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Drug Delivery

Drug Delivery - Poster Session E

Poster K1 - Tuning Drug Release Kinetics from Cell-Mimetic Drug Carriers

Saturday, October 26, 2024
10:00 AM – 11:00 AM EST
Location: Exhibit Hall E, F & G

Introduction:  Transport into the lymph node, where metastatic cells reside, is highly regulated and often excludes therapeutics, significantly decreasing the efficacy of standard chemotherapy. Using a "Trojan horse" strategy, our group has engineered a cell-mimetic drug carrier to home to the lymph node called cryo-shocked T-lymphocytes (CSTLs). These carriers leverage cellular properties to target and efficiently deliver small-molecule chemotherapeutics into the lymph node lobule. However, initial drug-loading strategies in CSTLs resulted in uncontrolled release kinetics, limiting total achievable doses at the target site. Therefore, we aimed to engineer the CSTLs to provide controlled, delayed, sustained release of the therapeutic agents by incorporating a hydrogelated core to the system. This version of the carriers are called hydrogelated T-lymphocytes (HTCs). We hypothesized that encapsulation of small molecule drugs inside a hydrogel core with tunable properties would enable a significant change to the small molecule payload release kinetics. In this study, we compared the drug release profiles of loaded HTCs to those of CSTLs to evaluate their potential for sustained drug delivery.

Materials and

Methods:  To create CSTLs, Jurkat cells (ATCC) were submerged in Doxorubicin (DOX) (MedChemExpress) laden media and DMSO and flash frozen in liquid nitrogen. The HTCs were produced by suspending Jurkat cells in a DOX-laden poly(ethylene glycol)-based gelation solution (PEG-diacrylate (PEG-DA) and initiator 2-hydroxy-4'-(2-hydroxyethoxy)-2 methylpropiophenone) and subjecting them to a single freeze-thaw cycle in a -80 freezer. After thaw, the HTCs were exposed to ultraviolet light to polymerize the intracellular hydrogel. To test DOX release from the drug carriers, samples were resuspended in 0.9% NaCl (saline), and placed in the apical chamber of a cell culture insert with fresh saline in the basal chamber. The wells were stored covered from light at 37 °C on a rocker with a speed of 15 rpm and a tilt of 8° for 7 days. The lower chamber was sampled at specific time points and replaced with fresh saline for volume consistency. Sampled solutions were assessed via plate reader, where the absorbance of DOX was measured at 480 nm. Saline only and unloaded carrier samples were used as controls. The average of three samples was compared to a DOX standard curve, and cumulative release curves for DOX for both carriers were generated for comparison.

Results, Conclusions, and Discussions: CSTLs and HTCs were successfully loaded with DOX, with loading efficiencies of 2.1% and 6.0%, respectively (Figure 1AB). HTCs were able to be loaded more efficiently than CSTLs, which translates to a fewer number of carriers to deliver the same dose of drug. CSTLs released 275.6 μg of DOX after 24 hrs and a total of 449.87μg total over 144 hours. HTCs released 1.3 μg of DOX after 24 hrs and were still in the linear phase of the phase release curve over 150 hrs (Figure 1C-inset). These data indicate that incorporating a hydrogel into our carrier system significantly slows the release of DOX and increases drug loading efficiency (Figure 1C). As such, this hydrogelation strategy significantly improves loading and release kinetics of our cell-mimetic carriers. Increased drug-loading efficiency and extended-release is beneficial to potentially create formulations that enable sustained release of therapeutics, locally within the lymph node. Both factors further optimize the amount of drug at the site of the disease, decreased dosing frequency, and less off-target accumulation leading to lower systemic toxicity for the patient.

Acknowledgements (Optional):