Shin-ichi Itoi

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.

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.

Regeneration of Central Nervous Tissue Using a Collagen Scaffold and Adipose-Derived Stromal Cells

Adipose-derived stromal cells (ASCs) include stem cells, which have the potential to differentiate into a variety of cell lineages. The regeneration of central nerves was examined using ASCs and a collagen scaffold. A cerebral cortex defect (3 × 4 × 3 mm3) was created in the left frontal lobe of 16 male rats. In one group (n = 8), collagen (3 × 4 × 3 mm3) seeded with DiI-labeled ASCs was implanted in the defect. In order to seed the ASCs, a combination of the rotary cell culture system and pressing the collagen scaffold gently several times with a glass rod was applied. In the control group (n = 8), collagen was implanted without ASCs. The rats were sacrificed at 1 month after the scaffold implantation. Histologically, 0.2% of the implanted ASCs were positive for anti-human/rat microtubule-associated protein 2 (MAP2) antibody and microvessels were present at a density of 4.6 ± 1.2/mm2 within the collagen scaffold-implanted area in each coronal section. In the control group, no MAP2-positive cells were detected and the microvessel density was 0.6 ± 0.4/mm2. These data suggest that ASCs seeded into a collagen scaffold may have the potential to promote regeneration of nervous tissue after cerebral cortex injury.

Histologic and electrophysiological study of nerve regeneration using a polyglycolic acid-collagen nerve conduit filled with collagen sponge in canine model.

OBJECTIVES To determine the rate of achieving electrophysiologically proved functional recovery by autonomic nerve regeneration, with the aid of an artificial nerve conduit. METHODS A polyglycolic acid (PGA) collagen nerve conduit filled with collagen sponge was interposed in a 10-mm-long gap of the right hypogastric nerve (HGN) in 16 dogs. Histologic evaluation of nerve regeneration and electrophysiological analysis at 2 weeks and 2, 3, 4, 5, 6, 7, and 8 months (n = 2, each) after surgery was performed, measuring the responses for the spermatic ducts (SD), bladder neck (BN), and prostate contraction, by stimulating the right lumbar splanchnic nerves (LSNs) from L2 to L4, after transection of the left HGN to eliminate substitutive pathways. RESULTS Two months after implantation, the regenerated neurofilaments were successfully extended through the graft from the proximal-to-distal direction. In 2 control dogs, electrostimulation of the right LSNs induced elevation of the intraluminal pressure of the SD, elevation of the BN pressure, and prostate contraction. No responses were observed in all dogs up to 6 months of follow-up after implantation. In 1 dog with a 7-month follow-up, electrostimulation elicited elevation of BN pressure alone. In both dogs with an 8-month follow-up, electrostimulation induced similar responses to control in all SD, BN, and prostate; however, after excision of the area of the interposed right HGN, no response was observed. CONCLUSIONS These results proved that regeneration of a 10-mm gap of the HGN, using a novel PGA-collagen nerve conduit could be achieved within 8 months.

Ventilatory support with a cuirass respirator after resection of bullous emphysema. Report of a Case.

cysts. The establishment of a cavernostomy track followed by thoracoscopic removal of the cyst remnants provides a suitable alternative to thoracotomy, especially when the space is infected. Thoracoscopic removal of live or uncomplicated hydatid cysts does not afford the advantage of capitonage for control of bronchial air leaks and may lead to spillage and pleural recurrence, 5 although we have not seen this, and so this procedure was not attempted for the cyst on the left side. It is anticipated that as expertise with and instrumentation for video-assisted thoracoscopic surgery continue to improve, such management may be preferred for live hydatid cysts as well. R E F E R E N C E S 1. Le Roux BT. Pulmonary hydatid disease. Thorax 1972;27(3): 365-367. 2. Aytac A, Yurdakul Y, Ikizler C, et al. Pulmonary hydatid disease: report of 100 cases. Ann Thorac Surg 1977;23:145-51. 3. Dogan R, Yuksel M, Cetin G, et al. Surgical treatment of hydatid cysts of the lung: report on 1055 patients. Thorax 1989;44:192-9. 4. Aggarwal P, Wali JP. Albendazole in the treatment of pulmonary echinococcosis. Thorax 1991;46:599-600. 5. Barrett NR, Thomas D. Pulmonary hydatid disease. Br J Surg 1952;40:222-44.

Right ventricular infarction during a lung lobectomy in a patient with chronic obstructive pulmonary disease: report of a case.

A 63-year-old man with a low forced expiratory volume in 1 s underwent a wedge resection for peripheral lung cancer; however, it relapsed in the residual lobe. We decided that a lobectomy was feasible after further examinations focusing on gas exchange. During the lobectomy right ventricle myocardial infarction occurred, possibly due to coronary spasm, and it was successfully treated with intra-aortic balloon pumping. The patient has been doing well without relapse for 7 years. Our findings indicate that some patients with low spirometry data may therefore be candidates for a lobectomy.

Contents Vol. 190, 2009

F. Beck, Leicester A.L. Boskey, New York, N.Y. R.C. Burghardt, College Station, Tex. G. Burnstock, London F. Eckstein, Salzburg A.C. Enders, Davis, Calif. C. Farnum, Ithaca, N.Y. R.H.W. Funk, Dresden N.E. Fusenig, Heidelberg A. Gibson, Phoenix, Ariz. M. Glickstein, London J.W. Hermanson, Ithaca, N.Y. C.J. Kirkpatrick, Mainz P. Köpf-Maier, Berlin W. Kummer, Giessen J.W. Lichtman, Cambridge, Mass. K.G. Marra, Pittsburgh, Pa. O. Ohtani, Toyama P.J. Reier, Gainesville, Fla. R. Roy, Los Angeles, Calif. R. Segal, Chapel Hill, N.C. F. Sinowatz, Munich M. Sittinger, Berlin T. Skutella, Tübingen G.B. Stark, Freiburg i.Br. E. Th ompson, Melbourne C.G. Widmer, Gainesville, Fla. in vivo, in vitro