From stem cells to viable autologous semilunar heart valve.

BACKGROUND: An estimated 275,000 patients undergo heart valve replacement each year. However, existing solutions for valve replacement are complicated by the morbidity associated with lifelong anticoagulation of mechanical valves and the limited durability of bioprostheses. Recent advances in tissue engineering and our understanding of stem cell biology may provide a lifelong solution to these problems. METHODS AND RESULTS: Mesenchymal stem cells were isolated from ovine bone marrow and characterized by their morphology and antigen expression through immunocytochemistry, flow cytometry, and capacity to differentiate into multiple cell lineages. A biodegradable scaffold was developed and characterized by its tensile strength and stiffness as a function of time in cell-conditioned medium. Autologous semilunar heart valves were then created in vitro using mesenchymal stem cells and the biodegradable scaffold and were implanted into the pulmonary position of sheep on cardiopulmonary bypass. The valves were evaluated by echocardiography at implantation and after 4 months in vivo. Valves were explanted at 4 and 8 months and examined by histology and immunohistochemistry. Valves displayed a maximum instantaneous gradient of 17.2+/-1.33 mm Hg, a mean gradient of 9.7+/-1.3 mm Hg, an effective orifice area of 1.35+/-0.17 cm2, and trivial or mild regurgitation at implantation. Gradients changed little over 4 months of follow-up. Histology showed disposition of extracellular matrix and distribution of cell phenotypes in the engineered valves reminiscent of that in native pulmonary valves. CONCLUSIONS: Stem-cell tissue-engineered heart valves can be created from mesenchymal stem cells in combination with a biodegradable scaffold and function satisfactorily in vivo for periods of >4 months. Furthermore, such valves undergo extensive remodeling in vivo to resemble native heart valves.

A psychological study on patients with masticatory muscle disorder and sleep bruxism.

Sleep bruxism (SB) has been believed to be related to stress and psychosocial factors, however their implicit relationship has remained unclear. This study was conducted on patients visiting our clinic with SB and masticatory muscle disorders (MMD) for the purpose of clarifying personality and behavioral traits. This study was conducted on patients of MMD visiting our clinic. The Rosenzweig Picture-Frustration study was performed on each patient. Twenty-seven (27) patients were divided into two groups: 17 patients with SB and 10 patients without. The SB group showed a significantly lower level of E (extrapunitive) reaction than the nonSB group. SB patients showed a significantly higher level of M (impunitive) reaction than those without SB. Concerning the directions of aggression, the percentage of E-A (extraaggression) was significantly lower in SB patients than in those without. On the other hand, the percentage of I-A (intraaggression) was significantly higher in patients with SB than those without. Our study found a new aspect of the patients with MMD and SB: they are not only intraaggressive, but are also unable to be extrapunitive and extraaggressive. Consequently, they are unable to demonstrate adequate self-assertiveness in stressful situations.

Mandibular nerve block treatment for trismus associated with hypoxic-ischemic encephalopathy.

BACKGROUND AND OBJECTIVES: We describe the use of mandibular nerve block for the management of bilateral trismus associated with hypoxic-ischemic encephalopathy. CASE REPORT: The patient was a 65-year-old man with bilateral trismus due to hypoxic-ischemic encephalopathy. Despite his impaired consciousness, we performed fluoroscopically guided bilateral mandibular nerve block. The bilateral symptoms were sufficiently improved, without obvious side effects, by injecting a local anesthetic near the right mandibular nerve and a neurolytic near the left mandibular nerve. CONCLUSIONS: Mandibular nerve block may be an effective treatment for patients with bilateral trismus due to ischemic-encephalopathy, even when consciousness is impaired.

Analysis of modified apolipoprotein B-100 structures formed in oxidized low-density lipoprotein using LC-MS/MS.

Oxidatively modified low-density lipoprotein (oxLDL) is one of the major factors involved in the development of atherosclerosis. Because of the insolubility of apolipoprotein B-100 (apoB-100) and the heterogeneous nature of oxidative modification, modified structures of apoB-100 in oxLDL are poorly understood. We applied an on-Membrane sample preparation procedure for LC-MS/MS analysis of apoB-100 proteins in native and modified low-density lipoprotein (LDL) samples to eliminate lipid components in the LDLs followed by collection of tryptic digests of apoB-100. Compared with a commonly used in-gel digestion protocol, the sample preparation procedure using PVDF membrane greatly increased the recovery of tryptic peptides and resulted in improved sequence coverage in the final analysis, which lead to the identification of modified amino acid residues in copper-induced oxLDL. A histidine residue modified by 4-hydroxynonenal, a major lipid peroxidation product, as well as oxidized histidine and tryptophan residues were detected. LC-MS/MS in combination with the on-Membrane sample preparation procedure is a useful method to analyze highly hydrophobic proteins such as apoB-100.

Tissue-engineered microvessels on three-dimensional biodegradable scaffolds using human endothelial progenitor cells.

Tissue engineering may offer patients new options when replacement or repair of an organ is needed. However, most tissues will require a microvascular network to supply oxygen and nutrients. One strategy for creating a microvascular network would be promotion of vasculogenesis in situ by seeding vascular progenitor cells within the biopolymeric construct. To pursue this strategy, we isolated CD34(+)/CD133(+) endothelial progenitor cells (EPC) from human umbilical cord blood and expanded the cells ex vivo as EPC-derived endothelial cells (EC). The EPC lost expression of the stem cell marker CD133 but continued to express the endothelial markers KDR/VEGF-R2, VE-cadherin, CD31, von Willebrand factor, and E-selectin. The cells were also shown to mediate calcium-dependent adhesion of HL-60 cells, a human promyelocytic leukemia cell line, providing evidence for a proinflammatory endothelial phenotype. The EPC-derived EC maintained this endothelial phenotype when expanded in roller bottles and subsequently seeded on polyglycolic acid-poly-l-lactic acid (PGA-PLLA) scaffolds, but microvessel formation was not observed. In contrast, EPC-derived EC seeded with human smooth muscle cells formed capillary-like structures throughout the scaffold (76.5 +/- 35 microvessels/mm(2)). These results indicate that 1) EPC-derived EC can be expanded in vitro and seeded on biodegradable scaffolds with preservation of endothelial phenotype and 2) EPC-derived EC seeded with human smooth muscle cells form microvessels on porous PGA-PLLA scaffolds. These properties indicate that EPC may be well suited for creating microvascular networks within tissue-engineered constructs.