Objective: To determine the effects of intratumoral injection of a hyaluronan-cisplatin nanoconjugate on local and systemic platinum concentrations and systemic toxicosis. Animals: 5 dogs with spontaneous soft tissue sarcomas (STSs). Procedures: For each dog, approximately 1.5 mL of hyaluronan nanocarrier conjugated with 20 mg of cisplatin was injected into an external STS. Blood samples were collected immediately before (0 hours) and at 0.5, 1, 2, 3, 4, 24, and 96 hours after hyaluronan-cisplatin injection for pharmacokinetic analyses. Urine samples were obtained at 0 and at 96 hours after hyaluronan-cisplatin injection for urinalysis. Each treated STS and its sentinel lymph nodes were surgically removed 96 hours after the hyaluronan-cisplatin injection. Inductively coupled plasma mass spectrometry was used to measure platinum concentrations in blood samples, tumors, and lymph nodes. Results: No tissue reactions were detected 96 hours after hyaluronan-cisplatin injection. Mean ± SD area under the curve, peak concentration, and terminal half-life for unbound (plasma) and total (serum) platinum were 774.6 ± 221.1 ng•h/mL and 3,562.1 ± 2,031.1 ng•h/mL, 56.5 ± 20.9 ng/mL and 81.6 ± 40.4 ng/mL, and 33.6 ± 16.1 hours and 51.2 ± 29.1 hours, respectively. Platinum concentrations ranged from 3,325 to 8,229 ng/g in STSs and 130 to 6,066 ng/g in STS-associated lymph nodes. Conclusions and Clinical Relevance: Intratumoral injection of the hyaluronan-cisplatin nanoconjugate was well tolerated in treated dogs. Following intratumoral hyaluronan-cisplatin injection, platinum concentration was 1,000-fold and 100-fold greater within treated tumors and tumor-draining lymphatics, respectively, compared with that in plasma.

Objective: To determine the expression and distribution of a disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS-4), its substrates aggrecan and versican, and their binding partner hyaluronan in laminae of healthy horses. Sample: Laminae from the forelimb hooves of 8 healthy horses. Procedures: Real-time quantitative PCR assay was used for gene expression analysis. Hyaluronidase, chondroitinase, and keratanase digestion of lamina extracts combined with SDS-PAGE and western blotting were used for protein and proteoglycan analysis. Immunofluorescent and immunohistochemical staining of tissue sections were used for protein and hyaluronan localization. Results: Genes encoding ADAMTS-4, aggrecan, versican, and hyaluronan synthase II were expressed in laminae. The ADAMTS-4 was predominantly evident as a 51-kDa protein bearing a catalytic site neoepitope indicative of active enzyme and in situ activity, which was confirmed by the presence of aggrecan and versican fragments bearing ADAMTS-4 cleavage neoepitopes in laminar protein extracts. Aggrecan, versican, and hyaluronan were localized to basal epithelial cells within the secondary epidermal laminae. The ADAMTS-4 localized to these cells but was also present in some cells in the dermal laminae. Conclusions and Clinical Relevance: Within digital laminae, versican exclusively and aggrecan primarily localized within basal epithelial cells and both were constitutively cleaved by ADAMTS-4, which therefore contributed to their turnover. On the basis of known properties of these proteoglycans, it is possible that they can protect the basal epithelial cells of horses from biomechanical and concussive stress.