Development of immune cell delivery system using biodegradable injectable polymers for cancer immunotherapy.

Immune cell delivery using injectable hydrogel attracts much attention for improving its therapeutic effect. Specifically, dendritic cells (DCs) are the trigger cells for immune responses, and DC vaccines are studied for improving cancer immunotherapy. Hydrogel-assisted cell delivery is expected to enhance the viability of the implanted cells. We recently reported temperature-responsive biodegradable injectable polymer (IP) formulation utilizing poly(ε-caprolactone-co-glycolide)-b-poly(ethylene glycol)(PEG)-b-poly(ε-caprolactone-co-glycolide) (tri-PCG). Tri-PCG-based IP was reported to exhibit immediate sol-to-gel transition in response to temperature increase, in vivo biodegradability, and excellent biocompatibility. In this study, tri-PCG-based IP was applied to DC delivery. IP encapsulated live DCs, and the DCs incorporated ovalbumin (OVA) as a model antigen and CpG-DNA (oligo DNA with adjuvant effect) in IP hydrogel. Results suggested that DCs encapsulated in IP hydrogel internalized OVA and CpG-DNA and DCs were maturated to present antigens to T cells. Moreover, subcutaneously injected tri-PCG-based IP prolonged the retention period of cell accumulation at injected sites. Tri-PCG IP hydrogel could release matured DCs as the degradation of the hydrogel progressed. Tri-PCG IP formulation improved treatment efficacy of OVA transfected mouse lymphoma (E.G7-OVA) tumor. Hence, tri-PCG IP is a promising platform for immune cell delivery.