Hydrocolloids of Egg White and Gelatin as a Platform for Hydrogel-Based Tissue Engineering.

Innovative materials are needed to produce scaffolds for various tissue engineering and regenerative medicine (TERM) applications, including tissue models. Materials derived from natural sources that offer low production costs, easy availability, and high bioactivity are highly preferred. Chicken egg white (EW) is an overlooked protein-based material. Whilst its combination with the biopolymer gelatin has been investigated in the food technology industry, mixed hydrocolloids of EW and gelatin have not been reported in TERM. This paper investigates these hydrocolloids as a suitable platform for hydrogel-based tissue engineering, including 2D coating films, miniaturized 3D hydrogels in microfluidic devices, and 3D hydrogel scaffolds. Rheological assessment of the hydrocolloid solutions suggested that temperature and EW concentration can be used to fine-tune the viscosity of the ensuing gels. Fabricated thin 2D hydrocolloid films presented globular nano-topography and in vitro cell work showed that the mixed hydrocolloids had increased cell growth compared with EW films. Results showed that hydrocolloids of EW and gelatin can be used for creating a 3D hydrogel environment for cell studies inside microfluidic devices. Finally, 3D hydrogel scaffolds were fabricated by sequential temperature-dependent gelation followed by chemical cross-linking of the polymeric network of the hydrogel for added mechanical strength and stability. These 3D hydrogel scaffolds displayed pores, lamellae, globular nano-topography, tunable mechanical properties, high affinity for water, and cell proliferation and penetration properties. In conclusion, the large range of properties and characteristics of these materials provide a strong potential for a large variety of TERM applications, including cancer models, organoid growth, compatibility with bioprinting, or implantable devices.

Assessment of 2D and 3D fractal dimension measurements of trabecular bone from high-spatial resolution magnetic resonance images at 3 T.

PURPOSE: In vivo two-dimensional (2D) fractal dimension (D2D) analysis of the cancellous bone at 1.5 T has been related to bone structural complexity and shown to be a potential imaging-based biomarker for osteoporosis. The objectives of this study were to assess at 3 T the in vivo feasibility of three-dimensional (3D) bone fractal dimension (D3D) analysis, analyze the relationship of D2D and D3D with osteoporosis, and investigate the relationship of D3D with spinal bone mineral density (BMD). METHODS: A total of 24 female subjects (67 +/- 7 yr old, mean +/- SD) was included in this study. The cohort consisted of 12 healthy volunteers and 12 patients with osteoporosis. MR image acquisitions were performed in the nondominant metaphysis of the distal radius with a 3 T MR scanner and an isotropic resolution of 180 microm. After segmentation and structural reconstruction, 2D and 3D box-counting algorithms were applied to calculate the fractal complexity of the cancellous bone. D2D and D3D values were compared between patients with osteoporosis and healthy subjects, and their relationship with radius BV/TV and spinal BMD was also assessed. RESULTS: Significant differences between healthy subjects and patients with osteoporosis were obtained for D3D (p < 0.001), with less differentiation for D2D (p = 0.04). The relationship between fractal dimension and BMD was not significant (r = 0.43, p = 0.16 and r = 0.23, p = 0.48, for D2D and D3D, respectively). CONCLUSIONS: The feasibility of trabecular bone D3D calculations at 3 T and the relationship of both D2D and D3D parameters with osteoporosis were demonstrated, with a better differentiation for the 3D method. Furthermore, the D3D parameter has probably a different nature of information regarding the trabecular bone status not directly explained by BMD alone. Future studies with subjects with osteopenia and larger sample sizes are warranted to further establish the potential of D2D and D3D in the study of osteoporosis.

Transesophageal Doppler Analysis of Coronary Sinus Flow A New Method to Assess the Severity of Tricuspid Regurgitation.

BACKGROUND: Severe mitral regurgitation induces reversal of flow in the pulmonary veins. We hypothesized that severe tricuspid regurgitation may disrupt normal coronary sinus flow. The purpose of this study was to analyze the Doppler flow pattern of the coronary sinus and to determine its value in the assessment of the severity of tricuspid regurgitation. METHODS: The coronary sinus flow was analyzed in 70 consecutive patients with some degree of tricuspid regurgitation (27 mild, 14 moderate, and 29 severe) and in 35 patients without tricuspid regurgitation. The coronary sinus flow was obtained by pulsed-Doppler transesophageal echocardiography in a transverse plane, which showed its drainage into the right atrium. RESULTS: The number of patients with adequate studies of the coronary sinus tended to increase with the severity of the tricuspid regurgitation. In patients without or with only mild tricuspid regurgitation the coronary sinus Doppler flow pattern was formed by two negative waves, a late systolic wave and another diastolic one with higher velocity and longer duration. The systolic wave became reversed in 21 (96%) of the patients with severe tricuspid regurgitation. The sensitivity, specificity, and diagnostic accuracy of the presence of a reversed systolic wave in the coronary sinus for the diagnosis of severe tricuspid regurgitation was 95%, 82%, and 80%, respectively. CONCLUSIONS: Significant tricuspid regurgitation modifies the coronary sinus flow pattern as assessed by transesophageal echocardiography. The presence of a reversed systolic flow in the coronary sinus appears to be a reliable new sign with good sensitivity, specificity, and diagnostic accuracy for the diagnosis of severe tricuspid regurgitation.