Elastomeric Fibrous Hybrid Scaffold Supports In Vitro and In Vivo Tissue Formation.

Biomimetic materials with biomechanical properties resembling those of native tissues while providing an environment for cell growth and tissue formation, are vital for tissue engineering (TE). Mechanical anisotropy is an important property of native cardiovascular tissues and directly influences tissue function. This study reports fabrication of anisotropic cell-seeded constructs while retaining control over the construct's architecture and distribution of cells. Newly synthesized poly-4-hydroxybutyrate (P4HB) is fabricated with a dry spinning technique to create anelastomeric fibrous scaffold that allows control of fiber diameter, porosity, and rate ofdegradation. To allow cell and tissue ingrowth, hybrid scaffolds with mesenchymalstem cells (MSCs) encapsulated in a photocrosslinkable hydrogel were developed. Culturing the cellularized scaffolds in a cyclic stretch/flexure bioreactor resulted in tissue formation and confirmed the scaffold's performance under mechanical stimulation. In vivo experiments showed that the hybrid scaffold is capable of withstanding physiological pressures when implanted as a patch in the pulmonary artery. Aligned tissue formation occurred on the scaffold luminal surface without macroscopic thrombus formation. This combination of a novel, anisotropic fibrous scaffold and a tunable native-like hydrogel for cellular encapsulation promoted formation of 3D tissue and provides a biologically functional composite scaffold for soft-tissue engineering applications.

Effect of the use of internal iliac artery for renal transplantation on penile vascularity and erectile function: a prospective study.

PURPOSE: We determined the effects of the use of internal iliac artery for renal transplantation on erectile function and penile hemodynamics in prospective fashion. MATERIALS AND METHODS: The study comprised 50 patients with chronic renal failure on hemodialysis without associated vascular risk factors. All patients were evaluated before and after renal transplantation with 6-month followup. All grafts were revascularized with end-to-end anastomosis to the right internal iliac artery. Before and after transplantation the patients were evaluated by detailed history, including the International Index of Erectile Function, clinical examination, laboratory investigations and pharmacodynamic penile color duplex ultrasonography. RESULTS: Erectile dysfunction was reported by 28% of the patients with chronic renal failure. This incidence becomes 26% after transplantation. Based on questionnaires post-transplantation erectile function compared to pre-transplant status was improved, deteriorated or remained static in 40%, 18% and 42% of transplant recipients, respectively. The International Index of Erectile Function showed no differences between pre-transplantation and posttransplantation sexual function except in the domain of sexual desire. In comparison to preoperative penile indices, there was a significant decrease in penile arterial blood flow in the 2 cavernous arteries (p <0.05). However, none of the patients had penile arterial insufficiency. CONCLUSIONS: Renal transplantation has varying effects on erectile function. In the majority of cases it has no negative effect on the quality of erection. In the absence of associated vascular risk factors unilateral interruption of the internal iliac artery decreases arterial penile blood flow but not to a degree that compromise erectile function.

Vasculogenic erectile dysfunction in renal transplant recipients--assessment of potential risk factors.

OBJECTIVES: This study was performed to determine the effects of renal transplantation on penile haemodynamics using pharmaco-stimulation and colour Duplex ultrasonographic examination and then to determine the possible vascular risk factors for impotence in these patients. MATERIAL AND METHODS: A total of 100 renal transplant recipients (RTRs; 80 impotent, 20 potent) and 20 potent uraemic patients on haemodialysis waiting for transplantation (control group) were included in the study. The patients were evaluated by means of detailed medical and sexual histories, clinical examination and laboratory investigations. The severity of erectile dysfunction was assessed using the International Index of Erectile Function questionnaire. Pharmacodynamic penile Duplex ultrasonography was carried out for all patients. RESULTS: The following factors were more commonly associated with impotent compared to potent RTRs: older age, diabetes mellitus, a longer pre-transplant duration of uraemia, impaired graft function and the use of cyclosporin A-based immunosuppressive therapy. Arterial occlusive disease was identified among 11 RTRs (11%), all of whom were impotent. Impotent RTRs had a significantly lower penile blood flow compared to potent RTRs or controls. Age, duration of pre-transplant uraemia and cyclosporin A level had a negative impact on penile haemodynamic parameters. CONCLUSIONS: Penile vascular insufficiency is less common in RTRs than previously reported. The pathogenesis of penile arterial occlusive disease in impotent RTRs is mainly due to associated vascular risk factors. After unilateral interruption of the internal iliac artery, an adequate penile blood supply is maintained in the majority of cases. Early transplantation may delay or prevent the development of penile vasculopathy.