Friday, July 24, 2015

PolySciTech PLGA-Fluorescein used for tracking nanoparticles as part of carboplatin based brain cancer therapy

PolySciTech (www.polyscitech.com) provides a wide range of polymers including PLGA-fluorescein conjugates. The fluorescein endcap absorbs blue colored light with a wavelength around 490 nm and then re-emits green colored light around 525nm wavelength. The practical application of this is that it allows for the PLGA formulation to be imaged using a fluorescent microscope or other device so that nanoparticles generated using this PLGA can be tracked as they flow through various systems and are uptaken into cells. Recently researchers from Bristol University, University of Bath, and Renishaw Plc did precisely this by combining AV01 and AV04 (PLGA-Fluorescein) along with unstained PLGA to generate carboplatin, a chemotherapy agent, loaded nanoparticles which could be tracked by fluorescence. They then tested these in cell culture and rat/porcine models along with a convection enhanced delivery system to improve delivery of carboplatin to the tumors. Read more: Arshad, Azeem, Bin Yang, Alison S. Bienemann, Neil U. Barua, Marcella J. Wyatt, Max Woolley, Dave E. Johnson, Karen J. Edler, and Steven S. Gill. "Convection-Enhanced Delivery of Carboplatin PLGA Nanoparticles for the Treatment of Glioblastoma." PLOS ONE 10, no. 7 (2015): e0132266. http://dx.plos.org/10.1371/journal.pone.0132266 You can see all articles referencing PolySciTech products here (https://akinainc.com/polyscitech/products/polyvivo/referenced_by.php)

“Abstract: We currently use Convection-Enhanced Delivery (CED) of the platinum-based drug, carboplatin as a novel treatment strategy for high grade glioblastoma in adults and children. Although initial results show promise, carboplatin is not specifically toxic to tumour cells and has been associated with neurotoxicity at high infused concentrations in pre-clinical studies. Our treatment strategy requires intermittent infusions due to rapid clearance of carboplatin from the brain. In this study, carboplatin was encapsulated in lactic acid-glycolic acid copolymer (PLGA) to develop a novel drug delivery system. Neuronal and tumour cytotoxicity were assessed in primary neuronal and glioblastoma cell cultures. Distribution, tissue clearance and toxicity of carboplatin nanoparticles following CED was assessed in rat and porcine models. Carboplatin nanoparticles conferred greater tumour cytotoxicity, reduced neuronal toxicity and prolonged tissue half-life. In conclusion, this drug delivery system has the potential to improve the prognosis for patients with glioblastomas.”

Nanoparticle generation protocol: “Carboplatin NP were produced using the double—emulsion method (W1/O1/W2). Briefly, 60 mg Poly (lactide-co-glicolide) (PLGA) (polymers with a 1:1 co-polymerization ratio ester ended (RG504 Mw 38-54KDa- Sigma-Aldrich, UK), acid ended (RG504H, Mw 38-54KDa—Sigma-Aldrich, UK) and poly(lactic acid) (PLA R203H Mw 18-24kDa- Sigma-Aldrich, UK) was dissolved in 2ml dichloromethane /ethyl acetate (DCM/EA) (both Sigma-Aldrich, UK) (2:8 V/V, O1 phase) and 0.7ml aqueous solution of carboplatin (10 mg/ml, W1 phase) (Accord Healthcare Limited, UK) was emulsified in the PLGA solution using a micro-tip probe sonicator (Model VC 600, Sonics & materials Inc., UK) set at level 4 for 3 minutes. Level 4 corresponded to 20 kHz at 45 W cm-2, and had been calibrated previously. Encapsulation and release of aqueous components from sonochemically produced protein microspheres.
The primary (W1/O1) emulsion was transferred into 40 ml of Polyvinyl alcohol- Mw 20 KDa (PVA) (MP Biomedicals, USA). 2.5% solution (W2 phase) and the mixture was probe sonicated at level 4 for 5 minutes. The W1/O1/W2 emulsion was agitated by a magnetic stirrer uncovered overnight at room temperature to remove the organic solvent. In order to obtain particles with the desired diameter, the particle solution was treated by centrifugation (Centrifuge 5804R, Eppendorf, UK) at 9000 rpm for 15 minutes which caused the large particles to form a pellet while the smaller particles remained in the supernatant. The pellet of large nanoparticles was discarded while nanoparticles in the supernatant were collected and washed by ultracentrifugation (40000rpm for 20 minutes, Motor type 70Ti/70.1Ti, L-80 ultracentrifuge, Beckman Coulter, UK). This pellet of nanoparticles was re-suspended in water, freeze-dried and stored at -20°C for further usage. For fluorescent carboplatin nanoparticles (fluorescein carboplatin NP), PLGA was substituted with the mixture of PLGA (Mw 38-54KDa) and PLGA-Fluorescein end cap copolymer (Mw 7KDa and 30K-40K, purchased from Polyscitech, AKINA, USA) with the weight ratio of 9:1, and processed as described.”
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