(M1330-03-14) Mesenchymal Stem Cell-Based Drug Delivery Approach for Effective Management of Pancreatic Cancer

Purpose: Pancreatic ductal adenocarcinoma (PDAC) is the 3rd leading cause of cancer-related death in the USA, with a five-year survival rate of only 13%. One of the significant causes of high PDAC mortality is the lack of early diagnostic markers. As a result, only 15% of PDAC patients are suitable for surgery, and the remaining patients have to rely on chemotherapy. However, conventional chemotherapeutics pose limitations with tumor non-specificity and dose-dependent toxicity, leading to poor therapeutic outcomes. Nanocarriers were developed with the promise of overcoming these limitations owing to their improved tumoral delivery and controlled release behavior. However, less than 1% of administered nanocarriers reach solid tumors, resulting in insufficient drug concentration at the tumor site to elicit an effective response. Thus, a new drug delivery approach is required to enhance the prognosis of PDAC. In this study, we used mesenchymal stem cells (MSCs) as carriers for tumor-selective delivery of paclitaxel (PTX).

Methods: Dibenzyl cyclooctane (DBCO)-functionalized poly(lactic-co-glycolic acid) (PLGA) nanocarriers encapsulating PTX (PTX-NP) were fabricated via solvent emulsification evaporation method. The particle size and surface charge of the nanoparticles were determined using the Zetasizer Nano ZS instrument. Transmission electron microscopy (TEM) was used to assess the morphology of the nanoparticles. HPLC determined the drug loading and entrapment efficiency of the nanoparticles after PTX extraction using methanol. Nanocarriers are loaded into MSCs via endocytosis and surface conjugation. Surface anchoring was performed by forming covalent bonds using click chemistry between the DBCO functionalities on the nanocarrier and the artificial azide group on the MSC (MSC-Az) surface. MSCs were treated with 25 µM of N-azidoacetylmannosamine-tetraacylated (Ac₄ManNAz) sugar for 3 days to generate artificial azide on their surface. MSC-Az was incubated with PTX-NP suspension (0.1 mg/mL) in a CO₂ incubator for 4 hours to generate nanoparticle-loaded MSCs (nano-MSCs). The PTX loading of nano-MSCs was determined by HPLC following lysis of the cells in RIPA buffer, freeze drying, and methanol extraction. The in vitro release of PTX from nano-MSCs was determined at 37°C using a complete MSC growth medium. In vitro cytotoxicity potential of nano-MSCs was performed against human pancreatic cancer cells (PANC-1) and mouse pancreatic cancer cells (KPC) using trans-well plates. The antitumor efficacy of nano-MSCs was evaluated in an orthotopic model of PDAC.

Results: The size and charge of PTX-NPs were 276 ± 3.9 nM and -17.6 ± 2.2 mV, respectively. The TEM analysis revealed that PTX-NPs were spherical and homogeneously distributed. PTX was successfully encapsulated into PLGA nanoparticles with a loading of 21.3 ± 2.1 % w/w and an encapsulation efficiency of 59.3 ± 3.1%. The optimal PTX loading capacity of nano-MSCs was 56 pg/cell. In vitro release study of nano-MSCs exhibited a sustained release profile where only 3.6% of the loaded PTX was released in 1 hour, while 73.54% was released in 7 days. Nano-MSCs showed dose-dependent cytotoxicity against PANC-1 and KPC cells. The IC₅₀ of nano-MSCs against PANC-1 and KPC cells were 1028 and 579 cells, respectively. Furthermore, in vivo studies revealed that nano-MSCs-treated mice exhibited significant PDAC tumor inhibition and the highest survival rate among other treatment groups, such as saline, control MSCs, PTX solution, PTX NP, and Abraxane.

Conclusion: We have successfully formulated PTX-loaded PLGA nanoparticles with high drug loading and encapsulation efficiency. Furthermore, we also successfully loaded PTX-NP in MSCs. More importantly, nano-MSCs appeared to be the most effective formulations for managing PDAC.


Physicochemical characterization of DBCO functionalized paclitaxel PLGA nanoparticle (PTX-NP). (A) Size distribution by number for PTX-NP. (B) Zeta potential distribution of PTX-NP. (C) Transmission electron microscopy image of PTX-NP. (D) In vitro release profile of PTX-NP in DPBS containing 0.1% (v/v) Tween 80 (pH 7.4) as release medium.

>In vitro characterization of nano-MSCs. (A) PTX content in MSC cells when incubated with PTX-NP at different times. (B) In vitro PTX release profile from nano-MSCs. (C) Dose-response curve for cytotoxicity of nano-MSCs against PANC-1 and KPC cells. (D) IC50 value of PTX solution, PTX nanoparticle, and PTX NP loaded MSCs in KPC and PANC-1.


Figure: Antitumor efficacy of PTX NP loaded nanoMSCs. Mice-bearing orthotopic were intravenously injected with either Saline, Abraxane (equivalent to 5mg kg−1 PTX), paclitaxel loaded nanocarriers (equivalent to 5mg kg−1 PTX, “PTX NP”), PTX Solution (equivalent to 5mg kg−1 PTX), PTX NP loaded nanoMSCs (2 × 106 MSC, nano-MSCs) All animals received respective treatments every 7 days Tumor size determined weekly using ultrasound (mean ± SEM; n = 8 ; 4 male and 4 female). ‘*’ indicates significantly lower from saline, Abraxane, PTX NP and PTX Soln (p < 0.05) from Abraxane;