Yuka Kondo

Decellularized tissue-engineered blood vessel as an arterial conduit

Arterial tissue-engineering techniques that have been reported previously typically involve long waiting times of several months while cells from the recipient are cultured to create the engineered vessel. In this study, we developed a different approach to arterial tissue engineering that can substantially reduce the waiting time for a graft. Tissue-engineered vessels (TEVs) were grown from banked porcine smooth muscle cells that were allogeneic to the intended recipient, using a biomimetic perfusion system. The engineered vessels were then decellularized, leaving behind the mechanically robust extracellular matrix of the graft wall. The acellular grafts were then seeded with cells that were derived from the intended recipient—either endothelial progenitor cells (EPC) or endothelial cell (EC)—on the graft lumen. TEV were then implanted as end-to-side grafts in the porcine carotid artery, which is a rigorous testbed due to its tendency for graft occlusion. The EPC- and EC-seeded TEV all remained patent for 30 d in this study, whereas the contralateral control vein grafts were patent in only 3/8 implants. Going along with the improved patency, the cell-seeded TEV demonstrated less neointimal hyperplasia and fewer proliferating cells than did the vein grafts. Proteins in the mammalian target of rapamycin signaling pathway tended to be decreased in TEV compared with vein grafts, implicating this pathway in the TEVs resistance to occlusion from intimal hyperplasia. These results indicate that a readily available, decellularized tissue-engineered vessel can be seeded with autologous endothelial progenitor cells to provide a biological vascular graft that resists both clotting and intimal hyperplasia. In addition, these results show that engineered connective tissues can be grown from banked cells, rendered acellular, and then used for tissue regeneration in vivo.

Eph-B4 prevents venous adaptive remodeling in the adult arterial environment

Stimulation of Eph-B4 prevents adaptive remodeling and preserves venous identity when veins are surgically placed into an arterial environment.

Optimal prosthetic graft design for small diameter vascular grafts.

Autogenous vein and arterial grafts, such as great saphenous veins and internal mammary and radial arteries, remain the gold standard conduits for vascular reconstruction. Expanded polytetrafluoroethylene (PTFE) grafts, which exhibit little inflammatory and thrombogenic reactivity, are the most commonly used material of choice for small diameter vascular grafts when autogenous grafts are not available. Several modifications of the basic graft have been attempted to enhance graft healing of expanded PTFE grafts, and little but definite experimental and clinical improvement has been achieved so far. The technique of vascular tissue engineering, in combination with stem cell research, may hold the key for the creation of a practical and successful small diameter prosthetic graft.

The Effect of L-Menthol Stimulation of the Major Palatine Nerve on Nasal Patency

Objective and subjective measurements of nasal patency were made before and after L-menthol stimulation of the palatal mucosa (supplied with the trigeminal nerve) in 15 normal adult subjects. The stimulation exerted indirect effect on the nasal cavity in that all subjects mentioned a cold sensation in their nose and a sensation of increased nasal patency, but no influence on nasal resistance to airflow was detected.

The effect of l-menthol stimulation of the major palatine nerve on subjective and objective nasal patency

To determine whether L-menthol stimulation of the major palatine nerve can affect nasal patency, we noted subjective and measured objective nasal patency before and after L-menthol stimulation of the palatal mucosa. L-Menthol stimulation of the palatal mucosa enhanced nasal sensation of airflow but nasal resistance was unaffected. By contrast, L-menthol stimulation after local anesthesia of the palatine nerve or of the nasal mucosa substantially diminished the subjective response of increased nasal patency but without affecting objective nasal patency. It is suggested that the effect of both direct stimulation by L-menthol of the major palatine nerve and its vapor action on the sensory nerve endings of the nasal mucosa produce an increase in the sensation of nasal patency without an increase in objective nasal patency.

Deep venous thrombosis caused by congenital absence of the inferior vena cava: Report of a case

Although anomalies of the inferior vena cava (IVC) are seen frequently in a clinical setting, congenital absence of the IVC (AIVC) is rare. However, anomalies of the IVC should be considered in young patients suffering from recurrent and idiopathic DVT. We report a case of DVT possibly caused by AIVC in a 27-year-old man, and discuss the clinical features, diagnosis, and treatment of this unusual entity.

Vascular endothelial growth factor-A inhibits EphB4 and stimulates delta-like ligand 4 expression in adult endothelial cells

BACKGROUND During vein graft adaptation to the arterial circulation, vascular endothelial growth factor (VEGF) A expression transiently increases before becoming downregulated; however, the role of VEGF-A in venous remodeling is not clear. In addition, although VEGF-A stimulates angiogenesis and determines arterial identity in nascent arterial endothelial cells (EC), the role of VEGF-A in regulating identity in adult venous EC is also not clear. MATERIALS AND METHODS EC, wild type (EphB4+/+) or heterozygous knockout (EphB4+/-), were stimulated with VEGF-A (0-100 ng/mL) and examined with quantitative polymerase chain reaction and western blotting. RESULTS VEGF-A (100 ng/mL) inhibited expression of EphB4 and stimulated expression of delta-like ligand 4 (dll4) but did not stimulate either notch or EphrinB2 expression in adult venous EC. Pretreatment with VEGF receptor 2-neutralizing antibody abolished VEGF-stimulated downregulation of EphB4 but not the upregulation of dll4. Pretreatment with PD98059 or wortmannin showed that VEGF-A downregulation of EphB4 and upregulation of dll4 are mitogen-activated protein kinase kinase and extracellular signal-regulated kinase dependent but phosphatidylinositol 3 kinase-Akt independent. Compared with VEGF-induced EphB4 downregulation and dll4 upregulation in control EC, reduced EphB4 signaling in EphB4+/- EC showed even further downregulation of EphB4 and upregulation of dll4. CONCLUSIONS Despite the genetic programming of arterial and venous EC fate, VEGF-A can repress venous identity in adult venous EC without induction of arterial identity. These changes in adult EC in vitro recapitulate the changes in identity described during vein graft adaptation to the arterial environment in vivo.

Age-Related Neointimal Hyperplasia Is Associated With Monocyte Infiltration After Balloon Angioplasty

Carotid angioplasty is associated with adverse events in elderly patients; it is unclear whether this is related to an altered inflammatory axis. The carotid arteries of young (6 months) or aged (22-24 months) Fischer 344 rats were balloon injured. Aged rats had reduced lumen area (0.18 ± 0.03 vs 0.24 ± 0.01 mm(2), p = .02) and increased neointimal thickening (0.15 ± 0.04 vs 0.08 ± 0.03 mm(2), p = .006). Aged rats had increased circulating monocytes (96 ± 21 vs. 54 ± 7; p = .002) as well as increased numbers of monocytes at the post-angioplasty site. Aged rats had sustained monocyte chemotactic protein-1 expression after angioplasty but young rats did not. Aged arteries also exhibited defective vasorelaxation and abnormal eNOS localization. Aged (≥80 years) human patients with high-grade carotid stenosis had increased number of monocytes (9.1% ± 0.4%) compared with younger (65-80 years) patients (8.1% ± 0.3%, p = .013). Aged rats develop neointimal hyperplasia after carotid angioplasty with increased numbers of monocytes, and elderly humans with carotid stenosis have increased numbers of circulating monocytes. These preliminary results may suggest a role for monocytes in the response to carotid angioplasty.

A comparison of current expressions of nasal patency

SummaryRhinomanometry is well established as a useful clinical method for objective assessment of nasal patency, although several expressions of nasal patency have been reported and universal standardization has not been achieved. In this communication, nasal resistances were calculated from the equation R = ΔP/V (R; resistance; ΔP; transnasal differential pressure; V; nasal airflow) at ΔP 100 Pa and at peak flow. Time-averaged nasal resistances and integrated nasal patencies were measured in 350 adult patients by Rhinorheograph MPR-1100 and processed by a NI-101 computer program. The values from the equation R = ΔP/V at ΔP 100 Pa were slightly lower than those from the same equation at peak flow or those from the time-averaging method. Correlations between the values of nasal resistance at peak flow and the time averaging method were very close to the line of identity. No significant correlations were demonstrated between integrated nasal patency and the values from the other three expressions. The differences of the results from these expression are discussed.

The Nogo-B-PirB axis controls macrophage-mediated vascular remodeling.

Objective Nogo-B mediates vascular protection and facilitates monocyte- and macrophage-dependent vascular remodeling. PirB is an alternate receptor for Nogo-B, but a role for the Nogo-PirB axis within the vascular system has not been previously reported. We examined whether Nogo-B or PirB play a role in regulating macrophage-mediated vascular remodeling and hypothesized that endothelial Nogo-B regulates vein graft macrophage infiltration via its alternate receptor PirB. Methods Vein grafts were performed using Nogo and PirB wild type and knockout mice. Human vein grafts were similarly analyzed. The hindlimb ischemia model was performed in PirB wild type and knockout mice. Accompanying in vitro work included isolation of macrophages from PirB wild type and knockout mice. Results Increased Nogo-B and PirB mRNA transcripts and protein expression were observed within mouse and human vein grafts. Both Nogo knockout and PirB knockout vein grafts showed increased wall thickness and increased numbers of F4/80-positive macrophages. Macrophages derived from PirB knockout mice had increased adhesion to fibronectin, increased EC-specific binding, and increased numbers of mRNA transcripts of M2 markers as well as MMP3 and MMP9. PirB knockout vein grafts had increased active MMP9 compared to wild type vein grafts. PirB knockout mice had increased recovery from hindlimb ischemia and increased macrophage infiltration compared to wild type mice. Conclusions Vein graft adaptation shows increased expression of both Nogo-B and PirB. Loss of PirB, or its endothelial ligand Nogo-B, results in increased inflammatory cell infiltration and vein graft wall thickening. These findings suggest that PirB regulates macrophage activity in vein grafts and that Nogo-B in the vein graft limits macrophage infiltration and vein graft thickening. PirB may play a more general role in regulating macrophage responses to vascular injury. Macrophage inhibition via Nogo-PirB interactions may be an important mechanism regulating vein graft adaptation to the arterial circulation.