Peripheral Nerve Defects: Repair Using Autogenous Vein Grafts Filled with PRP and Active Nerve Microtissues and Evaluation by Novel Multimodal Ultrasound Techniques

Background: Developing biocompatible nerve conduits that accelerate peripheral nerve regeneration, lengthening and functional recovery remains a challenge. The combined application of nerve microtissues and platelet-rich plasma (PRP) provides abundant Schwann cells (SCs) and various natural growth factors and can compensate for the deficiency of SCs in the nerve bridge, as well as the limitations of applying a single type of growth factor. Multimodal ultrasound evaluation can provide additional information on the stiffness and microvascular flow perfusion of the tissue. This study was designed to investigate the effectiveness of a novel tissue-engineered nerve graft composed of an autogenous vein, nerve microtissues and PRP in reconstructing a 12-mm tibial nerve defect and to explore the value of multimodal ultrasound techniques in evaluating the prognosis of nerve repair. Methods: In vitro, nerve microtissue activity was first investigated, and the effects on SC proliferation, migration, factor secretion, and axonal regeneration of dorsal root ganglia (DRG) were evaluated by coculture with nerve microtissues and PRP. In vivo, seventy-five rabbits were equally and randomly divided into Hollow, PRP, Micro-T (Microtissues), Micro-T+PRP and Autograft groups. By analysing the neurological function, electrophysiological recovery, and the comparative results of multimodal ultrasound and histological evaluation, we investigated the effect of these new nerve grafts in repairing tibial nerve defects. Results: Our results showed that the combined application of nerve microtissues and PRP could significantly promote the proliferation, secretion and migration of SCs and the regeneration of axons in the early stage. The Micro-T+PRP group and Autograft groups exhibited the best nerve repair 12 weeks postoperatively. In addition, the changes in target tissue stiffness and microvascular perfusion on multimodal ultrasound (shear wave elastography; contrast-enhanced ultrasonography; Angio PlaneWave UltrasenSitive, AngioPLUS) were significantly correlated with the histological results, such as collagen area percentage and VEGF expression, respectively. Conclusion: Our novel tissue-engineered nerve graft shows excellent efficacy in repairing 12-mm defects of the tibial nerve in rabbits. Moreover, multimodal ultrasound may provide a clinical reference for prognosis by quantitatively evaluating the stiffness and microvescular flow of nerve grafts and targeted muscles.

Outcomes after Arterial Reconstruction with Autogenous Vein Graft for Limb Salvage in Traumatized Extremity

Purpose: The patients with major vascular injuries in the traumatized extremity and underwent arterial reconstruction using autogenous vein grafts for limb salvage. This study aims to report the outcomes of arterial reconstruction with autogenous vein graft in patients.Methods: From February 2015 to April 2017, a study was retrospectively analyzed 13 patients with limb injuries caused by significant arterial damage and underwent arterial reconstruction using vascular autografts for limb salvage. Such as cause, Mangled Extremity Severity Scores (MESS), ischemic time, length of the grafted vein, reconstructed arterial status, and survival status were analyzed. Results: Among the patients analyzed, nine patients’ injuries were caused by traffic accidents and three industrial accidents, one fall down. Mean MESS was 6.2 (range, 5–8) and mean ischemic time was 12.3 hours (range, 5–25 hours). As arterial reconstruction, seven patients underwent posterior tibial artery reconstruction, three underwent popliteal artery reconstruction, two underwent anterior tibial artery reconstruction, and one underwent radial artery reconstruction; the greater saphenous vein was grafted in 12 reconstruction cases. Mean length of the grafted vein was 4.9 cm (range, 3–10 cm). All patients have salvaged injured limbs.Conclusion: Artery reconstruction using autogenous vein graft is an efficient treatment method when vascular damage cannot be directly repaired during limb salvage.

Massive hematuria due to an autogenous saphenous vein graft and urinary bladder fistula in an extra-anatomic iliofemoral bypass: a case report

Introduction Gross hematuria caused by rupture of an artery in the urinary tract is a rare but potentially fatal condition. Iliac artery aneurysms, pelvic surgery with radiation, vascular reconstructive surgery, surgery for stenosis of the ureteropelvic junction, and transplantation are reported to be associated with this condition. In the vascular reconstructive surgery group, the most common etiology is rupture of the degenerated artery or synthetic graft in the ureter. Case presentation We present a case of rupture of the small anastomotic pseudoaneurysm at the proximal anastomosis of a right iliofemoral autogenous vein extra-anatomic graft in the urinary bladder. To our knowledge, this is the first report of a rupture of an autogenous vein graft in the urinary bladder. Our patient, a 24-year-old Albanian farmer, was admitted to the emergency department in severe hemorrhagic shock induced by exsanguinating hematuria. He underwent immediate surgery, during which direct sutures to the bladder were placed and the saphenous graft was replaced with a synthetic one. The patient recovered completely, was free of hematuria, and showed no signs of pathological communication between the urinary and arterial tracts on postoperative cystoscopy and computed tomographic angiography during 2 years of follow-up. Conclusion The incidence of artery-to-urinary tract fistulas is growing due to the increasing use of urologic and vascular surgery, pelvic oncologic surgery, and radiation therapy. In addition to fistulas involving a degenerated artery and ureter or synthetic grafts and ureter, they can also involve an autogenous vein graft and the urinary bladder. In our patient, the fistula was a result of erosion of the bladder from a pseudoaneurysm at the proximal anastomosis of an autogenous vein iliofemoral bypass in an extra-anatomic position. Open surgery remains the best treatment option, although there is increasing evidence of successful endovascular treatment.

Platelet-Rich Fibrin Conduits as an Alternative to Nerve Autografts for Peripheral Nerve Repair

Background Peripheral nerves have limited regeneration capacity despite best efforts. Platelet-rich fibrin (PRF) contains growth factors that may stimulate peripheral nerve regeneration. This study verified whether nerve regeneration using autogenous vein conduits filled with PRF is comparable to autologous nerve graft, which is the standard treatment. Methods The sciatic nerve of the right paw of inbred rats was dissected, and a 10-mm segment was removed from rats randomized to receive autologous nerve graft (GRAFT) or vein conduit filled with PRF (PRF). A third group (SHAM) underwent surgery without nerve resection. The sciatic functional index (SFI) was measured 0, 30, 60, and 90 days postsurgery. Morphometry and morphology of the distal nerve injury were examined. Motor neurons in the anterior horn of spinal cord stained with FluoroGold and counted. Results No significant difference in SFI was observed between the GRAFT and PRF groups at any time point (all p > 0.05); however, SFI was lower in both groups compared with SHAM (p < 0.05). Morphometric and morphologic indexes were not significantly different between the GRAFT and PRF groups (p > 0.05); however, nerve fibers, axons, and myelin sheaths were thinner in both groups compared with SHAM (p = 0.0001). Average motor neurons' count was similar between the GRAFT and PRF groups (p = 0.91); the count was lower in both groups compared with SHAM (p = 0.002 and p = 0.001), respectively. Conclusion Autologous nerve GRAFT and PRF-filled autogenous vein conduits were associated with similar outcomes, and worse than those observed in SHAM controls. Vein conduits filled with PRF may be a favorable alternative treatment to nerve grafts.

Collagen External Scaffolds Mitigate Intimal Hyperplasia and Improve Remodeling of Vein Grafts in a Rabbit Arteriovenous Graft Model

Objectives. The aim of this study was to test the effects of collagen external scaffold (CES) in intimal hyperplasia of vein grafts and explore its underlying mechanisms. Methods. Thirty-six New Zealand white rabbits were randomized into no-graft group, graft group, and CES group. The rabbit arteriovenous graft model was established. In CES group, the vein graft was wrapped around with CES. The hemodynamic parameters of vein grafts were measured intraoperatively and 4 weeks after operation by ultrasonic examination. Histological characteristics of vein grafts were also evaluated 4 weeks later. The mRNA and protein levels of proliferating cell nuclear antigen (PCNA), active cleaved-caspase-3 (ClvCasp-3), and smooth muscle 22 alpha (SM22α) were measured 4 weeks later by quantitative real-time PCR and western blot. Results. CES significantly improved the hemodynamic stability of vein grafts, with higher blood velocity and blood flow. Similarly, CES also markedly mitigated intimal hyperplasia and inhibited dilatation of vein grafts. In CES group, the upexpression of PCNA and ClvCasp-3 and the downexpression of SM22α were inhibited. Conclusion. CES exerts beneficial effects in mitigating intimal hyperplasia and improving remodeling of autogenous vein grafts, which may be associated with reducing the proliferation and apoptosis and preserving the phenotype of VSMCs.