Sustained delivery of celecoxib from nanoparticles embedded in hydrogel injected into the biopsy cavity to prevent biopsy-induced breast cancer metastasis.

PURPOSE: We have previously reported that protracted Cyclooxygenase-2 (COX-2) activity in bone marrow-derived cells (BMDCs) infiltrating into biopsy wounds adjacent to the biopsy cavity of breast tumors in mice promotes M2-shift of macrophages and pro-metastatic changes in cancer cells, effects which were suppressed by oral administration of COX-2 inhibitors. Thus, local control of COX-2 activity in the biopsy wound may mitigate biopsy-induced pro-metastatic changes. METHODS: A combinatorial delivery system-thermosensitive biodegradable poly(lactic acid) hydrogel (PLA-gel) incorporating celecoxib-encapsulated poly(lactic-co-glycolic acid) nanoparticles (Cx-NP/PLA-gel)-was injected into the biopsy cavity of Py230 murine breast tumors to achieve local control of COX-2 activity in the wound stroma. RESULTS: A single intra-biopsy cavity injection of PLA-gel loaded with rhodamine-encapsulated nanoparticles (NPs) showed sustained local delivery of rhodamine preferentially to infiltrating BMDCs with minimal to no rhodamine uptake by the reticuloendothelial organs in mice. Moreover, significant reductions in M2-like macrophage density, cancer cell epithelial-to-mesenchymal transition, and blood vessel density were observed in response to a single intra-biopsy cavity injection of Cx-NP/PLA-gel compared to PLA-gel loaded with NPs containing no payload. Accordingly, intra-biopsy cavity injection of Cx-NP/PLA-gel led to significantly fewer metastatic cells in the lungs than control-treated mice. CONCLUSION: This study provides evidence for the feasibility of sustained, local delivery of payload preferential to BMDCs in the wound stroma adjacent to the biopsy cavity using a combinatorial delivery system to reduce localized inflammation and effectively mitigate breast cancer cell dissemination.

Preclinical characterization of macrophage-adhering gadolinium micropatches for MRI contrast after traumatic brain injury in pigs.

The choroid plexus (ChP) of the brain plays a central role in orchestrating the recruitment of peripheral leukocytes into the central nervous system (CNS) through the blood-cerebrospinal fluid (BCSF) barrier in pathological conditions, thus offering a unique niche to diagnose CNS disorders. We explored whether magnetic resonance imaging of the ChP could be optimized for mild traumatic brain injury (mTBI). mTBI induces subtle, yet influential, changes in the brain and is currently severely underdiagnosed. We hypothesized that mTBI induces sufficient alterations in the ChP to cause infiltration of circulating leukocytes through the BCSF barrier and developed macrophage-adhering gadolinium [Gd(III)]-loaded anisotropic micropatches (GLAMs), specifically designed to image infiltrating immune cells. GLAMs are hydrogel-based discoidal microparticles that adhere to macrophages without phagocytosis. We present a fabrication process to prepare GLAMs at scale and demonstrate their loading with Gd(III) at high relaxivities, a key indicator of their effectiveness in enhancing image contrast and clarity in medical imaging. In vitro experiments with primary murine and porcine macrophages demonstrated that GLAMs adhere to macrophages also under shear stress and did not affect macrophage viability or functions. Studies in a porcine mTBI model confirmed that intravenously administered macrophage-adhering GLAMs provide a differential signal in the ChP and lateral ventricles at Gd(III) doses 500- to 1000-fold lower than those used in the current clinical standard Gadavist. Under the same mTBI conditions, Gadavist did not offer a differential signal at clinically used doses. Our results suggest that macrophage-adhering GLAMs could facilitate mTBI diagnosis.