Author: Cadence Kong
Glioblastoma (GBM) remains one of the most lethal brain cancers due to its rapid growth, invasive behavior, and poor response to standard therapies. A major barrier to effective treatment is the blood-brain barrier (BBB), which prevents many drugs from reaching the tumor. Additionally, glioblastoma cells develop resistance quickly, making single-drug therapy less effective over time.
To address these challenges, this project combined two approaches:
- Designing a dual-drug nano-medicine capable of crossing the BBB and delivering two synergistic treatments.
- Conducting a cell-culture experiment to compare the effectiveness of free drugs versus the nanoparticle formulation on glioblastoma cells.
Drug Selection and Mechanistic Rationale
Temozolomide (TMZ):
Temozolomide is the standard chemotherapy for GBM and targets the hallmark of genome instability and mutation. It works by alkylating the O6 position of the guanine, a specific site on the DNA. This modification creates mismatches during replication that the cell repeatedly tries and fails to repeat, eventually causing double-strand breaks and apoptosis. GBM cells with weak DNA repair systems (low MGMT activity) are especially sensitive to TMZ.
Everolimus:
Everolimus was selected to complement TMZ by targeting a completely different hallmark: sustained proliferative signaling. Everolimus inhabits the mTOR pathway, a central regulator of cell growth, protein synthesis, and survival. mTOR is often overactive in glioblastoma, making it a critical therapeutic target. Inhibiting this pathway slows tumor proliferation, reduces angiogenesis, and can prevent or delay the development of resistance to TMZ.
Why these two drugs together?
TMZ directly damages DNA, while everolimus prevents turmeric regrowth and proliferation signaling. Because they attack different weaknesses of the cancer cell, they create a synergistic effect, meaning the combined impact is stronger than either drug alone.
Nanoparticle Formulation:
Choice of Nanoparticle Type:
A lipid-polymer hybrid Nanoparticle (LPHN) was used because it supports the co-delivery of two drugs with opposite solubilities:
- PLGA polymer core: encapsulates hydrophilic temozolomide
- Lipid shell: incorporates hydrophilic everolimus
- PEGlyation: increases circulation time in blood
- Transferrin surface ligand: helps transport the Nanoparticle across the BBB by binding the transferrin receptor, which is highly expressed in brain endothelial cells.
This hybrid system improves drug stability, loading efficiency, release control, and most importantly, transport into the brain.
Rationale Behind the Nano-medicine Design
The goal of this project was to engineer a delivery system capable of transporting two mechanistically distinct drugs into the brain while reducing systemic side effects. A lipid-polymer hybrid nanoparticle was chosen because it enhances BBB penetration, allows simultaneous loading of drugs with differing solubilities, and releases them in a controlled manner that improves synergy. Together, this strategy increases the likelihood of sustained tumor suppression and reduces the risk of treatment resilience.
Laboratory Methods
Cell Line and Culture Conditions:
Human glioblastoma cells were cultured in standard incubator conditions (37 degrees Celcius, 5% CO2) using a nutrient-rich medium supplemented with fetal bovine serum and antibiotics. Cells were grown in sterile T-flasks until they reached appropriate confluency for experimentation.
Experimental Groups
Cells were plated into multi-well plates and divided into four treatment groups:
- Control (untreated)
- Free Telemozolomide (TMZ)
- Free Everolimus
- TMZ + Everolimus Co-Loaded Nanoparticle
Concentrations were kept consistent across groups so differences were due to drug delivery method, not drug amount.
Treatment and Observation
Cells were created 24-48 hours, depending on assay requirements. During treatment, changes in cell appearance were observed using an inverted microscope:
- clumping
- rounding
- detachment
- reduced confluence
These morphological changes indicate apoptosis or reduced proliferation.
Viability Assay
Cell viability was measured using an MTT-type colorimetric assay. Living cells convert the reagent into a purple compound, allowing quantification using a plate reader.
Data Analysis
Absorbance readings were normalized to the control group. A dose-response comparison was made between free drugs and the nanoparticle formulation.
Microscopy Observations
- Control cells remained dense and healthy.
- TMZ-treated cells showed reduced confluence and some rounding.
- Everolimus-treated cells grew more slowly but remained relatively intact.
- Nanoparticle-treated cells showed the most dramatic effects: reduced cell density, membrane blebbing, and detachment consistent with apoptosis.
Viability Data
Quantitative analysis showed:
- TMZ alone: moderate viability reduction
- Evereolimus alone: modest growth inhibition
- Dual-drug nanoparticle: largest viability decrease of all groups
This data supports that the nanoparticle enhanced both delivery and drug synergy.
Conclusion
This project demonstrates that a dual-drug lipid-polymer hybrid nanoparticle can significantly enhance the effectiveness of temozolomide and everolimus against glioblastoma cells. By targeting two different cancer hallmarks and improving transport across the BBB, this system offers a promising strategy for improving GBM therapy. The in-vitro results provide strong preliminary evidence that co-delivery nanoparticles may outperform free-drug treatments and warrant further investigation in preclinical models.
Works Cited
Research Internship w/ NorthEastern Professor: Dr. Lara Milane
Edited by: Tammy Zhen and Maysoon
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