Gastrointestinal Bleeding Successfully Treated Using Interventional Radiology.

Gastrointestinal (GI) bleeding is an emergency medical condition that leads to hemorrhagic shock or circulatory instability if left untreated. A mainstay for treating GI bleeding is endoscopic therapy; more than 90% of GI bleeding can be staunched by endoscopic hemostasis. However, patients with unstable hemodynamics or GI bleeding that cannot be controlled by endoscopy require transcatheter embolization or surgical intervention. The development of several devices and embolization agents that are used in interventional radiology (IVR) leads to safe and accessible treatment via IVR. If endoscopic treatment fails, IVR is the second strategy. Herein, we report cases of GI bleeding that were successfully treated by IVR and discuss the therapeutic strategy.

In situ tissue engineering for tracheal reconstruction using a luminar remodeling type of artificial trachea.

BACKGROUND: After successful trials of tracheal reconstruction using mesh-type prostheses in canine models, the technique has been applied clinically to human patients since 2002. To enhance tissue regeneration, we have applied a new tissue engineering approach to this mesh-type prosthesis. METHODS: The prosthesis consists of a polypropylene mesh tube reinforced with a polypropylene spiral and atelocollagen layer. The cervical tracheas of 18 beagle dogs were replaced with the prosthesis. The collagen layer was soaked with peripheral blood in 6 of the dogs, with bone marrow aspirate in another 6, and with autologous multipotential bone marrow-derived cells (mesenchymal stem cells) in another 6. The dogs were humanely killed at 1 to 12 months after the operation. RESULTS: All 18 dogs survived the postoperative period. Bronchoscopically, 3 of 4 dogs in the peripheral blood group showed stenosis, whereas no stenosis was evident in all 8 of the dogs in the bone marrow and mesenchymal stem cell groups 6 months after the operation. Faster epithelialization and fewer complications, such as mesh exposure and luminal stenosis, were observed in these two groups than in the peripheral blood group. Histologically, the cells from autologous bone marrow were found to proliferate into the tracheal tissue during the first month. Cilial movement in these two groups was faster than that in the peripheral blood group and recovered to 80% to 90% of the normal level. CONCLUSIONS: Bone marrow aspirate and mesenchymal stem cells enhance the regeneration of the tracheal mucosa on this prosthesis. This in situ tissue engineering approach may facilitate tracheal reconstruction in the clinical setting.

Experimental repair of phrenic nerve using a polyglycolic acid and collagen tube.

OBJECTIVE: The feasibility of a nerve guide tube for regeneration of the phrenic nerve with the aim of restoring diaphragmatic function was evaluated in a canine model. METHODS: The nerve tube, made of woven polyglycolic acid mesh, had a diameter of 3 mm and was filled with collagen sponge. This polyglycolic acid-collagen tube was implanted into a 10-mm gap created by transection of the right phrenic nerve in 9 beagle dogs. The tubes were implanted without a tissue covering in 5 of the 9 dogs (group I), and the tubes were covered with a pedicled pericardial fat pad in 4 dogs (group II). Chest x-ray films, muscle action potentials, and histologic samples were examined 4 to 12 months after implantation. RESULTS: All of the dogs survived without any complications. x-ray film examination showed that the right diaphragm was paralyzed and elevated in all dogs until 3 months after implantation. At 4 months, movement of the diaphragm in the implanted side was observed during spontaneous breathing in 1 dog of group I and in 3 dogs of group II. In the dogs showing diaphragm movement, muscle action potentials were evoked in the diaphragm muscle, indicating restoration of nerve function. Regeneration of the phrenic nerve structure was also examined on the reconstructed site using electron microscopy. CONCLUSION: The polyglycolic acid-collagen tube induced functional recovery of the injured phrenic nerve and was aided by coverage with a pedicled pericardial fat pad.

Bronchoscopic treatment of postpneumonectomy bronchopleural fistula with a collagen screw plug.

OBJECTIVE: Bronchopleural fistula is a critical complication that may occur after pulmonary resection. Early closure of the fistula is required to prevent thoracic empyema or aspiration pneumonia. We have designed a novel procedure for bronchoscopic occlusion of the fistula with a collagen screw plug and assessed its feasibility in an experimental animal model. METHODS: Adult beagle dogs underwent right or left pneumonectomy, and the bronchial stump was closed with the Sweet method. A silicone bar (2 mm in diameter) was then placed in the middle of the bronchial stump. Seven days after the operation, the silicone bar was removed bronchoscopically, and fistula formation was confirmed. A screw-shaped 2% collagen screw plug (20 mm long and 3 mm in diameter) was mounted at the end of a modified endoscopic cannula and then inserted into the fistula. Autologous platelet-rich plasma was then soaked onto the inserted plug. RESULTS: Nine of 10 beagle dogs with bronchopleural fistula were treated successfully by plug occlusion. One dog died of pneumothorax caused by dislocation of the plug. Pathologic examination revealed that the collagen sponge had been replaced by fibrous tissue and that the fistula was covered with normal epithelium. Although soaking with platelet-rich plasma made the plug airtight immediately, the use of platelet-rich plasma seemed to make no distinct difference with respect to the treatment result or pathologic findings. CONCLUSION: Bronchoscopic occlusion with a collagen screw plug is a promising option for treatment of small bronchopleural fistulas after pulmonary surgery.

Experimental study on the regeneration of peripheral nerve gaps through a polyglycolic acid-collagen (PGA-collagen) tube.

We have developed a bioabsorbable polyglycolic acid (PGA) tube filled with collagen sponge (PGA-collagen tube) as a nerve connective guide, and compared its effectiveness with that of autograft in terms of nerve regeneration across a gap. The PGA-collagen tube was implanted into 24 beagle dogs across a 15-mm gap in the left peroneal nerve. The right peroneal nerve was reconstructed with the autograft harvested from the left side, as a control. After the surgery, the connective tissue extended from both cut ends in the PGA-collagen tube and connected again at the center. Pathologically, the collagen sponge in the tube provided adequate scaffolding for nerve tissue extension, and the nerve tissue reconnected within 3 weeks. Electrophysiologically, muscle-evoked potentials (MEPs) and compound nerve action potentials (CNAPs) were detected 18 days after the surgery. For up to 6 months postsurgery, CNAPs and somatosensory-evoked potentials (SEPs) on the PGA-collagen side had a shorter latency and larger peak voltage than those on the autograft side. The myelinated axons on the PGA side were larger in diameter than those on the autograft side. It is suggested that the PGA-collagen tube has the potential to be an effective alternative to conventional autografting for the repair of some peripheral nerve defects.

Sterilized, freeze-dried amniotic membrane: a useful substrate for ocular surface reconstruction.

PURPOSE: To examine the feasibility of using sterilized, freeze-dried amniotic membrane (FD-AM) as a substrate for cultivating autologous corneal epithelial cells for ocular surface reconstruction. METHODS: Human AM deprived of amniotic epithelial cells by incubation with EDTA was freeze dried, vacuum packed, and sterilized with gamma-irradiation. The resultant FD-AM was characterized for its physical, biological, and morphologic properties by stretch stress tests, immunohistochemistry, electron microscopy, and cell culture. In addition, 3 weeks after an ocular surface injury, the conjunctivalized corneal surfaces of eyes in eight rabbits were surgically reconstructed by transplantation of autologous cultivated corneal epithelial cells on FD-AM. RESULTS: A stretch stress test revealed no significant differences between sterilized FD-AM and cryopreserved AM. Immunohistochemistry for several extracellular matrix molecules and electron microscopic analysis of FD-AM revealed that the process of drying and irradiation did not affect its biological and morphologic properties. The corneal epithelial cells cultivated on FD-AM had four to five stratified, well-differentiated cell layers. Corneas that were grafted with the cultivated corneal epithelial cells on FD-AM were clear and were all epithelialized at 10 days after surgery. CONCLUSIONS: The sterilized, freeze-dried AM retained most of the physical, biological, and morphologic characteristics of cryopreserved AM; consequently, it is a useful biomaterial for ocular surface reconstruction.

Use of collagen sponge incorporating transforming growth factor-beta1 to promote bone repair in skull defects in rabbits.

The objective of this study was to evaluate the potential of collagen sponge incorporating transforming growth factor-beta1 (TGF-beta1) to enhance bone repair. The collagen sponge was prepared by freeze-drying aqueous foamed collagen solution. Thermal cross-linking was performed in a vacuum at 140 degrees C for periods ranging from 1 to 48 h to prepare a number of fine collagen sponges. When collagen sponges incorporating 125I-labeled TGF-beta1 were placed in phosphate-buffered saline (PBS) solution at 37 degrees C, a small amount of TGF-beta1 was released for the first hour, but no further release was observed thereafter, irrespective of the amount of cross-linking time the sponges had received. Collagen sponges incorporating 125I-labeled TGF-beta1 or simply labeled with 125I were implanted into the skin on the backs of mice. The radioactivity of the 125I-labeled TGF-beta1 in the collagen sponges decreased with time; the amount of TGF-beta1 remaining dependent on the cross-linking time. The in vivo retention of TGF-beta1 was longer in those sponges that had been subjected to longer cross-linking times. The in vivo release profile of the TGF-beta1 was matched with the degradation profile of the sponges. Scanning electron microscopic observation revealed no difference in structure among sponges subjected to different cross-linking times. The TGF-beta1 immobilized in the sponges was probably released in vivo as a result of sponge biodegradation because TGF-beta1 release did not occur in in vitro conditions in which sponges did not degrade. We applied collagen sponges incorporating 0.1 microg of TGF-beta1 to skull defects in rabbits in stress-unloaded bone situations. Six weeks later, the skull defects were covered by newly formed bone, in marked contrast to the results obtained with a TGF-beta1 free empty collagen sponge and 0.1 microg of free TGF-beta1. We concluded that the collagen sponges were able to release biologically active TGF-beta1 and were a promising material for bone repair.

Influence of dehydrothermal crosslinking on the growth of PC-12 cells cultured on laminin coated collagen.

Recently, we have demonstrated canine peroneal nerve regeneration with functional recovery across an 80 mm gap using a polyglycolic acid (PGA) -collagen tube filled with laminin coated collagen fibers. In that study, the laminin coating was applied before a dehydrothermal (DHT) treatment designed to extend preservation of laminin in situ. To address concerns that the biological activity of laminin might consequently be reduced, the present investigation examined the influences of DHT crosslinking on the activity of laminin in terms of neural cell growth in vitro. DHT crosslinking was performed on collagen (type I or IV) spread on glass in three groups: (1) before coating, (2) after coating, and (3) both before and after coating. PC-12 cells were disseminated in each of the three groups. All three groups were cultured, and the number of cells were compared statistically. Cell growth achieved through application of laminin coating after DHT crosslinking was statistically greater than that achieved when laminin coating was performed before crosslinking. A reduction in laminin activity induced by DHT crosslinking was demonstrated. The optimal timing for the crosslinking of biornaterials treated with trophic factors such as-laminin should be examined in terms of the effects of crosslinking on the activity of the trophic factors.

New type of tracheal bioartificial organ treated with detergent: maintaining cartilage viability is necessary for successful immunosuppressant free allotransplantation.

The present investigation examined the key factors in the preparation of low-antigenic tracheal allografts by detergent treatment in dogs. In group 1 (n = 5), the grafts were treated by detergent at room temperature for 48 h and rinsed with running water until use. In group 2 (n = 4), detergent treatment was performed at 4 degrees C for 48 h, but the rinsing step was omitted. In group 3 (n = 6), the grafts were treated at 4 degrees C for 48 h, rinsed thoroughly with physiologic saline, and stored at 4 degrees C. The grafts were then used for tracheal replacement without immunosuppressant in dogs. The epithelium and mixed glands had been removed completely from the grafts in groups 1 and 2, and in five of the six grafts of group 3. In groups 1 and 2, cartilage viability appeared to have been lost and all animals died of airway stenosis within 38 days. In group 3, the chondrocytes were viable and all animals survived uneventfully. These results suggest that maintaining cartilage viability in a tracheal graft is necessary for successful immunosuppressant-free allotransplantation and, consequently, to maintain an open airway. The treatment temperature and sufficient rinsing are key factors for maintaining cartilage viability of grafts.