Hydrogel system based on enzyme-mediated mild crosslinking reaction has been a promising approach in tissue engineering. Inspired by skin melanin synthesis and marine mussel adhesion, tyrosinase-mediated hydrogel crosslinking has been exploited as cell-friendly reactions and explicit reaction mechanisms. Hydrogel prepared by tyrosinase exhibits appealing properties as a dynamic scaffold for cell delivery and as a bioink for 3D bioprinting. Recapitulating the structure of the native extracellular matrix (ECM), innovative tyrosinase-mediated hydrogel crosslinking has now shifted to the field of translational medicine. Biomimetic hydrogel with in situ tyrosinase crosslinking can be efficiently and easily applicable to the disease model for therapeutic purposes. In this review, we will discuss a broad range of tyrosinase-mediated tissue engineering from the specific mechanism of tyrosinase reaction and designing a strategy for tyrosinase-mediated hydrogel crosslinking to dynamic applications in tissue engineering. In addition, we report the current challenges and future perspectives for the translational applications.

Myxomatous mitral valve disease (MMVD) is the most common heart disease in small breed dogs. Dogs with MMVD commonly show clinical signs of dyspnea due to cardiogenic pulmonary edema (CPE). Reticulocytosis in the absence of anemia (RAA) is a hematological finding in hypoxic conditions. We aimed to assess the prevalence of RAA in dogs with CPE due to MMVD, and evaluate whether RAA is reversible with amelioration of dyspnea. Twenty-nine client-owned dogs with CPE due to MMVD were included. Dogs who died within 6 weeks of the onset of CPE were included in the non-survival group, while the others comprised the survival group. Of the 21 dogs, RAA was observed in 17 dogs (80.9%). In the RAA group, the absolute reticulocyte count significantly decreased as CPE resolved (p < 0.001). The mean absolute reticulocyte count in the RAA group was 163.90 ± 50.77 on the first measurement and 78.84 ± 25.64 after resolution of CPE. In the RAA group, no significant differences in mean absolute reticulocyte count were observed between the survival and non-survival groups at either the first or second measurement. Our results indicate that RAA occurs in dogs with MMVD-related CPE and can resolve after resolution of CPE.

A 12-year-old mixed-breed dog presented with a 2-month history of abdominal distension. Radiographic examination, abdominal ultrasonography, and computed tomography revealed a mass in the cecum (15.0 × 11.9 × 4.5 cm). The cecal mass was surgically removed and examined histopathologically.Immunohistochemically, the neoplastic cells expressed S-100 and neuron specific enolase but not αsmooth muscle actin and CD117 (c-kit). These histologic and immunohistochemical features indicated that the mass was consistent with a malignant peripheral nerve sheath tumor (MPNST). In dogs, most MPNSTs arise from the brachial plexus, spinal nerve root, and skin of the extremities. However, gastrointestinal MPNSTs in dogs have not been described previously. To the best of our knowledge, this is the first report to describe cecal MPNST in a dog.

A 10-year-old female Pomeranian weighing 2.25 kg with a history of gradual weight loss and an intraabdominal mass confirmed with ultrasonography at a local hospital was referred to the Veterinary Medical Teaching Hospital, Jeju National University. Physical examination revealed abdominal distention. Blood analysis revealed hypoglycemia (57 mg/dL; reference range, 60-110 mg/dL). On abdominal ultrasonography, a heterogeneously hyperechoic mass measuring 7.51 × 10.6 cm was found at the level of the left kidney. Computed tomographic findings showed a unilateral left kidney mass with a 10-cm diameter and vessel contrast enhancement in the corticomedullary phase. Unilateral nephrectomy and ovariohysterectomy were performed because left ovary enlargement was observed during surgery. The renal mass was adjacent to the aorta and vena cava and attached to a portion of the small intestine, greater omentum, and left ovary. The mass was huge (12.5 × 10 × 7 cm) and was 16.5% of the body weight. Histopathological examination revealed renal cell carcinoma (RCC) and ovarian metastasis. After surgery, clinical signs improved remarkably, and serum glucose level returned to normal. As RCC is resistant to radiation and chemotherapy, the owner decided not to proceed with postoperative adjunctive therapies. To the best of our knowledge, this is the first case report of ovarian metastasis with huge RCC in a dog.