Cell and tissue responses at the interface with a chitosan hydrogel intended for vascular applications: in vitro and in vivo exploration.

AIMS: The need for small caliber vessels to treat cardiovascular diseases has grown. However, synthetic polymers perform poorly in small-diameter applications. Chitosan hydrogels can provide a novel biological scaffold for vascular engineering. The goal of this study was to explore host cell and tissue behavior at the interface with chitosan-based scaffolds in vitro and in vivo. METHODS AND RESULTS: in vitro, we assessed the ability of endothelial cells lining chitosan hydrogels to produce tissue factor (TF), thrombomodulin (TM) and nitric oxide. We showed that endothelial cells behave as a native endothelium since under stimulation, TF and TM expression increased and decreased, respectively. Endothelial cells seeded on chitosan produced nitric oxide, but no change was observed under stimulation. After in vivo subcutaneous implantation of chitosan hydrogels in rats, macrophage activation phenotypes, playing a crucial role in biomaterial/tissue, were explored by immunohistochemistry. Our results suggested a balance between pro- and anti-inflammatory signals since we observed an inflammatory response in favor of macrophage M2 phenotype. CONCLUSION: in vitro exploration of endothelial cell response at the interface with chitosan hydrogel showed a functional endothelium and in vivo exploration of tissue response revealed a biointegration of chitosan hydrogels.

Case Report of a Severe Recurrent Tongue Self-Injury in an Infant With Dystonia.

Dystonia is characterized by sustained or intermittent muscle contractions causing abnormal, often repetitive movements, postures, or both that are typically patterned, twisting, and sometimes tremulous. It is often initiated or worsened by voluntary action and associated with overflow muscle activation. In this article we report a case of severe oromandibular dystonia, which is a specific form of dystonia characterized by involuntary, action-induced tonic or clonic spasms of the masticatory, lingual, and pharyngeal musculature. Episodes of repeated tongue biting in a 17-month-old girl caused her to stay in the PICU for 4 weeks. These episodes were the consequence of dystonia induced by a perinatal stroke. We highlight the specific dental management that enabled us to treat the child without extractions. Facing this type of complex illness, we insist on the importance of interdisciplinary work with the goal of avoiding outdated techniques. The use of botulinum toxin seemed relevant.

Patterning of Endothelial Cells and Mesenchymal Stem Cells by Laser-Assisted Bioprinting to Study Cell Migration.

Tissue engineering of large organs is currently limited by the lack of potent vascularization in vitro. Tissue-engineered bone grafts can be prevascularized in vitro using endothelial cells (ECs). The microvascular network architecture could be controlled by printing ECs following a specific pattern. Using laser-assisted bioprinting, we investigated the effect of distance between printed cell islets and the influence of coprinted mesenchymal cells on migration. When printed alone, ECs spread out evenly on the collagen hydrogel, regardless of the distance between cell islets. However, when printed in coculture with mesenchymal cells by laser-assisted bioprinting, they remained in the printed area. Therefore, the presence of mesenchymal cell is mandatory in order to create a pattern that will be conserved over time. This work describes an interesting approach to study cell migration that could be reproduced to study the effect of trophic factors.

Human endothelial progenitor cell attachment to polysaccharide-based hydrogels: a pre-requisite for vascular tissue engineering.

A hydrogel was prepared from polysaccharides (pullulan/dextran/fucoidan) and evaluated as a novel biomaterial for Endothelial Progenitor Cell (EPC) culture. Using a cross-linking process with sodium trimetaphosphate in aqueous solution, homogeneous, transparent and easy to handle gels were obtained with a water content higher than 90%. Circular scaffolds (6 mm diameter and 2 mm thickness discs) were used for cell culture. Different types of EPCs were used: CD34+ derived ECs from cord blood and two sorts of CD133+ derived ECs from human bone marrow, old (30 days) and young (4 days) cells. EPCs were characterised as endothelial cells by immunofluorescent stainings for CD31 and Dil-Ac-LDL. CD133+ derived ECs from bone marrow were characterized by RT-PCR for CD31, VE-cadherin and KDR. HSVECs (Human Saphenous Vein Endothelial Cells) were used as control cells. We evaluated whether different kinds of EPCs could adhere on this novel hydrogel 4 h and 24 h after seeding, by a colorimetric quantitative test. EPCs adhered to hydrogels in serum- free conditions with values being over than 80% for young CD133+ cells at 4 h and 24 h. This pullulan-based hydrogel could constitute a suitable support for vascular cell adhesion as a pre-requisite for vascular tissue engineering.