Osteoarthritis (OA) is a family of degenerative diseases affecting multiple joint tissues. Despite the diverse etiology and pathogenesis of OA, increasing evidence suggests that macrophages can play a significant role in modulating joint inflammation, and thus OA severity, via various secreted mediators. Recent advances in next-generation sequencing technologies coupled with proteomic and epigenetic tools have greatly facilitated research to elucidate the embryonic origin of macrophages in various tissues including joint synovium. Furthermore, scientists have now begun to appreciate that macrophage polarization can span beyond the conventionally recognized binary states (i.e., pro-inflammatory M1-like vs anti-inflammatory M2-like) and may encompass a broad spectrum of phenotypes. Although the presence of these cells has been shown in multiple joint tissues, additional mechanistic studies are required to provide a comprehensive understanding of the precise role of these diverse macrophage populations in OA onset and progression. New approaches that can modulate macrophages into desired functional phenotypes may provide novel therapeutic strategies for preventing OA or enhancing cartilage repair and regeneration.

Novel cisplatin (CDDP)-loaded, polypeptide-based vesicles for the targeted delivery of cisplatin to cancer cells have been prepared. These vesicles were formed from biocompatible and biodegradable maleimide-poly(ethylene oxide)114-b-poly(L-glutamic acid)12 (Mal-PEG114-b-PLG12) block copolymers upon conjugation with the drug itself. CDDP conjugation forms a short, rigid, cross-linked, drug-loaded, hydrophobic block in the copolymer, and subsequently induces self-assembly into hollow vesicle structures with average hydrodynamic diameters (Dh) of ∼ 270 nm. CDDP conjugation is critical to the formation of the vesicles. The reactive maleimide-PEG moieties that form the corona and inner layer of the vesicles were protected via formation of a reversible Diels-Alder (DA) adduct throughout the block copolymer synthesis so as to maintain their integrity. Drug release studies demonstrated a low and sustained drug release profile in systemic conditions (pH = 7.4, [Cl(-)] = 140 mM) with a higher "burst-like" release rate being observed under late endosomal/lysosomal conditions (pH = 5.2, [Cl(-)] = 35 mM). Further, the peripheral maleimide functionalities on the vesicle corona were conjugated to thiol-functionalized folic acid (FA) (via in situ reduction of a novel bis-FA disulfide, FA-SS-FA) to form an active targeting drug delivery system. These targeting vesicles exhibited significantly higher cellular binding/uptake into and dose-dependent cytotoxicity toward cancer cells (HeLa) compared to noncancerous cells (NIH-3T3), which show high and low folic acid receptor (FR) expression, respectively. This work thus demonstrates a novel approach to polypeptide-based vesicle assembly and a promising strategy for targeted, effective CDDP anticancer drug delivery.

Background Heterotopic ossification (HO) may occur after musculoskeletal trauma, traumatic brain injury, and total joint arthroplasty. As such, HO is a compelling clinical concern in both military and civilian medicine. A possible etiology of HO involves dysregulated signals in the bone morphogenetic protein osteogenic cascade. Contemporary treatment options for HO (ie, nonsteroidal antiinflammatory drugs and radiation therapy) have adverse effects associated with their use and are not biologically engineered to abrogate the molecular mechanisms that govern osteogenic differentiation. Questions/purposes We hypothesized that (1) nanogelmediated short interfering RNA (siRNA) delivery against Runt-related transcription factor 2 (Runx2) and osterix (Osx) genes will decrease messenger RNA expression; (2) inhibit activity of the osteogenic marker alkaline phosphatase (ALP); and (3) inhibit hydroxyapatite (HA) deposition in osteoblast cell cultures. Methods Nanogel nanostructured polymers delivered siRNA in 48-hour treatment cycles against master osteogenic regulators, Runx2 and Osx, in murine calvarial preosteoblasts (MC3T3-E1.4) stimulated for osteogenic differentiation by recombinant human bone morphogenetic protein (rhBMP-2). The efficacy of RNA interference (RNAi) therapeutics was determined by quantitation of messenger RNA knockdown (by quantitative reverse transcription-polymerase chain reaction), downstream protein knockdown (determined ALP enzymatic activity assay), and HA deposition (determined by OsteoImage TM assay). Results Gene expression assays demonstrated that nanogelbased RNAi treatments at 1:1 and 5:1 nanogel:short interfering RNA weight ratios reduced Runx2 expression by 48.59% ± 19.53% (p \ 0.001) and 43.22% ± 18.01% (both p \ 0.001). The same 1:1 and 5:1 treatments against both Runx2 and Osx reduced expression of Osx by 51.65% ± 10.85% and 47.65% ± 9.80% (both p \ 0.001). Moreover, repeated 48-hour RNAi treatment cycles against Runx2 and Osx rhBMP-2 administration reduced ALP activity after 4 and 7 days. ALP reductions after 4 days in culture by nanogel 5:1 and 10:1 RNAi treatments were 32.4% ± 12.0% and 33.6% ± 13.8% (both p \ 0.001). After 7 days in culture, nanogel 1:1 and 5:1 RNAi treatments produced 35.9% ± 14.0% and 47.7% ± 3.2% reductions in ALP activity. Osteoblast mineralization data after 21 days suggested that Two of the authors (ARS, EH) contributed equally.

Unimolecular polymeric architectures are ideal candidates for drug encapsulation. In this study we report the facile yet well-controlled formation of a series of biocompatible and biodegradable core cross-linked star (CCS) polymers via the easily scalable, metal free, one-or two-step ring-opening polymerization (ROP) of ε-caprolactone, using poly(ethylene glycol) (PEG) as initiator and [4,4'-bioxepane]-7,7'-dione (BOD) as cross-linker. The resulting CCS polymers, which exhibit hydrophilic PEG blocks in their outer shell and hydrophobic poly(ε-caprolactone) (PCL) and BOD segments in their inner core, are watersoluble and amphiphilic and exist in a unimolecular state, both in organic solvents and in water. These properties provide the opportunity to easily stabilise water-insoluble, hydrophobic drugs in aqueous environments without the need for conjugation of the drug to the carrier and/or complex encapsulation techniques. The impact of hydrophilic/hydrophobic block length and core size on polymer properties was investigated via gel permeation chromatography (GPC) and dynamic light scattering (DLS). In addition, the change in drug encapsulation properties with varying hydrophilic/hydrophobic balance was studied using pirarubicina potent anthracyclineas a model hydrophobic drug. Formation of a drug-CCS polymer conjugate purely based on hydrophobic-hydrophobic interaction of the drug and the hydrophobic component of the CCS was verified by 1 H NMR and UV-Vis measurements, and the size change confirmed by DLS and transmission electron microscopy (TEM). The in vitro study of drug-CCS conjugate demonstrated significantly faster release of anthracycline from the CCS polymer under acidic conditions ( pH = 5.5) compared with normal physiological pH level (7.4). Furthermore, cytotoxicity and cellular uptake tests performed using Hela cells, demonstrated extremely low toxicity of the macroinitiators and CCS polymers even at high concentrations, while anthracycline-loaded CCS polymers exhibited similar IC 50 values to the free drug. Confocal laser scanning microscopy and flow cytometry confirmed high uptake efficiency and intracellular localisation of the CCS polymers upon uptake, respectively. † Electronic supplementary information (ESI) available: 1 H NMR spectra and GPC traces of CCS polymers. Correlation of drug loading content and the change in the core size of CCS polymers. See