Intraventricular placement of a spring expander does not attenuate cardiac atrophy of the healthy heart induced by unloading via heterotopic heart transplantation.

An important complication of the prolonged left ventricle assist device support in patients with heart failure is unloading-induced cardiac atrophy which proved resistant to various treatments. Heterotopic heart transplantation (HTx) is the usual experimental model to study this process. We showed previously that implantation of the newly designed intraventricular spring expander can attenuate the atrophy when examined after HTx in the failing heart (derived from animals with established heart failure). The present study aimed to examine if enhanced isovolumic loading achieved by implantation of the expander would attenuate cardiac post-HTx atrophy also in the healthy heart. Cardiac atrophy was assessed as the ratio of the transplanted-to-native heart weight (HW) and its degree was determined on days 7, 14, 21 and 28 after HTx. The transplantation resulted in 32±3, 46±2, 48±3 and 46±3 % HW loss when measured at the four time points; implantation of the expander had no significant effect on these decreases. We conclude that enhanced isovolumic loading achieved by intraventricular implantation of the expander does not attenuate the development of cardiac atrophy after HTx in the healthy heart. This indicates that such an approach does not represent a useful therapeutic measure to attenuate the development of unloading-induced cardiac atrophy.

Islets transplanted in immunoisolation devices: a review of the progress and the challenges that remain.

The concept of using an immunoisolation device to facilitate the transplantation of islets without the need for immunosuppression has been around for more than 50 yr. Significant progress has been made in developing suitable materials that satisfy the need for biocompatibility, durability, and permselectivity. However, the search is ongoing for a device that allows sufficient oxygen transfer while maintaining a barrier to immune cells and preventing rejection of the transplanted tissue. Separating the islets from the rich blood supply in the native pancreas takes its toll. The immunoisolated islets commonly suffer from hypoxia and necrosis, which in turn triggers a host immune response. Efforts have been made to improve the supply of nutrients by using proangiogenic factors to augment the development of a vascular supply in the transplant site, by using small islet cell aggregates to reduce the barrier to diffusion of oxygen, or by creating scaffolds that are in close proximity to a vascular network such as the omental blood supply. Even if these efforts are successful, the shortage of donor islet tissue available for transplantation remains a major problem. To this end, a search for a renewable source of insulin-producing cells is ongoing; whether these will come from adult or embryonic stem cells or xenogeneic sources remains to be seen. Herein we will review the above issues and chart the progress made with various immunoisolation devices in small and large animal models and the small number of clinical trials carried out to date.

Modified tip grafts and tip punch devices.

BACKGROUND: Nasal tip aesthetics depend on the graceful synergism between soft tissue and the underlying frame. Nasal projection and the nasal tip width are the two most important components of nasal aesthetics. The cartilage graft, which has a predictable ability to affect several of the anatomical components contributing to nasal tip aesthetics, is one of the most versatile tools used to modify nasal projection. The fundamental shortcoming of the current graft sculpturing technique, namely, the requirement of time to create an optimal tip graft, prompted the design of a tool for the precise and rapid sculpturing of cartilage used for nasal tip onlay and shield grafts. METHODS: This report describes a modified design of the Peck and Sheen grafts and introduces a new instrument, the tip graft punch. The unique features of the tip graft punch that facilitate the production of a symmetric, precisely proportioned cartilage grafts are highlighted. RESULTS: The tip graft punch has been successfully used on 49 patients over the past 2 years. CONCLUSIONS: The authors report a modification of nasal tip grafts and a simple and useful device for harvesting these grafts. This modification produces more natural and aesthetically pleasing results. The device saves surgery time, and provides a symmetric and anatomical graft design.

Vascularized tissue-engineered chambers promote survival and function of transplanted islets and improve glycemic control.

We have developed a chamber model of islet engraftment that optimizes islet survival by rapidly restoring islet-extracellular matrix relationships and vascularization. Our aim was to assess the ability of syngeneic adult islets seeded into blood vessel-containing chambers to correct streptozotocin-induced diabetes in mice. Approximately 350 syngeneic islets suspended in Matrigel extracellular matrix were inserted into chambers based on either the splenic or groin (epigastric) vascular beds, or, in the standard approach, injected under the renal capsule. Blood glucose was monitored weekly for 7 weeks, and an intraperitoneal glucose tolerance test performed at 6 weeks in the presence of the islet grafts. Relative to untreated diabetic animals, glycemic control significantly improved in all islet transplant groups, strongly correlating with islet counts in the graft (P<0.01), and with best results in the splenic chamber group. Glycemic control deteriorated after chambers were surgically removed at week 8. Immunohistochemistry revealed islets with abundant insulin content in grafts from all groups, but with significantly more islets in splenic chamber grafts than the other treatment groups (P<0.05). It is concluded that hyperglycemia in experimental type 1 diabetes can be effectively treated by islets seeded into a vascularized chamber functioning as a "pancreatic organoid."

Resultados del tratamiento conservador de las fracturas de cotilo / Results of the conservative treatment of acetabular fractures

Objetivos. Estudiar la evolución de pacientes con fracturas de cotilo tratadas de forma conservadora. Material y método. Se recogieron de forma consecutiva 37 casos de fracturas de cotilo, tratados de forma conservadora con un seguimiento mínimo de 5 años. Las fracturas se trataron con reposo en cama y tracción seguido de un período de descarga y otro de carga parcial. Los pacientes se valoraron clínica y radiográficamente. El tipo de tratamiento fue evaluado según la tracción empleada, el tiempo de descarga y de carga parcial. Se evaluó el grado de desplazamiento y su relación con la evolución posterior. Resultados. Veinte fracturas no presentaron desplazamiento, 8 un desplazamiento entre 2-5 mm y en 9 casos fue superior a 5 mm. Al final del seguimiento 8 pacientes presentaron dolor, 15 movilidad limitada y 8 signos radiográficos de artrosis. El grado de desplazamiento se correlacionó con el resultado final. Conclusiones. El tratamiento conservador puede ser una indicación en las fracturas de cotilo cuando el estado del paciente, el tipo de fractura o la calidad de hueso no permitan una osteosíntesis (AU)

Purpose. To study the evolution of patients with acetabular fractures treated conservatively Material and methods. A series of 37 consecutive cases treated conservatively was analyzed. The minimum follow-up was 5 years. Fractures were treated with bed rest and traction, which were followed by a non weight-bearing period and a partial weight period. Patients were clinically and radiographically assessed. The different kinds of treatment were evaluated on the basis of the type of traction used, the length of the non weight-bearing period and the duration of the partial weight bearing one. The degree of displacement was also considered, in particular as it related with the patients’ subsequent evolution. Results. Twenty fractures did not undergo any sort of displacement, 8 had a displacement of 2-5 mm, with 9 cases having a displacement higher than a 5 mm. At the end of follow-up, 8 patients experienced pain, 15 limited mobility and 8 had radiographic signs of osteoarthritis. The degree of displacement was correlated with the final result obtained. Conclusions. Conservative treatment can be an appropriate indication for acetabular fractures when the patient’s condition, the type of fracture or bone quality advise against performing an osteosynthetic procedure (AU)

A novel small animal model of left ventricular tissue engineering.

BACKGROUND: Complex congenital cardiac anomalies involving ventricular hypoplasia require either staged palliative reconstruction, converting the circulatory system to a single ventricle based pump, or allogeneic transplantation. Tissue engineering offers the potential for complete reconstruction of these defects, but is limited by the inability to model myocardial tissue engineering in a small animal. Our goal was to develop a small animal model for ventricular tissue engineering using rat heterotopic heart transplantation. METHODS: Donor hearts were explanted after cardioplegic arrest and the left ventricular volume was augmented by the implantation of a biodegradable engineered construct. The heart was then transplanted heterotopically into syngeneic recipients creating either a volume loaded, functioning left ventricle, or a non-functioning left ventricle. Some of the engineered constructs were seeded with multipotent bone marrow-derived mesenchymal progenitor cells before implantation. Animals were evaluated by echocardiography, morphology, histology, and immunohistochemistry after 1 month. RESULTS: A scaffolding constructed from polytetrafluoroethylene, polylactide mesh, and type I and IV collagen hydrogel resulted in minimal intracardiac inflammation without aneurysmal dilatation. Successful transplantation and differentiation of mesenchymal progenitor cells was accomplished using this scaffolding. No ventricular arrhythmias resulted from this surgical manipulation and echocardiography revealed both end systolic and diastolic volume augmentation with ventricular expansion. CONCLUSION: We have developed an in vivo model of ventricular tissue engineering using heterotopic heart transplantation. Future work will focus on construction of ventricular tissue around pre-fabricated vascular networks in order increase cellular engraftment for ventricular reconstruction.