Effect of Collagen and GelMA on Preservation of the Costal Chondrocytes' Phenotype in a Scaffold in vivo.

The aim of the study was to compare type I collagen-based and methacryloyl gelatin-based (GelMA) hydrogels by their ability to form hyaline cartilage in animals after subcutaneous implantation of scaffolds. Materials and Methods: Chondrocytes were isolated from the costal cartilage of newborn rats using 0.15% collagenase solution in DMEM. The cells was characterized by glycosaminoglycan staining with alcian blue. Chondrocyte scaffolds were obtained from 4% type I porcine atelocollagen and 10% GelMA by micromolding and then implanted subcutaneously into the withers of two groups of Wistar rats. Histological and immunohistochemical studies were performed on days 12 and 26 after implantation. Tissue samples were stained with hematoxylin and eosin, alcian blue; type I and type II collagens were identified by the corresponding antibodies. Results: The implanted scaffolds induced a moderate inflammatory response in both groups when implanted in animals. By day 26 after implantation, both collagen and GelMA had almost completely resorbed. Cartilage tissue formation was observed in both animal groups. The newly formed tissue was stained intensively with alcian blue, and the cells were positive for both types of collagen. Cartilage tissue was formed among muscle fibers. Conclusion: The ability of collagen type I and GelMA hydrogels to form hyaline cartilage in animals after subcutaneous implantation of scaffolds was studied. Both collagen and GelMA contributed to formation of hyaline-like cartilage tissue type in animals, but the chondrocyte phenotype is characterized as mixed. Additional detailed studies of possible mechanisms of chondrogenesis under the influence of each of the hydrogels are needed.

The Technique of Thyroid Cartilage Scaffold Support Formation for Extrusion-Based Bioprinting.

During biofabrication, a tissue scaffold may require temporary support. The aim of this study was to develop an approach of human thyroid cartilage scaffold temporal support formation. The scaffold 3D-model was based on DICOM images. XY plane projections were used to form scaffold supporting part. To verify the technique, collagen hydrogel was chosen as the main scaffold component. Gelatin was applied for the supporting part. To test the applicability of the approach, a model of thyroid cartilage scaffold with the support was printed. The scaffold corresponded to a given model, although some discrepancy in geometry was observed during verification by computed tomography.

p-Tyrosol Enhances the Production of New Neurons in the Hippocampal CA1 Field after Transient Global Cerebral Ischemia in Rats.

This study aimed at assessing the regenerative effect of p-tyrosol in transient global cerebral ischemia modeled in adult male Wistar rats by reversible occlusion of the three major vessels originating from the aortic arch and supplying the blood to the brain. p-Tyrosol was administered intraperitoneally in a dose of 20 mg/kg over 10 days after surgery. The death of NeuN+ mature neurons and the number of newly formed DCX+ neurons were assessed in the CA1 field of the hippocampus that is highly susceptible to damage in this model. We found that ischemia induced death of more than 50% mature neurons in the hippocampal CA1 field (p<0.001). p-Tyrosol stimulated the formation and growth of new neurons in the normally non-proliferative CA1 region of the hippocampus (p<0.05) and produced a neuroprotective effect on mature neurons (p<0.01).

Effect of Fluoxetine on Neurogenesis in Hippocampal Dentate Gyrus after Global Transient Cerebral Ischemia in Rats.

Changes in cerebral neurogenesis provoked by ischemia and the effect of fluoxetine on this process were studied using a three-vessel occlusion model of global transient cerebral ischemia. The global transient cerebral ischemia was modeled on male Wistar rats by transient occlusion of three major vessels originating from the aortic arch and supplying the brain (brachiocephalic trunk, left subclavian artery, and left common carotid artery). The cells expressing doublecortin (DCX, a marker of young neurons) were counted in the hippocampal dentate gyrus on day 31 after ischemia modeling. It was found that ischemia inhibited neurogenesis in the dentate gyrus in comparison with sham-operated controls (p<0.05), while fluoxetine (20 mg/kg/day) injected over 10 days after surgery restored neurogenesis to the control level (p<0.001).