VEGFC-loaded Lignin Nanoparticles
Vascular Endothelial Growth Factor C (abbreviated either VEGFC or VEGF-C) has been used in several preclinical models in regenerative medicine. Its potential applications range from repairing damaged heart tissue to treating neurodegenerative disorders. While repairing damaged hearts and brains is not realistic at this moment, VEGFC does offer a glimmer of hope for patients with lymphedema — a chronic condition that presently can only be treated symptomatically. Yet, despite promising preclinical and even some clinical trial data, one key hurdle remains: effective delivery.
The current frontrunner, adenoviral VEGFC (AdVEGFC) gene therapy, had progressed to phase II clinical trials, but the results were inconclusive. One possible explanation is that the amount or the duration of VEGFC production by AdVEGFC is insufficient. Its rapid inactivation by the immune system is a double-edged sword, making it a safe, but perhaps not very potent drug. This shortfall has sparked interest in novel delivery systems that bypass the immune system while providing controlled and sustained release.
In our latest preprint, we explore the potential of lignin nanoparticles (LNPs) as carriers for VEGFC, from synthesis to stability. Why lignin? Lignin, a major component of plant cell walls, is the second most abundant biopolymer on planet Earth, and it can be extracted from many different sources and synthesized into nanoparticles.
Our stability tests revealed that VEGFC is relatively stable on its own. It easily survives weeks of storage at elevated temperatures, and we have kept it at 4°C for a year without any significant loss of activity. It is also relatively stable against proteolytic attacks. It is not degraded by trypsin or thermolysin, and even withstands limited exposure to proteinase K. However, freezing and thawing cause it to lose activity (one cycle is acceptable, but after 32 cycles, it has lost most of its activity). Therefore, nanoparticle delivery might not be critical for protecting VEGFC from degradation, but sustained and delayed release would be its major advantage.
We loaded VEGFC onto the particles and evaluated its release profile. Our findings indicate not only successful encapsulation but also a delayed release pattern, suggesting that LNPs could serve as a slow-release depot for VEGFC. We discovered that VEGFC can hang around for a long time even on its own, as the difference between naked VEGFC and LNP-delivered VEGFC was less than we had expected. In a modified Ba/F3-VEGFR3/EpoR bioassay, naked VEGFC sustained cell survival and proliferation for more than a week, even though at the later time points, not to the same levels as LNP-bound VEGFC. Based on previous studies, we attribute the innate ability of VEGF-C to "hang around for a long time" to its affinity for specific extracellular matrix components and cell surface molecules such as heparan sulfate proteoglycans. Even though most of these interactions are mediated by the silk-homology domain of VEGFC (which was absent in our study, which used mature VEGFC), some of these interaction capabilities also seem to remain in mature VEGFC.
With this study, we dipped our toes for the first time into nanoparticle-based delivery of biologics. Our work supports the feasibility of LNPs as an alternative to viral vectors. However, there is room for improvement. One way to improve the delayed release is to modify VEGFC (as was done by Güç et al). However, instead of modifying a cDNA that codes for mature VEGF-C (as Güç et al. did), it might make sense to try pro-VEGFC. After all, pro-VEGFC is the endogenous, inactive "latent form" of VEGFC. That's what we'll try next. Check out the full preprint for detailed methodology and data!
Link to the preprint: https://doi.org/10.1101/2025.04.23.649697