrosis and inflammation. Further investigations into PAI-1 inhibitors have shown that the PAI-1 inhibitor causes the release of hematopoietic stem cells from bone marrow and differentiates them into hematopoietic cells. Hematopoietic stem cells from bone marrow have been shown to express high levels of PAI-1. The researchers found that, interestingly, PAI-1 inhibits the intracellular serine protease furin found in hematopoietic stem cells. PAI-1 inhibitor, however, activates intracellular furin, which then activates membrane-type matrix metalloproteinases which then release hematopoietic stem cells from bone marrow and differentiating them (Miyata, 2025).
Researchers decided to apply this knowledge to the treatment of chronic myelogenous leukemia (CML), a blood cancer. CML is caused by a proliferation of hematopoietic stem cells with a specific gene mutation and typically comes with a poor prognosis and death typically within 7-8 years if hematopoietic stem cell transplantation was not performed. In 2001, a tyrosine kinase inhibitor (TKI) was developed which significantly improved the survival rate of CML patients. However, despite the TKI treatment being necessary for survival in CML patients, its side effects led to a decrease in physical and mental quality of life and placed an economic burden on patients. Researchers hypothesized that implementing combined use of a PAI-1 inhibitor and a TKI may enhance the therapeutic effects of the TKI treatment and increase survival rates further in patients. After seeing success in murine models, the team moved to clinical trials, where a significant increase in therapeutic effect was seen with the combined treatment with no serious side effects observed (Miyata, 2025).
Conclusion
PAI-1 is an important protein with multiple complex functions throughout the body. Whether you’re studying aging and longevity, cancer treatments, inflammation, cellular death, plasmin/plasminogen activation, or one of the other systems PAI-1 is involved in, it’s important the samples you source for your research are ready to pull their weight. Innovative Research is the leading manufacturer and supplier of research-use PAI-1 products in the United States. Since 1994, Molecular Innovations was the first company in the world to bring PAI-1 to market and make it available to researchers worldwide. Molecular Innovations is now wholly owned by Innovative Research. If you’re looking for PAI-1 products such as proteins, antibodies, or ELISA kits, Innovative Research has the samples you need to make that next breakthrough discovery. Check out our website to browse our full product catalog and get in touch with us today.
If you have questions about PAI-1 products or are looking to order samples for your research, Innovative Research is here to help! You can get in touch with our team via email at sales@innov-research.com or by phone at (248) 896-0145.
Citations
Balsara RD, Ploplis VA. Plasminogen activator inhibitor-1: the double-edged sword in apoptosis. Thromb Haemost. 2008 Dec;100(6):1029-36. PMID: 19132226; PMCID: PMC3674867 (https://pmc.ncbi.nlm.nih.gov/articles/PMC3674867/).
Sillen M, Declerck PJ. A Narrative Review on Plasminogen Activator Inhibitor-1 and Its (Patho)Physiological Role: To Target or Not to Target? Int J Mol Sci. 2021 Mar 8;22(5):2721. doi: 10.3390/ijms22052721. PMID: 33800359; PMCID: PMC7962805 (https://pmc.ncbi.nlm.nih.gov/articles/PMC7962805/).
Toshio Miyata, Overview: PAI-1 inhibitors and clinical applications, Biomedical Journal, Volume 49, Issue 1, 2026, 100874, ISSN 2319-4170, https://doi.org/10.1016/j.bj.2025.100874 (https://www.sciencedirect.com/science/article/pii/S2319417025000484).
Mosbergen D. Want to Live Longer? First Find Out How Old You Really Are. TIME. Published December 23, 2025. Accessed March 11, 2026 (https://time.com/collections/future-of-living/7341841/longevity-age-cells-douglas-vaughan/).
Staff NM. Longevity Research You Can Use Today. Northwestern Medicine. Published February 27, 2026. Accessed March 11, 2026 (https://www.nm.org/healthbeat/medical-advances/science-and-research/longevity-research-you-can-use-today).
