Methotrexate-Loaded Four-Arm Star Amphiphilic Block Copolymer Elicits CD8⁺ T Cell Response against a Highly Aggressive and Metastatic Experimental Lymphoma

We have synthesized a well-defined four-arm star amphiphilic block copolymer [poly­(DLLA)-<i>b</i>-poly­(NVP)]₄ [star-(PDLLA-<i>b</i>-PNVP)₄] that consists of d,l-lactide (DLLA) and <i>N</i>-vinylpyrrolidone (NVP) via the combination of ring-opening polymerization (ROP) and xanthate-mediated reversible addition–fragmentation chain transfer (RAFT) polymerization. Synthesis of the polymer was verified by ¹H NMR spectroscopy and gel permeation chromatography (GPC). The amphiphilic four-arm star block copolymer forms spherical micelles in water as demonstrated by transmission electron microscopy (TEM) and ¹H NMR spectroscopy. Pyrene acts as a probe to ascertain the critical micellar concentration (cmc) by using fluorescence spectroscopy. Methotrexate (MTX)-loaded polymeric micelles of star-(PDLLA₁₅-<i>b</i>-PNVP₁₀)₄ amphiphilic block copolymer were prepared and characterized by fluorescence and TEM studies. Star-(PDLLA₁₅-<i>b</i>-PNVP₁₀)₄ copolymer was found to be significantly effective with respect to inhibition of proliferation and lysis of human and murine lymphoma cells. The amphiphilic block copolymer causes cell death in parental and MTX-resistant Dalton lymphoma (DL) and Raji cells. The formulation does not cause hemolysis in red blood cells and is tolerant to lymphocytes compared to free MTX. Therapy with MTX-loaded star-(PDLLA₁₅-<i>b</i>-PNVP₁₀)₄ amphiphilic block copolymer micelles prolongs the life span of animals with neoplasia by reducing the tumor load, preventing metastasis and augmenting CD8⁺ T cell-mediated adaptive immune responses

Tailored Chemical Properties of 4‑Arm Star Shaped Poly(d,l‑lactide) as Cell Adhesive Three-Dimensional Scaffolds

Biodegradable poly­(lactic acid) (PLA) is widely used to fabricate 3D scaffolds for tissue regeneration. However, PLA lacks cell adhering functional moieties, which limit its successful application in tissue engineering. Herein, we have tailored the cell adhesive properties of star shaped poly­(d,l-lactide) (ss-PDLLA) by grafting gelatin to their 4 arms. Grafting of gelatin on PDLLA backbone was confirmed by ¹H NMR and FTIR. The synthesized star shaped poly­(d,l-lactide)-<i>b</i>-gelatin (ss-pLG) exhibited enhanced wettability and protein adsorption. The modification also facilitated better cell adhesion and proliferation on their respective polymer coated 2D substrates, compared to their respective unmodified ss-PDLLA. Further, 3D scaffolds were fabricated from gelatin grafted and unmodified polymers. The fabricated scaffolds were shown to be cytocompatible to 3T3-L1 cells and hemocompatible to red blood cells (RBCs). Cell proliferation was increased up to 2.5-fold in ss-pLG scaffolds compared to ss-PDLLA scaffolds. Furthermore, a significant increase in cell number reveals a high degree of infiltration of cells into the scaffolds, forming a viable and healthy 3D interconnected cell community. In addition to that, burst release of docetaxal (DTX) was observed from ss-pLG scaffolds. Hence, this new system of grafting polymers followed by fabricating 3D scaffolds could be utilized as a successful approach in a variety of applications where cell-containing depots are used