Soma Guhathakurta

Inflammatory responses of tissue-engineered xenografts in a clinical scenario.

Acellular tissue-engineered (ATE) xenografts and homografts are used in clinical cardiovascular surgery. The present study examined the specific role of carbohydrate antigen (α-Gal and T-antigen) in immune response after decellularisation in tissue-engineered xenografts (porcine pulmonary artery and bovine jugular vein). An enzyme-linked immunosorbent assay (ELISA) was used to ascertain whether implantation of bioprostheses, ATE xenografts and mechanical valve replacement result in augmentation of anti-α-Gal IgM antibodies within eight days of surgery (each group, n=6). Kinetics of host inflammatory response on surgically explanted ATE xenografts was also studied. Immunostaining for α-Gal and T-antigen detected the presence of them in the native tissue but they were absent in processed ATE xenografts from the same tissue. A significant increase in the concentration of anti-α-Gal IgM antibodies was observed in the serum of bioprosthetic valve recipients as compared to ATE xenograft recipients (P<0.05). Organised collagen, and decreased inflammatory response with increase in endothelisation and vascularisation was evident beyond one year of surgery as compared to early periods in ATE xenografts. This study demonstrates that decellularisation of xenografts and further processing of these tissues enabled reduction of inflammatory stimulus with autologous recellularisation with no calcification.

Stem Cell Experiments and Initial Clinical Trial of Cellular Cardiomyoplasty

Growing myocardial cells from human stem cells and stem cell transplantation to repair injured myocardium are new frontiers in cardiovascular research. The 1st stage of this study was conducted to determine whether transplantation of autologous bone marrow stem cells into infarcted myocardium of sheep could differentiate into beating cardiomyocytes. The 2nd stage was to demonstrate transdifferentiation of human bone marrow mesenchymal stem cells to precursor cardiomyocytes in vitro, using a novel conditioning medium. In the 3rd stage, a clinical trial of stem cell implantation in patients with severe myocardial dysfunction involved injection of peripheral blood-derived endothelial precursor cells in 11 patients and autologous bone marrow mononuclear cells in 29. A marginal improvement in myocardial function was noted at 3 months (mean increase in ejection fraction, 6% ±1%), although it plateaued at 6 months. The trial proved to be safe because there was no procedure-related mortality. There is growing optimism that stem cell therapy may delay heart transplantation.

Triple Valve Replacement with Carpentier-Edwards Bioprostheses

We report a unique case of triple valve replacement with porcine bioprostheses in a young woman who remained asymptomatic 15 years later. Although in atrial fibrillation, she was taking only aspirin for anticoagulation until she delivered a normal child 2 years after surgery. Surprisingly, to date, her echocardiographic findings have remained the same as those after childbirth, and all the bioprostheses were functioning well, except for tricuspid annular calcification producing mild to moderate regurgitation.

A Simple and Safe Technique of Exposing Coronary Arteries

A gauze sling technique using two long thick gauze strips to rotate the heart on its longitudinal axis is described. This gives excellent exposure to the inferior and posterolateral wall of the heart. Any coronary system can be exposed easily by manoeuvring the free ends of the tapes for anchorage without requiring an assistant to hold the heart.