Bone marrow cells are able to increase vessels number during repair of sciatic nerve lesion.

The aim of this study was to compare the outcomes of nerve autografts (GRF) and venous grafts containing mononuclear bone marrow cells (BMCs) in sciatic nerve-lesioned rats. Control animals underwent sham operations (SHAM), received empty venous grafts (EPV), or received venous grafts containing BMC vehicle (AGR). Outcome was evaluated through sciatic functional index (SFI), morphometric and morphologic analyses of the nerve distal to the lesion, and the number of spinal cord motor neurons positive for the retrograde tracer, Fluoro-Gold. All groups exhibited poor results in SFI when compared to SHAM animals throughout the postoperative period. All groups also had a significantly greater fiber density, decreased fiber diameter, and decreased motor neuron number than the SHAM group. No significant difference between the GRF and BMC groups was observed in any of these parameters. On the other hand, vessel density was significantly higher in BMC than all other groups. BMC-containing venous grafts are superior to nerve autografts in increasing vessel density during sciatic nerve regeneration.

Differential functional coupling between human saphenous cryoallografts and arteries: importance of the arterial type and the biomechanical parameter evaluated.

The aim of this study was to characterize and compare human great saphenous veins (HGSVs), HGSV cryoallografts, expanded polytetrafluoroethylene (ePTFE) segments, and elastic and muscular arteries' biomechanics, so as to identify if the biomechanical coupling and the HGSV advantages with respect to ePTFE depend on the arterial type and/or on the biomechanical property considered. Pressure and diameter were measured in vitro, under arterial hemodynamic conditions, in elastic and muscular arteries, and in vascular substitutes: fresh and cryopreserved HGSV and ePTFE segments. The wall's dynamics (compliance, viscosity, and inertia), energy dissipation, and buffering were calculated. The coupling was quantified for each biomechanical parameter. Cryopreservation preserved HGSV biomechanics. The HGSV cryoallografts' dynamics, energetics, and buffering were lesser with respect to both arteries, but were higher than the ePTFE. The coupling differed, depending on the arterial type and property considered. The biomechanical coupling depended on the artery and property considered. HGSV cryoallograft advantages over ePTFE were arterial type and property independent.

[Viscoelastic and functional similarities between native femoral arteries and fresh or cryopreserved arterial and venous homografts]. / Acoplamiento viscoelástico y funcional entre arterias femorales nativas y homoinjertos arteriales y venosos, frescos y criopreservados.

INTRODUCTION AND OBJECTIVES: It is not yet known whether cryopreservation enables vessels to retain their viscoelastic properties or whether cryopreserved homografts are biomechanically more like native arteries than currently used vascular prostheses. The study objectives were: a) to determine whether our cryopreservation methodology enables arterial and venous homografts to retain their viscoelastic and functional properties; and b) to assess similarities between patients' femoral arteries, homografts, and other vascular prostheses in common use. METHODS: The pressure and the diameter and parietal thickness of 15 muscular (femoral) arteries were measured in patients using tonometry and echography, both noninvasive techniques. In addition, the pressure in and diameter and parietal thickness of 15 fresh and 15 cryopreserved human muscular (femoral) artery segments, saphenous veins, and 15 expanded polytetrafluoroethylene (ePTFE) vascular prostheses were measured in vitro under hemodynamic conditions similar to those in patients. A Kelvin-Voigt model of the segment wall was used to derive elastic (Epd, mm Hg/mm) and viscous (Vpd, mm Hg x s/mm) pressure-diameter indices, the buffering function (Vpd/Epd), and the conduit function (1/Zc, where Zc is the characteristic impedance). The incremental Young modulus, the pressure-strain elastic modulus, and pulse wave velocity were also calculated. RESULTS: No difference was observed between either the viscoelastic or functional properties of fresh and cryopreserved homografts. Arterial homografts were the most similar to the patient's arteries. CONCLUSIONS: Cryopreservation enabled venous and arterial homografts to retain their viscoelastic and functional properties. Of all the grafts investigated, arterial homografts were most similar, both biomechanically and functionally, to the patient's femoral arteries.

Artificial microvascular graft thrombosis: the consequences of platelet membrane glycoprotein Ib inhibition and thrombin inhibition.

Early thrombosis of artificial microvascular grafts (AMG, grafts < or = 2 mm internal diameter) prevents their reliable clinical use. The present studies were undertaken to examine the effect of hirudin, a thrombin-specific inhibitor, and of the F(ab')2 fragment of PG-1, a monoclonal antibody (MoAb) directed against guinea pig platelet membrane glycoprotein Ib (GPIb), on AMG patency in an animal model. One-centimeter long segments of expanded polytetrafluoroethylene (ePTFE), 0.88 mm internal diameter, were serially implanted as interposition grafts in the guinea pig femoral arterial systems bilaterally. A control group was treated with 0.5 mL saline intravenously (IV) 30 minutes before limb 1 and limb 2 graft implantation. Three experimental groups were treated with 0.5 mL saline IV before limb 1 graft implantation as an animal control and with either 0.5 mL saline containing 1.25 mg/kg IV PG-1 F(ab')2, (which inhibits ristocetin-induced platelet agglutination and von Willebrand factor binding), hirudin 1 mg/kg IV, or a combination of both agents before limb 2 graft implantation. GPIb inhibition, thrombin inhibition, and the combination resulted in a significant prolongation of AMG patency (P < .005). Whereas thrombin inhibition with hirudin prolonged AMG patency similar to that observed with GPIb inhibition, the combination of GPIb and thrombin inhibition provided the overall longest prolongation of AMG patency. These results indicate that both platelet membrane GPIb and thrombin play a role in AMG thrombosis.