Flexible and elastic porous poly(trimethylene carbonate) structures for use in vascular tissue engineering.

Biocompatible and elastic porous tubular structures based on poly(1,3-trimethylene carbonate), PTMC, were developed as scaffolds for tissue engineering of small-diameter blood vessels. High-molecular-weight PTMC (M(n) = 4.37 x 10(5)) was cross-linked by gamma-irradiation in an inert nitrogen atmosphere. The resulting networks (50-70% gel content) were elastic and creep resistant. The PTMC materials were highly biocompatible as determined by cell adhesion and proliferation studies using various relevant cell types (human umbilical vein endothelial cells (HUVECs), smooth muscle cells (SMCs) and mesenchymal stem cells (MSCs)). Dimensionally stable tubular scaffolds with an interconnected pore network were prepared by particulate leaching. Different cross-linked porous PTMC specimens with average pore sizes ranging between 55 and 116 microm, and porosities ranging from 59% to 83% were prepared. These scaffolds were highly compliant and flexible, with high elongations at break. Furthermore, their resistance to creep was excellent and under cyclic loading conditions (20 deformation cycles to 30% elongation) no permanent deformation occurred. Seeding of SMCs into the wall of the tubular structures was done by carefully perfusing cell suspensions with syringes from the lumen through the wall. The cells were then cultured for 7 days. Upon proliferation of the SMCs, the formed blood vessel constructs had excellent mechanical properties. Their radial tensile strengths had increased from 0.23 to 0.78 MPa, which is close to those of natural blood vessels.

[Distinguishing nodal naevus from melanoma metastases in the sentinel node in patients with melanoma]. / Een nodale naevus in de schildwachtklier bij patiënten met melanoom: onderscheid met melanoommetastase.

OBJECTIVE: Establishing the frequency of nodal naevi in lymph-node dissections from patients with a melanoma who have undergone a sentinel-node procedure and/or regional node dissection and distinguishing naevi from melanoma metastases. DESIGN: Retrospective and descriptive. METHODS: Patients with a nodal naevus in the sentinel node were selected from a database containing clinical and pathological data on all 65 patients who underwent a sentinel-node procedure for melanoma at our hospital between 1998 and 2001. Also data from the pathology department on the case frequency and the nodal frequency of nodal naevi in the total number of patients with melanoma in whom a sentinel-node procedure and/or therapeutic node dissection had been carried out during the same period, were examined. RESULTS: In 5 patients a nodal naevus was found in the sentinel node. The case frequency was 6.2% and the nodal frequency 0.65%. Distinction from melanoma metastases was made by the use of H&E colouring, localization, architectural and morphological features of the melanocyte cell clusters in the lymph node and sometimes after consultation with the National Melanoma Panel. Immunohistochemical markers provided supplementary information only. CONCLUSION: Nodal naevi in lymph nodes were not uncommon in people with melanoma and can be distinguished from the micrometastases from melanoma.