Although hyaluronic acid (HA) has been developed as a nanoparticle (NP; 320-400 nm) for a drug delivery system, the tissue targeting efficacy and the pharmacokinetics of HA-NPs are not yet fully understood. After a dose of 5 mg/kg of cyanine 5.5-labeled HA-NPs or HA-polymers was intravenously administrated into mice, the fluorescence was measured from 0.5 h to 28 days. The HA-NPs fluorescence was generally stronger than that of HA-polymers, which was maintained at a high level over 7 days in vivo, after which it gradually decreased. Upon ex vivo imaging, liver, spleen, kidney, lung, testis and sublingual gland fluorescences were much higher than that of other organs. The fluorescence of HA-NPs in the liver, spleen and kidney was highest at 30 min, where it was generally maintained until 4 h, while it drastically decreased at 1 day. However, the fluorescence in the liver and spleen increased sharply at 7 days relative to 3 days, then decreased drastically at 14 days. Conversely, the fluorescence of HA-polymers in the lymph node was higher than that of HA-NPs. The results presented herein may have important clinical implications regarding the safety of as self-assembled HA-NPs, which can be widely used in biomedical applications.

OBJECTIVE To create a bioactive synovium scaffold by infusing decellularized synovial-derived extracellular matrix (synECM) with synovial-derived mesenchymal stem cells (synMSCs). SAMPLE Synovium from the femoropatellar and medial femorotibial joints of equine cadavers. PROCEDURES The synMSCs were cultured in monolayer and not treated or cotransduced to enhance expression of green fluorescent protein (GFP) and human bone morphogenetic protein (BMP)-2. The synECM was decellularized with 0.1% peracetic acid and then seeded with synMSCs (0.5 × 10(6) cells/0.5 mL) by use of a 30% serum gradient. Samples were evaluated on days 0, 3, 7, and 14. Cell migration, differentiation, and distribution into the synECMs were determined by cell surface marker CD90, viability, histologic morphology, and fluorescence microscopy results and expression of GFP, BMP-2, hyaluronan (HA), and proteoglycan (PG). RESULTS At day 14, synMSCs were viable and had multiplied 2.5-fold in the synECMs. The synECMs seeded with synMSCs had a significant decrease in CD90 expression and significant increases in HA and PG expression. The synECMs seeded with synMSCs cotransduced with GFP, or BMP-2 had a significant increase in BMP-2 expression. CONCLUSIONS AND CLINICAL RELEVANCE The synECM seeded with synMSCs or synMSCs cotransduced with GFP, or BMP-2 yielded a bioactive synovial scaffold. Expression of BMP-2 by synMSCs cotransduced to enhance expression of BMP-2 or GFP and an accompanying increase in both HA and PG expression indicated production of anabolic agents and synoviocyte differentiation in the scaffold. Because BMP-2 can promote repair of damaged cartilage, such a bioactive scaffold could be useful for treatment of injured cartilage.

OBJECTIVE To evaluate gene transfer of recombinant adeno-associated viral (rAAV) vectors with AAV2 or AAV5 capsid and encoding hyaluronic acid (HA) synthase-2 (HAS2) into joints of healthy dogs. ANIMALS 22 purpose-bred Beagles. PROCEDURES Plasmid expression cassettes encoding canine HAS2 (cHAS2) were assessed in vitro for concentration and molecular size of secreted HA. Thereafter, rAAV2-cHAS2 vectors at 3 concentrations and rAAV5-cHAS2 vectors at 1 concentration were each administered intra-articularly into the left stifle joint of 5 dogs; 2 dogs received PBS solution instead. Synovial fluid HA concentration and serum and synovial fluid titers of neutralizing antibodies against AAV capsids were measured at various points. Dogs were euthanized 28 days after treatment, and cartilage and synovium samples were collected for vector DNA and mRNA quantification and histologic examination. RESULTS Cell transfection with plasmids encoding cHAS2 resulted in an increase in production and secretion of HA in vitro. In vivo, the rAAV5-cHAS2 vector yielded uniform genome transfer and cHAS2 expression in collected synovium and cartilage samples. In contrast, rAAV2-cHAS2 vectors were detected inconsistently in synovium and cartilage samples and failed to produce clear dose-related responses. Histologic examination revealed minimal synovial inflammation in joints injected with rAAV vectors. Neutralizing antibodies against AAV capsids were detected in serum and synovial fluid samples from all vector-treated dogs. CONCLUSIONS AND CLINICAL RELEVANCE rAAV5-mediated transfer of the gene for cHAS2 into healthy joints of dogs by intra-articular injection appeared safe and resulted in vector-derived cHAS2 production by synoviocytes and chondrocytes. Whether this treatment may increase HA production by synoviocytes and chondrocytes in osteoarthritic joints remains to be determined.