Cryosectioning and Immunostaining of Xenopus Embryonic Tissues

The Xenopus embryo is a classical vertebrate model for molecular, cellular, and developmental biology. Despite many advantages of this organism, such as large egg size and external development, imaging of early embryonic stages is challenging because of nontransparent cytoplasm. Staining and imaging of thin tissue sections is one way to overcome this limitation. Here we describe a step-by-step protocol that combines cryosectioning of gelatin-embedded embryos with immunostaining and imaging. The purpose of this protocol is to examine various cellular and tissue markers after the manipulation of protein function. This protocol can be performed within a 2-d period and allows detection of many antigens by immunofluorescence.

A decellularized porcine pulmonary valved conduit embedded with gelatin

To prepare a tissue-engineered pulmonary valved conduit (PVC) with good tensile strength and biocompatibility. Sixty adult porcine PVCs were used to determine the optimal decellularization time. Five juvenile porcine decellularized PVCs and five juvenile porcine crosslinked PVCs were subsequently prepared according to the optimized decellularization and crosslinking methods. All PVCs were implanted into juvenile sheep for 8 months and then were harvested for staining. With a low concentration of detergent (0.25% Triton X-100+0.25% sodium deoxycholate), the decellularization effect on porcine PVCs was complete by 24 hours, and there was minimal damage to the matrix. Gelatin embedding and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) crosslinking improved the biomechanical properties of decellularized PVCs and reduced their immunogenicity. After implantation, the diameter and thickness of the PVCs in the decellularized and crosslinked groups increased significantly. In both groups, the conduits were unobstructed, with soft and smooth inner walls and without thrombosis, ulceration or neoplasia. The valves slightly degenerated with mild to moderate regurgitation. CD31-positive endothelial cells were visible on the inner surface of the conduits and valves. Scattered smooth muscle actin-positive cells were found in the middle layer of the conduit. The percentage of CD4- and CD68-positive cells and the calcium content were highest in decellularized porcine PVCs and lowest in ovine PVCs. The percentage of the matrix that was laminin-positive in decellularized and crosslinked porcine PVCs was lower than it was in ovine PVCs. Gelatin-embedded and EDC-crosslinked porcine PVCs can be "hosted" in sheep, with good biocompatibility, growth potential, and reduced calcification.

Terahertz spectroscopy of gelatin-embedded human brain gliomas of different grades: a road toward intraoperative THz diagnosis

We applied terahertz (THz)-pulsed spectroscopy to study ex vivo the refractive index and absorption coefficient of human brain gliomas featuring different grades, as well as perifocal regions containing both intact and edematous tissues. Glioma samples from 26 patients were considered and analyzed according to further histological examination. In order to fix tissues for the THz measurements, we applied gelatin embedding, which allows for sustaining their THz response unaltered, as compared to that of the freshly excised tissues. We observed a statistical difference between the THz optical constants of intact tissues and gliomas of grades I to IV, while the response of edema was similar to that of tumor. The results of this paper justify a potential of THz technology in the intraoperative label-free diagnosis of human brain gliomas for ensuring the gross-total resection.