Clinically established hemostatic scaffold (tissue fleece) as biomatrix in tissue- and organ-engineering research

Various types of three-dimensional matrices have been used as basic scaffolds in myocardial tissue engineering. Many of those are limited by insufficient mechanical function, availability, or biocompatibility. We present a clinically established collagen scaffold for the development of bioartificial myocardial tissue. Neonatal rat cardiomyocytes were seeded into Tissue Fleece (Baxter Deutschland, Heidelberg, Germany). Histological and ultrastructural examinations were performed by DAPI and DiOC(18) staining and electron microscopy, respectively. Force measurements from the spontaneously beating construct were obtained. The constructs were stimulated with agents such as adrenalin and calcium, and by stretching. Passive stretch curves were obtained. Spontaneous contractions of solid bioartificial myocardial tissue (BMT), 20 x 15 x 2 mm, resulted. Contractions continued to week 12 (40% of BMTs) in culture. Histology revealed intercellular and also cell-fibril junctions. Elasticity was similar to that of native rat myocardium. Contractile force increased after topical administration of Ca(2+) and adrenaline. Stretch led to the highest levels of contractile force. In summary, bioartificial myocardial tissue with significant in vitro longevity, spontaneous contractility, and homogeneous cell distribution was produced using Tissue Fleece. Tissue Fleece constitutes an effective scaffold to engineer solid organ structures, which could be used for repair of congenital defects or replacement of diseased tissue.     

A multifunctional bioreactor for three-dimensional cell (co)-culture

Investigation of cell abilities to growth, proliferation and (de)-differentiation in a three-dimensional distribution is an important issue in biotechnological research. Here, we report the development of a new bioreactor for three-dimensional cell culture, which allows for co-cultivation of various cell types with different culture conditions in spatial separation. Preliminary results of neonatal rat cardiomyocyte cultivation are shown. Isolated neonatal rat cardiomyocytes were cultured in spatial separated bioreactor compartments in recirculating medium on a biodegradable fibrin matrix for 2 weeks. Glucose, lactate, and lactate dehydrogenase (LDH), pO2, pCO2, and pH levels were monitored in the recirculated medium, daily. Morphological characterization of matrix and cells was assessed by hematoxylin and eosin staining, and MF-20 co-immunostaining with 4',6-diamidino-2-phenylindole (DAPI). Cell viability was determined by LIVE/DEAD staining before cultivation and on day 3, 7, and 14. The optimized seeding density in the matrix was 2.0 x 10(7) cells retaining cellular proportions over the cell culture period. The bioreactor allows the maintenance of physiologic culture conditions with aerobic cell metabolism (low release of lactate, LDH), a high oxygen tension (pO2-183.7 +/- 18.4 mmHg) and physiological pH values (7.4 +/- 0.02) and a constant level of pCO2 (43.1 +/- 2.9) throughout the experimental course. The cell viability was sufficient after 2 weeks with 82 +/- 6.7% living cells. No significant differences were found between spatial separated bioreactor compartments. Our novel multifunctional bioreactor allows for a three-dimensional culture of cells with spatial separation of the co-cultured cell groups. In preliminary experiments, it provided favorable conditions for the three-dimensional cultivation of cardiomyocytes.     

Outcomes of Delayed Graft Function in Kidney Transplant Recipients Stratified by Histologic Biopsy Findings

Delayed graft function (DGF) after kidney transplantation is associated with an increased risk of graft failure. We studied the histologic findings among adult kidney transplant recipients transplanted between January 2000 and June 2015 who had DGF and had a kidney biopsy within 14 days of transplant. Death censored graft failure (DCGF) and death at 1 and 3 years after transplant were examined. A total of 269 transplant recipients fulfilled our selection criteria, of which 152 (56.51%) had acute tubular necrosis (ATN), 44 (16.4%) had acute rejection (AR), mainly T-cell mediated rejection (n = 31), 35 (13%) had ATN with AR (mainly T-cell mediated rejection, n = 26), and 38 (14.1%) had other pathology. Compared with those with ATN alone, kidney transplant recipients with AR alone had a significantly higher risk of DCGF at 1 year post transplant (adjusted hazard ratio = 3.70; 95% confidence interval 1.5-9.5; P = .006). Those with AR alone had an increased risk of DCGF at 3 years post transplant (hazard ratio = 3.10; 95% confidence interval 1.3-8.5; P = .01) in crude analyses. There was no association between DGF etiology and mortality. Early renal biopsy can be used to distinguish AR, which has protocolized treatments, from other etiologies. This could potentially alter allograft survival within 1 year of transplant complicated by DGF.     

Herztransplantation vs. „Destination“-Therapie

Advanced recipient age represents a contraindication in numerous transplant centers worldwide. Due to mprovements in immunosuppression and therefore also of long-term results after heart transplantation, more and more older patients are being listed for transplantation. The present paper describes the literature regarding heart transplantation in advanced age. Nevertheless, because of new allocation strategies in times of persistent donor organ shortage, heart transplantation could be restricted to younger recipients in the near future. Therefore, in the second part of the present paper the so-called destination therapy as an alternative to heart transplantation is described.     

Extrakorporale Unterstützungsverfahren bei Lungentransplantation

Zeitschrift für Herz-,Thorax- und Gefäßchirurgie - Die Lungentransplantation hat einen souveränen Stellenwert in der Therapie schwerer therapierefraktärer...